Neurophysiologic evaluation of patients with cervical spondylotic myelopathy

Abstract

BackgroundCervical spondylotic myelopathy (CSM) is a neurodegenerative disease caused by repetitive spinal cord damage that has resulted in significant clinical morbidity. The clinical evaluation of signs and symptoms, as well as neuroimaging and several neurophysiological tests, are used to make the diagnosis.ObjectivesTo investigate changes in the cutaneous silent period (CuSP), cortical silent period (CoSP), and H-reflex in CSM patients, and to correlate these tests with the Japanese Orthopedic Association (JOA) score and Nurick’s grading, as well as to determine the diagnostic value of each of them.MethodsTwenty patients (14 males and 6 females) with CSM were clinically diagnosed and documented by magnetic resonance imaging (MRI), and they were paired with another 20 healthy volunteers (13 males and 7 females) as a control group. CuSP, CoSP, and H-reflex tests were performed on both groups.ResultsIn CSM patients, CuSP latency and duration are substantially longer and shorter in CSM patients, respectively. The degree of changes in CuSP latency is well correlated with the severity of the disease. Further, CoSP duration is significantly shortened. The H-reflex parameters did not differ significantly between the patient and control groups.ConclusionThe shortened CoSP’s duration and the prolonged CuSP's latency suggest malfunction of the inhibitory and excitatory circuits in the spinal cord. The CuSP is more sensitive and specific than the CoSP in the diagnosis of a patient with CSM.