SERIAL SOMATOSENSORY AND BRAIN-STEM AUDITORY-EVOKED POTENTIALS IN MONITORING OF ACUTE SUPRATENTORIAL MASS LESIONS

Objective: To determine the relevance of serial evoked potentials (bra instem auditory evoked potentials and somatosensory evoked potentials) and clinical parameters (pupillary response and intracranial pressure ) in patients with acute supratentorial mass lesions. Design: Prospect ive case series of comatose patients with acute supratentorial mass le sions. Setting: Neurocritical care unit of a tertiary care center. Pat ients: Thirty consecutive patients with the following study inclusion criteria: a) clinical and computed tomography evidence of an acute sup ratentorial mass lesion; b) implantation of an intracranial pressure m onitoring device; and c) a persistent comatose state during the observ ation period. Interventions: Brainstem auditory evoked potentials, som atosensory evoked potentials, intracranial pressure, and pupillary res ponses were recorded at the time of three particular events: a) immedi ately after implantation of an epidural intracranial pressure monitori ng device; b) during intracranial pressure therapy; and c) at terminat ion of intracranial pressure therapy, Evoked potential results were ra nked into three categories: a) normal on both sides; b) abnormal or ab sent on one side; and c) evoked potentials on both sides abnormal or a bsent, Spearman's rank correlation was performed to analyze serial rec ordings, Cross tables were generated to determine the prognostic value of evoked potentials and clinical parameters, Fisher's exact test was applied to calculate statistical significance. Measurements and Main Results: Intracranial pressure values correlated with pupillary respon ses and brainstem auditory evoked potentials during and at the termina tion of intracranial pressure therapy, Pupillary findings correlated w ith brainstem auditory evoked potentials only at the time of terminati on of intracranial pressure therapy, There was no correlation between somatosensory evoked potentials and clinical parameters, Pupillary res ponses indicated a good or poor recovery during and at the termination of intracranial pressure therapy, Brainstem auditory evoked potential s and intracranial pressure values distinguished between good and poor outcome only at termination of intracranial pressure therapy. Somatos ensory evoked potential results did not predict outcome. Conclusions: Shortly after manifestation of supratentorial mass lesions, the result s of evoked potentials and clinical parameters indicate increased intr acranial pressure and incipient transtentorial herniation but do not p redict sequelae. Our results indicate that after institution of effect ive therapy, pupillary abnormalities and brainstem auditory evoked pot entials serve as valuable prognostic predictors, In contrast, somatose nsory evoked potentials reflect neither therapeutic efficacy nor outco me in our patient population.