Isolated transient myoclonus in the elderly: an under-recognized condition?
BACKGROUND
Cases of transient myoclonus without other neurological manifestations in the elderly have very rarely been reported.


OBJECTIVE
To report clinical features of elderly people with isolated transient myoclonus.


METHODS
Clinical and laboratory features of 11 consecutive patients with isolated transient myoclonus (six men and five women; mean age, 75 years) were reviewed. Transient myoclonus was defined as an acute onset of tremulous myoclonus with/without asterixis in adults without other neurological symptoms.


RESULTS
Preceding infections were recorded in five patients (pneumonia, two; upper respiratory tract infection, two; and septic arthritis of the shoulder, one). Myoclonus predominantly affected the head and/or neck (n=10) and upper extremities (n=11), compared with the trunk (n=2) and lower extremities (n=6). Asterixis was observed in six patients. Laboratory testing, neuroimaging, and electroencephalograms revealed no specific abnormalities. With or without treatment using benzodiazepines, myoclonus in all patients resolved completely within 1-4 days, although five had recurrence 2-19 months after their first episodes. Among these five patients, the accompanying asterixis patterns (presence or not) in four were different in the first and subsequent episodes.


CONCLUSIONS
Isolated transient myoclonus with or without asterixis may be more common than generally believed, and it could be a clinical entity or disease spectrum. Transient myoclonus is a benign condition in the elderly, but can be under-reported or misdiagnosed. Therefore, it is important to recognize that the elderly may have this syndrome.
Department of Neurology, Chiba Rosai Hospital, Chiba, Japan. Electronic address: hiragaa@yahoo.co.jp.
Akiyuki
A
Hiraga
Department of Neurology, Chiba Rosai Hospital, Chiba, Japan.
Ikuo
I
Kamitsukasa
Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan.
Satoshi
S
Kuwabara
D000368:Aged / Q000523:psychology*; D000369:Aged, 80 and over; D000927:Anticonvulsants / Q000627:therapeutic use; D001569:Benzodiazepines / Q000627:therapeutic use; D020820:Dyskinesias / Q000209:etiology; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009207:Myoclonus / Q000175:diagnosis* / Q000209:etiology; D059906:Neuroimaging; D012008:Recurrence
D000927:Anticonvulsants; D001569:Benzodiazepines
Asterixis; Elderly; Myoclonus