Mid- to late adult-onset (median age: 60 years; range: 20 to 90 years) of slowly progressive cerebellar ataxia with predominant gait impairment. Cerebellar dysarthria is present in only approximately 50-60% of patients and usually remains mild to moderate. Although some individuals eventually require assistance with mobility, use of a wheelchair is uncommon even after protracted disease duration.
Commonly associated neurologic findings include:
• Episodic ataxia: commonly triggered by physically demanding activities, alcohol intake, or caffeine that may manifest with diplopia, vertigo, dysarthria, and ataxia.
• Cerebellar ocular motor signs, such as saccadic pursuit, dysmetric saccades, rebound nystagmus, gaze-evoked nystagmus, impaired visual fixation suppression of the vestibulo-ocular reflex, and downbeat nystagmus (DBN). Early in the disease course, DBN may occur with other cerebellar oculomotor signs in isolation.
• Visual symptoms, such as diplopia, oscillopsia, and visual blurring.
• Vertigo and/or dizziness
• Vestibular hypofunction
Less commonly associated neurologic findings:
• Mild spasticity
• Postural tremor
• Autonomic dysfunction, mostly urinary urgency
• Mild sensory or sensorimotor axonal polyneuropathy
Brain MRI shows cerebellar atrophy in a substantial number of individuals, which is most pronounced in the vermis and is mostly mild to moderate
FGF14