Objective  To analyze the correlation between upper limb somatosensory evoked potential (SEP), peripheral nerve electrophysiological characteristics and motor function in patients with stroke.
Methods  Patients with subacute stroke admitted to the Department of Rehabilitation from June 2018 to March 2022 were consecutively included in this prospective study. SEP and peripheral nerve electrophysiological examination were performed on both upper limbs, which of the healthy and affected sides were compared, and motor function of the affected side was scored. The correlation of latent period of SEP P15, N20, P25, N13 and N9, sensory nerve conduction parameters, motor nerve conduction parameters of the hemiplegic upper limb and its motor function was analyzed.
Results  A total of 102 patients were included in this study, with an average age of (68.76±11.33) years and 78 males. The latent period of SEP P15[(16.90±1.67) ms vs.(16.27±1.50) ms, P<0.001], N20[(20.13±1.49) ms vs.(19.42±1.60) ms, P<0.001], P25[(24.39±1.75) ms vs.(23.70±1.50) ms, P<0.001], N13[(14.05±1.25) ms vs.(13.42±1.26) ms, P<0.001] and N9[(9.25±0.96) ms vs.(8.80±1.40) ms, P<0.001] of hemiplegic upper limb were greater than those of the healthy side. The  sensory nerve conduction velocity (SCV) [(48.93±6.82) m/s vs.(51.26±6.40) m/s, P<0.001] and amplitude [(22.54±9.91) μv vs.(32.71±17.68) μv, P<0.001] of median nerve (finger 1-wrist) of hemiplegic upper limb were lower than those of the healthy side; median nerve (finger 3-wrist) SCV[(49.26±7.31) m/s vs.(52.98±5.99) m/s, P<0.001] and amplitude [(24.71±11.39) μv vs.(38.57±20.21) μv, P<0.001] of hemiplegic upper limb were lower than those of the healthy side. The SCV[(48.72±7.46) m/s vs.(52.01±6.82) m/s, P<0.001] and amplitude [(19.51±11.35) μv vs.(25.74±13.44) μv, P<0.001] of ulnar nerve (finger 5-wrist) of hemiplegic upper limb were lower than those of the healthy side. The SCV[(54.53±6.06) m/s vs.(56.99±4.84) m/s, P<0.001] and amplitude [(11.37±6.04) μv vs.(14.53±7.89) μv, P<0.001] of ulnar nerve (superior wrist - elbow) of hemiplegic upper limb were lower than those of the healthy side.The motor nerve conduction velocity (MCV) [(54.79±4.89) m/s vs.(57.10±5.07) m/s), P<0.001] and amplitude [(8.42±3.85) μv vs.(10.00±3.72) μv, P<0.001] of median nerve (elbow-wrist) of hemiplegic upper limb were lower than those of the healthy side; the MCV[(53.12±6.81) m/s vs.(55.01±6.35) m/s, P<0.001] and amplitude [(6.89±2.56) μv vs.(8.78±2.26) μv, P<0.001] of ulnar nerve (superior wrist-elbow) were lower than those of the healthy side. The latent period of P15 (r=-0.358, P<0.001), N20 (r=-0.674, P<0.001) and P25 (r=-0.465, P<0.001) were negatively correlated with the Fugl-Meyer assessment upper extremity scale (FMA-UE) score. The amplitude of median nerve with electrode at finger 3-wrist was positively correlated with FMA-UE score (r=0.231, P=0.026), and the SCV of ulnar nerve with electrode at finger 5-wrist (r=0.292, P=0.006) and  at wrist - elbow (r=0.391, P<0.001) was positively correlated with the FMA-UE score; the amplitude of ulnar nerve with electrode at 5-wrist was positively correlated with the FMA-UE score (r=0.263, P=0.012); the MCV (r=0.22, P=0.037) and amplitude (r=0.223, P=0.034) of median nerve with electrode at elbow-wrist were positively correlated with the FMA-UE score; the MCV of ulnar nerve with electrode at superior wrist - elbow was positively correlated with the FMA-UE score (r=0.231, P=0.027) .
Conclusions  Stroke patients with hemiplegia are often accompanied by sensory conduction pathway injury and  peripheral nerve abnormality of hemiplegic upper limb, which are correlated with motor function of the affected side upper limb.