Rheumatoid Leptomeningitis due to Rheumatoid arthritis

A 76-year-old female presented with a 10-minute aphasic episode and bilateral leg numbness. Additionally, the patient had a six-month history of daily left leg focal clonic seizures and a two-month history of bilateral metacarpophalangeal joint synovitis.

Neurological symptoms were investigated via the use of CT and MRI. On the day of presentation, the CT head identified asymmetry of the brain parenchyma with effacement of sulci on the right (Figure 1). Further MRI findings on day two of admission showed right superior cerebral convexity sulcal high signal (Figure 2) with enhancement post gadolinium, in keeping leptomeningeal disease (Figure 3). X-ray images were also performed for ongoing synovitis. Moderate arthropathic changes were reported in the distal interphalangeal joints of the left ring, middle and index fingers and right index and middle fingers, with loss of joint space, subchondral cyst formation and osteophyte formation. Arthopathic changes in the second to fourth metacarpophalangeal joints of the right hand and all proximal interphalangeal joints were also noted.

Case progression

Neurology and rheumatology specialist involvement prompted further investigations. Biochemical tests identified positive rheumatoid factor and anti-CCP, confirming a Rheumatoid Arthritis (RA) diagnosis. Three lumbar punctures identified lymphocytic pleocytosis and an axillary biopsy confirmed reactive lymph nodes, providing insufficient evidence for any bacteria, viral or fungal pathology. Clinical, biochemical and radiological parameters were used to make a diagnosis of Rheumatoid Meningitis (RM).

Background

RM is a rare neurological complication of RA. Although the pathophysiology remains unclear, research suggests that meningeal inflammation is predominantly caused by lymphocyte and plasma cell infiltration [1]. Vasculitis of the meninges, brain parenchyma and spinal cord have also been documented; however, this is less prevalent [2].

Clinical Perspective

The most common neurological presentation of RM is altered mental state [1]. Other common symptoms include: cranial neuropathies, hemiparesis and seizures [3]. Few cases report RM presenting as mimics for stroke, Parkinsonism and supranuclear palsy [3][4][5]. RM does not correlate with RA onset or activity and can present before synovial symptoms manifest, complicating diagnosis further [6]. Due to the variability of presentations, imaging is vital to exclude other neurological causes.

Imaging Perspective

The most common RM radiological finding is leptomeningeal or pachymeningeal enhancement [1]. Leptomeningeal enhancement involves the pia and arachnoid layer and the sulci of the gyri or around the brainstem; whereas pachymeningeal enhancement affects the dural layer when the enhancement involves the cerebral convexity/ inner surface of calvarium, the falx, or the tentorium without extension into the cortical sulci. RM is a diagnosis of exclusion, and once these features are identified, a cascade of investigations to identify the cause of meningeal inflammation follows [7]. The gold standard for RM diagnosis is meningeal biopsy. However, in practice, these are uncommon due to the risks outweighing clinical benefit. Therefore, the utilisation of clinical, biochemical and radiological parameters are paramount when making the final diagnosis.

Outcome

Currently, there are no treatment guidelines for RM. The use of corticosteroids has been widely used; however, fatality was documented in 60% of cases [5]. Recent literature has identified the effectiveness of monoclonal antibodies; however, patients already on TNF-alpha inhibitors for RA have developed RM, and so treatment remains unclear [4]. Since starting prednisolone and hydroxychloroquine, repeat MRIs show reduction of leptomeningeal enhancement in this patient.

Teaching Points

In patients with pachy- or lepto-meningeal disease, rheumatoid meningitis should be considered in the differential diagnosis, particularly if signs of an arthropathy are present.

Written informed patient consent for publication has been obtained.