Aseptic meningitis caused by cellular debris may follow rupture or surgery on an intracranial cyst.


Cystic structures that can rupture into the CSF:

(1) craniopharyngioma (with cystic component)

(2) cholesteatoma

(3) epidermoid cyst

(4) intracranial dermoid cyst


Cysts lined by a squamous epithelium may contain oils that contribute to the irritation.


Clinical features:

(1) headache

(2) low-grade fever

(3) meningism

(4) depressed level of consciousness


Hydrocephalus may develop in chronic cases as fibrosis develops.


Laboratory findings on CSF examination:

(1) leukocytosis (neutrophilic if acute, lymphocytic if chronic)

(2) negative Gram stain

(3) sterile CSF culture (negative bacterial, fungal and viral cultures)

(4) possibly cellular debris and/or oily material


Following resection of an intracranial cyst it is recommended that followup scans be performed in order to detect cyst recurrence.


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