Epidemiology of Arachnoid Cysts of the Head and Spine in Children

Incidence and Prevalence

Cranial cysts

• 1% of intracranial mass lesions: Arachnoid cysts account for approximately 1% of intracranial mass lesions.
• Middle fossa most common: The most common location is the middle fossa (50% of all cysts), with a left side predominance. Other locations include frontal convexity and posterior fossa.

Spinal cysts

• Rare lesions: Both intra- and extradural cysts account for a relatively small number of the already rare number of arachnoid cysts. They are predominantly posterior to the cord and mostly in the cervical region, although some are seen in the lumbar region, as well.

Age Distribution

Cranial cysts

• Early childhood: Cranial cysts usually present in early childhood.

Spinal cysts

• Any age: Spinal cysts can present at any age, although thoracic cysts predominantly present during adolescence.

Sex Predilection

Cranial cysts

• Male predominance: Arachnoid cysts may be up to four times more common in boys.

Spinal cysts

• Intradural: No gender predominance is apparent.
• Extradural: Extradural arachnoid cysts are more common in males.

Geographic Distribution

• Not a factor

Risk Factors

• None known

Relationships to Other Disease States and Syndromes

Cranial cysts

• Hydrocephalus: Cranial arachnoid cysts may be related to hydrocephalus or anomalous CSF circulation.
• GAT 1: Bitemporal arachnoid cysts may be associated with a congenital metabolic disorder, GAT 1, which may make surgery hazardous due to a metabolic crisis triggered by anesthesia (14).

Spinal cysts

• Inflammation: Cysts may be due to loculated CSF secondary to scarring and inflammation from hemorrhage or infection.
• Associated syndromes: Incidence is seen in conjunction with Down syndrome, mucopolysaccharidosis, schizencephaly, and neurofibromatosis.
• Trauma: Cysts may be posttraumatic.