Leptomeningitis is meningitis affecting the pia and/or arachnoid membranes.
Pachymeningitis is meningitis affecting the dura mater.
Rheumatoid meningitis may include:
(1) rheumatoid nodules
(2) vasculitis, which can be necrotizing
(3) lymphocytic infiltration of the meninges with or without plasma cells
(4) epithelioid granulomas
Clinical findings:
(1) change in behavior
(2) altered level of consciousness
(3) seizure
(4) cranial nerve dysfunction
(5) hemiparesis or paraparesis
Meningeal enhancement can be seen on MRI.
Laboratory findings:
(1) elevated Rheumatoid factor (RF)
(2) elevated protein in the CSF with a variable iincrease in lymphocytes and monocytes
Most patients with rheumatoid meningitis are known to have rheumatoid arthritis but occasionally a patient will present without arthritis or other manifestations of RA.
Making the diagnosis can be difficult since there is a long differential diagnosis for septic and aseptic meningitis.
