Systematic Review of Parkinsonism in Cerebrotendinous Xanthomatosis.

Background: Cerebrotendinous Xanthomatosis (CTX) is a rare, inherited metabolic disease caused by pathogenic variants in CYP27A1. The clinical presentation of this progressive disease includes cognitive deficits, ataxia, peripheral neuropathy, and pyramidal signs, as well as bilateral cataracts and tendon xanthomas. In some cases, CTX also includes parkinsonism. The goals of this study are to develop a data source that provides improved characterization and awareness of parkinsonism in CTX.

Methods: We conducted a systematic review of the literature according to PRISMA guidelines to identify all published individuals diagnosed with CTX and parkinsonism. Clinical signs, imaging findings and treatment response to both chenodeoxycholic acid and dopaminergic medications were examined for 72 subjects.

Results: The average age of onset of parkinsonism in these CTX patients was 42 years, illustrating the early onset nature of parkinsonism in CTX. Functional dopaminergic imaging revealed the loss of presynaptic dopaminergic neurons in the substantia nigra which points to neurodegeneration of the dopaminergic system as the underlying pathophysiology for parkinsonism in CTX. Brain MRI showed abnormalities in the basal ganglia in 38% of subjects. MRI also showed abnormalities in the cerebellum in 88% of subjects which is typical for CTX and can be utilized to distinguish subjects with CTX and parkinsonism from individuals with other forms of atypical parkinsonism. Dopaminergic medication mitigated parkinsonism signs in most individuals with CTX.

Conclusion: CTX is a neurometabolic disease that can result in levodopa-responsive parkinsonism that should be included in the differential for atypical parkinsonism.