How To: ‘Parachute’ Technique for Reconstruction of Small Skull Base Defects of the Ventral Skull Base

TRIO How I Do It articles are reviews from The Laryngoscope designed to provide guidance on clinical and surgical techniques and practice issues from experts in the field.

Introduction

Cerebrospinal fluid (CSF) rhinorrhea is a consequence of a breakdown of the layers of the arachnoid membrane, dura matter, the bony skull base and periosteum, and the nasalmucosa (Neurosurgery. 2006;58:246–257). In the past few years, several endoscopic techniques have been described to close ventral skull base CSF leaks. These include local pedicled flaps (e.g., nasoseptal flap [Laryngoscope. 2006;116:1882–1886], turbinates [Laryngoscope. 2009;119:2094–2098]), regional pedicled flaps (e.g., pericranium [Laryngoscope. 2016;126:1736–1738], fascia temporalis [J Neurosurg. 2016;125:419–430]), free grafts (e.g., abdominal fat [Otolaryngol Head Neck Surg. 2016;154:540–546], fascia lata [Otolaryngol Clin North Am. 1984;17:591–599]), microanastomosed free flaps (Am J Rhinol Allergy. 2017;31:122–126), as well as synthetic grafts (ibid). Nowadays, most authors use multiple-layer reconstruction by combining these techniques to improve the success rate of endoscopic skull base reconstruction.

The choice of skull base reconstruction technique depends on the location and the size of the defect, as well as intracranial pressure. The graft can be placed in the extracranial or extradural spaces that are often used, or in the intradural space, which is technically more demanding.

In cases of small-size CSF leaks, we propose a new surgical technique with a good success rate that allows centering the intradural graft adequately on the defect. This “parachute” placement can be used with both autologous free grafts and synthetic materials.

Method

A retrospective chart review was performed to identify patients who had undergone endoscopic-guided transnasal duraplasty for small low-flow CSF leaks (<2 cm) of the ventral skull base at the Lariboisière University Hospital in Paris, France. Leaks that were reconstructed with other techniques were excluded. We report on the surgical technique, graft materials, and outcomes. All patients were imaged preoperatively with skull base computed tomography and magnetic resonance imaging.

The procedure is done under general anesthesia. The patient is positioned supine, with the patient’s head in a neutral position. An anterior and posterior ethmoidectomy is performed, associated most often with a middle turbinate removal. Then, the CSF leak site is identified endoscopically and measured. Site preparation begins by removal of the overlying mucosa. Abrasion of the adjacent and involved bone is generally advocated to stimulate osteoneogenesis. If needed, the bone defect is enlarged to see the limits of the dura defect. Then, an intradural and extradural circular dissection is performed with angled elevators to allow an underlay and overlay placement of the graft.