Objective: This review analyses the prevalence of painful dystonia in a cohort of children undergoing neuromodulation. The aim was to better understand the dystonic pain experience and evaluate improvements one year following initiation of deep brain stimulation (DBS) therapy.

Background: Dystonic pain is reported as prevalent in genetic, acquired and idiopathic dystonic conditions. However, it is yet to be systematically evaluated. There is an overall paucity of literature evaluating the effect of DBS on dystonic pain using validated, reliable methods. The methods that have been used in the literature are varied and at times inappropriate for the population being assessed.

Methods: Dystonic pain was assessed in a cohort of children (n=144) undergoing DBS. Assessment was multi-modal, six different pain assessment methods were used: intensity (proxy- Paediatric Pain Profile- PPP and self-report – Numerical Rating Scale – NRS); parental perception (CPCHILD questionnaire); pain frequency, pain severity and analgesia use. SPSS version 21 was used to analyse both the whole cohort, and separately, by etiological sub-classification; inherited DYT-positive dystonias (n=8), inherited heredodegenerative dystonias (n=9), acquired dystonias (n=37) including Cerebral Palsy (n= 21) and idiopathic dystonias (n= 8).

Results: We found that 44.5% (63/144) of this DBS cohort reported dystonic pain. Pain improved after DBS surgery in each group. Clinically significant improvements P<0.001 were noted in the whole cohort, using NRS (n=27), PPP (n=17/63) and the CPCHILD (n=48/63) assessments. Subjective reductions in frequency and severity were also reported. Very severe pain fell in 9/28 (30%) cases. Constant pain fell from 27/63 to 11/63 cases, a 40.7% reduction, and 18/63 (28.6%) became pain-free. We found a 40% reduction in children receiving daily medications and an increase of 46.1% not requiring analgesia. Whole cohort findings were comparable to results in the etiological sub-classifications, except the heredodegenerative group, where subjective improvements were noted only.

Conclusions: This is the first evaluation focusing on the impact of DBS surgery on dystonic pain in children. The multi-assessment approach in pain research reduces the risk of bias in an otherwise complex population, both to assess and to treat. Longitudinal data collection and the consideration of a multi-center research project would improve validity and reliability further. A reduction in dystonic pain should remain a goal for DBS surgery, particularly given the relationship between pain and poor quality of life, social isolation, self-perception and overall poor health status.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/dbs-neuromodulation-reduces-severe-dystonic-pain-in-children-and-young-people/