Outcomes of deep brain stimulation surgery in the management of dystonia in glutaric aciduria type 1.

Objectives: Glutaric aciduria type 1 (GA1) is a rare autosomal recessive organic acidaemia caused by deficiency of the glutaryl-CoA dehydrogenase enzyme. We describe the outcomes following deep brain stimulation (DBS) for the management of dystonia of children and adults with glutaric aciduria type 1 (GA1).

Methods: Cases with GA1 were identified from the institutional databases of two tertiary movement disorder services. Data were extracted from clinical records using a standardised proforma, including baseline clinical characteristics, imaging and neurophysiological findings, complications post-surgery, and outcomes as measured by the Burke-Fahn-Marsden Dystonia Rating Scale (BMFDRS) motor scores and the Canadian Occupation Performance Measure (COPM).

Results: A total of 15 children were identified aged 3-17.5 with a median age of 11.5 years at neurosurgery, and one adult undergoing DBS aged 31 years. Baseline BMFDRS motor score ranged from 58.5-114, median 105. GMFCS-equivalence level was 5 (i.e. non-ambulant) for 10/16 cases. Surgery was tolerated in all cases without evidence of metabolic decompensation. BFMDRS motor score 1-year post-surgery ranged from 57.5-108.5 (median 97.25) and at last follow-up 57.5-112 (median 104) (no statistically significant change compared to baseline at either time point, P > 0.05). COPM data were available for 11/13 children and young people (CAYP). Clinically significant improvement was reported in 7/11 at 1 year and 8/11 at last follow-up. Four CAYP transitioned to adult services. Death occurred in three cases during follow-up, in no case related to DBS.

Conclusion: DBS may be considered as a management option for children with GA1 who have appropriately selected goals for intervention.