Endoscopic Transsphenoidal Resection of a Medial Temporal Arachnoid Cyst in a Patient with Temporal Lobe Epilepsy

Abstract Introduction: 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 TLE is rare, and fenestration of cysts had variable results for seizure control. Here in, we report on control of TLE symptoms, following endoscopic trans-sphenoidal fenestration of 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. Case Description: A 26-year-old patient with 13 years history of TLE with uncontrolled symptoms despite taking a combination of AEDs (LTG, CBZ, LEV, CLB) was referred to our clinic. On neuroimaging, he had an arachnoid cyst in anteromedial part of temporal fossa without abnormality in mesial temporal structures which was extended to sphenoid sinus. Endoscopic endonasal trans-sphenoidal fenestration of the arachnoid cyst, followed by reconstruction of skull base was performed. The procedure resulted in improvement in seizure control during the 9-month follow-up and no sign of radiologic recurrence.  Discussion and Evaluation: Trans-sphenoidal endoscopic fenestration is a safe and feasible surgical approach for treatment of symptomatic arachnoid cysts in anteromedial part of middle fossa specially when they have extension toward lateral wall of sphenoid sinus. Conclusion:Endoscopic approach to arachnoid cysts of middle fossa has the privilege of avoidance of cortical injury accompanied by transcranial approaches, which is deleterious in epileptic patients.