ObjectiveTo explore the correlation between the functional status of upper limb motor neurons and motor function in stroke patients, and provide guidance for rehabilitation assessment and functional prognosis.MethodsThe stroke patients who were hospitalized in Department of Rehabilitation Medicine of Zhongda Hospital of Southeast University between November 2020 and January 2021 were selected. Motor unit number estimation (MUNE) and F wave were examined to evaluate the functional status of motor neuron. The Fugl-Meyer Assessment (FMA) and Modified Ashworth Scale (MAS) were used to evaluate the upper limb motor function. The correlations of electrophysiological parameters with FMA score and MAS score were analyzed respectively.ResultsA total of 42 patients were enrolled, and 16 patients were complicated with carpal flexor spasm on the affected side. Among the 42 stroke patients, the MUNE of the abductor pollicis brevis on the affected side was lower than that on the unaffected side (t=−3.466, P=0.001), and the percentage of F waves with different shapes on the affected side was significantly lower than that on the unaffected side (Z=−5.583, P<0.001). Among the 16 stroke patients with carpal flexor spasm, the F wave amplitude was higher on the affected side than that on the unaffected side (t=2.764, P=0.014), while the F wave latency on the affected side was not statistically significant compared with the unaffected side (Z=−0.595, P=0.552). Among the 42 stroke patients, the affected/unaffected side ratio of the percentage of F waves with different shapes was positively correlated with FMA score (rs=0.377, P=0.014), while the correlation between the affected/unaffected side ratio of MUNE and FMA score was not statistically significant (rs=0.104, P=0.513). Among the 16 stroke patients with carpal flexor spasm, the affected/unaffected side ratio of the F wave amplitude was positively correlated with the MAS score of the carpi flexor muscle (rs=0.550, P=0.027).ConclusionStroke may result into the number of functional motor neurons of the upper limbs of the hemiplegic side decreased and the excitability of motor neurons increased simultaneously, and which were related to motor function and muscle tone.