Paroxysmal kinesigenic dyskinesia associated with a pathogenic variant in the PRRT2 gene: a case report

Case presentation: A 16-year-old male presented with a 1-year history of involuntary movement attacks in his right members that last up to 15 seconds and occur 20 to 30 times daily. He denied having loss of sensitivity, sphincter relaxation, or tongue biting during episodes. Pain was not reported, and conscious level remains unaltered. Systems inquiry was unrevealing. He denied a family history of similar symptoms but his mother was diagnosed in adolescence with migraine with aura. The patient had no previous diagnosed pathology, comorbidities, previous surgeries, or is taking any medications. His vaccines were up-to-date. Upon evaluation, he was found to have dystonic findings triggered by sudden muscle movements. MRI of the brain was normal. He was treated with 2mg trihexyphenidyl once daily, after which there was a partial improvement of dystonia, but no change was seen in attack frequency. A karyotype revealed a mutation in the PRRT2 gene, suggesting a diagnosis of paroxysmal kinesigenic dyskinesia. Then, he initiated 200mg carbamazepine once daily, resulting in a complete reduction of attacks and dystonia. Discussion: Paroxysmal kinesigenic dyskinesia is a rare movement disorder characterized by sudden involuntary movements affecting one side of the body (unilateral) or both sides (bilateral). Diagnostic criteria require a (1) triggering factor, (2) attacks during less than a minute, (3) unaltered consciousness and no pain during episodes, (4) age of onset of symptoms between 1 and 20 years of age, and (5) clinical response to anticonvulsants. The karyotype was suggested because of PRRT2 heterozygous mutations being associated both with migraine and paroxysmal movement disorders. The identification of the mutation was characterized by a dominant pattern, that is, the allele probably was inherited from the patient’s mother, whose partial presence originated the migraine with aura. Final comments: This case report contributes to the understanding of the correlation between paroxysmal kinesigenic dyskinesia (PKD) and migraine with aura. The identification of a heterozygous mutation in the PRRT2 gene in the patient, along with the maternal history of migraine with aura, suggests a potential genetic link between these two neurological conditions. These finding underscores the importance of genetic research in the diagnosis and treatment of neurological disorders, enabling a more precise approach and faster diagnosis.