Somatosensory-Evoked Potentials and Clinical Assessments of Sensory Function Over Time in Patients With Subacute Stroke.

Objective: To demonstrate the utility of somatosensory evoked potentials (SEPs) following median nerve stimulation for chronological assessment of sensory function in patients with subacute stroke during rehabilitation. Design: Retrospective study. Patients: Forty-seven patients with hemiparesis due to stroke during the subacute phase. Methods: We screened 363 patients who underwent SEP measurements at a rehabilitation hospital. Among them, 47 who underwent SEP measurements within 1 week after admission and at least 2 weeks after the initial assessment were included in this study. Sensorimotor assessments, including the Semmes-Weinstein monofilament test (SWMT), pain sensation, position sensation, two-point discrimination, and Stroke Impairment Assessment Set (SIAS) motor tests simultaneously with SEP measurements were available for 20 of the 47 patients. The relationship between the SEP peak count and each sensorimotor assessment was examined. Results: SEP amplitudes and latencies showed no significant differences between the initial and second assessments (paired t-test, p  > 0.05). However, the counts of SEP peaks after NI (N20) increased (Wilcoxon signed-rank test, p  < 0.05), indicating changes in the SEP waveform. Furthermore, strong correlations were observed between SEP peak counts, stage, and all functional assessments (counts and SWMT, RS = -0.77, p < 0.001; counts and pain sensation, RS = -0.71, p < 0.001; counts and position sensation, RS = 0.75, p < 0.001; counts and two-point discrimination, RS = -0.74, p < 0.001; stage and SWMT, RS = -0.74, p < 0.001; stage and pain sensation, RS = -0.69, p < 0.001; stage and position sensation, RS = 0.74, p < 0.001; and stage and two-point discrimination, RS = -0.75, p < 0.001; all Spearman's rank correlation coefficients). Conclusion: Despite the limitations of the retrospective study design, our study highlights the utility of SEPs for evaluating sensory function in patients with subacute stroke, setting the foundation for further investigations on the use of SEPs to assess functional changes in patients with subacute stroke undergoing rehabilitation.