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Neurophysiological Monitoring during Surgery on the Central Nervous System: The Role of Evoked Responses
Soghomonyan S1*, Sandhu GS1, Stoicea N1, Kurnutala LN2, Cotterman-Hart S3,4, Christofi FL1, Bergese SD1,3
1 Department of Anesthesiology, Wexner Medical Center, Ohio State University, Columbus, OH, USA.
2 Department of Anesthesiology, University of Mississippi Medical Center, Jackson, Mississippi, USA.
3 Department of Neurological Surgery, Wexner Medical Center, Ohio State University, Columbus, OH, USA.
4 Department of Neurology, Wexner Medical Center, Ohio State University, Columbus, OH, USA.
*Corresponding Author
Suren Soghomonyan MD, Ph. D.,
Department of Anesthesiology,
Wexner Medical Center, The Ohio State University,
Doan Hall N411, 410 W 10th Avenue, Columbus, OH 43210,USA.
Tel: (614) 366-4805
Fax: (614)-366-1943
E-mail: email@example.com
Article Type: Review Article
Received: June 11, 2015; Accepted: July 06, 2015; Published: July 13, 2015
Citation: Soghomonyan S et al., (2015) Neurophysiological Monitoring during Surgery on the Central Nervous System: The Role of Evoked Responses. Int J Anesth Res. 3(6), 119-129. doi: dx.doi.org/10.19070/2332-2780-1500031
Copyright: Soghomonyan S© 2015. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited.
Neurosurgical, orthopedic and vascular interventions may be associated with an inherent risk of ischemia and structural damage to the central nervous system. Along with other modalities used to monitor the intraoperative nervous function, registration of evoked responses is intended to provide real-time feedback about the functional integrity of the central nervous system and help to prevent avoidable trauma during surgery. In this review, the principal indications and limitations of monitoring various evoked responses during surgery on the brain and spinal cord are discussed. Current approaches, recent advances and problems associated with intraoperative rhomboid fossa mapping, cranial nerve stimulation and electrooculographic monitoring are presented as well. The authors discuss the effects of general anesthesia on evoked responses and possible ways to avoid signal variability during registration. It is emphasized that only with close cooperation between neurosurgeons, anesthesiologists and neurophysiologists it will be possible to maximize the benefits of intraoperative monitoring of evoked responses and avoid misinterpretation of the results.
4.The Basics
5.Effects of anesthesia on EP
6.Monitoring during spinal surgery
7.EP monitoring during surgery on the brain
7.2 Olfactory EP (CN I)
7.3 Rhomboid fossa mapping and CN monitoring
7.4 Monitoring CN VII
7.5 Monitoring CN V
7.6 Monitoring CN VIII
7.7 Monitoring CN III, IV and VI
8.SSEP and MEP monitoring during brain surgery
Neurophysiological Monitoring; Evoked Potentials; Electrooculography; Rhomboid Fossa Mapping; Cranial Nerve Stimulation.
AEP: Auditory evoked potential(s); AVM: Arterio-venous malformation; BAEP: Brainstem acoustic evoked potential(s); CBF: Cerebral blood flow; CMAP: Compound muscle action potential(s); CN : Cranial nerve(s); CNAP: Compound nerve action potential(s); CNS: Central Nervous System; CPA: Cerebellopontine angle; EEG: Electroencephalography; EMG: Electromyography; EOG: Electrooculography; EP: Evoked Potentials; HFS: Hemifacial spasm; ICP: Intracranial pressure; INM: Intraoperative neuromonitoring; IPL: Interpeak latency; MAC: Minimal alveolar concentration; MEP: Motor evoked potential(s); MLAEP: Mid-latency auditory evoked potential(s); MR: magnetic resonance; MVD: Microvascular decompression; SEP: Sensory evoked potential(s); SHA: Superior hypophyseal artery; SSEP: Somatosensory evoked potential(s); TcMEP: Transcranial motor evoked potential(s); VEP: Visual evoked potential(s); TES: Transcranial electrical stimulation; TMS : Transcranial magnetic stimulation.
Real-time intraoperative assessment of central nervous structures, intends to decrease the perioperative morbidity and improve the outcome.
Several approaches have been used to monitor the intraoperative neurological function including patient awakening, and awake craniotomy under local anesthesia [[1-5]. However, general anesthesia is required in majority of cases necessitating application of neuromonitoring. The intraoperative electroencephalography (EEG) is discussed elsewhere [6-9]. The current review focuses on intraoperative monitoring of evoked responses during interventions on the central nervous system (CNS).
The Basics
Depending on proximity of the recording electrode to the signal generator, evoked potentials (EP) are categorized into near and far field potentials [10,11].
EP are characterized by amplitude, polarity, absolute and interpeak latencies (IPL), and central conduction time (applicable to somatosensory EP (SSEP) [12-14].
Sensory EP (SEP) are generated by stimulation of sensory receptors, nerves or tracts, while motor evoked responses - by transcranial electrical, magnetic or direct stimulation of the motor cortex, corticospinal tracts, brainstem, cranial nerves (CN), nerve roots or spinal cord.
EP may occasionally be associated with false-positive or falsenegative results [9,15-17]. Clinical judgment and understanding the limitations of neuromonitoring modalities are required for correct interpretation of intraoperative EP changes. The optimal warning signal threshold level should be defined as choosing increasingly stringent warning criteria trades specificity for sensitivity.
The EP peak amplitudes are significantly smaller compared to EEG and require multiple stimulations, frequency filtering and signal averaging to be extracted from the underlying noise [12,13]. Commonly, relative rather than absolute signal amplitude changes are used to assess intraoperative EP dynamics [13,,19,20]. A latency increase (>10%) or a decrease in peak amplitude below a conventional threshold level (usually < 50%) are considered as significant and alert for potential risk of ischemia or structural damage [13,,19,21]. However, these criteria are not based on empirical evidence, and are disputed by others.
Factors affecting intraoperative EP include ambient electrical noise, electrode type, impedance, placement site, their movement and dislodgement, equipment malfunction, pre existing neurological pathology, anesthesia, drugs, hypothermia, arterial hypotension, development of pneumocephalus, etc., [10,15,16,21].
SSEP are used to monitor the integrity of ascending somatosensory pathways. The intensity, frequency and duration of stimulation depend on the nerve stimulated [12]. The evoked response is then measured along the somatosensory ascending pathway at Erb's point (brachial plexus), C2-C7 vertebrae, or from the scalp over the primary somatosensory cortex [13]. A variation of this technique is the spinal cord-to-scalp stimulation [23].
SSEP are insensitive to motor impairment [15]. However, isolated motor pathway ischemia and trauma rarely happen, and SSEP are being effectively used to monitor spinal function during surgery. Importantly, the lower extremity SSEP propagation includes additional components passing via spinocerebellar pathways, which may explain the method's sensitivity to ischemia beyond the somatosensory zone [as cited in 11].
Median Nerve SSEP is not diagnostic for interventions below C8 [13], and tibial or peroneal nerve SSEP are used in such cases. Unlike upper extremity SSEP, stimulation of the posterior tibial nerve evokes a bilateral EP, probably due to the position of the somatosensory cortex in the longitudinal fissure [24].
Motor evoked potentials (MEP) are used to monitor the descending motor pathways (Figure 1 and 2). Two commonly used methods of MEP registration are transcranial electrical motor evoked potentials (TcMEP) and transcranial magnetic stimulation (TMS). The latter method is mostly used for preoperative topographic assessment. Direct cortical stimulation may be applied during surgery within highly eloquent cortical regions [3] or during surgery on the brainstem and CN.
MEP is recorded at the spinal level (D- and I- waves) or from periphery - compound muscle action potential (CMAP) [13]. Smaller muscles of the hand or foot are recommended as sites for electromyography (EMG) and CMAP recording due to richer innervation. However, modern day multichannel recordings have the potential of detecting root-level injuries rather than just gross insults to the spinal cord. The MEP amplitude changes are more sensitive and specific than latencies [25].
Acoustic evoke potentials (AEP) are produced by applying click sound stimulation to the ears with subsequent recording of EP from vertex/mastoidal electrodes. A background "white" noise is applied to the contralateral ear to mask conductive noise stimulation. More commonly in the operating room, earphones with foam inserts are used to block external noise as well as minimize the crosstalk to the contralateral ear. Traditional AEP require a relatively long averaging period of approximately 90 seconds for each ear [9,,26]. Stable acoustic brainstem responses strongly correlate with preserved postoperative hearing, while their loss may not reliably predict the hearing outcome.
Brainstem auditory evoked potentials (BAEP) are commonly used to monitor the auditory pathways and brainstem integrity during surgery [10]. Most commonly, a 50% decrease in BAEP peak amplitudes and 0.5–1.0 msec increase in latencies on 2-3 consecutive trials are used as warning criteria during monitoring.
Electrocochleography (ECoG) and CN VIII compound nerve action potentials (CNAP) are used to monitor the acoustic nerve function during surgery. Their signals are significantly stronger compared to BAEP, and less averaging is required [13,,26].
Mid-latency auditory evoked potentials (MLAEP) are not applicable for intraoperative monitoring of auditory nerves because of high sensitivity to anesthetics. However, they may be used to measure the depth of anesthesia [11,27,28].
Visual evoked potentials(VEP) are monitored during procedures when visual pathways are at risk. However, this modality is not commonly used because of notorious variability under anesthesia. Intraoperatively, VEP are recorded from the vertex and occipital electrodes after a flash light stimulation to retina. The P100 component of VEP is associated with visual cortical activity. However, no exact neural generators can be linked to P100 because of polysynaptic nature of signal propagation.
Effects of anesthesia on EP
Sensitivity of EP to anesthesia depends on the modality and pharmacological characteristics of anesthetic drugs. VEP are especially sensitive to general anesthesia due to the polysynaptic nature of signal transmission. SSEP are less sensitive, while the BEAP are relatively resistant to commonly used anesthetic doses.
A more detailed discussion of the interaction between general anesthesia and EP is out of the scope of this article and can be found elsewhere [10,29,30,31].
EP suppression induced by inhalational anesthetics is more pronounced compared to intravenous drugs [10,13]. Nevertheless, low doses of inhalational agents (0.5 MAC for TcMEP and up to 0.8 MAC for SSEP) can be effectively used during surgery combined with low-dose infusions of remifentanil (0.05 mcg/ kg/min), propofol (50 mcg/kg/min), and/or dexmedetomidine (0.2-0.3 mcg/kg/h) [30,,33]. Their use will stabilize the anesthesia and reduce the risk of patient movements during critical stages of surgery.
Kempton and colleagues (2010) applied balanced anesthesia with isoflurane, N2O (in 94%), propofol (in 4.5%) and vecuronium for partial muscle relaxation in 247 patients undergoing scoliosis correction [34]. In 91%, the investigators recorded monitorable responses with anesthetic MAC levels > 0.5, while TcMEP could be recorded in 39% with MAC > 1.0.
Sevoflurane, owing to its solubility profile and fast elimination, is the induction agent of choice in young children, when EP monitoring is planned [35].
Most intravenous hypnotics suppress the EP in a dose-dependent way, while etomidate and ketamine increase SSEP amplitudes [10]. Opioid-induced EP suppression is proportional to lipophilicity and dose of the drug. In commonly used doses, opioids have minimal effects on EP and can be safely used during monitoring. High doses of remifentanil cause a 20%-80% decrease in P37 peak amplitude of SSEP with < 10% latency increase [36].
Benzodiazepines produce mild to moderate EP inhibition [10], which is less pronounced compared to inhalational agents. Administration of remifentanil and midazolam reduces the anesthetic requirements and increases the efficacy of EP registration [37]. Dexmedetomidine has been proposed as a useful adjunct to total intravenous anesthesia (TIVA) during monitoring [38]. It reduces the propofol requirements without affecting the anesthesia quality. The drug can be effectively combined with ketamine and fentanyl during intraoperative neuromonitoring (INM) [39].
Lidocaine (1.5 mg/kg/h) is an effective adjunct to general anesthesia during EP monitoring as it reduces anesthetic requirements and the incidence of patient movements in response to surgical stimulation [40].
MEP are more sensitive to inhalational anesthetics and relaxants, and therefore, anesthetic conditions optimized for TcMEP will usually produce acceptable SSEP [29,41,42]. Partial muscle relaxation can be used during MEP monitoring, which may even improve the signal quality, however, most of neurophysiologists refrain from using relaxants after tracheal intubation [13,43,44].
Direct cortical stimulation as well as increasing stimulation intensity and frequency can help to overcome some of the volatile anesthetic-induced MEP depression [29].
Another factor influencing the quality of EP monitoring is anesthesia stability. Bolus drug injections and changes in inhalational anesthetic dose may result in long-lasting EP suppression and should be avoided [29,38,41,44,45]. Besides choosing the right drug combination, it is important to keep the anesthesia depth and drug administration rate stable. When properly conducted,both inhalation and intravenous anesthesia generally yield anesthetic conditions appropriate for INM [41].
Intraoperative EP signal tends to degrade over time independent of anesthetic dose [46. Signal fade is proportional to the anesthesia length and is more pronounced in young children and myelopathic patients [37,46]. Differentiation between anesthesia-related signal fading and event-related EP degradation may be problematic.
Physiologic parameters should be maintained stable throughout surgery to exclude any interference with INM.
Monitoring during spinal surgery
Spinal surgery carries the inherent risk of tissue damage with development of postoperative neurological deficit. INM during spinal interventions intends to reduce such risk by providing a real-time feedback to the surgeon [47]. Based on INM, modifications in anesthesia and surgery are made to avoid irreversible tissue damage [48].
Since their introduction, SSEP have become the most commonly used monitoring method in spinal surgery [12,47]. Their main advantage over MEP is continuous registration throughout the anesthesia and surgery (Figure 3). SSEP do not preclude intraoperative use of muscle relaxants, which makes anesthesia management easier. Limitations of the method include sensitivity to anesthesia, hemodynamic changes and hypothermia [10,49,50].
The optimal stimulation intensity to induce SSEP is one that evokes a visible muscle twitch or a muscle twitch plus sensory threshold. It is determined by evoking a maximal amplitude nerve action potential recorded at Erb's point – Fpz (median nerve) or popliteal fossa – medial condyle of tibia (tibial nerve) [51].
In young children, myelination is incomplete which may affect the EP [8,12]. Neurodevelopmental disorders in children may present with higher EP thresholds, possibly, due to neuronal atrophy and altered synaptogenesis [52,53]. Thus, neuromonitoring in pediatric patients requires experience of EP interpretation in this patient population.
Resection of the intramedullary spinal tumors is a high-risk procedure, and the most commonly used approach to such tumors is via dorsal median raphae. While electrical stimulation with subsequent recording of peripheral nerve or muscle responses is the standard approach, a newer technique with bipolar stimulation with subsequent SSEP recording has been suggested to identify the safe entry zone while approaching the tumor [54]. The safe incision zone is identified by characteristic phase-reversal of the EP. SSEP during upper cervical spine surgery may also detect brainstem ischemia caused by surgery [55].
SSEP and MEP have also been successfully used during syringomyelia surgery [56].
As a single monitoring modality, SSEP has a comparatively low sensitivity, and significant motor deficit may develop with preserved signal. On the other hand, intraoperative SSEP alerts may not be related with new neurological deficit in the postoperative period [57].
Combination of SSEP with MEP significantly improves the efficacy of monitoring [58]. Other fields of SSEP application include orthopedic, vascular surgery and procedures on peripheral nerves [59-64].
Spinal cord to scalp stimulation is an alternative although less commonly used method of SSEP monitoring [23].
A critical limitation of SSEP is the temporal summation, occasionally, requiring time intervals sufficient for permanent neurological damage [47]. Another inherent limitation is the low sensitivity in revealing isolated motor pathway injury [65]. Most of the studies reporting false-negative results with SSEP monitoring described insensibility of SSEP in cases of anterior spinal artery syndrome selectively affecting the antero-lateral column of spinal cord [23]. Any electrophysiological test will provide information only on specific neural structures and pathways propagating the signal, and there will always be clinical situations when local isolated damage to a region adjacent but functionally unrelated to the monitored pathway will remain unrecognized. Naturally, neither SSEP nor TcMEP are very good for predicting clinical deterioration in the opposite test's neurological counterpart [66].
MEP require more restrictive anesthesia requirements, may cause patient movements and have less clearly defined criteria for raising the alarm [48]. Nevertheless, MEP became a significant step towards safer and less traumatic surgery.
Merton and Morton (1980) were the first to describe transcranial electrical stimulation in humans [67,23,47]. Later on, application of high-frequency multi-pulse electrical stimulation with relatively low voltages improved the reproducibility of the method and, along with improvements in anesthesia protocols, led to widespread use of MEP during spinal surgery [47].
MEP can be evoked via transcranial or direct cortical stimulation. However, the noninvasive transcranial stimulation is the preferred method [15].
Numerous methods to monitor the motor pathways have been suggested: spinal cord to spinal cord technique, neurogenic and myogenic MEP, triggered and free-running EMG, recording the D- and I-waves and CMAP, which all have their indications, advantages and limitations [8,20,23,47]. Among them, the most commonly used methods are D-wave registration using epidural or spinal electrodes and CMAP recorded from the muscles of interest. These methods can be applied separately or in combination with free-running EMG.
D-waves reflect direct activation of the corticospinal pathways and are used mainly during surgery on proximal (above T10) spinal cord [68,47,15,23,69]. A 20–50% decrease in D-wave amplitude or a 10% increase in latency is indicative of possible postoperative neurological deterioration [47,70-72].
EMG recording of transcranial MEP (CMAP) allows for assessment of the entire motor pathway including the peripheral nerve. [47] During monitoring, muscle relaxants generally should be avoided and anesthesia levels kept stable, although some centers prefer partial muscle relaxation during surgery.
For TcMEP monitoring, muscle relaxants are used for intubation only, and if they still are to be used, a target T2/Tbaseline of 0.5 is recommended [43,73].
Muramoto et al. (2012) suggest using absolute and relative (to baseline) cutoff CMAP amplitudes (12%, 1.9μV and 25%, 3.6μV, respectively) as indicators of neurological deterioration [18]. Threshold stimulation level (increase of threshold stimulus > 100 V) can be used as a criterion to detect intraoperative neurological deterioration [66] as cited in [72].
CMAP is more sensitive to ischemia than D-wave and SSEP, however, the D-wave amplitude correlates better with long-term motor outcome.[as cited in [9] A critical weakness of CMAP is the intermittent character of monitoring [47].
Adverse effects of TcMEP include cardio-vascular reactions, metabolic acidosis, tongue laceration, patient movements, and seizures [53]. TcMEP synchronization with ECG may help to avoid arrhythmias [63]. The possibility of false positive TcMEP should also be considered [74].
Triggered EMG is used to detect medial pedicle breach by a vertebral screw and is used in minimally invasive spinal surgery [15,47,72].
The main advantage of free-running EMG over the other methods of motor pathway monitoring is continuous data acquisition [47]. The method is not specific and it is sensitive to changes in anesthesia and temperature, pre existing neurological deficit, electrical artifacts, and electrode positioning [8]. EMG combined with intermittent TcMEP has been suggested as a better way to monitor the motor pathways [75].
H-reflexes and F-waves strongly depend on anesthesia level and are not currently considered part of a standard clinical practice [72].
EP monitoring during surgery on the brain
The reported incidence of postoperative visual deterioration reaches 10% and varies from 3% to 38% among patients undergoing surgery for ophthalmic aneurysms, epilepsy and tumor resection in the vicinity of the optic tracts, chiasm and pituitary area [76,77]. Postoperative visual loss has been described even after spinal surgery [58,78,79]. VEP monitoring is indicated during surgery in vicinity of the visual pathways and during neurovascular procedures [10,77,80]. After initial enthusiasm, intraoperative VEP recording failed to show consistency with no clear development over decades of standard protocols for this monitoring technique.[as cited in [81]]
Many literature reports show lack of correlation between the VEP and postoperative visual outcome attributable to pre existing visual dysfunction, technical difficulties as well as changes in anesthesia and physiological parameters [10,11,76,82,83].
The reproducibility of VEP during transsphenoidal surgery is 89.6%, which is much lower than that for SSEP or BAEP [82].
Other reports indicate on usefulness of intraoperative VEP [9,76,80,83,87]. Goto et al. (2007) reported of a patient with paraclinoid aneurysm where the superior hypophyseal artery (SHA) originated from the aneurysmal body [88]. During surgery, the VEP reversibly disappeared every time after attempts of SHA temporary clipping. Surgery was modified, and a permanent clip was placed on the aneurysm body sparing the SHA. The patient had no visual disturbance postoperatively.
Application of specially designed goggles and discs for stimulation, co-registration of electroretinogram, use of TIVA and other modifications help to overcome the technical obstacles and improve the diagnostic value of VEP [80,83]. Unfortunately, impaired preoperative vision is a major predictor of postoperative deterioration, and a strong dependence of VEP on intact vision constitutes a significant limitation [89].
Several authors used invasive methods of intraoperative visual evoked response registration with encouraging results [75,84]- [87,90-92].
Despite the controversies and conflicting results, recent advances in technology and anesthesia technique enhance the enthusiasm towards VEP and justify further research in this field.
Anterior cranial fossa surgery is related to an increased risk of loss of the olfactory function [77,93,94].
Anosmia may have a significant impact on quality of life, as depression and decrease in overall satisfaction with life have been associated with this complication [77]. Sato et al. (1996) proved experimentally and clinically the feasibility of intraoperative registration of stable and reproducible olfactory EP [94].
The method is not currently used in clinical practice, and requires further research.
Rhomboid fossa surgery requires high precision and carries the risk of serious trauma to vital structures [8,95-98]. The brainstem contains vital centers, nuclei and pathways concentrated within a small volume, making surgery in this area extremely challenging. The situation becomes even more complex with distortion of normal anatomy by the growing tumor.
SSEP and BAEP together monitor only 20% of the brainstem [as cited in [98] and, therefore, monitoring the motor function is important to increase the surgical safety and better control the extent of tumor resection.
Both mono-and bipolar and either constant-current or constantvoltage stimulation can be applied to locate the CN and their nuclei before tumor resection [95,96,99]. Stimulation intensity commonly starts at 2.0 mA and is reduced to the threshold level once the motor nucleus or CN is identified, or it can start at low levels and then progressively increased to elicit CMAP from the monitored muscle [98-100]. Stimulation of CN IX–X can evoke hypotension and bradycardia, while current intensities exceeding 2 mA may trigger cardiovascular reactions [as cited in [98,99].
For security reasons, the stimulation of any point should not exceed 5 seconds [97]. Negative stimulation results must not be interpreted as absence of CN nuclei under the probe. Instead, repetitive stimulation may be required through the tumor mass during resection in order to detect the CN nuclei [96].
Rhomboid fossa mapping monitors only the efferent pathways of the brainstem reflexes, and the patients may still develop bulbar dysfunction despite uneventful stimulation.
Monitoring the lower CN (IX-XII) during resection of low brainstem lesions is important to avoid associated atrophy of tongue muscles, dysphagia and loss of the cough reflex [11,17,95].
Evoked responses or free-running EMG can be registered using specially designed wire electrodes with 2-mm bare hook tips inserted into the soft palate or pharyngeal wall (CN IX), false vocal cords (CN X), lateral wall of intrinsic tongue muscle (CN XII), trapezius muscle, (CN XI) or, alternatively, surface electrodes attached to a laryngeal mask or endotracheal tube may be used [17], [95,96,98,99,101,104].
Spontaneous EMG recorded from the false vocal cords can be used effectively to monitor the recurrent laryngeal nerve function during anterior cervical discectomy and fusion [105].
CN VII is frequently monitored during cerebellopontine angle (CPA) and rhomboid fossa surgery [11,95,97]. To monitor the facial nerve, EMG, observation, video-monitoring, CMAP, and MEP can be used.
High frequency (>30 Hz), high-amplitude (100–200 μV) and long-lasting trains on facial EMG are related to worse postoperative facial nerve outcome [26].
An alternative or, perhaps, supplementary method to the intraoperative facial EMG registration is intraoperative direct observation or video-recording of the facial muscular activity [26].
Registration of CMAP following electrical stimulation of CN VII or the brainstem is a method of intermittent monitoring of the nerve integrity. To provide a real-time feedback to the surgeon, the evoked EMG signal triggers a sound alarm [26]. It is important to remember that CMAP registered after the intracranial stimulation will depend on stimulation intensity and allow for monitoring only the section from the stimulation site to the recording point, even though normal functioning of facial muscles requires integrity of the whole pathway [106-108]. Another limitation is the possibility of signal spread after facial nerve stimulation (Figure 4).
Intraoperative monitoring of facial MEP allows for monitoring of the whole facial motor pathway [97]. A high correlation exists between the postoperative nerve function and final-to-baseline MEP ratio [106]. Initial contralateral single-pulse stimulation is recommended before recording the MEP to exclude any signal misinterpretation caused by direct electrical extracranial spread. [100,106]
Cranial base and CPA procedures carry the risk of trigeminal nerve damage, and the incidence of de novo trigeminal symptoms following removal of cranial base meningiomas reaches 11% [109]. Consequences of intraoperative CN V damage include facial numbness, pain, decreased corneal sensitivity, disabled corneal reflexes, lacrimal dysfunction, hypersensitivity to light, cataracts, and corneal ulceration. Monitoring of CN V can be accomplished by using a free-running EMG or CMAP (masseter muscle) following intracranial stimulation. Despite the ability to identify the nerve intraoperatively, the methods' diagnostic value is questionable [110]. An alternative approach is monitoring the trigeminal SSEP [111,112].
Blink reflexes are elicited by stimulation of the supraorbital branch of CN V, which induce a motor response in orbicular muscles consisting of a short-latency ipsilateral response (R1) of about 10 msec followed by bilateral polysynaptic responses of longer latency (R2~30 msec and R3~75-90 msec) [113]. The blink reflexes are extremely sensitive to anesthesia, however, application of stimulation trains allows for monitoring the R1 response in patients under TIVA or light inhalational anesthesia [113,114].
Intraoperative monitoring of the blink reflex may become a valuable tool in neurosurgery, but the method needs validation in a larger group of patients.
BAEP are monitored during tumor removal at CPA, microvascular decompressions of CN VII and V (Figure 5), surgery on brainstem, and neurovascular interventions [5,11,97,115-117]. BAEP are the least sensitive to changes in perioperative variables and drug actions [11]. However, conductive and sensorineural deafness on the surgery side preclude intraoperative BAEP monitoring.
The mechanisms of intraoperative acoustic nerve damage and hearing impairment are multiple and include cerebellar retraction with nerve stretching, direct mechanical trauma, electrical coagulation, high-energy electrical stimulation, and ischemia due to damage or vasospasm of the internal auditory artery [11,26].
There are numerous studies showing improving hearing outcome with BAEP monitoring during acoustic neuroma surgery [as cited in [9, 11, 118].
BAEP changes are assessed by comparing with the baseline recordings [16,116]. Jahangiri et al. (2012) used the following criteria as warning signs during brainstem surgery: complete obliteration of peaks III and/or V and increase in peak V latency > 1 msec [95]. Others recommend a 50% decrease of peak amplitudes and >0.5 msec increase in wave V latency or even 20% changes in amplitudes and 0.1 msec delay in latency [16,116].
IPL are less susceptible to host-related variables like age, gender and stimulation intensity when compared with peak V absolute latency [116]. However, the majority of these parameters are, at best, warning signs that alert the surgeon; among them only maintenance of peaks I and V has been consistently shown to correlate with better postoperative hearing preservation rates, although others have found poor correlation between postoperative hearing and BAEP [26].
False-positive and false-negative results of BAEP monitoring are explained by anesthesia, hypothermia, ear problems, as well as surgical manipulations not involving the auditory pathways and nuclei [16,26,115,119,118].
In contrast to BAEP, intraoperative ECoG and acoustic nerve CNAP record near-field potentials directly from the nerve, which ensures higher quality of signal and significant decrease in acquisition time [26]. While ECoG record the cochlear potential via transtympanic electrode, the CNAP are monitored directly from the acoustic nerve. In both cases, standard click stimulation is applied to generate the electrical potential.
Thus, BAEP, ECoG and CNAP are valuable modalities which can help to preserve postoperative hearing and prevent irreversible damage to brainstem structures.
The oculomotor, trochlear and abducens nerves are predominantly motor nerves with a few proprioceptive afferents terminating in the mesencephalic nucleus of CN V [120]. Intraoperative damage to these nerves will cause diplopia and seriously affect the lifestyle[120]. Both free-running EMG and CMAP after intracranial stimulation are used to monitor the oculomotor function and find a safe entry zone to the tegmental lesions [98, 121].
Electrooculography (EOG) is based on registration of the corneo- retinal electrical potential projected on the tissues surrounding the eye [120, 122, 123]. Eye movements cause orientation changes of the corneo-retinal potential thus allowing for monitoring spontaneous eye movements during surgery. In contrast to EMG, the method is noninvasive, and surface plate electrodes can be used to record the vertical and horizontal eye movements on separate channels. High amplitude (> 300 mcV) waves and trains of waves correlate with intraoperative tissue damage in the midbrain region, while small amplitude waves (50-150 mcV) and trains indicate possible trauma to the ponto-medullary area. EOG is not diagnostic for CPA pathology due to artifacts induced by irritation of the facial nerve [120].
A limitation of EOG is susceptibility to artifacts generated by electrical coagulation and stimulation.
SSEP and MEP monitoring during brain surgery
SSEP are sensitive to changes in cerebral blood flow (CBF), although signal changes appear more slowly compared with EEG. [6, 9, 118]. In contrast to SSEP, EEG does not require averaging, covers larger cortical areas and is more sensitive to ischemia. However, SSEP is more specific and can detect ischemia in deeper structures including the brainstem. Unilateral SSEP changes on the side of surgery allow for differentiating between local ischemia caused by arterial clamping and global CBF derangement [124]. Combination of SSEP with MEP reduces the incidence of false-negative responses during carotid endarterectomy and helps to determine indications for temporary shunting [125, 126].
On the other hand, co-registration of SSEP with BAEP is 86% sensitive and 98% specific in predicting the neurological deficit during resection of cerebral AVM. [115]
Surgery on cerebral aneurysms carries the risk of intraoperative ischemia in 5% of cases. (as cited in [19] ) SSEP changes correlate with intraoperative CBF reduction, which makes that modality a valuable monitoring method during aneurysm surgery.According to Kang et al. (2013), SSEP monitoring is indicated when the aneurysms are supplied by internal carotid, anterior, middle, and posterior cerebral arteries [19]. Simultaneous BAEP recording may be required during posterior circulation surgery, even thoughthis combination yields an unacceptably high false-negative rate of 25% during basilar artery surgery. (as cited in [127]) Accidental clamping of small perforator arteries during basilar aneurysm surgery may result in infarctions involving the thalamus, internal capsule, and midbrain, with resultant alterations in consciousness, hemiparesis or hemiplegia in the postoperative period. In such patients, combination of SSEP with TcMEP will improve the safety and increase the efficacy of INM [128].
Surgery in the territory of territory of anterior cerebral arteries places at risk cortical areas controlling the lower extremities. In these cases, lower extremity SSEP is indicated, [9] while median nerve SSEP is the method of choice for aneurysms supplied by the middle cerebral and carotid arteries.
Significant SSEP changes during aneurysm surgery occur in 6.5% of cases [127]. Irreversible changes carry an 80% risk of postoperative stroke in patients with unruptured aneurysms, while the risk is 20% with reversible SSEP changes [127].
Intraoperative pneumocephalus, especially during sitting craniotomies, may significantly impact the SSEP registration [16, [127]. Multimodal neuromonitoring, which includes SSEP, direct electrical stimulation and MEP, has become an essential component during surgery in highly eloquent areas including cortical zones of language and motor control as well as deep-seated gliomas [3, 5, 95, 130-138].
During such interventions, ischemic events are the major source of permanent postoperative motor dysfunction, whereas, parenchymal resection represents a minor reason for neurological consequences [139]. A new motor deficit may be reversible if MEP recovery is achieved by early signs and appropriate modifications are made in the surgical procedure [110]. SSEP and MEP monitor distinct neuronal pathways, and both methods may be considered supplementary.
In conclusion, evoked responses are a valuable mode of INM. The selection of specific EP depends on location of the lesion, preexisting pathology, clinical experience with the method, and other factors. Sensitivity of the signal to general anesthetics and changes in physiological parameters during surgery must be taken into account. Advancements in INM technologies, neurosurgical technique and anesthesia significantly improve the quality and efficacy of neurosurgical procedures, reduce morbidity and improve the neurological outcome. Several above described methods still are not commonly used, and further research is required before their widespread application in clinical practice.
An active interaction between anesthesiologists, neurosurgeons and the neurophysiology team working in the operating room is a prerequisite for successful intraoperative EP monitoring and timely interpretation of the data.
The authors would like to thank Andrei M. Jipa, medical student from the University of Cincinnati College of Medicine, for his active participation in preparation of the manuscript.
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- Gempt J, Krieg SM, Huttinger S, Buchmann N, Ryang YM, et al. (2013) Postoperative ischemic changes after glioma resection identified by diffusion-weighted magnetic resonance imaging and their association with intraoperative motor evoked potentials. J Neurosurg 119(4):829-836.


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(More) coming attractions from David Cicilline
As part of our ongoing coverage on candidates and their messaging, here's some of the latest in a new email fundraising pitch from David Cicilline (sent as a letter from campaign spokeswoman Nicole Kayner):
The more Paul Ryan (remember him? He's the guy that wrote the bill to end Medicare) and Eric Cantor (the chief cheerleader for shutting down the government last summer) find out about Brendan Doherty, the more they want to add him to their ranks in Congress. So just this week they committed to further prop-up his candidacy through their "Young Guns" program, a recruitment tool used by the national Republicans to train and elect conservatives across the country.
Brendan Doherty's plan to slash corporate taxes, end the capital gains tax and change Social Security benefits for anyone born after 1960 fits right into the Republicans' economic philosophy to take care of the rich and let the rest of us hope that the wealth trickles down. National Republicans know he will be one more reliable vote for their agenda and they are throwing their support behind him.
Other graduates of the Young Guns program include Allen West, the tea party Republican who told President Obama and other Democrats to "get the hell out of the United States," David Rivera, who is facing ethics charges for the misuse of campaign funds, and Sean Duffy, the MTV Real World alum who said that he was struggling to make ends meet on a six-figure congressional salary but advocated for cutting the salaries of public employees.
You can tell a lot about a candidate by who they choose to associate with. And just like Doherty joined with far-right former Gov. Carcieri in Rhode Island, he has quickly aligned himself with the most conservative Republican members in the U.S. Congress. He has even gone so far as to call the Paul Ryan budget that ends Medicare a "prudent approach"
Doherty's loyalty is being rewarded and national Republicans recently sent out a press release hitting David that was later called a "Pants on Fire" lie by Politifact. We can only expect more of these desperate attacks as they try to get one more vote in Congress for their dangerous fiscal and social policies.
Your help in standing up to these Tea Party Republicans is much appreciated. Doherty tries to talk a lot about bipartisanship but it's becoming clearer who his true friends and campaign backers really are.
Barry permalinkFebruary 8, 2012 9:35 pm
Rep. Cicilline's message works for me. No doubt the right-wing will try to frame this election on the basis of Doherty's police personality and Providence's finances, but a Representative in Congress actually does vote on medicare, environment, tax fairness, reproductive freedom, consumer protection, and the like. And the right-wing House Republican caucus is firmly against all those things.
- Campaign snapshot: High gas prices + Cicilline's politics of empathy « On Politics
- Cicilline surrogates hitting Gemma, Doherty on abortion rights « On Politics
- Cicilline, Gemma camps use Ryan pick to try to nationalize the RI-CD1 race against Doherty « On Politics
- Brendan Doherty's challenge — separating himself in voters' minds from the national GOP « On Politics
- Unsurprising: Cicilline set for more, not fewer, TV debates « On Politics
- New Cicilline spot links Doherty with Romney « On Politics
- Why Doherty doesn't support changing the Violence Against Women Act « On Politics
- Six things to watch for in tonight's CD1 debate between Cicilline and Doherty « On Politics

subset: commoncrawl


text: SOUTH BURLINGTON The Vermont Commons School recently hosted its annual Night of Glory awards ceremony. The ceremony included inducting students into the National Honor Society and recognizing student athletes for their leadership and commitment as a member of a Vermont Commons sports team. Night of Glory was held in South Burlington at Vermont Commons and was attended by scores of students, parents and faculty. Below is a list of the students who were recognized. 2008 National Honor Society Inductees from Vermont Commons School Sam T. Barrocas, 12th grade (Hinesburg) Joseph G. Congdon, 10th grade (Charlotte) William M. Hayden, 11th grade (Shelburne) Celina M. Hickson, 11th grade (St. George) Maura C. Huddleston, 12th grade (Weybridge) Alexandria L. Mason, 11th grade (Burlington) Catherine L. Mueller, 10th grade (Enosburg Falls) James Trask, 11th grade (Georgia) SOCCER Awards (coed sport for students in grades 7-12): LEADERSHIP: Will Hayden, 11th grade (Shelburne) COMMITMENT: Catie Mueller, 10th grade (Enosburg Falls) VOLLEYBALL Awards (at Vermont Commons, volleyball is a coed sport for students in grades 7-12) LEADERSHIP: Kelsey Boudette, 12th grade (Burlington) COMMITMENT: Frances Russell, 12th grade (Charlotte) VARSITY BASKETBALL Awards (J.V. basketball is a coed sport for students in grades 7-12): LEADERSHIP: Toby Hinsdale, 12th grade (Charlotte) COMMITMENT: Will Hayden, 11th grade (Shelburne) J.V. BASKETBALL Awards (J.V. basketball is a coed sport for students in grades 7-12) COMMITMENT: Callie McGarghan, 9th grade (Charlotte) LEADERSHIP: Evan Sturtevant, 9th grade (Shelburne)


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VDR 1.7.7 I have installed the mplayer plugin
and read the MANUAL in the xine plugin, consequently modified mplayer.sh to call xineplayer instead of mplayer So far so good but when I open the mplayer plugin and play any file (for example a .avi ) the movie displays correctly but there is no way to pause it, or otherwise control it. I press pause and I see the pause symbol on the screeen but whereas playing normal vdr recordings it works fine, with the mplayer plugin and xineplayer the movie does not pause. Anybody has experienced this and more important found a way to get this working? _______________________________________________ vdr mailing list email@example.com http://www.linuxtv.org/cgi-bin/mailman/listinfo/vdr


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What's the best way to cook dove?
I like whole small birds like quail and dove in a "looing sauce".
1 or 2C soy sauce, 1/2 cup sake,1/4 cup brown sugar; then aromatics, a couple cloves of garlic, 2 star ansie, about 8 quarter sized slices of ginger, Orange peel, lemon peel.
Make enough to cover the birds. Add more soy and some water to be sure the birds submerge. A small plate will help hold them down.
Bring to a boil..add birds (put kitchen twine in a loop under the wings). Bring back to boil after you add the birds---TURN OFF THE HEAT. Cover. Wait 20 mins.
Hang the birds up with the twine and let them drip dry (use a hair dryer to speed that up). After the skin is very dry...drop them in about 2 cups of hot oil to crisp up the skin---they're fully cooked at that point from the simmering the sauce. Just crisp up the skin.
You can save the looing sauce and freeze to use again. Cornish game hens are good--but for those let rest in the sauce 1 hr to cook through.
My favorite way is to clean the dove breast so you have those two yummy small lumps of meat. Place a lemon slice between them. Salt and Pepper over all. Wrap in back. Cook in hot smoker for 10 minutes.
Most people over cook dove. It does not need much cooking time. Avoid all recipes that call for cooking for hours on end. They are nasty!
I just made the dove risottos from AFIELD - you simmer the breasts in water with bay leaf, then strain the liquid and save it. Pick the meat off the bone and chop it. Then the risotto - saute minced onion in a little butter. Add sliced mushrooms, then arborio rice. Start ladling in that bay/dove stock, stirring all the while. When the rice is to your liking stir in the meat, along with a pat of butter and some parmesan. The bay broth and dark dove meat really make it something special.


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Bridge&lord bl5634 essential btn cardi. Fabric: 95% merino, 5% cashmere. Care label: warm hand wash. Occasion: casual style: classic woman,arty chick suits shape: hourglass,rectangle
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Start a "Find It For Me" to notify hundreds of Australian Boutiques that you're looking for it and then be notified if it comes back in stock.


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|Ulyana Sergeenko in Dior haute couture at paris fashion week TommyTon
Take my picture the insightful short fashion film into the mad world of street style and the monster It has become! Tim Blanks,Suzi Lui and Tommy Ton are some of the people telling us there thoughts on this mad phenomenon. While I was watching this video all I could think about was this september when I go to London with my small but mighty Canon EOS 1100D camera to attend the shows and do a little street style photography. I always knew it would be mad and hectic and crazy but watching this film is making me nervous I will just be a little amateur amongst the masses of crazy street style photogs and a few paps, Im expecting my street style pics to be blurry and dreadful looking. I will also be attending the shows, so will I dress up like a mad hatter for the street style photogs...NO! What irritates me are the attention seekers, wearing a tutu and holding a red balloon, wandering around lincoln center is not fashion on any level and seeing this in this film mad me slightly ill! Thats not to say I don't love Anna Dello Russo or other of the slightly eccentric street style favs, they are much more fabulous and they look amazing for example the pic of Ulyana Sergeenko in a Dior couture dress she has probably bought for a few hundred thousand pounds just makes me drool sweet fashion saliva! But this mass crazy street style culture is something I adore and yes there are those ridiculous attention seeking idiots that enrage me, but simply looking through Tommy Tons street style pics just define what fashion is at the moment and as I've said they make me drool sweet fashion saliva!


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"Seawater on the streets." One immediately knows that, notwithstanding the alliterative allure, something is not right. And when one is in Annapolis, Maryland, and the Alex Haley Scuplture Group is literally reading in the waves, it is plain disconcerting. The National Oceanic and Atmospheric Administration calls this "nuisance flooding," and has just issued a report,Sea Level Rise and Nuisance Flood Frequency Changes around the United States, that takes sea level rise down to the day-to-day and documents the quotidian, long-term repetitive inundations that are regularly besetting portions of the American littoral. Annapolis and its sometimes aquatic sculpture grace the cover of the report and also top the list of areas experiencing the most increase in nuisance flooding.
The report is based on the National Water Level Observation Network (NWLON), whose gauges have been monitoring tides for decades, even, in many cases, nearly a century. NOAA scientists have applied their expertise and formulae and provided valuable results. The report is quite technical. For example, "[t]rends derived from linear regression on the annual number of nuisance flood days are statistically significant at the 90% level at 41 of the 45 gauges analyzed." Report at 9-10. However, while the Report may be technical, the graphs are plain. Even non-technical people can understand the scatter plots showing an accelerating trend of nuisance flooding or the bar charts that show the increase in annual days of flooding.
Where is this increase occurring, and when? The Report identifies the Mid-Atlantic, Chesapeake Bay, North and South Carolina and southern Texas as experiencing a higher value of "nuisance flood days" – greater than 20 annually. Report at 9. By way of comparison, in the 1950s the frequency of nuisance flooding across the United States (the return period) was of the order of 1-5 years. Today "the probabilities of a nuisance flood event have increased throughout much of the U.S., with return periods typically <0.25 year (3 months) at most NOAA gauges." Report at 16. Besides Annapolis, areas recently suffering over 20 nuisance flood days on average per year include Atlantic City and Sandy Hook, N.J., Charleston, S.C., and Washington, D.C.
The significance of this is easy to visualize: "overwhelmed stormwater drainage capacity, frequent road closures, and general deterioration and corrosion of infrastructure not designed to withstand frequent inundation or salt-water exposure." Report at vi.
But there are other more subtle impacts. Nuisance flooding immerses a community in a rising sea level. That may prompt a review of coastal property boundaries and, because the State owns the land below mean high water (or, in some cases, mean low water), a transfer of property to the State with the accompanying effect on tax base and property ownership may materialize with substantial impact on the community. Even without a redrawing of property lines, properties subject to increased flooding are likely to lose value, reducing or eliminating nest eggs, retirement security and loan collateral. In such circumstances, transaction professionals (lawyers, real estate agents) may wish to evaluate the disclosures their client sellers need to make and the warranties their client buyers should require.
Rising sea levels are bringing the ocean into areas it used to avoid. The new bucket list for some destinations may literally mean to bring a bucket.


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Alcoa (NYSE:AA) is scheduled to release its second quarter results on July 8. The aluminum giant is hoping to build upon its strong first quarter, which saw earnings surge despite weak aluminum prices.
The reason Alcoa was able to report strong earnings last quarter was because its value-added businesses are all starting to do just that, add value to the company. It's a move that's really beginning to reward the company's investors as Alcoa's stock has vastly outperformed the market this year.
In looking ahead to the second quarter, the company's value-add business segments will again be front and central, which is why investors should pay special attention to what Alcoa has to say about these segments this quarter. But Alcoa's value-add segments aren't the only area of importance this quarter as I see three important areas investors need to watch when Alcoa reports second quarter earnings, which I've detailed in the below slideshow presentation. If the company's stock is going to continue to reward investors this year, then it needs to continue to deliver improvements in these three areas.
Matt DiLallo has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.


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Q&A Categories
Find a Question:
KPN wants to expand coverage fiberglass
KPN wants to expand the coverage of its fiber optic network. At present, 2.1 million Dutch households can take a fiber subscription, but that number has increased less in 2015 than in previous years.
KPN mentions the plan for the greater fiber coverage in its strategy for the coming years, which presents the provider Monday to investors on Capital Markets Day. Tweakers is trying to reach the provider wants to extend for an explanation of where and to what extent the coverage, but KPN still has no explanation.
The past year leveled off growth in the fiberglass cover KPN. Meanwhile, 2.16 million households can purchase a subscription with fiberglass, 159,000 more than a year ago. That is both absolutely and relatively the least increase in the number of households with fiber in years. came in 2014 and 2013, for example, more than 350,000 households with fiber.
The provider has in recent years focused on the acceleration of the copper compound with techniques like pair bonding and VDSL vectoring. Therefore, the provider put less attention on fiber-to-the-home. KPN was late 2014 fiber company Reggefiber wholly ownedViewing:-339
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text:
Workshop on Emotional Intelligence for Professional Development
Sale Date Ended
Workshop on Emotional Intelligence for Professional Development
Sale Date Ended
Page Views : 402
This is to inform you that we are organizing an experiential workshop on Emotional Intelligence for Professional Development &Stress Management on 22nd August 2015 (4m- 8pm). Please confirm your participation by registering at
When we are dealing with machines or computers, if we press the right button (IQ) we get the desired result. But in our professional life you have to deal with human computers and these human computers have emotions. Therefore Emotional Intelligence (EQ) plays vital role in building relationship and in maintaining long-term relationship. There is a saying, "people join companies and leave their bosses." The truth is, "we take decision emotionally and justify them rationally".
The objective of the workshop is to make the participants aware of the importance and practice of Emotional Intelligence (EQ) in life. The program has been designed keeping in mind the needs of the present fast changing corporate scenario.
BENEFITS: The program helps to become better Communicator, Decision maker, Negotiator, Interpersonal Skills, Enhances Confidence and LEADERSHIP SKILLS
- You will be able to deal with your own emotion and emotion of the people around.
- The program will help you to eradicate psychosomatic illness such as Headache, arthritis, hypertension & high blood pressure.
- Due to suppressed emotions such as anxiety, fear, conflict and tension 90% corporate employees are suffering from psychosomatic health disorders.
You will overcome worries, tension, stress and all psychological problems. You will save doctors fees and suffering
The workshop is limited to 12 participants only. Please register soon confirm you place in the workshop.


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Programming language and the programmers all over the world experienced a new wave of change when PHP7 launched. This web-based application is compatible with mobile, enterprises solutions, and cloud platforms. However, there are a lot more to learn about this version to get comfortable while programming. It has got two new operators and many more exciting changes to ease the PHP lovers around the globe. Let's dig out what are those to get a quality knowledge supplement.
First and foremost thing that immediately gets noticed is its speed. PHP7 has an almost double speed of operation as that of PHP 5.6. Regarding consistency, it stands high as compared to its earlier versions. This means you will gain more proficiency than before as unwanted time lags will not be there.
Improved open source scripting:
PHP5 was using Zend Engine II at its heart, but PHP7 has got an upgraded version, Zend Engine III. It can significantly improve the performance level. As it has been written in C that interprets PHP, the functionality gets enhanced. It comes under the code name of PHPNG (Next Generation). This ensures that PHP7 is a must-try affair for every programmer around the globe.
Manual Variable declaration:
PHP 7, unlike its previous shades, enables you to specify your desired variable through its Type Declaration feature. It not only makes your code easy to read but also enables you to make small changes to variables without bringing any effect to the overall result. Earlier, this feature was not present and PHP was automatically setting up the variables. This changeover need not require you to declare data types as variables will still have them attached. However, you can make some radical changes. For instance, you can add a string to an integer, and it won't result in any programming error.
For example,
Function abx(): array {
Return [ ];
Consider the example shown above. It defines array type of variable. With return type declaration used above, the function will return only the array. You can use this logic for other returns types such as int, float, and bool. Thus, being a weakly typed language, PHP7 can help you enhance the quality of the code.
Handling Fatal Errors:
A slight mistake from your side and your script may get into a fatal error. This is a common problem that every programmer experiences and previous PHP versions used to stop the script without involving the error handler. However, PHP 7 gives a little relief. An exception will be thrown instead of closing the entire script down.
Easy User-land CSPRNG:
It is nothing but an application space present outside the Kernel. Easy User-land CSPRNG can be covered by privilege separation. This API enables you to use PHP 7 with ease. It is reliable and is used to generate cryptographically secure pseudo-random numbers. No doubt, these random data were also present in the earlier versions, but none of them were as secured at this time. The importance of random numbers goes primarily while designing the program for generating frequently changing random passwords.
Introduction of two new operators:
If you're upgrading to PHP7, then you will get to know about two new operators; Spaceship operator (<=>) or Combined comparison and Null Coalesce Operator. Let's get to know about these operators in brief.
Spaceship operator (<=>) or Combined comparison
This one has got behavior similar to strcmp() or version_compare(), but the good thing is that all generic PHP values can get utilized through this new operator in combination with usual semantics like <, <=, ==, >=, >, etc. The comparison rules used is same as that of the previous semantics.
This spaceship operator has got simple usage funda. This operator "(expr) <=> (expr)" will fetch you a value ZERO if both operands are of same value. If the left side is greater than the right side, you will get ONE and -ONE for vice versa condition.
To understand about its behavior better, see how it returns results in case of the followings:
Echo 11 <=> 11; //0
Echo 11.5 <=> 12.5; //-1
Echo c <=> b; //1
Use usort() along with this operator to make the ordering easier.
Null Coalesce Operator
"??" this is the symbol of Null Coalesce operator. If you want to assign a value to nullable or reference type files, this one can be your savior. If the operand is not null, the operator will return you left-hand operand, and if the reverse is the case, you will get right-hand operand in return.
In PHP7, without engaging this operator, if you are trying to assign a nullable value to a non-nullable one, you will get compile time error for sure. However, the use of "??" operator won't let that happen.
See the below example for more clarity.
Int? a = null; //here a is a nullable value type
Int x = 0; //here a is a non-nullable value type
X = a;
You will get compile time error as below:
Cannot implicitly convert "int"; to "int." An explicit conversion exists.
Anonymous class:
A new entry to PHP7 is "anonymous classes." These classes have no name and can be defined simply with a keyword "new class." The functionality goes in the similar line as that of an object of named class. They have internally generated names so, we need not define them again. They are useful for creating one-off objects.
For example, consider the below one;
Anonymous class_Image
Earlier, for creating a new class, it was required to override a property or method. That was extending the named class. However, with Anonymous class, your job will be easy for creating a simple one-off object.
If you want to encapsulate the items, then Namespace is what you will be looking for in PHP7. It can import a group of classes, functions, and constraints from the same namespace.
See this example below.
Before PHP7, you need to work as below:
Use xyz\abc\class Z
Use xyz\abc\class Y as newcode
After PHP7, you can work as below:
Use xyz\abc\ {class Z, class Y as newcode};
Here, we have highlighted the most important ones. However, there is a long list of the same. There are few technical advantages also. For instance, it is a commonly known fact that Linux is a more favorable playground for PHP rather than Windows and until now, it was running smoothly on 32-bit Windows, but the current version supports 64-bit windows as well. Therefore, with so much of changeovers, PHP7 can be quoted as one of the major release after PHP5 since 2004. Try to keep digging this new platform to gain maximum output with minimum input.


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Code: KL366
Area: Apokoronas
City: Chania, Crete
Location: Kokkino Chorio
Plot size: 1020sqms
Price: 160,000€
This plot of land for sale in Apokoronas Chania Crete is located in the village of Kokkino Chorio with open, unobstructed sea views of Souda Bay and White Mountains that can never be lost. It is a gradient plot of land of 1020sqms, in the village boundaries, with a high building density of 400sqms situated between the villages of Plaka and Kokkino Chorio. It is ideal for the construction of a luxury residence or a small development for an investment in tourism.
Kokkino Chorio is a small, traditional Greek village on the coast of the Apokoronou Peninsula, from here the views across Souda Bay to the Akrotiri Peninsula are magnificent. It is only a few minutes' drive from Plaka with tavernas and bars, and the lovely sandy beach of Almyrida. Just further down you will find Kalives where there are more sandy beaches, shops for your day to day needs and a variety of other amenities. The beautiful historic city of Chania is just 30 minutes away from Kalyves, as is the international airport of Chania.
Village: 1 km
Chania airport: 32 kms
Souda port: 19 kms
Nearest beach: 4 kms
Chania city center: 25 kms
Shops & amenities: 1 km
- Beach nearby
- Mountain View
- Sea View
- Utilities Nearby
- Within Residential Area
Area Information
The village of Kokkino Chorio:
Kokkino Chorio is an unspoilt, traditional village in the Apokoronas region of Chania, located high on the mountain and offers breathtaking views over the Bay of Souda. The village was one of the sites used in the 1964 film Zorba the Greek. It is a small, hospitable village with a couple of small shops, kafeneion and tavern. More shops and restaurants can be found in the village of Plaka, 3kms away. Kokkino Chorio features a glass factory which produces hand made glass using traditional glass blowing techniques. The coastline northwest of the village is a very interesting place for a stroll due to the ground formation and the various caves.
The region of Apokoronas:
Apokoronas is situated at the foot of the White Mountains in the north-eastern corner of the Chania prefecture and is one of the greenest regions of Crete. The area features numerous interesting sights, such as Lake Kournas, the island's only freshwater lake and the archeological site of Aptera with its superb views of Souda Bay. Apokoronas features an abundance of historic and picturesque villages with traditional taverns and thriving seaside resorts with beautiful sandy beaches along the coast like Kalyves, Almyrida and Georgioupolis.


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Transparency Market Research Reports incorporated a definite business overview and investigation inclines on "Ultraviolet (UV) Coatings Market - Global Industry Analysis, Size, Share, Growth, Trends, and Forecast 2016 - 2024" This report likewise incorporates more illumination about fundamental review of the business including definitions, requisitions and worldwide business sector industry structure.
Albany, NY -- (SBWIRE) -- 06/03/2016 -- Global Ultraviolet (UV) Coatings Market: Description
Ultraviolet or UV cured coating refers to the application of a shiny coating on surfaces such as plastics, wood, paper, and others with the help of UV radiation to ensure excellent coverage and light stability. UV coatings are better than conventional coating techniques as they offer good abrasion resistance, high shine finish, very less drying time, and high clarity. UV coatings are also environment friendly and free of solvents. As a result, they do not emit VOCs when cured. During the coating of a surface with UV radiation, a chemical reaction in the form of chain polymerization occurs. Radiation with UV energy leads to highly reactive photoinitiators that cross-link the acrylates to form a plastic film within milliseconds.
In terms of formulation, UV coatings are broadly classified into water-based and solvent-based segments. UV coatings are used on various surfaces such as metals, glass, plastic, wood, paper, and others. UV coatings on wood surface are high in demand owing to the low volatile organic compound (VOC) emissions, superior quality, and increasing applications of these coatings in the wood and furniture industry.
Interpret a Competitive outlook Analysis Report with FREE PDF Brochure: http://www.transparencymarketresearch.com/sample/sample.php?flag=B&rep_id=11708
The U.S., Germany, and China are the key countries driving the demand for UV wood coatings. Less curing time and the green nature of UV coatings have propelled their usage across a number of end-use sectors such as architecture, industrial, aviation, textile, automotive, marine, electronics, and others. The industrial sector is contributing significantly toward the growth of the global UV coatings market, followed by the electronics sector. The growing demand for plastic coatings for electronic parts and flooring has further pushed the growth of the market.
Global Ultraviolet (UV) Coatings Market: Overview
The rapid growth of the electronics industry and growing environmental awareness have boosted the growth of the global UV coatings market. The rise in the demand for coatings across industrial applications has impacted the market positively. The superior characteristics of UV coatings such as improved resistance and higher gloss finish, along with minimum to zero percentage emission of VOCs have further fuelled the demand for UV coatings. The growing trend of graphics art on wooden, plastic, and glass surfaces is expected to aid the market's growth. The low operational cost of UV coatings also contributes significantly to the demand from the market.
However, low price competitiveness and niche applications might hamper the growth of the market during the forecast period. The global UV coatings market has a huge potential for growth with the introduction of greener UV coatings applications. Market players are investing in extensive research activities to develop environment-friendly UV coatings such as bio-based UV coatings. The introduction of such coatings is expected to broaden the application scope of the global UV coatings market.
Global Ultraviolet (UV) Coatings Market: Region-wise Outlook
The global UV coatings market has been divided into four key segments: Europe, Asia Pacific, North America, and Rest of the World. Among the key regions, Asia Pacific is expected to drive the demand from the market during the forecast period with countries such as China, Japan, and South Korea emerging as the biggest consumers of UV coatings. In these countries, the rapid growth of the electronics industry has fuelled the demand for high-performance UV coatings. Stringent environmental regulations have led to innovations and developments in the UV coatings market in the region.
Browse the full Research report at: http://www.transparencymarketresearch.com/ultraviolet-coatings-market.html
Some of the key players in the global UV coatings market are AkzoNobel N.V., The Dow Chemical Company, PPG Industries Inc., 3M, Asian Paints Ltd., The Valspar Corporation, The Sherwin-Williams Company, DIC Corporation, Axalta Coating Systems LLC, and Royal DSM N.V. The market players are focusing on new product launches as well as joint ventures and partnerships to expand their businesses.
The report offers a comprehensive evaluation of the market. It does so via in-depth qualitative insights, historical data, and verifiable projections about market size. The projections featured in the report have been derived using proven research methodologies and assumptions. By doing so, the research report serves as a repository of analysis and information for every facet of the market, including but not limited to: Regional markets, technology, types, and applications.
About Transparency Market Research
Transparency Market Research (TMR) is a market intelligence company, providing global business information reports and services. Our exclusive blend of quantitative forecasting and trends analysis provides forward-looking insight for thousands of decision makers. TMR's experienced team of Analysts, Researchers, and Consultants, use proprietary data sources and various tools and techniques to gather and analyze information.
Our data repository is continuously updated and revised by a team of research experts, so that it always reflects the latest trends and information. With a broad research and analysis capability, Transparency Market Research employs rigorous primary and secondary research techniques in developing distinctive data sets and research material for business reports.