Myoclonus and Ataxia

Alternative Names

  • Dentate Cerebellar Ataxia
  • Dentatorubral Atrophy
  • Primary Dentatum Atrophy
  • Progressive myoclonus ataxia
  • Ramsay Hunt Syndrome
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WHO-ICD-10 version:2010

Diseases of the nervous system

Systemic atrophies primarily affecting the central nervous system

OMIM Number

159700

Mode of Inheritance

Autosomal dominant heterogeneous

Description

Myoclonus and Ataxia, formerly known asRamsay Hunt Syndrome, is a rare autosomal dominant disorder characterised by generalized myoclonus associated with cerebellar dysfunction. The common clinical features observed among these patients are myoclonus, generalized-onset seizure, and ataxia. A few patients with this syndrome has been noted to have lesions in the dentate nucleus of the cerebellum.

Epidemiology in the Arab World

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Other Reports

Algeria

Genton et al. (1990) reviewed the cases of 43 patients Ramsay Hunt syndrome and originating from around the western Mediterranean, with a large number of northern African subjects, mainly of Algerian origin. These patients formed a homogeneous group and were followed up for a mean period of 11.6 years. Onset of the disease occurred between 6 and 17 years (mean: 11.2) and the transmission appears to be recessive. The clinical features include: action myoclonus, generalized epileptic seizures, mild cerebellar signs and lack of dementia. EEG features include normal background activity, spontaneous fast generalized spike-wave discharges, photosensitivity, lack of activation during nREM sleep and vertex/rolandic spikes during REM sleep. Prognosis of the disease is variable, even within families, but the progression seems to be slow in a majority of patients. Genton et al. (1990) noted that Ramsay Hunt syndrome can be distinguished from mitochondrial encephalomyopathy and is less severe than Baltic myoclonus. They also proposed that the condition could be more properly described as Mediterranean myoclonus.

Kuwait

Shakir et al. (1992) studied eight patients from three Arab families from the Arabian Peninsula and portraying myoclonus, ataxia, infrequent seizures, and minimal intellectual impairment. Based on the latest terminology, genetic and clinical definition of Baltic myoclonus, Ramsay Hunt syndrome and Unverricht-Lundborg disease, Shakir et al. (1992) proposed that the study cohort falls under the category of progressive myoclonic ataxia of the Unverricht-Lundborg type. Furthermore, this study points out that this disorder exists beyond Scandinavia.

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