Case Report: Long-Term Suppression of Paroxysmal Kinesigenic Dyskinesia After Bilateral Thalamotomy

Background: Paroxysmal kinesigenic dyskinesia (PKD) is a movement disorder characterized by transient dyskinetic movements, including dystonia, chorea, or both, triggered by sudden voluntary movements. Carbamazepine and other antiepileptic drugs (AEDs) are widely used in the treatment of PKD, and they provide complete remission in 80–90% of medically treated patients. However, the adverse effects of AEDs include drowsiness and dizziness, which interfere with patients' daily lives. For those with poor compatibility with AEDs, other treatment approaches are warranted.Case Report: A 19-year-old man presented to our institute with right hand and foot dyskinesia. He had a significant family history of PKD; his uncle, grandfather, and grandfather's brother had PKD. The patient first experienced paroxysmal involuntary left hand and toe flexion with left forearm pronation triggered by sudden voluntary movements at the age of 14. Carbamazepine (100 mg/day) was prescribed, which led to a significant reduction in the frequency of attacks. However, carbamazepine induced drowsiness, which significantly interfered with his daily life, especially school life. He underwent right-sided ventro-oral (Vo) thalamotomy at the age of 15, which resulted in complete resolution of PKD attacks immediately after the surgery. Four months after the thalamotomy, he developed right elbow, hand, and toe flexion. He underwent left-sided Vo thalamotomy at the age of 19. Immediately after the surgery, the PKD attacks resolved completely. However, mild dysarthria developed, which spontaneously resolved within three months. Left-sided PKD attacks never developed six years after the right Vo thalamotomy, and right-sided PKD attacks never developed two years after the left Vo thalamotomy without medication.Conclusion: The present case showed long-term suppression of bilateral PKDs after bilateral thalamotomy, which led to drug-free conditions.

PRRT2 Gene Analysis of Paroxysmal Kinesigenic Dyskinesia (PKD) in Thai Children

Objective: To examine the frequency of the proline-rich transmembrane protein-2 (PRRT2) gene mutation in Thai patients with paroxysmal kinesigenic dyskinesia (PKD). Material and Methods: A retrospective study of children aged 0-18 years with a diagnosis of PKD at Siriraj Hospital. The genetic analyses of the PRRT2 gene were done by bidirectional Sanger sequencing.Results: Twelve patients with PKD were included. The known PRRT2 mutation, c.649dupC (p.Arg217Profs*8), was identified in three of the patients (25.0%), one of the nine sporadic cases (11.1%) and two of the three familial cases (66.6%), all from different families. PKD had a complete response to carbamazepine treatment regardless of PRRT2 mutation status. Conclusion: Our study provided the new details of the clinical phenotypes and PRRT2 gene analysis findings for Thai PKD. PRRT2 mutations were identified in our Thai PKD patients with increased detection rates in the familial PKD cases. The c.649dupC (p.Arg217Profs*8) was also found to be a hot-spot mutation in our Thai PKD patients. Furthermore, this study demonstrates the importance of PRRT2 gene analysis in order to properly diagnose and treat these patients.