Focal task-specific lower extremity dystonia associated with intense repetitive exercise: a case series.
BACKGROUND
Focal task-specific dystonia of the lower extremity associated with intense repetitive exercise has recently been recognized. The clinical course, treatment response and prognosis remain poorly understood.


METHODS
Individuals with lower extremity task-specific dystonia evaluated at UCSF's Movement Disorders Center (2004-2012) were eligible for this descriptive case study series if he/she had a history of strenuous and prolonged exercise involving the lower extremity and had no abnormal neurological or medical conditions to explain the involuntary movements. Data was gathered from the medical history and a self-report questionnaire. The findings were compared to 14 cases previously reported in the literature.


RESULTS
Seven cases (4M/3F) were identified with a diverse set of exercise triggers (cycling, hiking, long-distance running, drumming). The mean age of symptom onset was 53.7 ± 6.1 years. The median symptom duration prior to diagnosis was 4 (9.5) years. Several patients underwent unnecessary procedures prior to being appropriately diagnosed. Over a median of 2 (3.5) years, signs and symptoms progressed to impair walking. Seven patients had improvement in gait with treatment (e.g. botulinum toxin injections, benzodiazepines, physical therapy, bracing, body weight supported gait training and/or functional electrical stimulation of the peroneal nerve) and six returned to a reduced intensity exercise routine.


CONCLUSIONS
Isolated lower extremity dystonia associated with strenuous, repetitive exercise is relatively uncommon, but disabling and challenging to treat. The pathophysiology may be similar to task-specific focal dystonias of the upper limb. Prompt recognition of leg dystonia associated with extreme exercise could minimize unnecessary testing and procedures, and facilitate earlier treatment.
Department of Neurology, University of California, San Francisco, 1635 Divisadero Street, 5th floor Suites 520-530, San Francisco, CA 94115, USA. Electronic address: maya.katz@ucsfmedctr.org.
Maya
M
Katz
Nancy N
NN
Byl
Marta
M
San Luciano
Jill L
JL
Ostrem
D000368:Aged; D020821:Dystonic Disorders / Q000175:diagnosis* / Q000209:etiology* / Q000503:physiopathology; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D035002:Lower Extremity / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D005082:Physical Exertion / Q000502:physiology
Botulinum toxin; Dystonia; Exercise; Focal dystonia; Task-specific