Contribution of initial median-nerve somatosensory evoked potentials and brainstem auditory evoked potentials to prediction of clinical outcome in cerebrovascular critical care patients: A statistical evaluation

In a prospective study of 200 patients with cerebrovascular disease (48 intracerebral hemorrhages, [ICH]; 64 subarachnoid hemorrhages, [SAH]; 38 supratentorial and 40 infratentorial ischemic strokes), we assessed the individual and combined prognostic value of median-nerve somatosensory evoked potentials (SEP) and brainstem auditory evoked potentials (BAEP) within 72 hours of admission. Clinical outcome was graded in three ranked categories according to a modified Glasgow Outcome Scale. Likewise, the initial SEP and BAEP findings were graded in a three-class score. In all groups, the SEP were significantly correlated with outcome (P < 0.01). Likewise, after partialling out the prognostic effect of SEP, the contingency between BAEP and outcome was statistically significant, except in ICH (P = 0.07). The contingencies of SEP and outcome in ICH and supratentorial infarcts were higher than the corresponding partial contingencies for BAEP, while the latter were higher in infratentorial infarction and SAH. Therefore, in all disease groups except for SAH, the multiple contingency coefficients ranging from 0.67 to 0.75 were statistically significant and greater than either simple or partial contingencies alone. The results of the two evoked potential modalities combined permit statistically significant superior prognostication in most cerebrovascular diseases when compared to those of either of the modalities alone.