Updated assessment and current classification of spinal meningeal cysts

TLDR

Spinal meningeal cyst classification in the literature is unclear, confusing, and sometimes histologically misleading. The authors propose a three‑category classification of spinal meningeal cysts based on 22 cases. The classification relies on imaging—CT myelography to confirm cyst–subarachnoid communication, MRI to detect cystic masses—and final confirmation by operative inspection and histology. CT myelography confirming communication enables accurate diagnosis of spinal meningeal cysts and excludes other masses.

Abstract

✓ The classification of spinal meningeal cysts (MC's) in the literature is indistinct, confusing, and in certain categories histologically misleading. Based on a series of 22 cases, the authors propose a classification comprising three categories: spinal extradural MC's without spinal nerve root fibers (Type I); spinal extradural MC's with spinal nerve root fibers (Type II); and spinal intradural MC's (Type III). Although water-soluble myelography may disclose a filling defect for all three categories, computerized tomographic myelography (CTM) is essential to reveal communication between the cyst and the subarachnoid space. Communication demonstrated by CTM allows accurate diagnosis of a spinal MC and rules out other mass lesions. Magnetic resonance imaging appears useful as an initial study to identify an intraspinal cystic mass. Final characterization is based on operative inspection and histological examination for all three categories.