Crystal Violet Staining Facilitates Boundary Recognition in the Removal of Spinal Arachnoid Pathology.

Spinal arachnoid cysts are relatively uncommon lesions, broadly classified as either congenital or acquired. Acquired cysts may develop following trauma, hemorrhage, or post-infectious inflammation. Depending on their location, these cysts can cause a range of symptoms, including quadriplegia, pain, sensory disturbances, and gait impairment. Surgical resection may be indicated in cases with significant neurological symptoms. We report the case of a 77-year-old woman who presented with persistent bilateral leg numbness and pain. Magnetic resonance imaging revealed a suspected intradural spinal arachnoid cyst or arachnoid web at the Th7-8 level, and surgery was planned to relieve the symptoms. A laminectomy was performed, revealing a cystic, membrane-like structure in the subdural space. By injecting a crystal violet staining solution into the cyst, we enhanced the visibility of the boundary between the normal arachnoid membrane and the cyst, allowing for complete resection. Postoperatively, the patient experienced improvement in leg pain and numbness. This case demonstrates that crystal violet staining can facilitate clear boundary recognition during arachnoid cyst resection, enabling more precise cyst removal.