Objectives: To characterize neurophysiological subcortical abnormalities in myoclonus-dystonia and their modulation by alcohol administration.
Methods: Cerebellar associative learning and basal ganglia-brainstem interaction were investigated in 17 myoclonus-dystonia patients with epsilon-sarcoglycan (SGCE) gene mutation and 21 age- and sex-matched healthy controls by means of classical eyeblink conditioning and blink reflex recovery cycle before and after alcohol intake resulting in a breath alcohol concentration of 0.08% (0.8 g/l). The alcohol responsiveness of clinical symptoms was evaluated by three blinded raters with a standardized video protocol and clinical rating scales including the Unified Myoclonus Rating Scale (UMRS) and the Burke Fahn Marsden Dystonia Rating Scale (BFMDRS).
Results: Patients showed a significantly reduced number of conditioned eyeblink responses before alcohol administration compared to controls. While the conditioning response rate decreased under alcohol intake in controls, it increased in patients (ANOVA: alcohol state x Group p = 0.004). Blink reflex recovery cycle before and after alcohol intake did not differ between groups. Myoclonus improved significantly after alcohol intake (p = 0.016). The severity of action myoclonus at baseline correlated negatively with the conditioning response in classical eyeblink conditioning in patients.
Interpretation: The combination of findings with reduced baseline acquisition of conditioned eyeblink responses and normal blink reflex recovery cycle in patients that improved significantly by alcohol intake suggests a crucial role of cerebellar networks in the generation of symptoms in these patients. This article is protected by copyright. All rights reserved.