SLC20A2-Associated Idiopathic Basal Ganglia Calcification-Related Recurrent Psychosis Response to Low-Dose Antipsychotics: A Case Report and Literature Review

Idiopathic basal ganglia calcification (IBGC), also known as Fahr's disease or primary familial brain calcification, manifests as bilaterally symmetric calcifications in the brain. Clinical symptoms range from movement disorders to cognitive impairment and psychiatric symptoms. Since 2012, IBGC has been reported as an inherited disorder with several causative genes, including SLC20A2; however, the genotype-phenotype association remains unclear. Furthermore, longitudinal follow-up studies investigating the prognosis of neuropsychiatric symptoms in IBGC are lacking. A 36-year-old woman who experienced recurrent psychosis since the age of 30 years was admitted to our hospital. Her symptoms included delusions, hallucinations, disorganized speech, and grossly disorganized behavior. Cranial CT revealed calcification of the bilateral basal ganglia and dentate nucleus. The possibility of metabolic or endocrinological disorders causing secondary calcification was excluded via laboratory examinations. The genetic analysis revealed SLC20A2 mutation, and therefore, she was diagnosed with definite IBGC. At the age of 37, 42, and 43 years, similar psychosis recurred due to a decrease in medication. Each episode was relieved within one week with a low dose of risperidone (1.5-2 mg/day p.o.). Eventually, remission was maintained with risperidone (1.5 mg/day). To our knowledge, genetically confirmed case of IBGC with psychosis has been rarely reported. Recurrent psychosis can be the sole symptom of SLC20A2-associated IBGC and may be remitted with a low dose of risperidone. Literature review including eight case reports shows no superiority between medications. Although our case indicates that a low dose of antipsychotics can alleviate symptoms without any side effects and should be continued to prevent relapse in some patients with IBGC, there has been still shortage of the clinical evidence. Further longitudinal studies on genotype-phenotype associations may expedite personalized medicine for patients with IBGC.