February 24, 2022
A 21-year-old Chinese man with an 11-year-long worsening of myoclonic epilepsy, ataxia, and cognitive impairment; his father had cerebellar atrophy and his father’s elder sister had epilepsy.
Dentatorubral-Pallidoluysian Atrophy (DRPLA)
- Background:
- Dentatorubral-pallidoluysian atrophy (DRPLA) is an autosomal dominant spinocerebellar ataxia caused by the expansion of a CAG repeat in the ATN1 gene.
- It is relatively prevalent in Japan, about 3–7/1,000,000. In Caucasian patients with cerebellar ataxia, DRPLA accounts for 0.25%. It is also rare in China.
- Clinical Presentation:
- Symptoms of DRPLA are highly variable, even in the same pedigree.
- Juvenile-onset cases are more likely to present with myoclonic epilepsy.
- Older patients tend to present with choreoathetosis, cerebellar ataxia, and dementia.
- Key Diagnostic Features:
- Atrophy of the brainstem tegmentum
- Cerebellar atrophy, especially dentate nuclei
- Periventricular and/or deep white matter hyperintensity on T2WI
- T2WI hyperintensity is common in adult-onset cases but usually absent in juvenile-onset cases.
- Generalized cerebral atrophy, especially in juvenile-onset cases
- Differential Diagnoses:
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Multiple system atrophy: Not hereditary; prominent autonomic nervous system involvement; “hot cross bun” sign on MRI
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Other types of autosomal dominant spinocerebellar ataxia (SCA1, SCA2, SCA3, SCA6, etc.)
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Nonautosomal dominant cerebellum atrophy: Friedreich ataxia, cerebrotendinous xanthomatosis, MELAS
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Acquired cerebellum atrophy: Alcohol, phenytoin toxicity
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The diagnosis and differentiation from the above considerations is confirmed on genetic testing.
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Treatment:
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There is no cure for DRPLA.
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Death often occurs before the age of 50 years.
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