Endoscopic Transsphenoidal Fenestration of a Medial Temporal Arachnoid Cyst With Extension to Sphenoid Sinus in a Patient With Temporal Lobe Epilepsy

Arachnoid cysts are developmental cystic lesions which may be found as an incidental finding on neuroimaging or present with symptoms of headache, seizure and neurologic deficit. Presentation with seizure is more common with larger sizes and temporal location. Presentation with Temporal Lobe Epilepsy (TLE) is rare, and fenestration of cysts has variable results for seizure control. We reported controlling TLE symptoms following endoscopic transsphenoidal fenestration of an arachnoid cyst. The anteromedial location in middle fossa, extension toward sphenoid sinus and normal appearance of mesial temporal structures on MRI encouraged us to consider this surgical approach.

A 26-year-old patient with a 13-year history of TLE with uncontrolled symptoms despite taking a combination of AEDs (LTG, CBZ, LEV, CLB) was referred to our clinic. Neuroimaging revealed an arachnoid cyst in anteromedial part of temporal fossa which extended to sphenoid sinus, but showed no abnormality in mesial temporal structures. Endoscopic endonasal transsphenoidal fenestration of the arachnoid cyst was performed, and followed by reconstruction of the skull base. The procedure improved the seizure control during the 9-month follow-up and no sign of radiologic recurrence was observed.

Transsphenoidal endoscopic fenestration is a safe and feasible surgical approach for treatment of symptomatic arachnoid cysts in anteromedial part of middle fossa especially when they extend toward lateral wall of sphenoid sinus. This surgical corridor has the privilege of avoiding cortical injury accompanied by transcranial approaches, which is deleterious in epileptic patients.