Supplementary Material for: Successful Treatment of a Paroxysmal Kinesigenic Dyskinesia Patient with Carbamazepine-Induced Stevens-Johnson Syndrome Using Oxcarbazepine Monotherapy: A Case Report

Paroxysmal kinesigenic dyskinesia (PKD) is a rare condition characterized by abnormal involuntary movements that are precipitated by a sudden movement. PKD is often misdiagnosed with psychogenic movement disorders. Carbamazepine is usually the first choice of medication due to its well-established evidence but could induce Stevens-Johnson syndrome. We report a 21-year-old male patient with PKD referred to our movement disorders clinic after being misdiagnosed with conversion syndrome. PRRT2 gene testing using next-generation sequencing revealed a mutation in c.649dupC p. (Arg217fs). The patient responded well to carbamazepine but had to withdraw the treatment due to carbamazepine-induced Stevens-Johnson syndrome after 3 weeks of medication. Our patient did not respond to trials of levetiracetam and phenytoin but finally responded well to oxcarbazepine. The patient was followed up for 4 years, during which he had no attacks and no side effects. Here, we present a PKD case with carbamazepine-induced Stevens-Johnson syndrome successfully treated with oxcarbazepine despite the risk of cross-reactive skin eruption between these antiepileptics. Careful history taking and examining patient’s attacks are crucial to accurate diagnosis and treatment in PKD patients.

发作性运动诱发性运动障碍（Paroxysmal kinesigenic dyskinesia, PKD）是一种罕见疾病，以突发运动诱发的异常不自主运动为主要特征。该病常被误诊为心因性运动障碍。卡马西平因循证证据充分，通常作为PKD治疗的首选药物，但可能诱发史蒂文斯-约翰逊综合征（Stevens-Johnson Syndrome）。
本文报告1例21岁男性PKD患者：该患者曾被误诊为转换综合征，后转诊至我院运动障碍专科门诊。采用下一代测序技术进行PRRT2基因检测，结果显示其存在c.649dupC p.(Arg217fs)突变。患者初始对卡马西平治疗应答良好，但用药3周后因出现卡马西平诱导的史蒂文斯-约翰逊综合征而不得不停药。后续尝试左乙拉西坦与苯妥英钠治疗均无应答，最终奥卡西平治疗取得满意效果。
患者随访时长达4年，随访期间未再出现运动障碍发作，亦未发生任何不良反应。本文报道的这例PKD患者，在使用卡马西平治疗期间出现史蒂文斯-约翰逊综合征，尽管两类抗癫痫药物存在交叉皮肤不良反应风险，但经奥卡西平替代治疗后成功控制病情。对于PKD患者而言，详尽的病史采集与发作特征评估是实现精准诊断与个体化治疗的关键。