An extra-parenchymal and intra-arachnoidal collection of fluid with a composition similar to that of cerebrospinal fluid.
Comment:
Arachnoid cysts can be found on the brain, or on the spine. Intracranial arachnoid cysts usually occur adjacent to the arachnoidal cistern. Spinal arachnoid cysts may be extradural, intradural, or perineural.
Synonyms:
exact_synonym:
Fluid-filled sac located in membrane surrounding brain or spinal cord