Spastic ataxias.

The presence of spasticity and pyramidal features is a hallmark of some of hereditary ataxias, such as autosomal-recessive spastic ataxia of Charlevoix-Saguenay, other primary spastic ataxias, Friedreich ataxia, or ataxia with isolated vitamin E deficiency. Certain spastic paraplegias, such as spastic paraplegia 7, may present as an ataxic phenotype and often share common pathophysiologic pathways with cerebellar ataxias. Because of the rarity and genetic heterogeneity of these conditions, their molecular diagnosis remains challenging and time consuming. Herein we review the clinical, epidemiologic, and genetic features of the best-defined spastic ataxias with a focus on autosomal-recessive spastic ataxia of Charlevoix-Saguenay, one of the most frequent ataxias worldwide, which presents with a unique early-onset spastic ataxia phenotype. We briefly discuss other genetic and metabolic multisystem disorders where spastic ataxia is a secondary feature. Emphasis is placed on their typical age of onset and key clinical and imaging features that enable discrimination between these complex diseases.