Orbital Inflammation can be visualized by black blood MRI in isolated polymyalgia rheumatica

OBJECTIVE: Giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) are considered as manifestations of a shared disease spectrum (GCA-PMR spectrum disease, GPSD). Data on orbital involvement in isolated PMR and across the spectrum remain limited. This study evaluated inflammatory intraorbital MRI findings across the GCA-PMR spectrum. METHODS: This retrospective observational study included patients with isolated PMR and combined GCA-PMR (presence of both clinical diagnoses and fulfilling classification criteria of GCA plus PMR). Patients with GCA and no signs and symptoms of PMR were not included. Contrast-enhanced MRI of the orbits was assessed for inflammatory findings, including optic nerve sheath enhancement and ophthalmic artery vessel wall enhancement. Imaging findings were correlated with clinically reported orbital symptoms. RESULTS: 73 isolated PMR patients had evaluable MRI of the orbits. Nine (12.3%) showed intraorbital inflammatory changes: bilateral optic nerve sheath enhancement (n = 8) and bilateral ophthalmic artery enhancement (n = 4). None had clinical or imaging evidence of large-vessel vasculitis. Two patients reported acute visual symptoms, both with corresponding orbital MRI findings.63 GCA-PMR patients had evaluable MRI of the orbits. Intraorbital findings were present in 20 (31.7%), most commonly bilateral optic nerve sheath (n = 16) and bilateral ophthalmic artery enhancement (n = 11). Fourteen patients reported acute visual symptoms; ten had corresponding MRI findings, while four were MRI-negative. CONCLUSION: Inflammatory orbital changes occur in patients with GCA-PMR and isolated PMR. Orbital and ophthalmic artery involvement may arise even without overt GCA, supporting a large overlap between GCA and PMR highlighting the potential value of orbital MRI.