Involvement of respiratory muscles in adult-onset dystonia: a clinical and electrophysiological study.

Involvement of respiratory muscles is unusual in dystonia, but its occurrence may be underestimated either because it is not conspicuous or because it is improperly imputed to another cause. Three patients who had adult-onset dystonia and who were exhibiting respiratory problems were examined clinically and electrophysiologically. In the three patients the onset was focal-cervical in two and blepharospasm in one. The respiratory problems appeared later. The first patient had involuntary deep and loud inspirations combined with spasms of axial dystonia, the second complained of breathing arrests, and the third had deep inspirations mainly on speaking or reading aloud, thus causing broken speech. Electromyographic findings, including of the diaphragm, were quite consistent with a respiratory involvement in these three cases of dystonia. Assuming that respiratory troubles could be in the first sign of a focal dystonia, electrophysiological studies of respiratory muscles could be used to confirm this.