Transient myoclonic state with asterixis presenting as persistent hyperperfusion on single-photon emission computed tomography: A case report

Abstract

Transient myoclonic state with asterixis is characterized by sudden onset generalized myoclonus and asterixis without consciousness impairment. Electrophysiological studies have shown that myoclonus correlates with cortical hyperexcitability localized in the primary motor cortex during the symptomatic period. However, it is unclear whether this excitability remains in the asymptomatic period. Here, we report a 79-year-old Japanese man who presented with transient myoclonic state with asterixis. He had been diagnosed with progressive non-fluent aphasia and he suffered from rhythmic myoclonus; predominantly in the neck, shoulders and upper extremities. Asterixis was observed in the forearms. Brain 123I-iodoamphetamine single-photon emission computed tomography showed focal hyperperfusion in the bilateral precentral gyri even at 3 months after remission of the myoclonus. These data suggest that cortical hyperactivity was persistent without symptoms and led to transient myoclonic state with asterixis, which could have been due to the underlying neurodegenerative disorder of progressive non-fluent aphasia.