![]() ![]() ![]() Pyramidal signs (hyperreflexia and spasticity) are commonly found in patients with SCA1 and SCA3 cognitive impairment has been reported in association with SCA2, SCA12, SCA13, SCA17 chorea may manifest in patients with SCA17 or dentatorubral-pallidoluysian atrophy (DRPLA). The frequency of the occurrence of each disease within the autosomal dominant cerebellar ataxia (ADCA) population is noted in Table 1. 9 Often the autosomal dominant ataxias cannot be differentiated by clinical or neuroimaging studies they are usually slowly progressive and often associated with cerebellar atrophy, as seen from brain imaging studies ( Figure 1). 4, 5, 6, 7, 8 Scales for rating symptoms and signs of ataxia have been published. Table 1 indicates a few distinguishing clinical features for each type. The age of onset and physical findings in the autosomal dominant ataxias overlap. Synonyms for autosomal dominant cerebellar ataxias (ADCAs) used prior to the identification of the molecular genetic basis of these disorders were Marie’s ataxia, inherited olivopontocerebellar atrophy, cerebello-olivary atrophy, or the more generic term, spinocerebellar degeneration.Ĭlinical features of ADCA. 1, 2, 3 Autosomal dominant cerebellar ataxias The possibility of an acquired cause of ataxia needs to be considered in each individual with ataxia because a specific treatment may be available.Īs discussed above, the hereditary ataxias can be subdivided by mode of inheritance, (i.e., autosomal dominant, autosomal recessive, X-linked, and mitochondrial), gene in which causative mutations occur, or chromosomal locus. Establishing the diagnosisĮstablishing the diagnosis of hereditary ataxia requires:ĭetection on neurological examination of typical clinical signs including poorly coordinated gait and finger/hand movements, dysarthria (incoordination of speech), and eye movement abnormalities such as nystagmus, abnormal saccade movements, and ophthalmoplegia.Įxclusion of nongenetic causes of ataxia (see Differential Diagnosis below).ĭocumentation of the hereditary nature of the disease by finding a positive family history of ataxia, identifying an ataxia-causing mutation, or recognizing a clinical phenotype characteristic of a genetic form of ataxia.ĭifferential diagnosis of hereditary ataxia includes acquired, nongenetic causes of ataxia, such as alcoholism, vitamin deficiencies, multiple sclerosis, vascular disease, primary or metastatic tumors, and paraneoplastic diseases associated with occult carcinoma of the ovary, breast, or lung, and the idiopathic degenerative disease multiple system atrophy (spinal muscular atrophy). ![]() For instance, cone–rod retinal dystrophy in conjunction with familial ataxia may suggest spinocerebellar ataxia (SCA)7 Native American origin or co-occurrence of epilepsy would raise the possibility of SCA10. Particular signs beyond ataxia may guide the clinician in pursuit of directed genetic testing when investigating the cause of ataxia. In addition, patients may develop ophthalmoplegia (limitations of eye movement), spasticity, neuropathy, and cognitive/behavioral difficulties. The clinical manifestations of the hereditary ataxias are progressive incoordination of movement and speech, and a wide-based, uncoordinated, unsteady gait. However, the best testing strategy is based on assessing relative frequencies, ethnic predilections, and recognition of associated phenotypic features such as seizures, visual loss, or associated movement abnormalities. Diagnostic genetic testing is complicated because of the large number of relatively uncommon subtypes with extensive phenotypic overlap. Four autosomal recessive types have dietary or biochemical treatment modalities (ataxia with vitamin E deficiency, cerebrotendinous xanthomatosis, Refsum, and coenzyme Q10 deficiency), whereas there are no specific treatments for other ataxias. Autosomal recessive ataxias usually have onset in childhood the most common subtypes are Friedreich, ataxia-telangiectasia, ataxia with oculomotor apraxia type 1, and ataxia with oculomotor apraxia type 2. The most common subtypes are spinocerebellar ataxia 1, 2, 3, 6, and 7, all of which are nucleotide repeat expansion disorders. There are more than 35 autosomal dominant types frequently termed spinocerebellar ataxia and typically having adult onset. The hereditary ataxias are a highly heterogeneous group of disorders phenotypically characterized by gait ataxia, incoordination of eye movements, speech, and hand movements, and usually associated with atrophy of the cerebellum. ![]()
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