Utilizing the Transpterygoid/Parapharyngeal Corridor for Free Flap Reconstruction of Cranio-orbital Defects: A Case Series

In cases that require large reconstruction of the skull base, a free flap may be considered. During planning, surgeons should be aware of available pedicle corridors. In this report, we describe our experience with the transpterygoid/parapharyngeal corridor for reconstruction of cranio-orbital defects in two patients.

This corridor was first described in a cadaver study by Rivera-Serrano and colleagues. Similar to their description, we create the corridor endoscopically through a transpterygoid approach. Removal of the posterior maxillary wall and pterygoid plate enables access to the pterygopalatine fissure and infratemporal fossa. Neck exploration is performed for vessel exposure and the dissection is carried medially to the pterygomasseteric sling at the mandibular angle to identify the medial pterygoid muscle. With blunt dissection through the parapharyngeal space, the corridor is completed. A large Penrose drain facilitates tunneling of the flap through the corridor for microvascular anastomosis. Herein, we describe two cases in which we utilized this corridor for cranio-orbital reconstruction.

The first patient is a 32-year-old male who presented with sudden onset epistaxis, blurred vision, and left retroorbital pain. His imaging revealed a large destructive sinonasal mass with skull base erosion. Biopsy was consistent with a malignant peripheral nerve sheath tumor. He received neoadjuvant chemotherapy and subsequently underwent left orbital exenteration, transorbital extradural resection of the anterior and middle fossa skull base tumor, and resection of infratemporal fossa contents. Due to the large cranio-orbital defect with dural and carotid exposure, a transpterygoid/parapharyngeal tunnel was created for anterolateral thigh free flap reconstruction with facial artery anastomosis. The patient's postoperative course was uncomplicated, and he was discharged on postoperative day 6. He has since undergone adjuvant chemoradiation and at 6-month follow-up was noted to have a completely mucosalized flap with no evidence of CSF leak.

The second patient is a 52-year-old male with history of adenoid cystic carcinoma of the right posterior ethmoid and sphenoid sinuses. He previously underwent anterior craniofacial resection with orbital reconstruction followed by radiation. He experienced local recurrence treated with gamma knife radiosurgery and additional radiation. He subsequently developed a frontal brain abscess which was aspirated and treated with chronic antibiotic suppression. He experienced recurrent infectious bouts despite chronic antimicrobial therapy and ultimately experienced total loss of vision. Due to these complications, the decision was made to proceed with right orbital exenteration and resection of necrotic neoplastic tissue. Because of the defect size, and due to a significant prior radiation history; recruitment of non-radiated tissue was performed for safe reconstruction. A corridor was created, and a right anterolateral thigh free flap was tunneled through the orbital defect. The facial artery was used for anastomosis. The postoperative course was uncomplicated, and he was discharged on postoperative day 7. Four-month follow-up revealed an intact flap covering the skull base with no evidence of CSF leak.

To our knowledge, this is the first in-vivo case series reporting successful skull base reconstruction utilizing the transpterygoid/parapharyngeal corridor. This technique is feasible and allows for safe skull base reconstruction with tunneling of the pedicle for microvascular anastomosis.