Objective: To describe the response of hyperkinetic dystonia in four pediatric patients with dyskinetic CP to combined DBS stimulation in thalamus and pallidum.

Background: Dystonia in dyskinetic CP consists of both hypertonic and hyperkinetic components.  Clinically, both fixed inserted postures (hypertonic) and variable inserted movements (hyperkinetic) are triggered by attempts at voluntary movement.  In our experience, stimulation in globus pallidus internus (GPi) alone can ameliorate hypertonic components but has more limited effect on hyperkinetic components.

Method: Retrospective chart review and video analysis was performed on four pediatric cases of dyskinetic CP and significant hyperkinetic dystonia who underwent DBS surgery. Videos from pre-operative and six-month follow-up visits were rated on the Burke-Fahn-Marsden dystonia rating scale (BFMDRS) which is sensitive to both hyperkinetic and hypertonic dystonia, as well as the Unified Dystonia Rating Scale (UDRS) which is more sensitive for the hyperkinetic components of dystonia. Additionally, we used UDRS scale to rate improvement in hyperkinetic dystonia of upper and lower limbs following the initial thalamic programming visit.

Results: All patients had DBS implanted in bilateral GPi, as well as varying subnuclei of the thalamus, Vo, VA, or Vim according to preoperative depth electrode evaluation of efficacy.  The average reduction in dystonic symptoms was 19% on the BFMDRS.  Pre-operatively, hyperkinetic components were evident in all four patients in the upper extremities. Reduction in the upper extremity component of the UDRS at 6 months was on average 53% across all subjects, which is significant for this test.  Furthermore, two subjects with pelvis/proximal leg hyperkinetic dystonia showed reduction in lower extremity hyperkinetic movements. In addition, we reviewed initial thalamic programming which showed improvement of the hyperkinetic component within minutes of initiating thalamic stimulation (in the absence of GPi stimulation) in all four patients with a significant reduction in the UDRS scale (53,7% on average).

Conclusion: Combined GPi and thalamic deep brain stimulation may have better efficacy in reducing hyperkinetic components of dystonia compared to GPi alone.  Controlled studies with a larger cohort of patients will be required to confirm this hypothesis.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/hyperkinetic-dystonia-in-dyskinetic-cerebral-palsy-responds-to-combined-dbs-stimulation-in-thalamus-and-pallidum/