# Arachnoid Cysts: Management > Arachnoid cyst management for NEET-SS Neurosurgery: Galassi grading, middle fossa cysts, fenestration versus shunt and the incidental cyst problem. - Canonical URL: https://prepelephant.com/topics/neet-ss/neurosurgery/arachnoid-cysts-management - Exam / course: NEET-SS · Subject: Neurosurgery - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Arachnoid Cysts: Management", PrepElephant, https://prepelephant.com/topics/neet-ss/neurosurgery/arachnoid-cysts-management ## Direct answer Galassi grading gives the middle fossa arachnoid cyst its working language: type I is small, biconvex and spindle-shaped in an intact middle fossa; type II is larger, rectangular, displacing the temporal lobe and opening the Sylvian fissure; type III is huge, filling and expanding the entire middle fossa with midline shift — and grade predicts both symptom likelihood and the difficulty of making the cyst behave. Most arachnoid cysts are congenital pockets of cerebrospinal fluid within a split arachnoid lining, found incidentally, and the central management decision is restraint: an asymptomatic cyst, however large, with a normal neurological examination is observed, because the risks of surgery exceed the cyst's own. Symptomatic cysts — headache reliably linked, seizures, focal deficit, macrocephaly in children — are treated by fenestration into the basal cisterns or ventricle, increasingly endoscopically, with cystoperitoneal shunting reserved for fenestration failures. The complication that colours counselling is post-traumatic subdural haematoma over a middle fossa cyst, a real consideration in contact-sport discussion. ## What you must remember - **Locations by frequency:** middle cranial fossa (the Galassi territory) is commonest, then retrocerebellar, suprasellar, cerebral convexity and spinal. - **Galassi I-III anatomy:** I small and spindle-shaped; II medium, rectangular, temporal lobe displaced with fissure opening; III large, fossa expanded, midline shift — grade III cysts are the ones that become surgical conversations. - **The imaging signature:** cerebrospinal fluid density on CT and intensity on MRI (low T1, high T2, fluid-attenuated inversion recovery suppression), no enhancement, no diffusion restriction; temporal bone expansion and thinning reveal chronicity. - **Surgical options in order:** endoscopic fenestration (cystocisternostomy or cystoventriculostomy) as first choice, open microsurgical fenestration when endoscopic anatomy defeats, and cystoperitoneal shunt as fallback — hardware and infection are its price. - **The subdural story:** middle fossa cysts associate with post-traumatic subdural haematoma and hygroma, so head-injury counselling and contact-sport discussion belong in the outpatient consultation. - **Indian context:** the incidental-cyst MRI epidemic reaches Indian radiology reports too — the discipline of not operating on incidental findings is cheaper and safer than the surgery, a point of access economics as much as judgement. ## When to operate on a middle fossa cyst A nine-year-old is referred for headaches after an MRI done for the problem reports a right middle fossa cyst expanding the temporal bone. The consultation is an exercise in causality: are the headaches plausibly the cyst's — worse with Valsalva, morning, or accompanied by nausea — or ordinary tension-type headaches in a school-going child? A careful history here reveals weekend headaches related to screen use and a completely normal examination with a Galassi I, or at most a II, cyst: the decision is observation with a defined interval scan and headache diary, and the family is specifically counselled about head injury and return for any deterioration after trauma. Change one variable — the cyst is Galassi III with midline shift and the child has papilloedema-free but progressive left hemianopia or refractory epilepsy localised to the temporal region — and surgery earns its place: endoscopic fenestration of the cyst wall into the basal cisterns, with intraoperative confirmation of flow, reserving a cystoperitoneal shunt for those who reaccumulate. The operation is judged by symptoms and radiological stability, not by disappearance — a cyst that shrinks halfway and stops causing problems is a success. ## How the exam frames it The single-best-answer version asks what to do with an incidental arachnoid cyst: the answer is observation, and any operative option is the distractor. The viva version probes the surgical logic — fenestration restores physiological CSF circulation and avoids lifelong hardware, which is why it precedes shunting — and then the Galassi grade as a predictor of both symptomatology and technical difficulty. The final favourite is the trauma question: a young man with a known middle fossa cyst sustains a minor head injury and deteriorates — the diagnosis to blurt is subdural haematoma over the cyst, and the management is a trauma pathway, not a cyst clinic. ## Frequently asked questions ### What are the Galassi grades of middle fossa arachnoid cyst? Type I small and spindle-shaped, type II rectangular with temporal lobe displacement, and type III large with expansion of the whole middle fossa and midline shift. ### How should an incidentally discovered, asymptomatic cyst be managed? With observation and interval imaging, since surgical risks exceed the natural risk of an asymptomatic cyst. ### What is the preferred operation for a symptomatic arachnoid cyst? Endoscopic fenestration into the basal cisterns or ventricular system, with open fenestration or cystoperitoneal shunting reserved for failures. ### Why are middle fossa cysts relevant to contact-sport counselling? They predispose to post-traumatic subdural haematoma or hygroma after relatively minor head injury. ### On which sequences does an arachnoid cyst follow cerebrospinal fluid? Hypodense on CT, T1-hypointense and T2-hyperintense on MRI with fluid attenuation on FLAIR, without enhancement or diffusion restriction.