Clinical phenotype analysis of paroxysmal kinesigenic dyskinesia

Background Paroxysmal kinesigenic dyskinesia (PKD) is a disorder characterized by recurrent and brief dystonic or choreoathetoid attacks that are induced by sudden voluntary movement with highly clinical and genetic heterogeneity. We aimed to investigate the clinical features of PKD in a large Chinese population. Methods One hundred and ninety five patients diagnosed as primary PKD were recruited. For all of the participants, neurological examinations were conducted and clinical manifestations were recorded and summarized in self - made uniform registration form for PKD patients. Clinical characteristics were statistically analyzed and compared between familial and sporadic PKD patients.  Results Among all of the 195 PKD patients in the present study, the gender ratio was 4.42∶1 (male∶ female). The average age of onset was (12.32 ± 3.49) years. There were 162 patients (83.08%) manifestated with pure form and 33 (16.92%) with complicated form of PKD. Among them 16 patients (8.21%) had essential tremor (ET), and 144 patients (73.85% ) had premonitory symptom. The percentage of patients manifested as dystonia, chorea and mixed form during episodic attacks were 68.72% (134/195), 4.10% (8/195) and 27.18% (53/195) repectively. There were 134 cases (68.72% ) had facial involvement. It was recorded that 115 (58.97%), 54 (27.69%) and 26 (13.33%) patients had frequency of attack 20-30 times/d respectively. The percentages of patients whose duration of attack 30-60 s were 60% (117/195), 29.74% (58/195) and 10.26% (20/195) respectively. There were 64 patietns (32.82%) with family history of PKD and 131 (67.18%) were sporadic PKD patients. Up to 40% (78/195) of patients did not require/take medications, as they had minor clinical manifestations or concerns about the side effects of anticonvulsants. Among 117 patients (60% ) prescribed with anticonvulsants, 114 patients showed a good response, including complete control (N = 106) and partial control (N = 8), and 3 patients were nonresponsive. In comparison with sporadic PKD patients, familial PKD patients had earlier age of onset ( t = 2.376, P = 0.019) and shorter duration of attack ( χ 2 = 7.731, P = 0.021) respectively. Conclusions We summarized the clinical characteristics of PKD patients in mainland China. Through the analysis of large sample data, we hope to improve and standardize the diagnosis and treatment of PKD clinically. DOI: 10.3969/j.issn.1672-6731.2017.07.006