6.4.2 Headache attributed to primary angiitis of the central nervous system (PACNS)

Identification: Female patient, 42 years old, previously healthy, not on any medications. Current Illness History: Progressive headache for 8 weeks, diffuse, pressure-like (intensity 6-8/10). Atypical Characteristics: Partially responsive to NSAIDs. Worsens at night and upon waking. Associated with: Progressive cognitive deficit (recent memory), episodes of transient diplopia, alternating limb paresthesias. No fever, weight loss, or systemic symptoms. Neurological Examination: Cognition: MMSE 24/30 (deficit in calculation and recall). Focal Signs: Mild motor asymmetries (4+/5 right upper limb), asymmetric brisk reflexes (R > L). Fundoscopy: Discrete bilateral papilledema. Complementary Exams: Brain MRI with contrast: Multiple areas of T2/FLAIR hyperintensity (bilateral subcortical), irregular leptomeningeal enhancement, no tumoral lesions or masses. MR Angiography: Multifocal segmental stenoses in medium-caliber arteries, areas of reduced perfusion in affected territories. CSF: Lymphocytic pleocytosis (45 cells/mm3), elevated proteins (80 mg/dL), elevated IgG index (0.7), negative cultures and cytology. Leptomeningeal biopsy (gold standard): Perivascular lymphomonocytic infiltrate, fibrinoid necrosis of the vascular wall, histopathological confirmation of PACNS.