Spinocerebellar ataxias
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Synopsis
All forms share cerebellar signs such as altered gait, diplopia, and excessive clumsiness – although not necessarily all signs nor to the same degree. Family members may have symptoms such as difficulty with hand-eye coordination, speech difficulty, hypotonia, developmental delay, cognitive impairment, and vision impairment that may or may not be suggestive of inherited cerebellar disease. Autosomal recessive cerebellar ataxia is more common in patients younger than 30 years of age, while the autosomal dominant and X-linked forms are adult-onset.
- Autosomal dominant – A heterogenous group of genetic disorders producing symptoms of cerebellar dysfunction, including gait and limb ataxia, dysarthria, and diplopia. Some are associated with non-cerebellar symptoms such as peripheral neuropathies, cognitive deficits, and visual impairments. There are over 30 clinically and genetically distinct autosomal dominant cerebellar ataxias. It can initially present in childhood or early adulthood, but is generally associated with a later onset and slower progression compared with the recessive ataxias. Nearly all of the autosomal dominant ataxias do eventually progress to severe disability. Treatment is symptomatic, with physical therapy, acetazolamide, and baclofen being used commonly.
- Autosomal recessive – The most common form of inherited ataxia. In contrast to the autosomal dominant ataxias, symptoms are usually clinically significant before adulthood. Areflexia is also more commonly present in recessive ataxias compared with other hereditary forms. Friedreich ataxia is the most common recessive ataxia. In addition to cerebellar dysfunction, patients with Friedreich ataxia often develop diabetes, cardiomyopathy, and scoliosis. The next most common recessive ataxia is ataxia-telangiectasia, which presents in the first few years of life with dysarthria, oculomotor abnormalities, recurrent infections, and oculocutaneous telangiectasias, in addition to ataxia. Treatment varies based on which recessive ataxia is present.
- X-linked – An uncommon form of hereditary ataxia; predominantly males are affected. Heterogenous in the degree of neurologic and cognitive abnormalities that may occur. The only X-linked ataxia that occurs with any frequency is fragile X tremor ataxia syndrome. This form of recessive ataxia has an adult onset (after 50 years of age) in contrast to the other recessive ataxias, which can appear in childhood or infancy. Its characteristic intention tremor and progressive ataxia occur in patients who have the fragile X premutation rather than fragile X disease proper. That is, patients with a smaller number of trinucleotide repeats in the FMR1 gene are affected. Patients with this disease may also exhibit neuropathy, autonomic dysfunction, or cognitive deficits.
Codes
ICD10CM:G11.1 – Early-onset cerebellar ataxia
SNOMEDCT:
129609000 – Spinocerebellar ataxia
Differential Diagnosis & Pitfalls
- Paraneoplastic cerebellitis
- Cerebellar arteriovenous malformation
- Cerebellar tumor
- Ataxia-telangiectasia syndrome
- Episodic ataxia (eg, type 1, type 2)
- Multisystem atrophy (MSA) cerebellar subtype
- Chronic alcohol use
- Mercury poisoning
- Chronic Dilantin use
- Vitamin E deficiency
- Abetalipoproteinemia
- Multiple sclerosis
- Pelizaeus-Merzbacher disease
- Fragile X ataxia syndrome
- Friedreich ataxia
- Miller Fisher syndrome
- Ramsay-Hunt syndrome
- Dandy-Walker cyst
- Arnold-Chiari malformation
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Last Updated: 03/29/2017
Spinocerebellar ataxias
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