Case presentation: A 70-year-old female was admitted due to imbalance associated to high fever, headache, photophobia, myalgia, and emesis for 5 days. She denied other symptoms or predisposing agents. At examination, there was a global asymmetric cerebellar syndrome, without other findings. Laboratory work-up showed lymphocytosis, leucopenia, thrombocytopenia, and increased liver enzymes. Serologic exams were negative for syphilis, HIV, hepatitis B and C viruses, CMV, rubella, toxoplasmosis, and trypanosomiasis in peripheral blood, and for CMV, herpes simplex and varicella-zoster viruses, and toxoplasmosis in cerebrospinal fluid. Brain MRI with angiography was unremarkable. During hospital stay, there was complete recovery of systemic symptoms and gradual improvement of the cerebellar syndrome. She was discharged for outpatient follow-up, during which a positive IgM (MAC-ELISA) for Dengue virus was identified. First evaluation was 54 days after onset; she had a mild subjective imbalance complaint, with normal neurological exam. She has been followed for four years since onset, remaining asymptomatic, without any cerebellar signs. Discussion: Neurotropism in Dengue fever, as direct viral or immunomediated damage, has been well recognized. Its spectrum comprises many presentations; however, association with cerebellar syndrome is extremely rare, with only seven other cases published. Acute cerebellar ataxia is characterized by normal neuroimaging and complete recovery up to three years. In Dengue cases, recovery happened from one week to two months. Currently, there are no other reports with long-term follow-up. Conclusion: Dengue virus is a rare, but probably underdiagnosed, cause of acute cerebellar ataxia. Recovery is fast, and, in our case, persistent, without recurrence or evolution to any degenerative disease.
