the syndrome of the trephined ( st ) results in reversible neurologic symptoms or behavioral disturbance and has been described after craniectomy . the term was originally coined by grant in 1939 and was thought to be largely psychiatric in nature , attributed to a  sense of vulnerability  from the lack of an intact cranial vault . the syndrome has also been called the  syndrome of the sinking skin flap  by yamaura and makino . the spectrum of symptoms resulting from this syndrome can range from seizures , headache , neurospsychiatric disturbance , focal weakness , midbrain syndromes , and parkinsonian symptoms . initial series of patients with this syndrome were small , to which a variety of case reports have been added since its first description . the significance of this syndrome has increased in recent years due to the increasing popularity of large craniectomies for such pathology as trauma and malignant infarction . it remains poorly characterized in terms of risk factors , incidence , diagnosis , and clinical spectrum . this study aims to report the prevalence , clinical characteristics , and radiological signs associated with the syndrome of the trephined . a retrospective analysis was performed after irb approval , with the aim to assess the clinical spectrum and radiographic features of st . all patients undergoing craniectomy for any reason followed by cranioplasty within a 30-month period were included for analysis based on review of our facility 's operative procedures database , and a case - control analysis was conducted comparing those with and without st , as defined by clinical criteria of a neurologic deficit which improved within 3 weeks of cranioplasty . the symptom complex , reason for craniectomy , craniectomy size , demographic data , and radiographic findings were noted . both clinical follow - up data and radiographic studies were reviewed . radiographic findings were gleaned from both pre and postoperative computed tomography ( ct ) imaging . the craniectomy size was defined as the maximal anteroposterior diameter as visualized on ct , based on previous work by our group . radiographic findings noted included ventricular effacement , midline shift , and a sunken scalp flap contour as seen on ct . midline shift was measured in the standard fashion at the level of the foramen of monroe . a sunken scalp flap contour was noted if the scalp flap margin was located below the level of the cranium . statistical analysis included comparison of the two groups using p values , with statistical significance being defined as a p value of less than 0.05 . between - group comparisons using discrete numerical data were analyzed using fisher 's exact test ( with a freeman - halton extension for the analysis of a 2  4 contingency table ) . between - group comparisons using continuous numerical data were analyzed using unpaired t - tests . the entire patient cohort consisted of 29 patients . the average age was 34.7 years . the underlying reason for craniectomy consisted of trauma , infarction , infection , and hemorrhage , although the most common pathology was trauma [ figure 1 ] . 7 patients developed st ( 24% of the total cohort ; 25.9% of the patients for which follow up was available ) . bar graph demonstrating the distribution of etiologies for craniectomy in those patients developing st , the syndrome presented either as a chronic arrest of rehabilitation ( five patients ) or as acute deterioration ( two patients ) . the presenting symptoms included tremor , paresis , aphasia , and behavioral / cognitive deficits . st did not occur in any patients undergoing craniectomy for infection , which may relate to a smaller overall craniectomy size ( average 8.1 cm ) . time between craniectomy and cranioplasty varied from 4 weeks to up to 1 year , depending upon patient condition and comorbidities . there was no statistically significant difference in patient age or craniectomy size between st and non - st groups , although there was a non - statistically significant trend toward st development in older patients and those with larger craniectomies [ table 1 ] . an association between sunken skin flap , midline shift , and ventricular effacement and st was observed [ table 1 ] . skin flap sinking is the most sensitive and ventricular effacement the most specific predictor with 86% and 95% , respectively [ table 2 ] . both of the acutely deteriorated patients demonstrated all three radiographic indicators ( 2/2 ) , while only one of the five chronic st patients demonstrated all three radiographic indicators . radiographic and clinical characteristics between the st ( syndrome of the trephined ) group , and the non - st group sensitivity and specificity of radiologic factors to predict syndrome of the trephined a 45-year - old male suffered a malignant , left hemispheric infarction . because of his young age , and at the strong request of his wife , who noted that he would wish to be alive even if hemiparetic and aphasic as long as he was able to enjoy watching his horses in his yard , a partial temporal lobectomy as well as decompressive craniectomy was performed for brain swelling and decreased consciousness . post - operatively he experienced a prolonged hospital course complicated by a post - operative wound infection requiring multiple wound washouts . he was able to be discharged to rehab alert and participatory , but hemiparetic on the right with complete expressive aphasia as expected from his stroke . he did well with rehabilitation but due to medical issues and the requirement for clearance from infectious disease prior to his cranioplasty , did not present for cranioplasty until 12 months after his craniectomy . at that time he was ambulatory with a cane , although spastic on the right side , and continued to have expressive aphasia . ct scan demonstrated only a sunken skin flap contour , but other radiographic signs were absent [ figure 2 ] . the patient underwent placement of a customized cranial implant without complication and was able to be discharged the next day . the patient 's wife noted immediate improvement in his ability to verbalize after surgery , and upon his 2 week follow up he was noted to be fluent and conversant , although he has remained spastic and has been unable to return to work . axial , non - contrasted computed tomography of the head demonstrating preoperative ( left ) and post - operative ( right ) imaging after cranioplasty in a patient with plateau of speech rehabilitation a 45-year - old male suffered a malignant , left hemispheric infarction . because of his young age , and at the strong request of his wife , who noted that he would wish to be alive even if hemiparetic and aphasic as long as he was able to enjoy watching his horses in his yard , a partial temporal lobectomy as well as decompressive craniectomy was performed for brain swelling and decreased consciousness . post - operatively he experienced a prolonged hospital course complicated by a post - operative wound infection requiring multiple wound washouts . he was able to be discharged to rehab alert and participatory , but hemiparetic on the right with complete expressive aphasia as expected from his stroke . he did well with rehabilitation but due to medical issues and the requirement for clearance from infectious disease prior to his cranioplasty , did not present for cranioplasty until 12 months after his craniectomy . at that time he was ambulatory with a cane , although spastic on the right side , and continued to have expressive aphasia . ct scan demonstrated only a sunken skin flap contour , but other radiographic signs were absent [ figure 2 ] . the patient underwent placement of a customized cranial implant without complication and was able to be discharged the next day . the patient 's wife noted immediate improvement in his ability to verbalize after surgery , and upon his 2 week follow up he was noted to be fluent and conversant , although he has remained spastic and has been unable to return to work . axial , non - contrasted computed tomography of the head demonstrating preoperative ( left ) and post - operative ( right ) imaging after cranioplasty in a patient with plateau of speech rehabilitation st is likely to have an increasing prominence with the growing popularity of decompressive craniectomy for a variety of pathologic entities . the original pathology was thought to be compression of the underlying cortex by infolded scalp skin . implicated csf hydrodynamic abnormalities including resting pressure , sagittal sinus pressure , buffer volume , elastance at resting pressure , and pulse variations at resting pressure . changes in oscillatory csf flow at the craniovertebral junction were demonstrated on dynamic phase - contrast mri by dujovny , et al . sakamoto , et al . found improved cerebral blood flow in a total of three total patients with st after cranioplasty . we saw no patients with a craniectomy for infection develop st ; however , our finding may be confounded by the smaller craniectomy size in this group . in our series , this is a greater incidence than the commonly reported rates of st for patients undergoing decompressive craniectomy for trauma and may indicate underdiagnosis . in the retrospective series 164 patients undergoing dc , honeybul and ho report an incidence of only 1.2% . however , in a later article they document an overall improvement in functional independence measure after cranioplasty in patients with craniectomy , noting that the syndrome of the trephined may be more common than previously thought . additionally , a retrospective review of 38 patients after decompressive craniectomy for trauma revealed a significantly larger percentage of st , with 26% of patients developing a  motor trephine syndrome  consisting of monoparesis our combination of etiologies makes determination of exact incidence by etiology difficult , however the etiology of craniectomy was significantly related to the development of st , with no patients undergoing craniectomy for infection going on to develop this syndrome ; however , this may be confounded by a smaller craniectomy size in patients with post op infections . although in the recent literature , st is mentioned most frequently in relation to trauma , patients with non - traumatic hemorrhage and malignant infarction also developed st in our series . st may manifest as either chronic arrest of rehabilitation or as acute deterioration and therefore physicians involved in the post - surgical care of these patients as well as rehabilitation should have a high index of suspicion for the development of this syndrome . the presentation of chronic arrest of rehabilitation has previously been described in a series of two cases by janzen and colleagues . acute deterioration has been described in cases by bijlenga and gottlob , where a sudden change in neurological status occurred in a patient with previously normal functioning , which improved with cranioplasty . both presentations were seen in our series ; however , chronic arrest of rehabilitation was more common and more difficult to diagnose . we found that there was a non - statistically significant trend toward the development of st with a larger craniectomy . there is furthermore a non - significant trend toward the development of st in older patients . it is possible that these factors would become statistically significant in a larger series of patients . ventricular effacement , midline shift , and sunken scalp flap contour were all significantly more common in the st group . mass effect was most specific for st while sunken scalp flap contour was most sensitive . these predictive factors may aid in diagnosis of st and also in counseling of patients and family as to expectations of improvement after cranioplasty , or in timing of the cranioplasty procedure . importantly , all of these findings were also seen in patients without st , making the diagnosis a primarily clinical one rather than radiographic . de araujo and colleagues have recently reported on the importance of an asymmetric optic nerve sheath diameter as a possible predictive factor for neurologic improvement following cranioplasty although that was not explored in our study . however , there is a paucity of literature describing st and we attempt to add to that knowledge . the collection of prospective additionally , the exploration of pre - operative ct findings and their relation to later development of st may be useful for further study . radiologic factors may be important clues for the diagnosis of st , with a sunken skin flap contour being most sensitive and mass effect being most specific . medical providers involved in the post - surgical care and rehabilitation of these patients should maintain a high index of suspicion for st .
object : craniectomy is a common neurosurgical procedure . syndrome of the trephined ( st ) occurring after craniectomy results in neurologic symptoms that are reversible with cranioplasty . 
 while well - documented , previous literature consisted of case reports , symptom spectrum and risk factors have not been well characterized.materials and methods : a retrospective review of 29 consecutive cases who underwent decompressive craniectomy within a 30-month period was performed . 
 patients were considered affected by st if a previously stable neurological deficit improved within 3 weeks after cranioplasty . 
 prevalence of st was measured and association with demographic information , clinical symptoms patterns , indication for and size of craniectomy , as well as radiological signs were tested.results:seven patients ( 24% ) developed st . 
 chronic rehabilitation arrest was more common than acute neurologic decline . 
 factors such as craniectomy size and patient age did not reach statistical significance in development of st . 
 radiographic factors were predictive , with a sunken skin flap contour being most sensitive , while ventricular effacement was most specific.conclusion:st may have a higher incidence than previously thought , with a chronic rehabilitation arrest being a more common presentation than an acute decline . 
 medical providers involved in the post surgical care and rehabilitation of these patients should maintain a high index of suspicion for st .