Irregular Tremulous Movements and Infrequent Seizures: A Clinical-Electrophysiological Diagnosis of Benign Adult Familial Myoclonus Epilepsy.

We report a case involving a 31-year-old male without any known precipitating injuries presenting with involuntary finger movements and rare seizures. There was a noted family history of tremulous movements. Yet the characteristics of his finger movements were irregular and not typical of essential tremor (ET). Electrophysiological examinations, including video EEG, showed no epileptic discharges, and brain MRI results were normal. However, somatosensory evoked potentials (SEP) revealed the presence of giant SEP, and a positive cortical (C)-reflex was observed, leading to a clinical diagnosis of benign adult familial myoclonus epilepsy (BAFME). Management with valproic acid and perampanel resulted in a significant reduction of symptoms. This case highlights the necessity of considering BAFME in the differential diagnosis for atypical tremorous finger movements, especially with a relevant family history, and the critical role of electrophysiological findings indicative of cortical hyperexcitability.

[A case of idiopathic propriospinal myoclonus accompanied by giant somatosensory evoked potential].

A 41-year-old man visited our clinic because of headache with fever, suggestive of aseptic meningitis. His headache improved in a few days. His neurological examination showed positive jolt accentuation and myoclonus of the thoracoabdominal muscles extending to extremities upon patellar tapping. His myoclonus had been occurring spontaneously from early adolescence, especially in relaxed states such as drowsiness. The myoclonus was not triggered by tactile, auditory, or visual stimulation. Polymyography revealed that the myoclonus originated around the T4 spinal level and slowly propagated both upward and downward. These findings were indicative of spontaneous and reflex propriospinal myoclonus (PSM). No abnormalities were seen on brain and spinal MRI. Furthermore, the amplitude of the cortical component of the somatosensory evoked potential (SEP) after electrical stimulation of the tibial nerve was enlarged bilaterally. It was speculated that the ascending signals from the myoclonus generator at T4 to S1 may have modulated the excitability and inhibitory function of S1 in this patient. This report may be the first case of idiopathic PSM accompanied by giant SEP.

Long-term efficacy of low-dose perampanel for progressive myoclonus epilepsy in a patient with Gaucher disease type 3.

PURPOSE: We report the case of a patient with progressive myoclonus epilepsy due to Gaucher disease type 3 whose seizures and ability to perform activities of daily living were significantly improved after starting low-dose perampanel therapy. CASE: Our patient's generalized tonic-clonic seizures and myoclonus did not improve despite the administration of multiple antiseizure medications and enzyme replacement therapy. The myoclonus reduced following pharmacological chaperone therapy, but this effect was temporary, and the generalized tonic-clonic seizures continued to occur. However, the generalized tonic-clonic seizures disappeared following treatment with 2 mg/day of perampanel. In addition, the decrease in myoclonus dramatically improved motor function such as talking, eating, and walking and stabilized the patient's mental status. These effects have been sustained for more than 4 years. CONCLUSION: Perampanel is expected to be effective in the treatment of progressive myoclonus epilepsy associated with Gaucher disease type 3 and should be considered the drug of choice for this condition.

Nationwide survey in Japan endorsed diagnostic criteria of benign adult familial myoclonus epilepsy.

PURPOSE: Benign adult familial myoclonus epilepsy (BAFME) is an autosomal dominant disease representing tremulous myoclonus or cortical tremor and infrequent generalized seizures. We aimed to delineate detailed epidemiological backgrounds in patients with Japanese BAFME and to establish diagnostic criteria based on clinical and electrophysiological findings. METHODS: After a previous survey on the current nationwide state of myoclonus epilepsy of adults in Japan, we conducted this survey to delineate the clinical characteristics of Japanese BAFME patients, using a questionnaire to obtain details for individual patients. Based on clinical diagnostic criteria, we analyzed demographic and clinical characteristics of 101 BAFME patients in 74 families. RESULTS: BAFME patients were predominantly female and were widely distributed throughout Japan. Ninety-two patients (91.1%) showed signs of cortical tremor and 84 (83.2%) showed epileptic seizures. Epileptic seizures were infrequent in BAFME patients, but 22.6% of patients had more than one seizure per year at the maximum. Three patients (3.0%) showed cerebellar ataxia, eight (7.9%) showed cognitive impairment, and 13 (12.9%) had psychiatric symptoms. Brain MRI was normal in 74% of patients, and the remaining patients had non-specific abnormal findings. Sodium valproate and clonazepam were the primary drugs used for BAFME patients. The older patients showed significantly more severe and higher rates of abnormal electrophysiological results, which were suggestive of cortical hyperexcitability. CONCLUSION: Our study successfully delineated the overall clinical characteristics of Japanese BAFME. The correlation between the genetic, clinical, and electrophysiological results will be very important to further elucidate the pathophysiology and treatment of BAFME in the future.