Bilateral Inferior Turbinate Flap for Repair of Skull Base Dehiscence after Proton Beam Radiotherapy for Clival Chordoma

Clival chordomas are rare, aggressive, notochord-derived tumors with an incidence of approximately 8 per 10 million. Management consists of surgery, commonly with an endoscopic endonasal approach (EEA), and adjuvant proton beam radiotherapy. After resection, vascularized coverage of the ventral skull base is paramount to avoid complications such as cerebrospinal fluid (CSF) leak and meningitis. This is often achieved using a nasoseptal flap (NSF) at the time of initial surgery. NSF failure is estimated to occur in at least 2% of cases, requiring alternative options using flaps from the lateral nasal wall, temporoparietal fascia (TPF), nasal turbinates, or anterolateral thigh (ALT).

We present the case of a 29-year-old patient with a history of intranasal substance abuse, chronic rhinosinusitis and clival chordoma. She underwent subtotal resection via EEA, a far lateral craniotomy for residual disease, reconstruction with bilateral NSF, and adjuvant proton beam radiotherapy at an outside hospital in 2013. Six years later, the patient presented with purulent meningitis and widespread skull base osteomyelitis secondary to NSF necrosis, possibly due to insufflation of recreational drugs. She underwent an EEA for debridement and drilling of the petrous osteomyelitis. A 1.5 cm × 1.5 cm dural defect with egress of CSF was noted. Review of prior proton fields demonstrated relative sparing (2,600–4,200 cGy) of the bilateral pterygopalatine fossae. To address this, a right-sided, vascularized, superiorly based inferior turbinate mucoperiosteal flap was rotated posteriorly over the defect. On follow-up endoscopy, there was no postoperative CSF leak. Blood and intranasal cultures were negative; she completed a course of broad-spectrum IV antibiotics and was taken to surgery for repeat debridement 8 weeks later. The right ITF was well-healed; however, there was a small region of persistently exposed bone over the left petrous apex. This was drilled widely, and a left-sided ITF was rotated posteriorly for coverage. At 6-month follow-up, nasal endoscopy revealed full mucosalization without infection, dehiscence or CSF leak. The patient's leukocytosis and inflammatory markers had normalized, and she had returned to her prior neurological baseline with trace CN VII weakness and longstanding unilateral CN XII weakness.

In this case, we utilized bilateral ITF to reconstruct a clival defect complicated by acute osteomyelitis despite prior proton therapy to the skull base. Other reconstructive options such as TPF and ALT flaps were discussed; however, the ITF was considered to be most appropriate in the setting of infection and for reserving more complex salvage flap options in case of ITF failure. This case highlights the utility of ITF in reconstructing the ventral skull base for patients in whom nasoseptal flap reconstruction has failed.

Fig. 1 T1 MRI image of chordoma prior to treatment. MRI, magnetic resonance imaging.

Fig. 2 Proton beam radiation fields demonstrating relative sparing of the pterygopalatine fossa (2,600–4,200 cGy).

Fig. 3 (A) Intraoperative image of skull base ORN prior to debridement, (B) right inferior turbinate flap with persistent skull base dehiscence, (C) left inferior turbinate flap with well-healed defect.

Fig. 4 Follow-up MRI demonstrating enhancing bilateral inferior turbinate flaps and closure of CSF fistula. MRI, magnetic resonance imaging.