Objective:

To increase awareness of this rare and underrecognized form of aseptic meningitis. 

Background:

Rheumatoid meningitis (RM) is a rare disorder that is historically difficult to diagnose given its diverse range of reported clinical presentations and lack of clear pathognomonic findings. RM is typically a diagnosis of exclusion, made only after ruling out alternative infectious and malignant disease. Common laboratory findings include elevated rheumatoid factor (RF) and anti-citrullinated peptide (anti-CCP) antibody. MRI may show leptomeningeal or pachymeningeal involvement, primarily in a frontoparietal location pattern. CSF analysis typically reveals a pleocytosis with a moderate elevation in protein level. Treatment generally consists of high dose steroids followed by immunotherapy. 

Design/Methods:

A 69-year-old male with a history of longstanding rheumatoid arthritis on immunosuppressive therapy with methotrexate and recent addition of abatacept presented to our tertiary referral center with progressive neurologic deficits. He initially developed sudden, bilateral sensorineural hearing loss and dizziness with reported normal brain imaging. Six months later, he developed seizures and rapid functional decline with severe cognitive impairment. 

Results:

An MRI brain revealed multifocal leptomeningeal and pachymeningeal enhancement with a relatively unremarkable appearance of the subjacent parenchyma, primarily focused in the right frontoparietal region. CSF studies were remarkable for a mild pleocytosis and a moderate elevation in CSF protein. RF was markedly elevated at 227 IU/mL as was anti-CCP antibody at >200 units. Extensive serum and CSF infectious and oncologic testing were negative. He was treated with 5 days of IV methylprednisolone with a rapid improvement in his cognition. Alternative immunosuppressive therapy for RA with methotrexate and rituximab has resulted in sustained functional stability. 

Conclusions:

While rare, RM should be considered in the differential of a patient with aseptic meningitis of unclear etiology, with or without a history of rheumatoid arthritis. Early detection and treatment are essential to the prevention of long-lasting sequela of the disease.