Predictive value of sensory and cognitive evoked potentials for awakening from coma.
OBJECTIVE
To determine the prognostic role of late auditory (N100) and cognitive evoked potentials (MMN) for awakening in a cohort of comatose patients categorized by etiology.


METHODS
The authors prospectively studied a series of 346 comatose patients. Coma was caused by stroke (n = 125), trauma (n = 96), anoxia (n = 64), complications of neurosurgery (n = 54), and encephalitis (n = 7). Patients were followed for 12 months and classified as awake or unawake. Univariate and multivariate analyses were performed using regression logistic and Cox models.


RESULTS
Pupillary light reflex, N100, middle-latency auditory evoked potentials, age, and etiology were the most discriminating factors for awakening. Statistical analysis showed that pupillary reflex was the strongest prognostic variable for awakening (estimated probability 79.7%). The estimated probability of awakening rose to 87% when N100 was present and to 89.9% when middle-latency evoked potentials (MLAEPs) were present. It was 13.7% when pupillary reflex was absent in anoxic patients. When MMN was present, 88.6% of patients awakened. No patient in whom MMN was present became permanently vegetative.


CONCLUSIONS
Pupillary reflex is the strongest prognostic variable, followed by N100 and MLAEPs allowing a reliable model for awakening. The presence of MMN is a predictor of awakening and precludes comatose patients from moving to a permanent vegetative state. Evaluation of primary sensory cortex and higher-order processes by middle-latency-, late, and cognitive evoked potentials should be performed in the prognosis for awakening in comatose patients.
Department of Clinical Neurophysiology, Hospices Civils de Lyon, France. catherine.fischer@chu-lyon.fr
Catherine
C
Fischer
Jacques
J
Luauté
Patrice
P
Adeleine
Dominique
D
Morlet
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001930:Brain Injuries / Q000150:complications; D002648:Child; D003071:Cognition / Q000502:physiology; D003128:Coma / Q000209:etiology / Q000503:physiopathology*; D018450:Disease Progression; D004660:Encephalitis / Q000150:complications; D005071:Evoked Potentials; D005072:Evoked Potentials, Auditory; D016057:Evoked Potentials, Auditory, Brain Stem; D005260:Female; D005500:Follow-Up Studies; D015600:Glasgow Coma Scale; D006801:Humans; D002534:Hypoxia, Brain / Q000150:complications; D015993:Life Tables; D008297:Male; D008875:Middle Aged; D018458:Persistent Vegetative State / Q000209:etiology / Q000503:physiopathology*; D011183:Postoperative Complications / Q000503:physiopathology; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D011930:Reaction Time; D020127:Recovery of Function; D012025:Reflex, Pupillary; D020521:Stroke / Q000150:complications; D014851:Wakefulness