Case report Rheumatoid meningitis can present MRI findings that mimic chronic subdural haematoma Kaoru Yagita, Akiyo Shinde, Toshihiko Suenaga Department of Neurology, Tenri Hospital, Tenri, Nara, Japan Correspondence to Dr Kaoru Yagita, ​yagita.​k@​gmail.​com Accepted 19 July 2019 Summary A 65-year-old woman with long-standing rheumatoid arthritis (RA) experienced a recurrent tingling sensation in her left arm followed by aphasia and a tingling sensation in her right arm. A subsequent imaging study showed bilateral subdural fluid accumulation and we initially diagnosed her with a transient ischaemic attack and chronic subdural haematoma (CSDH). The cerebral spinal fluid study revealed an inflammatory response without any indications of infection or malignant tumours. After a meningeal biopsy, we redefined the diagnosis to rheumatoid meningitis (RM), and the patient showed remarkable improvement with prednisolone administration. RM should be considered as an alternative diagnosis when examining central nervous system diseases in patients with RA, as RM presents a highly variable clinical picture with image findings similar to those of CSDH. Background Rheumatoid meningitis (RM) is a rare central neurological complication of rheumatoid arthritis (RA). We encountered a patient with long-standing RA with RM who was misdiagnosed with chronic subdural haematoma (CSDH) as a result of her brain MRI findings. Case presentation © BMJ Publishing Group Limited 2019. No commercial re-use. See rights and permissions. Published by BMJ. To cite: Yagita K, Shinde A, Suenaga T. BMJ Case Rep 2019;12:e229642. doi:10.1136/bcr-2019229642 A 65-year-old woman with a 10-year history of RA was admitted to our neurology department, with a tingling sensation in her right arm and then developed mild aphasia. Her RA had been well controlled by iguratimod and methotrexate for a long time, but her intake of methotrexate stopped 6 months before the onset of symptoms. Approximately 2 months prior to admission, she experienced a transient tingling sensation in her left upper limb. The abnormal sensation occurred 3–4 times per day, with a duration of between 5 and 10 min. Light headaches and elementary hallucinations appeared concurrently. Two weeks prior to admission, she experienced a transient tingling sensation on the left side of her tongue and was diagnosed with a transient ischaemic attack (TIA) and began a regimen of aspirin (100 mg/ day) and clopidogrel (75 mg/day). A fluid-attenuated inversion recovery (FLAIR) MRI sequence of the patient’s brain showed an area of hyperintensity in the bilateral subdural spaces. Therefore, in our opinion, her condition may have been complicated by CSDH (figure 1A). Her diffusion-weighted image (DWI) revealed that the right subdural lesion had restricted diffusion, while the left side appeared normal (figure 1B,C). Her abnormal sensations and headaches continued despite the use of dual antiplatelet drugs. Two weeks after the MRI study, she experienced a tingling sensation in her right upper limb and could not speak. Her family called for an ambulance and she was admitted to our department. Her medical history included no remarkable illnesses other than RA. She was a non-smoker and did not drink alcoholic beverages. On examination, she had no tingling sensations, but had mild aphasia; repetition and comprehension were partially impaired while naming was retained. There were no other marked systemic symptoms such as fever, arthralgia, respiratory manifestation and skin lesions. The mild aphasia disappeared 3 hours after admission and there were no other abnormal neurological findings. Subsequently, her transient aphasia and tingling sensations recurred on several occasions. Investigations Laboratory tests showed an increased platelet count 43.2×104/μL (normal<34.8×104 µL), C reactive protein (CRP) level 2.69 mg/dL (normal<0.14 mg/dL), and erythrocyte sedimentation rate of 83 mm/hour (2