[Usefulness and limitations of polymygraphic recordings in dystonia].
BACKGROUND
Diagnosis of dystonia is based on well-known clinical findings, but electrophysiological explorations can help to establish the diagnosis.


METHODS
We report 179 patients presenting primary or secondary dystonia. Polymyographic recordings were available for all. We studied activation patterns of agonist and antagonists muscles (prolonged bursts, co-contraction), presence of antagonistic gestures and other associated movement disorders such as tremor or myoclonus.


RESULTS
83.9 percent of patients presented abnormalities which evoked dystonia (prolonged bursts: 75.3 percent, co-contraction: 48.7 percent, successful antagonistic gesture successful with reduction or suppression of EMG activity, 8.7 percent). For the patients who presented no EMG abnormality, diagnosis was maintained in 22 cases because of the limitations of the exploration: intermittent symptoms, dystonia involving deep muscles which were not recorded by the surface electromyogram, or difficulties to reproduce the conditions of apparition of the dystonic symptoms during examination or to recognize a pathologic EMG pattern in hand cramps for instance. Another diagnosis was retained because of the polymyographic findings in 16.2 p.cent of these patients, particularly those who had tremor associated with dystonia (essentially diagnosis of primary writing tremor).


CONCLUSIONS
Polymyography is an effective tool for confirming clinical findings.
Service de Neurologie et Pathologie du Mouvement, Clinique Neurologique, CHRU, Lille.
A
A
Delval
P
P
Krystkowiak
F
F
Cassim
L
L
Skrzypzak
A
A
Destée
P
P
Derambure
L
L
Defebvre
D000328:Adult; D004421:Dystonia / Q000175:diagnosis* / Q000503:physiopathology; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology; D009207:Myoclonus / Q000503:physiopathology; D009213:Myography; D012189:Retrospective Studies; D014103:Torticollis / Q000503:physiopathology; D014202:Tremor / Q000503:physiopathology