Dr. Yushuang Zhong, Resident Physician.
The fact that auditory evoked potentials (AEPs) have been used widely as a measure of the depth of anesthesia highlights the importance of auditory modality in consciousness-related neural processing during anesthesia, a phenomena more specifically known as Intra-operative awareness (IOA). The phenomena of IOA has seldom been observed from the perspective of consciousness itself. This perspective is especially important because the dimensions of IOA exist in the subconscious domain of mind as much as they exist in the conscious domain of explicit recall. Two important aspects of these subconscious manifestations of IOA are the implicit recall phenomena and post-operative dreams related to anesthesia experiences. Here we present an integrated auditory-consciousness based model of IOA. We start with a brief description of auditory awareness and the factors affecting it. Further, we proceed to the evaluation of conscious and sub-conscious information processing by auditory modality and their interactions during and after intraoperative period. Further, we show that both conscious and subconscious auditory processing affect the IOA experience and both have serious psychological implications on the patient subsequently. These effects could be prevented by using auditory evoked potential during monitoring of anesthesia, especially the Mid-latency Auditory Evoked Potentials (MLAERs). To conclude, we propose that the use of Auditory evoked potential should be universal with general anesthesia use in order to prevent the occurrences of distressing outcomes resulting from both conscious and subconscious auditory processing during anesthesia.
Alkire M T, Hudetz A G, Tononi G. Consciousness and anesthesia. Science 2008; 322: 876-880.
Alkire MT, Miller J. General anesthesia and the neural correlates of consciousness. Prog Brain Res 2005; 150: 229-244.
Bastuji H, García-Larrea L, Franc C. Maugière F. Brain processing of stimulus deviance during slow-wave and paradoxical sleep: a study of human auditory evoked responses using the oddball paradigm. Clinical Neurophysiology 1995; 12: 155-167.
Drummond JC. Monitoring depth of anesthesia. Anesthesiology 2000; 93: 876-82.
Franks NP. General anesthesia: from molecular targets to neuronal pathways of sleep and arousal. Nature Rev Neurosci 2008; 9:370-386.
Ghoneim MM, Block RI, Haffarnan M, Mathews MJ. Awareness during anesthesia: risk factors, causes and sequelae: A Review of reported cases in the literature. Anesth Analg 2009; 108: 527-535.
Griefahn B, Scheuch K, Jansen, G, Spreng M. Protection goals for residents in the vicinity of civil airports. Noise and Health 2004; 6: 51-62.
Heinke W, Kenntner R, Gunter TC, Sammler D, Olthoff D, Koelsch S. Differential effects of increasing propofol sedation on frontal and temporal cortices: an ERP study. Anesthesiology 2004; 100:617–25.
Heinke W, Koelsch S. The effects of anesthetics on brain activity and cognitive function. Curr Opin Anaesthesiol 2005; 18:625–31.
John ER, Prichep LS. The anesthetic cascade: A theory of how anesthesia suppresses consciousness. Anesthesiology 2005; 102: 447-471.
Karakas S, Cakmak ED, Bekçi B, Aydin H. Oscillatory responses representing differential auditory processing in sleep. International Journal of Psychophysiology 2007; 65:40-50.
Lamy D, Mudrik L, Deouell LY. Unconscious auditory information can prime visual word processing: a process-dissociation procedure study. Conscious Cogn 2008; 17(3):688-98.
Leslie K, Skrzypek H, Paech MJ, Kurowski I, Whybrow T. Dreaming during anesthesia and anesthetic depth in elective surgery patients. Anesthesiology 2007; 106:33-42.
Lydic R, Baghdoyan HA. Sleep, anesthesiology and the neurobiology of arousal state control. Anesthesiology 2005; 103: 1268-1295.
Merikle PM, Daneman M. Memory for events during anaesthesia: a meta-analysis. In: Bonke B, Bovill JG, Moerman N, eds. Memory and Awareness in Anaesthesia III. Assen, The Netherlands: Van Gorgum, 1996; 108-21.
Muzet A. Environmental noise, sleep and health. Sleep Medicine Reviews 2007; 11: 135-142.
Myles PS, Leslie K, McNeil J, Forbes A, Chan MT. Bispectral index monitoring to prevent awareness during anaesthesia: The B-Aware randomized controlled trial. Lancet 2004; 363:1757–63.
Nordby H, Hugdahl K, Stickgold R, Bronnick K, Hobson JA. Event-related potentials (ERPs) to deviant auditory stimuli during sleep and waking. NeuroReport 1996; 7: 1082-1086.
Perrin F, García-Larrea L, Maugière F, Bastuji H. A differential brain response to the subject’s own name persists during sleep. Clinical Neurophysiology 1999; 110: 2153-2164.
Plourde G, Belin P, Chartrand D, Fiset P, Backman S B, Xie G, Zatorre R J. Cortical Processing of Complex Auditory Stimuli during Alterations of Consciousness with the General Anesthetic Propofol. Anesthesiology 2006; 104:448 –57.
Pockett S. Anesthesia and the electrophysiology of auditory consciousness. Conscious Cogn 1999; 8(1):45-61.
Portas Ch, Krakow K, Allen Ph, Josephs O, Armony, JL, Frith CD. Auditory processing across the sleep-wake cycle: simultaneous EEG and fMRI monitoring in humans. Neuron 2000; 28: 991-999.
Reinsel R, Veselis R, Dnistrian A, Feshchenko V, Beattie B, Duff M. Midazolam decreases cerebral blood flow in the left prefrontal cortex in a dose-dependent fashion. Int J Neuropsychopharmacol 2000; 3:117–27.
Samuelsson P, Brudin L, Sandin RH. Intraoperative dreams reported after general anaesthesia are not early interpretations of delayed awareness. Acta Anaesthesiol Scand 2008; 52(6):805-9.
Sandhu K, Dash HH. Awareness During Anaesthesia. Indian J Anaesth 2009; 53(2): 148–157.
Schacter DL, Church B. Implicit memory in amnesic patients: when is auditory priming spared? J Int Neuropsychol Soc 1995; 1(5):434-42.
Sender D, Kaiser A, Klasing S, et al. Midlatency auditory evoked potentials and explicit and implicit memory in patients undergoing cardiac surgery. Anesthesiology 1994; 80: 493-501.
Simpson TP, Manara AR, Kane NM, Barton RL, Rowlands CA, Butler SR. Effect of propofol anaesthesia on the event-related potential mismatch negativity and the auditory-evoked potential N1. Br J Anaesth 2002; 89: 382–8.
Utting JE. In: Awareness: Clinical aspects, Consciousness, Awareness and Pain in General Anaesthesia. Rosen M, Lu JN, editors. London: Butterworths; 1987. pp. 171–9.
Ypparilla H, Karhu J, Westere´n-Punnonen S, Musialowicz T, Partanen J. Evidence of auditory processing during postoperative propofol sedation. Clin Neurophysiol 2002; 113:1357–64.
Yu F, Yuan J, Luo Y. Auditory-induced emotion modulates processes of response inhibition: an event-related potential study. NeuroReport 2009; 20:25–3.
Zatorre RJ, Evans AC, Meyer E, Gjedde A: Lateralization of phonetic and pitch discrimination in speech processing. Science 1992; 256:846–9.