One-Piece Modified Gasket Seal Technique

Background: The gasket-seal closure has proved to be an effective method for closure of the anterior cranial base and prevention of postoperative CSF leak following endoscopic endonasal surgery. We present our preliminary results with a modification of the gasket-seal technique, utilizing a porous high-density polyethylene plate/rectus sheath fascia construct for primary closure without intracranial fat packing.

Surgical Technique: Under endoscopic guidance, the skull base defect is sized using a small cut ruler or cottonoid as a standard reference. A polyethylene plate (MEDPOR TSI Barrier, Stryker CMF, Kalamazoo, MI, USA) is cut to the shape of the defect, oversizing by 1-2 mm circumferentially.

A left-lower-quadrant or subumbilical incision is made to sharply harvest an oversized (compared with the plate) fascial free tissue graft. The fascial defect is closed with interrupted #0 absorbable polyfilament (VICRYL, ETHICON, Inc, Somerville, NJ, USA) to prevent incisional hernia.

On the back table, the fascia graft is secured directly to the plate, with the inner surface of the fascia apposed to the inner (smooth) surface of the plate. The fascia is held tense over the plate, affixed with multiple small straight hemostatic clamps, with 3-5 mm of fascia overlapping on all sides. It is then secured to the plate with three or four 4-0 braided nylon stitches (NUROLON, ETHICON, Inc, Somerville, NJ, USA) placing the knot on the outside of the plate.

Using a three-handed endoscopic technique, a manipulating instrument (8 Fr suction or a short, blunt cervical nerve hook) is used to rotate the plate into position and guide it into the epidural space while a grasper is used to provide counter-tension by gently pulling the plate outward. This ensures that the plate does not sink too deeply and provides tactile feedback when the plate is properly countersunk. The construct is used for primary closure without intracranial fat grafting. The defect is then covered with a nasoseptal flap in standard fashion.

Results: We have used this technique in five cases of expanded endonasal endoscopic approach for suprasellar pathology (two craniopharyngioma, two tuberculum meningiomas, one planum meningioma). There have been no postoperative CSF fistulae. There was one case of aseptic meningitis treated with a prolonged course of steroids. There have been no graft site complications (infection, hematoma, or hernia).

Conclusions: The one-piece modified gasket-seal closure is a safe and effective method for reconstruction of endonasal defects of the anterior skull base. Rectus sheath fascia is an appropriate dural substitute for free tissue grafting with low donor site morbidity. The construction of the one-piece graft on the back table saves a significant amount of time and lowers the learning curve for multilayered closure.