Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is a rare autosomal recessive spastic ataxia initially identified in the region of Charlevoix-Saguenay, in the province of Quebec, Canada.
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Epidemiology
Although initially described in Canada, ARSACS has since been reported in other regions of the world, including the Netherlands 9, Brazil 7, Italy 4, France 10, Iran 13, Japan, Turkey and Tunisia 12.
Clinical presentation
ARSACS typically manifests in infancy, however, late-onset (i.e. adult-onset) forms have been described. The classic triad of presentation clinical features includes 13:
cerebellar ataxia
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pyramidal involvement, leading to spasticity
preferentially affecting the lower limbs
sensorimotor polyneuropathy
Other clinical features include distal amyotrophy, dysarthria, retinal optic nerve hypermyelination, bowel and bladder dysfunction, and intellectual disability 12,13.
Pathology
Genetics
CARSACS is caused by mutation in the SACS gene, which is located on chromosome 13q12.12 and is inherited in an autosomal recessive pattern 12. The SACS gene codes for the protein sacsin, which is expressed highly in motor neurons and by cerebellar Purkinje cells 13.
Radiographic features
MRI
Common radiographic features on MRI include 1-5,11,13,14:
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atrophy of the superior cerebellar vermis
inferior vermis remains relatively spared
T2/FLAIR hypointensities in the pons with a characteristic tigroid, linear, striated or striped appearance
cervical cord atrophy
T2 hyperintense rim around the thalamus
corpus callosum thinning
Treatment and prognosis
Management is supportive as there is no disease-modifying treatment available.