Reconstruction of cranial base defects using the Medpor Titan implant: cranioplasty applications in acoustic neuroma surgery.

INTRODUCTION Reconstruction of cranial defects is an essential component of skull base surgery as it aids in restoring functionality, providing coverage of intradural structures, and achieving optimal cosmesis. In acoustic neuroma surgery, tumor removal and subsequent reconstruction of the skull base defect are equally important elements. All three approaches utilized in acoustic neuroma surgery (retrosigmoid, translabyrinthine, and middle fossa) benefit from cranioplasty. In the retrosigmoid approach, the use of cranioplasty to cover the suboccipital bony defect has been shown to reduce the severity of postoperative headaches. Cerebrospinal fluid (CSF) leakage rates have decreased in patients who undergo cranioplasty of the temporal bone defect following the translabyrinthine approach, most likely due to applied pressure to the underlying fat graft. Finally, temporal hollowing resulting in unsightly sunken defects can be prevented with reconstruction of the squamous temporal defect created after a middle fossa approach. The ideal material for reconstruction should provide structural support and soft tissue coverage, and be inert and durable, easy to shape and contour, and applicable to a variety of different skull base defects. Although autologous bone has a desirable biocompatibility profile, it must be harvested from a donor site, which may be undesirable due to longer operative times, increased risk of infection, and difficulty with graft contouring. Also, there is a limited amount of autologous bone available, which is an additional drawback. Other alternative reconstructive materials include titanium mesh, hydroxyapatite cement, polymethyl methacrylate (PMMA), and porous polyethylene. Each has its own advantages and disadvantages. The Medpor Titan implant (Porex Surgical, Inc., Newnan, GA) is a material that is composed of a hybrid of titanium mesh, surrounded on both sides by a sheet of high-density porous polyethylene. Titanium is a commonly used metal for cranioplasty. Its malleability allows for easy contouring of the implant, while its high tensile strength ensures superior protection for intracranial components. Porous polyethylene is an inert material that has been used in the past for a variety of applications, including craniomaxillofacial and orbital reconstruction. It is composed of high-density polyethylene with interconnected pores that allow for tissue growth into the implant. The utilization of porous polyethylene with embedded titanium has been described for orbital reconstruction, but to date there is no literature present about its use in cranioplasty of temporal bone defects after acoustic neuroma surgery. In this report, we describe our cranioplasty technique for the skull base reconstruction of bony defects created after acoustic neuroma surgery using the Medpor Titan implant. The surgical nuances are illustrated in each of the three acoustic neuroma approaches, including retrosigmoid, translabyrinthine, and middle fossa approach.