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Early somatosensory evoked potential grades in comatose traumatic brain injury patients predict cognitive and functional outcome*

Houlden, David A. PhD; Taylor, Amanda B. MD; Feinstein, Anthony MD; Midha, Rajiv MD; Bethune, Allison J. BSc; Stewart, Craig P. MA; Schwartz, Michael L. MD

doi: 10.1097/CCM.0b013e3181c031b3
Clinical Investigations

Objectives: To relate early somatosensory evoked potential grades from comatose traumatic brain injury patients to neuropsychological and functional outcome 1 yr later; to determine the day (within the first week after traumatic brain injury) that somatosensory evoked potential grade best correlates with outcome; to determine whether somatosensory evoked potential grade improvement in the first week after traumatic brain injury is associated with improved outcome.

Design: Prospective cohort study.

Setting: Critical care unit at a university hospital.

Patients: Median nerve somatosensory evoked potentials were obtained from 81 comatose patients with traumatic brain injury. Somatosensory evoked potential grades were calculated from results obtained on days 1, 3, and 7 after traumatic brain injury. Glasgow Outcome Scale, Barthel Index, Rivermead Head Injury Follow-up Questionnaire, General Health Questionnaire, Stroop Color-Word Test, Paced Auditory Serial Addition Task, and Symbol-Digit Modalities Test scores were obtained 1 yr after injury.

Interventions: None.

Measurements and Main Results: Somatosensory evoked potential grade on days 1, 3, and 7 related significantly with Glasgow Outcome Scale and Barthel scores (day 3 better than day 1) but did not relate with Rivermead Head Injury Follow-up Questionnaire or General Health Questionnaire scores. Day 3 and day 7 somatosensory evoked potential grades related significantly with Stroop scores. Day 3 somatosensory evoked potential grades related significantly with Symbol-Digit Modalities Test scores. Patients with bilaterally present but abnormal somatosensory evoked potentials, whose somatosensory evoked potential grade improved between days 1 and 3, had marginally better functional outcome than those without somatosensory evoked potential grade improvement.

Conclusions: Day 3 somatosensory evoked potential grade related to information-processing speed, working memory, and the ability to attend to tasks 1 yr after traumatic brain injury. Day 3 somatosensory evoked potential grade had the strongest relationship with functional outcome. Somatosensory evoked potential grades were not related to emotional well-being.

From the Department of Surgical Neuromonitoring (DAH, ABT, AJB, CPS), Department of Psychiatry (AF), Division of Neurosurgery (MLS), Sunnybrook Health Sciences Centre, Toronto, ON, Canada; and the Division of Neurosurgery (RM), University of Calgary, Calgary, AB, Canada.

This study was supported, in part, by Grant ONAO-#00173 received from the Ontario Neurotrauma Fund (DAH, AF, RM, MLS).

Work was performed, in part, at Sunnybrook Health Sciences Centre, Toronto, ON, Canada.

The authors have not disclosed any potential conflicts of interest.

For information regarding this article, E-mail: david.houlden@sunnybrook.ca

© 2010 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins