Endoscopic Endonasal Repair of Recurrent Cerebrospinal Fluid Leak With Adipofascial Anterolateral Thigh Free Flap: Case Report and Review of Literature

Extended endoscopic endonasal surgery has revolutionized the resection of anterior skull base tumors. Compared with open surgery, this minimally invasive technique results in improved tumor visualization, higher rates of total resection, superior neurologic outcomes, and decreased length of hospital stay.¹ Repair of the dura and cranial base defect is performed in a multilayered fashion with a variable combination of dural substitutes, sealants, acellular dermal matrix, fat and fascia autografts, and vascularized intranasal flaps.² A risk of all approaches for resection of skull base tumors is postoperative cerebrospinal fluid (CSF) leak. Low-volume leaks may be successfully managed with lumbar drain placement; in contrast, high-volume leaks require reoperation for defect closure.³ In patients with prior surgery or a history of local radiation, dural defect repair with vascularized intranasal flaps may not be a viable option. Regional extranasal pedicled flaps are also usually limited by the arc of rotation into the cranial base. Free tissue transfer is challenging in these patients due to limited exposure and lack of external access incisions.

Although minimally invasive access methods for free flap reconstruction of the central cranial base via the maxilla or the neck have recently been described, there is still a paucity of these reports in the medical literature.⁴ They allow the flap and pedicle to be inset within the space confines of the endonasal approach. Here, we report a case of recalcitrant CSF leak that was repaired endoscopically with an anterolateral thigh adipofascial free flap. This technique is detailed along with a current review of literature.

A 53-year-old woman underwent emergency craniotomy at an outside institution for an extensive sellar mass extending into both frontal lobes and presenting with an intraparenchymal and ventricular hemorrhage. A subtotal resection was performed, and pathology was consistent with a pituitary adenoma. She presented to our institution 2 years later with complaints of worsening vision. Magnetic resonance imaging revealed a 3.5-cm sellar mass abutting the cavernous sinus and extending to the orbital apex with a large suprasellar and inferior frontal component. Tumor resection was performed via frontal craniotomy with the plan for a second stage for endoscopic resection. The patient underwent resection of the sellar component of the tumor via extended endoscopic endonasal trans sphenoid approach 9 months later. A high-flow CSF leak was noted during tumor resection, and therefore a lumbar drain was placed. The cranial base defect was reconstructed in a multilayered fashion using acellular dermal matrix, Duraseal (polyethylene glycol sealant), Surgicel (oxidized regenerated cellulose), and a pedicled nasoseptal flap. Merocel packing (hydroxylated polyvinyl acetate) was placed in both nasal passages for 3 days. However, the patient developed CSF rhinorrhea postoperatively, and the volume of CSF leak increased substantially with clamping of the lumbar drain. The anterior skull base was explored endoscopically, and egress of CSF was noted around the nasoseptal flap; the flap was reset and bolstered with a middle turbinate flap. A ventriculoperitoneal shunt was also placed, especially because the patient had a history of significant intraventricular hemorrhage and dilated ventricles. This resulted in resolution of rhinorrhea. However, a follow-up computed tomography scan 10 days later showed significant frontal pneumocephalus. The patient was therefore readmitted and was started on antibiotics. A multidisciplinary discussion was held, and it was concluded that the best option for repair of the CSF leak was a vascularized flap.

The patient was taken to the operating room for endoscopic endonasal exploration of the anterior cranial base. The previously placed nasoseptal and middle turbinate flaps were partially nonviable and debrided. The acellular dermal matrix, sealants, and granulation tissue were removed. The cranial base defect was exposed and revealed a high-flow CSF leak (Figure 1).

An upper lip gingivobuccal sulcus incision was made. The anterior face of the maxilla was exposed subperiosteally up to the infraorbital nerve. Openings were made in the anterior maxillary wall, followed by the medial maxillary wall using osteotomes, Kerrison rongeurs, down-biting forceps, and drills. A corridor was thus created to the anterior skull base. The facial vessels were accessed via a submandibular incision 2 cm below the mandibular border. A subcutaneous tunnel through the cheek was made from the facial vessels to the gingivobuccal sulcus incision. Hemostasis was assured in the tunnel.

An anterolateral thigh free flap was harvested. This fasciocutaneous flap is based on the descending branch of the lateral circumflex femoral artery, which is a branch of the profunda femoris artery.⁵ A single fascial perforator was incorporated in the flap. The skin paddle was discarded, leaving an adipofascial flap 4 x 30 cm in size (Figure 2). The superficial surface of the pedicle was marked for orientation.

The flap was introduced through the gingivobuccal sulcus incision and passed through the anterior and medial maxillectomies into the posterior nasopharynx (Figure 3). The pedicle was passed from the gingivobuccal sulcus incision to the neck incision via the subcutaneous cheek tunnel. A Penrose drain was used for pedicle delivery through the cheek, and the previously placed orientation marks were used to ensure that the pedicle was not twisted. Microsurgical anastomosis was performed between the facial vessels and the descending branch of the lateral circumflex femoral vessels. A piece of fat was placed behind the pedicle to prevent kinking of the vessels as they transitioned from their subcutaneous location to the deeper plane in the neck.

Flap inset was performed endonasally. Acellular dermal matrix was placed as an onlay on the cranial side of the defect. TISSEEL (fibrin sealant) was sprayed over the defect. The flap was then placed over the defect. Flap pliability allowed tight packing and complete obliteration of the sphenoid sinus. A red rubber catheter was placed in the nasal cavity to provide support to the flap. A nasal trumpet was placed in the contralateral nasal passage to keep the airway open. Gingivobuccal sulcus and neck incisions were closed. The patient underwent an immediate postoperative computed tomography scan that showed significant decrease in the volume of the pneumocephalus.

The postoperative course was unremarkable. The CSF rhinorrhea resolved, and the patient was discharged home 1 week later. Follow-up endoscopy at 10 months showed viable flap. Magnetic resonance imaging at 18 months showed the presence of a vascularized flap in the anterior skull base (Figure 4). Final pathology was consistent with a silent corticotroph adenoma.

Endoscopic endonasal approaches are increasingly used for anterior skull base surgery. As the indications of this technique have expanded, so have the complexity of cases and the size of defects.¹ Reconstruction of the anterior cranial base is typically undertaken in a multilayered fashion using combinations of autologous fat or fascia grafts, acellular dermal matrix, and vascularized intranasal flaps.^1,2 In high-flow CSF defects, repair with vascularized intranasal local flaps significantly decreases the incidence of CSF leaks.² A recent meta-analysis showed that the overall leak rate after endoscopic endonasal skull base surgery is 7.2% but varies dramatically depending on the size of the pathology, location, size of defect, and whether the case is primary.⁶ This risk is increased by an intraoperative CSF leak, larger size of the defect, obesity, certain tumors, posterior fossa defects, and perioperative radiation.^1,2,6,7 CSF leaks can be morbid as they may lead to meningitis, tension pneumocephalus, and hydrocephalus. Low-flow leaks may resolve with bed rest and CSF diversion with a lumbar drain. High-flow leaks almost always require surgical repair with grafts and intranasal flaps, most commonly a nasoseptal flap.⁸ Other available flaps include the middle turbinate, inferior turbinate, and lateral nasal wall mucoperiosteal flaps.¹ However, in case of recalcitrant leaks requiring repeat operations, intranasal flaps options may be inadequate or even not available in patients who have undergone prior resections. Regional pedicled flaps that can reach the central cranial base include pericranial flaps and the temporoparietal fascia flap.^9,10 However, pericranial flaps may not reach posterior cranial base defects, and their blood supply may be tenuous in patients who have previously undergone craniotomy.¹¹ The temporoparietal fascia flap has its pivot point at the lateral skull base, resulting in the most distal and least perfused part of the flap covering the defect. Therefore, in recurrent high-flow CSF leaks, free flaps can provide well-vascularized tissue for salvage reconstruction of anterior skull base defects. Free flaps are especially useful in patients with previous radiation, as local tissues vascularity is compromised.

The major challenge with free flap reconstruction of the cranial base is the extremely limited access provided by the endoscopic endonasal approach. There is very little space for flap manipulation. Furthermore, there is no corridor to the neck recipient vessels. Two techniques have been described for free flap reconstruction via the endonasal route: the transmaxillary and the transcervical approaches.^12-20 The transmaxillary approach is described in detail above. In the transcervical approach, a neck incision is made to create a passage to the skull base via the parapharyngeal or prevertebral/retropharyngeal space.⁴ Dissection is then carried in this space up to the skull base defect. The flap pedicle is passed through this transcervical access to the neck, and the flap is inset endonasally. This technique is advantageous for large flaps that would be difficult to pass through the transmaxillary route. Table 1 is a summary of the published reports of free flap reconstruction of the skull base in conjunction with endoscopic endonasal approaches.

The adipofascial anterolateral thigh flap has several advantages compared with other flap types. It has a long pedicle that can easily reach the neck and has a good size match with facial vessels. The donor site is very favorable in terms of morbidity. Adipofascial flaps have a robust blood flow, are easily trimmed, and are pliable, thus facilitating passage of the flap atraumatically using endoscopic instruments.¹⁶ In contrast, muscle flaps tend to be bulkier, thus complicating transnasal passage.¹² Omentum flaps have been used for intracranial repairs; however, this flap is somewhat flimsy and may be difficult to manipulate atraumatically with endoscopic instruments.²¹

There are very few reports of the transmaxillary approach for cranial base reconstruction (Table 1). This report adds to the body of literature and affirms the effectiveness of this technique.

Affiliations: ¹Aga Khan University, Karachi, Pakistan; ²Plastic and Reconstructive Surgery Service, Memorial Sloan-Kettering Cancer, New York, NY; ³Head and Neck Surgery Service, Memorial Sloan-Kettering Cancer, New York, NY; ⁴Department of Neurosurgery, Memorial Sloan-Kettering Cancer, New York, NY

Correspondence: Farooq Shahzad, MBBS, MS, FACS, FAAP; shahzadf@mskcc.org

Funding: This research was funded in part through National Institutes of Health/National Cancer Institute Cancer Center Support Grant P30 CA008748.

Disclosures: None of the authors has a financial interest in any of the products, devices, or drugs mentioned in this manuscript.