Middle cranial fossa

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Status

Done

Parent item

Arachnoid cyst

Number

• 50-65% of all arachnoid cyst

Galassi classification

• Type I:
• small size, located in the anterior temporal lobe.
• No mass effect
• Free communication with Subarachnoid space
• Tx with microsurgical fenestration

• Type II:
• medium-size, located in the anterior and middle temporal fossa. Temporal lobe displaced.
• Slow communication with Subarachnoid space
• Tx with endoscopic fenestration

• Type III:
• constitutes a large oval or round cyst that fills the entire temporal fossa. Large mass effect.
• Little communication with Subarachnoid space
• Tx with endoscopic fenestration

Tx

• Surgical: no difference in all 3
• Endoscopic,
• endoscopic fenestration is the preferred primary surgical modality.
• Microsurgical,
• Only be considered when symptoms are unchanged after endoscopic treatment
• Shunting
• Only be considered when symptoms are unchanged after endoscopic treatment

• ICP monitoring useful for T1 and T2 but not T3
• To may help to rule out operative treatment in Type I, confirm raised ICP in Type III (but inconsistent in type II).