52. Not every rheumatologic headache is giant cell arteritis: a case of aseptic meningitis on a background of rheumatoid arthritis

INTRODUCTION: A 65-year-old Caucasian lady had a background of longstanding seropositive rheumatoid arthritis (RA) for which multiple disease modifying drugs and biologics had been tried, but then stopped due to either inefficacy or intolerance. She presented with possible vasculitis and was initially treated and investigated for giant cell arteritis (GCA). CASE DESCRIPTION: This patient presented with temporal headache and right-sided visual field loss, with tenderness over a weakly palpable right temporal artery. No jaw claudication or other cranial nerve abnormality and peripheral nervous system examination was normal. She was commenced on prednisolone and the ophthalmologist decided against temporal artery biopsy. She subsequently developed episodes of tonic-clonic seizure and reduced consciousness, which would be unexplained by GCA. ESR 70 and CRP 28. ANCA and ANA negative, rheumatoid factor positive and anti-CCP antibodies >600. Gadolinium-enhanced MRI brain showed subdural effusions in the left frontal/parietal lobes alongside effacement of the gyri, indicating lepatomeningitis. Lumbar puncture showed increased cerebral spinal fluid (CSF) protein of 1.25g/L (0.1-0.4) and mildly reduced glucose of 2.1mmol/L (2.2-3.9). CSF was negative for acid fast bacilli, lyme disease, cryptococcal antigen, PCR for viruses and TB, culture and extensive immunological screening. Tuberculosis T-Spot test was negative whilst PET-CT demonstrated widespread polyarthropathy but no evidence of an underlying malignancy. The patient was referred for meningeal biopsy; however it was considered too high-risk given her medical co-morbidities. As an inpatient, she developed pneumonia and two myocardial infarctions. For the next four months, she was seizure-free on levetiracetam, but still experienced right-sided facial twitching. She was commenced on a reducing regime of prednisolone on the assumption of rheumatoid meningitis and also given 12-month empirical therapy to cover for possibility of TB meningitis, although this was deemed less likely. Initially she responded to prednisolone but upon dose reduction, she noticed worsening incoordination and unsteadiness, with simultaneous joint flare-up, indicating that immunosuppression was beneficial to her neurological status. Azathioprine was introduced as a steroid-sparing agent but she developed abnormal liver function and hence mycophenolate has been used instead. No side effects have been reported; she has remained seizure-free and reports an improvement in her neurological status. DISCUSSION: Initially it was appropriate to treat as GCA given very typical history. However, the presence of other unexplained symptoms and MRI findings led the decision that the diagnosis was not purely vasculitic in origin. MRI brain and CSF findings were consistent with aseptic meningitis, typically where there is meningeal inflammation with negative Gram stain and culture of CSF, often with pleocytosis. Although predominantly caused by enteroviruses; it can occur secondary to malignancy, drugs and autoimmune disease. These causes were considered, however the presence of active rheumatoid arthritis made a diagnosis of rheumatoid meningitis likely. This uncommon complication of seropositive rheumatoid arthritis was described by Bathon et al as having three hallmark neuropathological findings; rheumatoid nodules, pachymeningitis and vasculitis. A diagnostic challenge is the lack of correlation between synovitis and neurological presentation. Presentation ranges from cranial/peripheral nerve dysfunction to seizures and altered mental state. In the CSF we expect to find high protein and reduced glucose with sporadic pleocytosis. Findings from MRI and CSF analysis can be variable. Ultimately rheumatoid meningitis as described in the literature is diagnosed by histopathology at biopsy, but this is not always available in clinical practice, and sometimes empirical treatment has to be given. KEY LEARNING POINTS: Rheumatoid meningitis is a rare complication of RA, but can present with stroke-like episodes or seizures, so this diagnosis should always be considered in RA patients presenting in such a way. Despite high mortality and the lack of any evidence-based guidelines, combinations of steroids alongside cyclophosphamide, azathioprine and methotrexate are reported to have improved prognosis in some patients. The lack of any RCT evidence means the condition has to be managed according to expert opinion, which may require close co-operation between specialties such as neurology, infectious diseases and rheumatology to achieve a good outcome. CONFLICTS OF INTEREST: The authors have declared no conflicts of interest.