To describe Balint syndrome as an unusual presentation of paraneoplastic autoimmune encephalitis and review the current literature.

Anti-N-Methyl-D-Aspartate receptor (NMDAR) encephalitis is one of the most common types of autoimmune encephalitis with highest incidence in children and young adults. The heterogenous clinical manifestations are often under-recognized and can result in delayed diagnosis and treatment, which is associated with worse prognosis. Two cases of partial Balint syndrome associated with non-paraneoplastic NMDAR encephalitis in young adults have been reported. 

We describe a case of partial Balint syndrome secondary to NMDAR encephalitis in a middle-aged woman with recent history of breast cancer. We also review the current literature on this presentation.

A 49-year-old female presented with new onset seizures two years after being diagnosed with stage II invasive ductal carcinoma (in remission). She developed behavioral changes and movement disorder over the next year. MRI brain showed mild T2-signal abnormalities in the bilateral temporal lobes. Initial cerebrospinal fluid (CSF) analysis was unremarkable. A serum Mayo paraneoplastic antibody panel was also negative. Computed tomography(CT) chest/abdomen/pelvis did not reveal malignancy. She was treated with plasmapheresis and high-dose corticosteroids followed by a taper with improvement in seizure and movement disorder, but with persistent behavioral disturbance. Repeat CSF analysis 22 months after symptom onset was positive for NMDAR antibody (Mayo autoimmune encephalitis panel), consistent with NMDAR encephalitis. Two years after the first symptom, the patient developed difficulty with navigation while walking. Neuro-ophthalmologic exam was suggestive of partial Balint syndrome, with simultagnosia and optic apraxia, without definite optic ataxia.

This case highlights Balint syndrome as a manifestation of NMDAR encephalitis. All components of Balint syndrome should be examined, especially in cases with navigation or visual complaints, and attention may prompt earlier recognition of autoimmune encephalitis.