Supplementary Material for: Long-Term Follow-Up with Video of a Patient with Deafness-Dystonia Syndrome Treated with DBS-GPi
Background: The prevalence of deafness-dystonia syndrome (DDS) is relatively low. To our knowledge, only 2 cases of this syndrome treated with deep brain stimulation (DBS) have been reported. Objectives: We present a patient with DDS of unknown cause, refractory to medical treatment, who has been successfully treated with DBS of the internal globus pallidus (DBS-GPi) and followed up for 4 years. Methods: A 21-year-old male, with progressive bilateral sensorineural hearing loss since the age of 3, developed dystonic movements at the age of 12. The patient presented with progressive segmental craniocervical dystonia with jaw-opening, tongue protrusion, retrocollis and gradual overflow including upper limb dystonia. Pharmacological therapy was ineffective. At the age of 17, the patient's condition deteriorated with the risk of developing a dystonic state. Results: DBS-GPi implantation resulted in a striking improvement. The Burke-Marsden-Fahn Dystonia Rating Scale (BMFDRS) score improved from 75 points before the surgery to 10 points at 3 months after DBS-GPi implantation. Neurological examination at the age of 21 showed mild dystonic movements, mainly oromandibular dystonia (BMFDRS: 15 points). The clinical phenotype of our patient was consistent with Mohr-Tranebjaerg syndrome (MTS). We performed genetic analysis of the TIMM8A gene (the only gene in which mutations are known to cause MTS), but the result was negative; however, other potentially new mutations have to be considered. Conclusions: Based on our case with the longest reported follow-up of 4 years and 2 earlier reports, we advise to consider DBS-GPi in patients with DDS with unsatisfactory effect of pharmacological treatment.