Ab0790 unilateral relapsing primary central nervous system vasculitis: description of 3 cases from a single institutional cohort of 216 cases

Background Some cases of unilateral primary central nervous system vasculitis (PCNSV) with relapsing disease involving the same brain hemisphere have been described [1]. Objectives The aim of this study was to define the frequency and characteristics of patients with unilateral relapsing involvement in a large cohort of patients with PCNSV. Methods We retrospectively studied a cohort of 216 patients with PCNSV seen at the Mayo Clinic, Rochester, MN from 1983 to 2022. Data collected for all cases included comprehensive information about clinical findings, laboratory tests, imaging, CNS biopsy or autopsy, therapies, flares, follow-up functional status and cause of death. Cerebral biopsy specimens were reviewed by one neuropathologist (CG). Angiograms and MRIs were reviewed by a neuroradiologist. For the present study, we specifically identified those patients with at least two flares and imaging at diagnosis and at follow-up showing vasculitis confined to one cerebral hemisphere. Results Twenty-five patients (19.8%) had at least two flares. 3 of them (1.4%) had unilateral relapsing vasculitis. All 3 patients had angiography-negative and biopsy-positive PCNSV. One patient had amyloid beta-related angiitis (ABRA), while the other 2 patients had granulomatous-necrotizing and lymphocitic vasculitides, respectively. Hemisphere involvement occurred on the left in two, and on the right in one. In all three patients the main presenting clinical manifestation at diagnosis and at the time of flares was seizures. All had multiple flares (from 4 to 10) and were treated with different traditional immunodepressive drugs and rituximab (RTX) for the steroid-resistance. They received long-term treatment (more than 2 years) with fixed high-dose prednisone (PDN) (in one 40 mg/daily, in the other two 20 mg/daily) because the vasculitic process flared when the PDN dose was reduced. One patient had at MRI prominent leptomeningeal enhancement, while the other two had cerebral lesions with gadolinium enhancement. In all three patients the vasculitic process was confined to the same cerebral hemisphere at diagnosis and during the flares, and at the last available brain MRI performed 35 months, 167 months, and 65 months after the diagnosis, respectively. All 3 patients at last follow-up had slight disability with mild cognitive impairment; one case also had mild left hemiparesis. Spinal fluid examination at diagnosis was normal in 2 patients. Conclusion Unilateral relapsing involvement represents a rare subset of PCNSV with peculiar characteristics and can be observed in all neuropathological patterns. References [1]AbdelRazek MA, Hillis JM, Guo Y, et al. Unilateral Relapsing Primary Angiitis of the CNS: An Entity Suggesting Differences in the Immune Response Between the Cerebral Hemispheres. Neurol Neuroimmunol Neuroinflamm. 2021 Jan 5;8(2):e936. Acknowledgements: NIL. Disclosure of Interests None Declared.