Pedicled frontal periosteal rescue flap via eyebrow incision for skull base reconstruction (SevEN-002)

Abstract

Purpose: Cerebrospinal fluid (CSF) leakage is one of the major complications after endoscopic endonasal surgery. The reconstructive nasoseptal flap is widely used to repair CSF leakage. However, it could not be utilized in all cases; thus, there was a need for an alternative. We developed a pericranial rescue flap that could cover both sellar and anterior skull base defects via the endonasal approach. A modified surgical technique that did not violate the frontal sinus and cause cosmetic problems was designed using the pericranial rescue flap.

Methods: We performed 12 cadaveric dissections to investigate the applicability of the lateral pericranial rescue flap. An incision was made, extending from the middle to the lateral part of the eyebrow. The pericranium layer was dissected away from the galea layer, from the supraorbital region towards the frontoparietal region. With endoscopic assistance, the periosteal flap was raised, the flap base was the pericranium layer at the eyebrow incision. After a burr-hole was made in the supraorbital bone, the pericranial flap was inserted via the intradural or extradural pathway.

Results: The mean size of the pericranial flap was 11.5 cm × 3.2 cm. It was large enough to cross the midline and cover the dural defects of the anterior skull base, including the sellar region.

Conclusion: We demonstrated a modified endoscopic technique to repair the anterior skull base defects. This minimally invasive pericranial flap may resolve neurosurgical complications, such as CSF leakage.

Keywords: CSF leak; Endonasal approach; Endoscopic surgery; Pericranial flap; Skull base.

Fig. 1

Schematic diagram of the surgical procedure. a, b The medial margin of the skin incision was at the supraorbital notch. From the supraorbital notch, about 3 cm incision was considered sufficient for the pericranial flap. After skin retraction, the periosteal layer was dissected superiorly under endoscopic view. An additional incision was made at the point where dissection was not possible due to the natural skull curvature (red line). c, d Through the burr-hole on the supraorbital area, the pericranial flap was inserted in the medial direction via the extradural or intradural pathway. The pericranial flap could cover the sellar and anterior skull base defects

Fig. 2

Schematic procedure for additional incision and burr-hole. a Approximately 10 cm superiorly from the eyebrow incision, further periosteal dissection was impossible due to the natural shape of the skull. b At this point, we made an additional incision. Through this additional incision, we could harvest a longer periosteal flap. c After a periosteal incision with a No. 12 blade, we pulled out the periosteal flap via the eyebrow incision. d We made a single burr-hole on the supraorbital area. Then, we inserted the pericranial flap via the intradural or extradural pathway

Fig. 3

Repositioning of the pericranial flap (PC) via the endonasal endoscopic approach. a A flap inserted through the supraorbital burr hole is partially visible on the margin of a pre-made cribriform defect (endonasal view). b Flap repositioning was done via endonasal endoscopic approach. As a result, the cribriform plate defect was fully covered (endonasal view). c Endoscope view via a supraorbital burr hole. Pedicled pericranial flap inserted to cover the cribriform plate defect (arrow)

Fig. 4

Endoscopic endonasal view of the anterior skull base. a Dural defect area before pericranial flap placement. The dura defect on the cribriform plate area was pre-made prior to the periosteal flap harvest. CP, cribriform plate; P, pituitary region; C, clivus. b Using this nasoseptal flap, an attempt was made to cover the dural defect in the cribriform plate. The end of the nasoseptal flap could not reach the cribriform plate area. c Using our lateral pericranial flap method, the flap could fully cover the anterior frontal base, sellar, and clivus regions