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

Clin Neurophysiol. 2003 Sep;114(9):1615-27. 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.

Publication types

  • Comparative Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Auditory Cortex / physiology*
  • Coma / classification
  • Coma / etiology
  • Coma / physiopathology*
  • Cross-Sectional Studies
  • Electric Stimulation
  • Electroencephalography
  • Evoked Potentials, Auditory / physiology*
  • Evoked Potentials, Somatosensory / physiology*
  • Female
  • Glasgow Coma Scale
  • Humans
  • Hypoxia-Ischemia, Brain / complications
  • Hypoxia-Ischemia, Brain / physiopathology
  • Magnetic Resonance Imaging
  • Male
  • Median Nerve / physiology
  • Middle Aged
  • Persistent Vegetative State / physiopathology
  • Recovery of Function
  • Somatosensory Cortex / physiology*
  • Stress Disorders, Post-Traumatic / complications
  • Stress Disorders, Post-Traumatic / physiopathology
  • Stroke / complications
  • Stroke / physiopathology
  • Time Factors
  • Tomography Scanners, X-Ray Computed