Disease or Syndrome
arachnoid cyst
[ uh-rak-noid sist ]
Subclass of:
Central Nervous System Cysts; Cyst
Definitions related to arachnoid cysts:
  • A disorder with extraparenchymal cysts, intra-arachnoidal collections of fluid, the composition of which is close to that of cerebrospinal fluid. They are often asymptomatic.
    OrphaNet
    INSERM, 2021
  • An extra-parenchymal and intra-arachnoidal collection of fluid with a composition similar to that of cerebrospinal fluid.
    Human Phenotype Ontology (HPO)
    The Human Phenotype Ontology Project, 2025
  • 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.
    NCI
    U.S. National Cancer Institute, 2021
  • Intracranial or spinal cavities containing a cerebrospinal-like fluid, the wall of which is composed of arachnoidal cells. They are most often developmental or related to trauma. Intracranial arachnoid cysts usually occur adjacent to arachnoidal cistern and may present with HYDROCEPHALUS; HEADACHE; SEIZURES; and focal neurologic signs. (From Joynt, Clinical Neurology, 1994, Ch44, pp105-115)
    NLM Medical Subject Headings
    U.S. National Library of Medicine, 2025
  • Arachnoid cysts are sacs filled with cerebrospinal fluid (CSF) that are located between the brain or spinal cord and the arachnoid membrane, one of the three membranes that cover the brain and spinal cord. Arachnoid cysts can be primary or secondary. Primary arachnoid cysts are congenital (present at birth), resulting from abnormal...
    NIH Genetic and Rare Diseases
    National Center for Advancing Translational Sciences
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This content should not be used in place of medically-reviewed decision support reference material or professional medical advice. Some terms may have alternate or updated definitions not reflected in this set. The definitions on this page should not be considered complete or up to date.