This study aims to clarify the cerebral lesion patterns in PCNSV to enhance understanding of the pathology and improve diagnostic accuracy.

Primary central nervous system vasculitis (PCNSV) is a rare autoimmune disease that affects only the brain and spinal cord, without systemic vasculitis findings. Its clinical presentation is highly heterogeneous and can often mimic other neurological diseases. The literature on the distribution of cerebral lesions in PCNSV is limited.

Brain MRIs of patients with PCNSV were analyzed. To create a comprehensive lesion heatmap, MRI scans were spatially normalized to the ICBM-152 template using SPM12 software. Lesions were delineated with ITK-SNAP and lesion density heatmaps were generated with MRIcroGL to visualize lesion distribution across the brain.

Eleven patients (6 male, 5 female) with PCNSV were included in the study. The median age of the patients was 48 years (IQR: 41-56). The median follow-up period was 5 years (IQR: 3.5-7.0). The median baseline and final modified Rankin scores (mRS) of the patients were 2 (Baseline mRS IQR: 1-2, final mRS IQR: 1.5-3.0). A monophasic course was observed in 6 patients (55%), while a multiphasic course was observed in 5 patients (45%). Five patients were diagnosed using brain biopsy, five using conventional angiography, and one using vessel wall MRI angiography. Heat map analysis revealed that the most commonly affected areas were the centrum semiovale, deep gray matter, and the frontal and occipital horns of the lateral ventricles. In contrast, very limited involvement was observed in the cortical gray matter, brainstem, and cerebellum.