Clinical and nerve electrophysiological features of patients with propriospinal myoclonus: A report of 5 cases

Objective To investigate the clinical and nerve electrophysiological features of patients with propriospinal myoclonus (PSM), and to improve the understanding of this disease. Methods A retrospective analysis was performed for the medical records of five patients with PSM who were treated at Electroencephalogram Monitoring Center of our hospital from July 2019 to September 2021. Their clinical and nerve electrophysiological features were summarized, and they were followed up to observe the efficacy of drug treatment. Results All fivepatients met the diagnostic criteria for PSM, among whom there were three male patients and two female patients, with involuntary myoclonus of the body as the main symptom. The age of onset of PSM ranged from 28 to 50 years. There were three patients with idiopathic PSM and two with secondary PSM. All five patients underwent video electroencephalography (V-EEG) and electromyography examinations, and no abnormal discharges were observed du-ring the ictal period, while only electromyographic artifacts were observed. Myoelectricity mainly originated from the abdomen and the trunk, with a conduction velocity of 1.4-13.7 m/s and a burst duration of 100-1 000 ms. Medications such as clonazepam could effectively reduce myoclonic seizuresin PSM patients. Conclusion Understanding the clinical and nerve electrophysiological features of PSM is the key to its diagnosis. V-EEG is an important basis for the differential diagnosis of PSM, characterized by the absence of abnormal discharges during the ictal period and the presence of myoclonic electromyographic bursts on electromyography. Clonazepam has a good therapeutic effect on the symptoms of PSM.