Sleep Behavior Disorder Linked to Different Ataxia Types

A new study was recently published in the journal Parkinsonism & Related Disorders, revealing that sleep disorders can be helpful in the differentiation of different ataxia types. The study is entitled “Differential Diagnosis of Sporadic Adult-Onset Ataxia: The Role of REM Sleep Behavior Disorder” and was conducted by researchers at the Hospital de Clínicas, Federal University of Paraná, Brazil and the Movement Disorders Centre, Toronto Western Hospital, Canada.

Ataxia is defined as a neurological sign characterized by the lack of voluntary coordination of muscle movements. Individuals with this condition experience impairment in coordination and balance. Sporadic ataxia corresponds to the development of ataxia symptoms during adulthood in individuals with no family history of the disease. Ataxia can be difficult to diagnose and it can be either cerebellar, if only the cerebellum is affected, or cerebellar plus, if accompanied by extra-cerebellar features like weakness, rigidity, or spasticity of the muscles, dementia or neuropathy (dysfunction of the peripheral nerves).

Sporadic adult-onset ataxia of unknown etiology (idiopathic) comprises a group of degenerative, non-hereditary disorders for which the cause is unknown. In this study, researchers conducted a retrospective analysis on 50 sporadic adult-onset ataxia Brazilian patients who were followed-up regularly during a period of up to 21 years, to assess whether their diagnosis was kept or whether it progressed to a cerebellar form of multiple system atrophy.

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Researchers evaluated clinical, neurological, genetic and laboratory data on the 50 adult patients enrolled in the study. Special attention was paid to sleep disorders as these have been reported to have a high prevalence among patients with neurodegenerative diseases.

Using genetic tests, the team found that all 50 patients were negative for ataxia disorders like Friedreich’s ataxia, fragile X permutation tremor-ataxia syndrome (FRXTAS) and several types of spinocerebellar ataxia. A total of 48% of the patients were diagnosed with multiple system atrophy and the remaining 52% with sporadic adult-onset ataxia. Interestingly, REM (rapid eye movement) sleep behavior disorder, a sleep disorder in which individuals physically act out vivid dreams with vocal sounds and often violent arm and leg movements, was diagnosed in 46% of the patients, being reported in 83.3% of patients with probable multiple system atrophy and in 11.5% of those with sporadic ataxia. The results suggested that the diagnosis of REM sleep behaviour disorder could be helpful in the differentiation between multiple system atrophy and sporadic adult-onset ataxia.

The team concluded that of all patients with sporadic adult-onset ataxia analyzed, almost half evolved towards multiple system atrophy and that the prevalence of REM sleep behavior disorder in patients with multiple system atrophy was significantly high. The authors suggest that REM sleep behaviour disorder could represent a complementary tool in the differentiation between different ataxia types.