Anti-Ma2-associated encephalitis

Case contributed by Gabrielle Matta
Diagnosis almost certain


Previously well man presented to his GP with hypersomnolence, cataplexy, vertical gaze palsy and hyperphagia. Sleep studies supported a narcolepsy diagnosis, which improved minimally with pharmacotherapy. Over the next year, he deteriorated, experiencing memory problems, choreoathetosis, myoclonus, ataxia and dysarthria. He then presented in a confusional state characterized by psychosis and profound hypersomnolence.

Patient Data

Age: 35
Gender: Male

MRI Brain with contrast


Right temporo-insular T2 hyperintensity is identified. This is associated with gyral and possibly leptomeningeal enhancement in the anterior temporal pole and anterior insula. No associated diffusion restriction or convincing CBV increase. Left hippocampal formation demonstrates subtle FLAIR hyperintensity, raising the possibility of contralateral involvement. Remainder of the brain is normal. No region of diffusion restriction to suggest acute infarct. Incidental right maxillary sinus mucous retention cyst.

MRI showed extensive T2 and FLAIR hyperintensity involving the right insula and medial temporal structures, extending to the anteromedial right temporal pole, with a small focus of leptomeningeal enhancement.

Case Discussion

CSF analysis showed raised protein with oligoclonal bands (also in serum) and Immunoblot confirmed positivity for anti-Ma2 antibodies, also present in serum.

Right medial temporal brain biopsy revealed a perivascular, poleoclastic T-cell mediated inflammatory process without evidence of malignancy.  The patient was diagnosed with anti-Ma2-associated encephalitis, frequently associated with testicular germ cell neoplasia in men.

Testicular ultrasound showed foci of macrocalcification in the right testis. A right orchiectomy was undertaken.  Pathological analysis confirmed the presence of a classic seminoma along with extensive intratubular germ cell neoplasia (“ITGCN”). The decision was made subsequently to remove the contralateral testis, which showed low volume ITGCN, without invasive seminoma. The patient was treated with immunosuppression and had clinical and radiological stabilization. The serum anti-Ma2 titer reduced from 1:160 to 1:40.

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