Transpterygoid transposition of a temporoparietal fascia flap: a new method for skull base reconstruction after endoscopic expanded endonasal approaches.

BACKGROUND: Endoscopic expanded endonasal approaches (EEAs) for the resection of lesions of the anterior and ventral skull base can create large defects that present a significant risk of postoperative cerebrospinal fluid (CSF) leak. These defects, especially in patients who received preoperative radiotherapy, are best reconstructed with vascularized tissue. The Hadad-Bassagasteguy flap, a pedicled nasoseptal flap, is our preferred method for reconstruction. This option is not available, however, in patients who underwent a previous posterior septectomy or in those with tumors that invade the pterygopalatine fossa (PPF) or sphenoid sinus rostrum. In this scenario, we have used a temporoparietal fascial flap (TPFF) for the reconstruction of large surgical defects.

METHODS: We developed a new technique for the transposition of the TPFF into the nasal cavity to reconstruct skull base defects after EEA. The flap is harvested using a conventional hemicoronal incision but is then advanced to the defect using a temporal-infratemporal tunnel and an endonasal transpterygoid approach. The latter is created using an endoscopic endonasal approach that involves the resection of the posterior wall of the antrum, dissection of the PPF, and partial resection of the pterygoid plates. These maneuvers open a bone window to accommodate the flap. The soft tissue tunnel, extending from the temporal to the infratemporal and then to the PPF, is opened with percutaneous tracheostomy dilators. We present a detailed description of the surgical technique and a retrospective review of two cases in which we used this technique.

RESULTS: Two patients with large CSF fistulas who had undergone preoperative radiotherapy were reconstructed transposing the TPFF through a transpterygoid tunnel. We obtained an adequate exposure for placing the flap endonasally, and the flap provided complete coverage of the skull base defect. Both CSF leaks were resolved without any additional morbidity from the flap or the access technique.

CONCLUSION: The TPFF is a reliable and versatile method for the reconstruction of the anterior, middle, clival, and parasellar skull base after EEAs. Its harvesting requires an external incision; thus, it is not our preferred method of reconstruction. It is recommended for large dural defects in patients with previous posterior septectomy and previous radiation treatment.