title: Change in the pattern of cervical dystonia might be the cause of benefit loss during botulinum toxin treatment.
abstract: The muscular patterns of cervical dystonia were identified by polymyographic recordings in 76 patients before botulinum toxin treatment. The leading muscles were considered to be those which started dystonic movement and which showed constant and maximal activity during all dystonic movements. The dystonic muscles were repeatedly treated by local Injections of botulinum toxin. Sixteen patients showed (after repeated injections) loss of the benefit of local applications of botulinum toxin after various periods of time. Repeated polymyographic recordings were performed in these patients during the loss of the benefit of injected botulinum toxin. In four patients repeated polymyographic recordings showed an Identical pattern of cervical dystonia, but the activity of previously injected muscles was apparently decreased. In 12 patients only minimum or no activity was recorded in muscles which had previously been treated with botulinum toxin, but the pattern of cervical dystonia was changed. Different patterns of cervical dystonia with different leading muscles, but with identical directions of head deviation, were observed in six patients. In another six patients, the head deviation direction was to the opposite side and was accompanied by a change of the leading muscle and a change of the muscular pattern of dystonia. These results suggest either that dystonic activity from the cerebral generator changes to new effectors during the peripheral blockade of primary dystonic muscles, or that a change of generators at different levels of the CNS occurs. It may be neccessary to carry out repeated polymyographic recordings throughout the period of loss of benefit of previously successful local botulinum toxin injections.
authors.affiliation: Masaryk University, 1st Department of Neurology, Sv. Anna Faculty Hospital, Brno, Czech Republic.
authors.forename: P
authors.initials: P
authors.lastname: Kaňovský
authors.forename: J
authors.initials: J
authors.lastname: Dufek
authors.forename: H
authors.initials: H
authors.lastname: Halačková
authors.forename: I
authors.initials: I
authors.lastname: Rektor