Movement Disorders in Hereditary Cerebellar Ataxia.

Background: Hereditary cerebellar ataxia (HCA) represents a complex group of disorders, with a wide spectrum of neurological symptoms. Among these, non-ataxia movement disorders (MD) have been increasingly acknowledged, with variable frequency across different forms.

Objectives: To characterize the type and frequency of MD in patients with HCA. To identify factors associated with MD and analyze their impact on disability.

Methods: We conducted a prospective study starting in 2017, with annual visits according to a structured protocol. Patients were selected from the study database and their clinical and genetic features analyzed.

Results: The cohort comprised 193 symptomatic patients. Machado-Joseph disease (MJD, also SCA3 or ATX-ATXN3) and cerebellar ataxia, neuropathy and vestibular areflexia syndrome (ATX-RFC1) were the most common autosomal dominant (AD) or recessive forms, with a frequency of 14.0% and 15.0%, respectively. MD were present in 95 (54.4%), with dystonia being the most common (49.2%). Tremor was identified in 10.9%, Parkinsonism in 4.1% and chorea in 3.6% patients. Myoclonus and tics were rare (2.6% and 0.5%). The presence of MD was associated with AD inheritance and ATXN3. MD, regardless of type, correlated with higher SARA score at baseline, increased fall frequency, confinement to wheelchair, and earlier occurrence of falls and of permanent use of walking aid.

Conclusions: Movement disorders, particularly dystonia, were common in our cohort. This highlights the possible role of the cerebellum in MD, but also extra-cerebellar involvement in some HCA. Presence of MD significantly worsened motor disability, highlighting the need for strategies of early identification and tailored management.