Alcohol responsive myoclonus
The Handle lies in the response of the myoclonus to small amounts of alcohol. There are very few alternative conditions that improve with small amounts of alcohol.
A 39 yr man presented to the neurology clinic an account of a jerky head tremor and jumping movement of the trunk since the age of 14y. His son and father have a similar condition. The body jerks were usually relieved by an alcoholic drink. Past health was otherwise unremarkable.
Medication: Ramipril for hypertension
When examined there were recurrent jerky horizontal head tremors and the head was intermittently twisted to the left side. There were abrupt flexion movements of the trunk. There was a postural tremor of the outstretched arms and a dystonic pen grip.
What is the most likely diagnosis?:
Wilson’s disease
Chore-acanthocytosis
Myoclonic dystonia
Segawa’s disease
Dystonia musculorum deformans
Answer: Myoclonic dystonia due to DYT11 mutation. Autosomal dominant disorder
The Handle lies in the response of the myoclonus to small amounts of alcohol. There are very few alternative conditions that improve with small amounts of alcohol. The main one is classical essential tremor i.e. without dystonia. Myoclonic dystonia has been reported in some Canadian families with the DYT 15 mutation.
Wilson’s disease may cause any type of involuntary movement but alcohol responsiveness is not recognised. The vacuous facial appearance is a great clue along with a wing-beating tremor (see Video 8.??) and Kayser-Fleischer rings.
Chorea-acanthocytosis presents with chorea rather than myoclonus. Useful Handles are involuntary ejection of food or protrusion of the tongue, vocal tics, headbanging, belching, vocalisations causing overlap with Tourette and Lesch-Nyhan syndrome. The diagnosis is confirmed by finding acanthocytes in the blood and a low/absent level of chorein in red cells
Segawa’s disease (Dopamine responsive dystonia; DYT5) presents usually in childhood with fluctuating dystonia that often simulates cerebral palsy. Typically the dystonia is aggravated/ induced by exercise. It is worse in the afternoon and better in the morning or after sleep. It responds well to small doses of levodopa
Dystonia musculorum deformans (DYT1). This is a form of severe progressive generalised dystonia that starts in childhood affecting the lower limbs first before becoming widespread.
By Professor Chris Hawkes