Objective:

To report a case of paraneoplastic rhombencephalitis with rapidly progressive dementia secondary to Anti-Ri/ANNA-2 antibodies and reversible brain stem lesion

Background:

The Anti-Ri/ANNA2 antibody belongs to a subgroup linked to malignancy, primarily breast carcinoma and small cell lung carcinoma. Due to the diverse clinical presentation, diagnosis can be challenging, making early recognition and prompt intervention essential for enhancing patient prognosis.

Design/Methods:

Chart review

Results:

A 67-year-old right-handed woman presented to the hospital for progressive cognitive decline, gait instability, diplopia, dysphagia, and facial twitching. The neurologic exam was significant for mild cognitive impairment, bilateral ptosis, ophthalmoparesis, bulbar weakness, jaw dystonia, ataxia and hyperreflexia. Magnetic resonance imaging (MRI) of the brain revealed patchy non-enhancing T2 hyperintensity within the brainstem. Infectious and metabolic workup was unrevealing, but serum and cerebrospinal fluid studies autoimmune panel showed reactivity for anti-neuronal nuclear antibody- Type 2 (ANNA-2) suggesting a paraneoplastic etiology for rhombencephalitis. Malignancy workup revealed invasive poorly differentiated ductal carcinoma of the breast. Repeating MR of the brain four weeks after initiation of steroid treatment showed resolution of the brain stem lesion but with minimal clinical improvement. 

Conclusions:

Subacute gait ataxia, ophthalmoparesis, cognitive decline with bulbar manifestations, and jaw dystonia should raise suspicion for Anti-RI/ANNA2 rhombencephalitis. Although subsequent imaging studies may exhibit improvement in signal abnormalities after treatment, radiological improvement does not necessarily translate into clinical improvement. Early recognition is important in facilitating prompt cancer detection, intervention, and consequently, enhanced patient outcomes.