[Myoclonus and it's associated factors in Creutzfeldt-Jakob disease]

Objective: To analyze features and the related factors of myoclonus of 47 patients with probable or possible Creutzfeldt-Jakob disease (CJD). Methods: All patients diagnosed with"suspected CJD" and hospitalized in Xuanwu Hospital from January 2013 to November 2015 were included, and their clinical information and myoclonus features were analyzed. Age, clinical, course and manifestation, EEG, MRI, CSF14-3-3 features between myoclonus positive group and negative group were compared, and the correlation between myoclonus features and these factors was analyzed using Spearman correlation analyses. Results: (1) Occurrence rate of extrapyramidal symptoms (P=0.028), visual impairment (P=0.025) and dyssomnia (P=0.004) were higher in myoclonus positive group, the differences were significant. Spearman correlation analysis showed that myoclonus was related to extrapyramidal symptoms (P=0.024), visual impairment (P=0.030) and dyssomnia (P=0.001). (2) EEG features showed no significant difference between myoclonus positive and negative group. The 17 myoclonus positive patients were divided into three subgroups, typical EEG change group 52.94%(9/17), atypical EEG change group 23.53%(4/17) and no EEG change group 23.53%(4/17). Difference of myoclonus and other clinical manifestations were not significant among the three subgroups(P>0.05); correlation analysis also found no statistically significant correlation between myoclonus and EEG (P=0.201). Conclusions: Myoclonus often occurs after the damage of locomotor system (including pyramidal tract, extracorticospinal tract and cerebellum) among CJD patients, and it is related to extrapyramidal symptoms , visual impairment and dyssomnia . There is undefined correlation between myoclonus and periodic sharp wave complexes (PSWC) in EEG.