Prospective evaluation of the prognostic significance of evoked potentials in acute basilar occlusion

Abstract

Objective: To establish valid prognostic parameters in patients with acute basilar artery occlusive disease.

Design: A prospective study.

Setting: Neurocritical care unit at the University of Heidelberg.

Patients: Twenty-three patients (12 male, 11 female; 32 to 69 yrs of age, median 54) with acute basilar occlusions.

Interventions: Angiography, brainstem auditory and somatosensory evoked potentials.

Measurements and main results: Clinical and electrophysiologic data were obtained before angiography and thrombolytic therapy. Outcome was classified according to a slightly modified Glasgow Outcome Scale at discharge from the intensive care unit (ICU). Level of consciousness was determined in four classes: awake (n = 4); somnolence (n = 7); stupor (n = 4); and coma (n = 8). Bilateral recordings of brainstem auditory and somatosensory evoked potentials were ranked in three categories: normal; one side normal; and both sides abnormal. Of 23 sets of evoked potential recordings, brainstem auditory evoked potentials were normal in seven patients, one side abnormal in four patients, and both sides abnormal in 12 patients. Somatosensory evoked potentials were normal in eight patients, one side abnormal in eight patients, and both sides abnormal in seven patients. A combination of both evoked potential modalities demonstrated normal results in three patients, one side abnormal recordings in six patients, and both sides abnormal findings in 14 patients. Outcome was ranked in three groups: five individuals had a good recovery or moderate disability; two patients remained severely disabled; and 16 patients persisted either in a locked-in state or died. Statistical analysis using Fisher's exact test demonstrated a significant correlation between the initial brainstem auditory evoked potential findings and outcome (p < .005), while for the initial somatosensory evoked potentials a significant correlation with outcome was not identified (p = .089). All patients with normal brainstem auditory and somatosensory evoked potential findings did well, whereas all patients with bilateral (both sides) abnormal brainstem auditory evoked potential and bilateral abnormal somatosensory evoked potential remained locked-in or died.

Conclusion: Initial brainstem auditory evoked potential and somatosensory evoked potential testing are valid prognostic parameters on which to base therapeutic decisions in patients with acute basilar occlusion.