Arachnoid Cyst

**Semantic type:** Finding

**Definition:** An intracranial or spinal cyst which contains fluid and is composed of arachnoid cells. Intracranial arachnoid cysts may present with headaches, seizures and hydrocephalus. Spinal arachnoid cysts may present with symptoms of radiculopathy.

**Synonyms:** - Leptomeningeal Cyst