Keyhole Microsurgical Middle Fossa Arachnoid Cyst Fenestration: 2-Dimensional Operative Video.

Surgical options for symptomatic intracranial arachnoid cysts include cyst shunting and microscopic or endoscopic fenestration. We advocate a microsurgical keyhole approach for the durable fenestration of middle fossa arachnoid cysts, taking advantage of the superior magnification, depth perception, and illumination of the operating microscope, as well as the ability to use bimanual surgical technique and variable suction to ensure safe manipulation of arachnoid membranes and fenestration of these lesions into the deep cisterns. Key technical aspects of this approach demonstrated in this video (Video 1) include performance of a dime-sized temporal craniotomy; strict microsurgical technique with sharp dissection via a No. 11 blade, sharp microdissectors, and microscissors; disruption of the arachnoid membranes overlying cranial nerves II/III, the internal carotid artery, and the posterior communicating artery; and fenestration of the membrane of Lilliquist through the opticocarotid, oculomotor, and/or supratrochlear triangles. The utility of this approach is illustrated by the case of a 5-year-old male with a history of headaches and interval progression of a left temporal grade 2 arachnoid cyst, who experienced symptom resolution and cyst shrinkage after keyhole microsurgical fenestration.