page_title: Charcot–Wilbrand syndrome
section_title: Polysomnography
hierarchical_section_title: Charcot–Wilbrand syndrome / Detection Methods / Polysomnography
caption_attribution_description: English: This is a screenshot of a polysomnographic record (30 seconds) representing Rapid Eye Movement Sleep. EEG highlighted by red box. Eye movements highlighted by red line.
context_page_description: Charcot–Wilbrand syndrome describes dream loss following focal brain damage specifically characterised by visual agnosia and loss of ability to mentally recall or "revisualize" images. The name of this condition dates back to the case study work of Jean-Martin Charcot and Hermann Wilbrand, and was first described by Otto Potzl as “mind blindness with disturbance of optic imagination”. MacDonald Critchley, former president of the World Federation of Neurology, more recently summarized CWS as “a patient loses the power to conjure up visual images or memories, and furthermore, ceases to dream during his sleeping hours”. This condition is quite rare and affects only a handful of brain damage patients. Further study could help illuminate the neurological pathway for dream formation.
context_section_description: A Polysomnography test (PSG) records the biological changes during sleep through monitoring the brain (Electroencephalography, EEG), eye movement (Electrooculography, EOG), heart rhythm (Electrocardiogram, ECG), and muscle activity (Electromyography, EMG).  Typically a complete PSG requires a minimum of 12 channels and 22 wire attachments and produces a “score” or report.  Sleep stages are identifiable through comparison of the EEG, EOG and EMG channels with stages 1 and 2 being defined as light sleep, 3 being slow wave sleep and 4 being REM sleep.  Additionally a PSG can reveal “arousals” or sudden shifts in brain wave activity.  Analyzing the resulting amount of REM sleep in combination with patient reported dream experience has been the method of choice for recent dream studies.  In particular researchers can wake the patient mid-REM sleep and ask for dream experience, which in normal patients would enhance their recollection and dream count.  Absence of dream experience suggests the presence of CWS and this test method can also help to illustrate whether the patient is suffering from an inability to recall visual images or complete dream loss.
caption: 30 second Polysomnography report of REM sleep with EEG boxed in red and eye movements indicated by red line.
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