The present patient was given a diagnosis of “definite RA” based on a score of 7 on the new 2010 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) classification criteria. Rheumatoid meningitis (RM) is defined as a condition of inflammation of the meninges or dura mater with cell infiltration. In the past, most RM cases were reported as autopsy cases, but the number of reported cases of RM has increased along with the increase in patients with long-standing disease and advances in diagnostic imaging. In many patients, RA is in the very early stage or long-term, and the disease duration is said to be ≥10 years for 50% or more [3]. The present patient presented 6 months after her diagnosis of RA, and thus was in the comparatively early stages of the disease; although the reason for that is not clear, it is consistent with earlier reports [4, 7]. In addition, although it did not correlate with her arthritic activity, the onset of RM was sudden and at a time when her RA activity was stable. There have been scattered reports of the use of intravenous steroid pulse therapy and oral steroids (1 mg/kg) [7, 8]. Even when there is improvement with treatment, caution must be taken regarding possible relapse or recurrence, but the present patient did not relapse up to 6 months later.
The neurological symptoms of RM may be hemiplegia, monoplegia, impaired consciousness, psychiatric symptoms, convulsions, and sensory impairment [9]. These symptoms are usually slowly progressive or transient [8]. However, to the best of our knowledge, there have been only two reports of patients with stroke-like attacks [10, 11]. Thus, although rare, RMSA should be included in the differential diagnosis of acute ischemic stroke presenting within the time window for thrombolytic therapy. The present patient is the first reported case of RMSA who was treated with rt-PA. MRI is helpful to differentiate it from acute ischemic stroke when it is performed on hospitalization.
The present patient’s symptoms rapidly improved in the early treatment period. It is possible that the brain-protective agent, edaravone, which was co-administered with intravenous rt-PA, contributed to that improvement. Free radicals have been reported to be involved in the vasculitis and cerebral edema associated with encephalitis as well [12], and to some extent, the administration of edaravone, a free radical scavenger, makes sense. MRI and biopsy findings have primary importance in the diagnosis of RM [3, 8]. A meningeal biopsy was not performed in the present case because of the rapid improvement of symptoms. However, the MRI findings were typical for RM, with a restricted ADC at the subarachnoid space adjacent to the right frontotemporal cortex. This linear high-intensity lesion on DWI is thought to result from proteinaceous debris accumulation at the subarachnoid space adjacent to the parenchyma with meningeal lymphocytic infiltration [13].
Evidence to date indicates that endovascular procedures provide clinical benefit in selected patients with acute ischemic stroke [14,15,16,17]. Thus, there is a trend toward CT-based prompt intravenous administration of rt-PA treatment rather than more time-consuming MRI study. In a comprehensive meta-analysis, stroke-mimicking patients were found to have a significantly lower risk for intracerebral hemorrhage and systemic complications than patients with true acute ischemic stroke (risk ratio = 0.33, 95% confidence interval, 0.14–0.77; p = 0.01) [18]. However, if the patients with RMSA would be susceptible to hemorrhagic transformation after receiving iv-tPA, it should be better to adopt the MRI first strategy for every patients with a history of RA. In the present case, it is particularly important that neither adverse events nor bleeding complications were observed, suggesting the safety of CT-based thrombolytic therapy even in RA patients.