Fahr's syndrome due to hypoparathyroidism revisited: A case of parkinsonism and a review of all published cases.

Introduction: Fahr's syndrome due to hypoparathyroidism refers to bilateral basal ganglia (BG) calcifications and manifests with movement disorders, seizures, cognitive and behavioral symptoms.
Case Presentation: We report a case of a 74-year-old woman, who presented with parkinsonism due to post-surgical hypoparathyroidism and normal DaT scan, despite extensive calcifications of the BG, periventricular white matter, and cerebellum.
Methods: A comprehensive literature review of all reported cases of Fahr's syndrome due to hypoparathyroidism was conducted in the electronic databases PubMed and Web of science. Moreover, demographic and clinical characteristics of the patients overall were calculated and associated with radiological findings.
Results: We reviewed a total of 223 cases with Fahr's syndrome due to hypoparathyroidism (124 female, 99 male). Mean age on presentation was 44.6 ± 17.7 years. Thirty nine percent of patients had idiopathic hypoparathyroidism, 35.4 % acquired and 25.6 % pseudohypoparathyroidism. Almost half of the patients had tetany, seizures or a movement disorder and approximately 40 % neuropsychiatric symptoms. The patients with a movement disorder had a 2.23 likelihood of having neuropsychiatric symptoms as well (OR 2.23, 95 % CI 1.29-3.87). Moreover, there was a statistically significant association between the phenotype severity (i.e. the presence of more than one symptom) and the extent of brain calcifications (χ ² = 32.383, p = 0.009).
Conclusion: Fahr's syndrome is a rare disorder, which nonetheless manifests with several neurological symptoms. A head CT should be considered for patients with hypoparathyroidism and neurological symptoms. More studies using DaT scan are needed to elucidate the effects of calcifications on the dopaminergic function of the BG.
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