Abstract
Myoclonus-dystonia (M-D) is a young onset movement disorder typically involving myoclonus and dystonia of the upper body. A proportion of the cases are caused by mutations to the autosomal dominantly inherited, maternally imprinted, epsilon-sarcoglycan gene (SGCE). Despite several sets of diagnostic criteria, identification of patients most likely to have an SGCE mutation remains difficult. Forty consecutive patients meeting pre-existing diagnostic clinical criteria for M-D underwent a standardized clinical examination (20 SGCE mutation positive and 20 negative). Each video was reviewed and systematically scored by two assessors blinded to mutation status. In addition, the presence and coexistence of myoclonus and dystonia was recorded in four body regions (neck, arms, legs, and trunk) at rest and with action. Thirty-nine patients were included in the study (one case was excluded owing to insufficient video footage). Based on previously proposed diagnostic criteria, patients were subdivided into 24 "definite," 5 "probable," and 10 "possible" M-D. Motor symptom severity was higher in the SGCE mutation-negative group. Myoclonus and dystonia were most commonly observed in the neck and upper limbs of both groups. Truncal dystonia with action was significantly seen more in the mutation-negative group (p < 0.05). Coexistence of myoclonus and dystonia in the same body part with action was more commonly seen in the mutation-negative cohort (p < 0.05). Truncal action dystonia and coexistence of myoclonus and dystonia in the same body part with action might suggest the presence of an alternative mutation in patients with M-D.
Highlights
Myoclonus–dystonia (M–D) is a rare movement disorder, characteristically with onset in the first two decades of life [1]
Presentation and progression of motor symptoms may vary, ranging from an early childhood-onset form starting with upper body or lower limb involvement and progressing to upper limbs involvement to a later-onset form, with predominant upper body symptoms and frequent cervical involvement
The SGCE mutation-positive cohort included a greater number of cases with motor symptom onset
Summary
Myoclonus–dystonia (M–D) is a rare movement disorder, characteristically with onset in the first two decades of life [1]. Motor features are typically of myoclonic jerks, predominantly involving the upper body, involving the lower limbs, face, and larynx in up to a quarter of cases [2,3,4]. Clinical Predictors of SGCE Mutation [5, 6]. Both the myoclonus and dystonia may be exacerbated by posture, action, or stress. Alcohol consumption is widely reported to improve motor symptoms, the myoclonus, resulting in excess alcohol consumption in some cases [8, 9]. Several studies have identified psychiatric symptoms in M–D cohorts, including anxiety, panic attacks, and obsessive–compulsive disorder [10,11,12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
