RESUMEN
Arachnoiditis ossificans (AO) is a rare disorder characterized by calcification of arachnoid membranes first described by Kaufman and Dunsmore in 1971. It is a very rare cause of spinal canal stenosis leading to neurological compromise presenting with progressive lower extremity myelopathy. It has been described to be a sequela of various conditions previous intradural surgery, myelograms, vascular malformations and adhesive arachnoiditis. Associated conditions may include syringomyelia. The imaging findings on MRI may be confusion. Preferred diagnostic method is non contrast computed tomography (CT). Surgical intervention is still controversial and can include decompression. The authors report the case of 48 years female presenting with gradually progressing paraparesis. Magnetic resonance imaging of the spine revealed a spinal cord syrinx but with an extramedullary intradural hypo-intensity. A computed tomography scan clearly demonstrated the abnormality and its extent. We present a unique case of syringomyelia resulting from spinal arachnoiditis ossificans and review the relevant literature. This case reports a unique presentation of arachnoiditis ossificans with syringomyelia in which etiology is not clear. We also highlight the difficulty is diagnosis on MRI and need of non-contrast CT.