Progressive hearing loss and cerebellar ataxia in anti-Ma2-associated autoimmune encephalitis.

A 38-year-old Brazilian man presented with a two-year history of progressive bilateral hearing loss, cerebellar ataxia, emotional lability and hypersexuality. A limbic-brainstem syndrome was suspected and neuroimaging studies performed, disclosing marked brainstem signal changes (Figure). Cerebrospinal fluid analysis disclosed a mild protein increase. During paraneoplastic screening, testicular ultrasonography disclosed a heterogeneous complex mass in the right testicle (Figure) and serum anti-Ma2 antibodies were detected. Anti-Ma2-associated encephalitis classically emerges in the context of seminomatous and nonseminomatous testicular tumors and presents with a complex spectrum of neurological manifestations1, including limbic encephalitis, atypical parkinsonism, cerebellar ataxia, brainstem dysfunction, myelopathy, radiculoplexopathy, REM sleep behavior disorder and narcolepsy1,2.