A Case Study of Deafness-Dystonia-Optic Neuropathy & Treatments

Purpose: DDON, also known as Mohr-Tranebjaerg syndrome is an inherited disorder of an Xp22 mutation of the mitochondrial transport protein TIMM8A. This mutation leads to progressive dystonia, otic neuropathy, and visual disturbances. Most patients will progress to dementia by early adulthood. Methods: We report on a teenage male with DDON and the treatments he received at Cook Children’s Medical Center (CCMC). Results: A 15-year-old patient with a prior diagnosis of DDON presented to CCMC for treatment of worsening dystonia. He communicated by gesture and sign language, and relied on a iPad. His increasing dystonia made him incapable of communicating effectively, particularly dystonia of the upper extremities. He was was previously treated with botulinum toxin chemodenervation, however, that treatment had lost efficacy as a relief of dystonia. He received Deep Brain Stimulation (DBS) of the globus pallidus internus (GPi). Since receiving DBS implants, several programming adjustments have been made and have led to a decrease in severity of symptoms. The patient was also started on a trial of baclofen to decrease muscle dystonia. Following a good response to trial, the patient was implanted with an intra-thecal baclofen pump (ITB) to decrease the dystonia of the trunk and lower extremities that had progressed. Over five years of treatment, scores on disability scales such as the Burke-Fahn-Marsden dystonia scale have slowly worsened as the disease has progressed. Concern was expressed about efficacy of the treatment, so a trial of observed time without DBS was performed. Marked worsening of disability was noted, showing that therapy has slowed the progression of this patient’s disease. Future care includes monitoring of DBS implants and transitioning care to another provider closer to the patient’s home. Conclusions: This is the fourth known case of DBS used in DDON treatment. This is also the first reported combination of ITB and DBS. Compared to other cases, this patient’s outcomes with DBS have not been as marked, due to some unique brain anatomy. ITB is a unique treatment for DDON and has shown some of the most efficacious results for this patient.