MOTOR AND COGNITIVE FUNCTIONS IN CHILDREN WITH GENERALIZED DYSTONIA AFTER PALLIDAL DEEP BRAIN STIMULATION

Introduction: Deep Brain Stimulation of Globus Pallidus Internus (DBS-GPi) was proposed as valid treatment option in pediatric dystonia refractory to medical therapy. Efficacy on motor symptoms is enough demonstrated while effects on cognitive functions are poorly studied. Development of neurostimulation systems with new deep electrode configurations might result in more effective stimulation. Materials and methods: We studied motor and non-motor effects of multicontact neural interface systems for DBS- Gpi in 9 patients affected by drug-resistant generalized dystonia. We use Burk-Fahn-Marsden Dystonia Rating Scale (BFMDRS) and Subjective Benefit Rating Scale (SBRS) to assess improvement rate on motor fitnctions and comfort, and Wechsler Intelligence Scale for Children (WISC-IV) with its 4 main domains to assess changes on cognitive functions. We implanted two rechargeable DBS systems, Activa RC Medtronic in 6 patients and Vercise Boston Scientific in 3 patients, respectively connected to 12 circumferential electrodes and 6 directional electrodes. Results: At 6-month follow-up average of BFMDRS motor subscore and BFMDRS disability subscore showed respectively improvement of 75% and 70% which reached 82% and 77% at 12-month follow-up. SBRS indicated mean subjective benefit as good which remained stable at 12-month follow-up. There was greater improvement in BFMDR movement and disability scores as well as SBRS score in 6 patients with primary dystonia. Most successful result appeared in DYT1+ children. Side effects occurred in 3 patients with circumferential electrodes. No patients had deterioration of cognitive functions at WISC-IV and at 4 main domains; 2 patients implanted with directional electrodes had mild improvement in executive functions. Conclusion: GPi-DBS is effective for motor function in pediatric patients with drug-resistant dystonia and does not adversely affect cognitive functions. Improvement on motor symptoms increases over time. Directional electrodes allow better results and less side effects. Studies with a larger number of patients are needed to better define the potential effects on cognitive functions and repercussions on the evolutionary trajectory.