A case of PRRT2 mutation with temporary cerebellar diffusion restriction that mimics acute cerebellitis.

Purpose - This case report presents a pa- tient with recurrent cerebellitis attacks cha-racterized by acute cerebellar diffusion restriction due to a PRRT2 gene mutation, who demonstrated complete recovery.Case report -  A 21-year-old female patient was admitted to our hospital with imbalance, vomiting, dizziness, and speech disorder. Neurological examination showed bilateral abnormal cerebellar tests. Diffusion restriction was seen in the right cerebellar hemisphere, and hyperintensity was seen in the same regions on the T2-Flair MRI sequence. The viral panel, culture, and biochemistry of cerebrospinal fluid (CSF) examinations were all within normal ranges. We diagnosed the patient with acute cerebellitis. A three-month corticosteroid treatment regimen was initiated after the first episode, and subsequent relapses were managed similarly. The patient's MRI results and clinical findings both fully improved. However, two more attacks were documented in the patient's history like the other attacks. The patient experienced recurring episodes and has a history of infantile epilepsy. Whole exome sequencing revealed compound he- te- rozygous pathogenic PRRT2 variants: he-terozygous c.649dupC (p. Arg217Profs*8) and a heterozygous 16p11.2 microdeletion encompassing PRRT2 gene.Conclusion - Biallelic pathogenic PRRT2 variants usually cause a severe phenotype compared to monoallelic variants. PRRT2 should be considered in cases of episodic movement disorders with reversible cerebellar diffusion restriction, as they may underlie recurring acute cerebellitis episodes. Longterm monitoring may be crucial for manage- ment.