The prognostic value of evoked responses from primary somatosensory and auditory cortex in comatose patients

• Published in: Clinical neurophysiology 2003-09, Vol.114 (9), p.1615-1627
• Main Authors: Logi, F, Fischer, C, Murri, L, Mauguière, F
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Auditory Cortex - physiology; Biological and medical sciences; Coma; Coma - classification; Coma - etiology; Coma - physiopathology; Cross-Sectional Studies; Electric Stimulation; Electrodiagnosis. Electric activity recording; Electroencephalography; Evoked Potentials, Auditory - physiology; Evoked Potentials, Somatosensory - physiology; Female; Glasgow Coma Scale; Humans; Hypoxia-Ischemia, Brain - complications; Hypoxia-Ischemia, Brain - physiopathology; Investigative techniques, diagnostic techniques (general aspects); Magnetic Resonance Imaging; Male; Median Nerve - physiology; Medical sciences; Middle Aged; Middle latency auditory evoked potentials; Nervous system; Outcome prediction; Persistent Vegetative State - physiopathology; Post-anoxic coma; Recovery of Function; Somatosensory Cortex - physiology; Somatosensory evoked potentials; Stress Disorders, Post-Traumatic - complications; Stress Disorders, Post-Traumatic - physiopathology; Stroke - complications; Stroke - physiopathology; Time Factors; Tomography Scanners, X-Ray Computed; Traumatic brain injury
• ISSN: 1388-2457; 1872-8952
• DOI: 10.1016/S1388-2457(03)00086-5

Objective: To evaluate somatosensory and auditory primary cortices using somatosensory evoked potentials (SEPs) and middle latency auditory evoked potentials (MLAEPs) in the prognosis of return to consciousness in comatose patients. Methods: SEPs and MLAEPs were recorded in 131 severe comatose patients. Latencies and amplitudes were measured. Coma had been caused by transient cardiac arrest ( n=49), traumatic brain injury ( n=22), stroke ( n=45), complications of neurosurgery ( n=12) and encephalitis ( n=3). One month after the onset of coma patients were classified as awake, still comatose or dead. Three months after (M3), they were classified into one of the 5 categories of the Glasgow outcome scale (GOS). Results: At M3, 41.2% were dead, 47.3% were conscious (GOS 3–5) and 11.5% had not recovered consciousness. None of the patients in whom somatosensory N20 and auditory Pa were absent did return to consciousness and in the post-anoxic group, reduced cortical amplitude too was always associated with bad outcome. Conversely, N20 and Pa were present, respectively, in 33/69 and 34/69 patients who did not recover. Conclusions: The prognostic value of SEPs and MLAEPs in comatose patients depends on the cause of coma. Measurement of response amplitudes is informative. Abolition of cortical SEPs and/or cortical MLAEPs precludes post-anoxic comatose patients from returning to consciousness (100% specificity). In any case, the presence of short latency cortical somatosensory or auditory components is not a guarantee for return to consciousness. Late components should then be recorded.