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

Katsuya Kobayashi; Takefumi Hitomi; Riki Matsumoto; Masako Watanabe; Ryosuke Takahashi; Akio Ikeda

doi:10.1016/j.seizure.2018.07.014

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

Seizure. 2018 Oct:61:14-22. doi: 10.1016/j.seizure.2018.07.014. Epub 2018 Jul 19.

Authors

Katsuya Kobayashi¹, Takefumi Hitomi², Riki Matsumoto¹, Masako Watanabe³, Ryosuke Takahashi¹, Akio Ikeda⁴

Affiliations

¹ Department of Neurology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
² Department of Neurology, Kyoto University Graduate School of Medicine, Kyoto, Japan; Department of Respiratory Care and Sleep Control Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan; Department of Clinical Laboratory Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan. Electronic address: hitomi46@kuhp.kyoto-u.ac.jp.
³ Department of Psychiatry, National Center Hospital, National Center of Neurology and Psychiatry, Kodaira, Japan; Shinjuku Neuro Clinic, Tokyo, Japan.
⁴ Department of Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, Kyoto, Japan. Electronic address: akio@kuhp.kyoto-u.ac.jp.

PMID: 30053653
DOI: 10.1016/j.seizure.2018.07.014

Abstract

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.

Keywords: Cortical hyperexcitability; Cortical tremor; Epileptic seizure; Giant somatosensory evoked potential (SEP).

MeSH terms

Adult
Aged
Aged, 80 and over
Anticonvulsants / therapeutic use
Electroencephalography
Epilepsies, Myoclonic / complications
Epilepsies, Myoclonic / diagnosis*
Epilepsies, Myoclonic / drug therapy
Epilepsies, Myoclonic / epidemiology*
Evoked Potentials, Somatosensory / physiology*
Family Health*
Female
Health Surveys
Humans
Japan / epidemiology
Male
Middle Aged
Neuroimaging
Seizures / etiology
Surveys and Questionnaires
Tremor / etiology
Young Adult

Substances

Anticonvulsants