Clinical and laboratory characteristics of focal laryngeal dystonia: study of 110 cases.

Spastic dysphonia is a syndrome often producing a strain-strangle voice. We have previously classified most of these patients as having focal laryngeal dystonia, a disorder of central motor processing. In a study of 1,280 cases of dystonia registered at the Dystonia Clinical Research Center at the Columbia-Presbyterian Medical Center, we found 110 patients who had vocal cord involvement. These patients had historical information evaluated for age of onset (mean 34.6 years), duration of symptoms (mean 13.8 years), sex (1.4:1 female to male) family history (positive in 23%), and primary (66%) and secondary (34%) etiology; neurological evaluation for other dystonic involvement (25% with segmental cranial involvement, 23% with generalized dystonia) or tremor (irregular 23%, regular 6% on EMG). Treatment options were evaluated and included speech therapy, psychotherapy, biofeedback (with limited success), systemic medication (limited success except in abductor cases), nerve section (with late failure rate), and the use of botulinum toxin (improvement in all 34 injected patients).