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A very rare and progressive cerebellar dyssynergia with intention tremor first localized to one extremity, convulsions, and myoclonic epileptic jerks. Ragged red fibers are seen on muscle biopsies.

Dentate Cerebellar Ataxia; Dentatorubral Atrophy; Primary Dentatum Atrophy.

First described by James Ramsay Hunt, an American neurologist in 1921.

Autosomal dominant with reduced penetrance.

Neurological lesions or anomalies are often observed (cerebellar dentate nucleus, degeneration of globus pallidus, elevated cerebrospinal fluid [CSF] uric acid); muscle biopsy shows presence of ragged red fibers that probably are caused by mitochondrial abnormalities, which could explain the pathophysiology of this syndrome. Controversy exists about considering Ramsay Hunt syndrome as a specific entity.

Association of myoclonus ataxia and occasional seizures.

Neurological signs are isolated. No other association is known. Myoclonus, cerebellar ataxia, intention tremor, and occasional tonic-clonic seizures are the only symptoms.

Evaluate the neurological repercussion (clinical, EEG, CT) and muscular status.

Patients should be considered epileptic and the use of anesthetic agents inducing seizures (e.g., enflurane, sevoflurane) should be avoided.

The antiepileptic medication(s) should be continued until the morning of surgery. Because of the presence of muscular abnormalities and risk (undocumented) of hyperkalemic response it is recommended to avoid succinylcholine. Consider interaction between antiepileptic treatment and anesthetic drugs.

Juvenile Paralysis Agitans of Hunt: Autosomal dominant, this syndrome is characterized by mask-like facies, parkinsonism, tremor, bradykinesia, dysarthria, rigidity, gait disturbance, and flexion dystonia of fingers. Progression is slow. Onset in teens or earlier.

Dyssynergia Cerebellaris Myoclonica of Hunt (Cerebelloparenchymal Disorder V, Spinodentate Atrophy): Autosomal recessive with ataxia, myoclonic jerks, dentate neuron loss superior, and cerebellar peduncle fiber loss.

Hunt JR: Dyssynergia cerebellaris myoclonica—Primary atrophy of the dentate system: A contribution to the pathology and symptomatology of the cerebellum. Brain 44:490, 1921.
Marsden CD, Obeso JA: Viewpoints on the Ramsay Hunt syndrome: 1. The Ramsay Hunt syndrome is a useful clinical entity. Move Disord 4:6, 1989.  [PubMed: 2494439]

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