see also Spinal meningocele.
Spinal meningeal cysts can be classified according to a system published by Nabor et al. 1).
type I: extradural meningeal cyst without neural tissue
type Ia: extradural spinal arachnoid cyst
type Ib: sacral meningocele
type II: extradural meningeal cyst containing neural tissue, e.g. Tarlov cyst
type III: intradural spinal arachnoid cyst