Osteoradionecrosis of the skull base
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TOPIC REVIEW
Osteoradionecrosis of the skull base John P. Leonetti1 · Jeffrey R. Weishaar1 · David Gannon2 · Grant A. Harmon3 · Alec Block3 · Douglas E. Anderson4 Received: 25 October 2019 / Accepted: 18 March 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Radiation therapy (RT) is often necessary for the treatment of head and neck cancers. Osteoradionecrosis (ORN) is a rare, but potentially serious complication of RT. RT leads to the destruction of vasculature in radiated tissue causing hypoxia and tissue necrosis. ORN can occur in any bone, but bones with naturally poor blood supply appear to be more susceptible. Bones of the skull base are susceptible, with ORN occurring in the anterior, central, and lateral skull base. Risk factors include cancer type and location, radiation dose, and a variety of patient factors. Patients often present with pain, bleeding, and foul odor and are typically found to have exposed and necrotic bone. Treatment options vary depending on the severity, but typically include pentoxifylline and vitamin E as well as surgical debridement, with less evidence supporting hyperbaric oxygen therapy. Recognition and prompt treatment of ORN will allow for improved patient outcomes. Keywords Osteoradionecrosis · Skull base · Head and neck cancer · Radiation therapy
Introduction
Etiology
Each year, 53,000 Americans develop head and neck malignancies, causing 10,860 deaths, accounting for 3% of all new cancer diagnoses [1]. Worldwide, head and neck cancers are even more common causing 650,000 new cases and 330,000 deaths [2]. Radiation therapy (RT) is commonly used for head and neck cancers, but has potentially deleterious side effects. Osteoradionecrosis (ORN) is a debilitating side effect caused by radiation therapy, leading to destruction of vasculature, leading to hypoxia and tissue necrosis. Recognition and prompt treatment of ORN will allow for improved patient outcomes.
Marx described the pathophysiology of ORN as the generation of a nonhealing wound following radiation to that area. In addition to tumor cells, radiation therapy damages healthy cells of the vascular endothelium. This creates a triad of hypoxia, hypocellularity, and hypovascularity. As the normal cycle of collagen tissue regeneration continues, the damaged tissue is no longer able to repair itself (Fig. 1) [3]. Radiation treatment can cause ORN in any bone, but bones with naturally poor blood supply, such as the mandible, appear to be more susceptible [4]. ORN is most commonly observed in the mandible, with an incidence of 8.2% in head and neck cancer patients, but reported incidence varies widely [5, 6]. Bones of the skull base are also susceptible, with ORN affecting the temporal bone, basisphenoid–basiocciput, ethmoid and maxillary facial bones (Fig. 2) [7]. Unfortunately, epidemiologic data of osteonecrosis specific to bones of the skull base are not well reported [8]. However, there are some studies which document the incidence for specific malignancies. Among anterior skull base
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