Temporal paragangliomas

Abstract

Temporal paragangliomas (PGL) are usually limited to the paraganglionar system with a sporadic or familial origin. Familial PGL have recently been shown to be associated with germline alterations in SDH group of genes, and occasionally are associated with a variety of genetic multisystemic disorders (von Hippel-Lindau disease, multiple endocrine neoplasia type 2 and neurofibromatosis type 1). Temporal bone PGL are normally located in the region of the jugular foramen and on the promontory along the Jacobson nerve. Occasionally, vagal PGL may reach the jugular foramen and behave as jugular PGL. Treatment of temporal PGL must be based on the biological behavior of the tumour, age and medical condition of the patient, location and size of the PGL, and potential for treatment induced morbidity. The main treatment modalities for PGL are surgery and radiation therapy. Patients with large temporal PGL whose resection would result in potentially disabling morbidity are often selected for radiation therapy or wait and scan policy. Small tympanic PGL where resection may be carried out with a low morbidity risk can be removed through an endomeatal tympanotomy. Jugular PGL limited to the infralabyrinthine region involving only the vertical segment of the ICA, can benefit of an extended facial recess approach, which allows a postoperative normal hearing and facial nerve function. For more extensive disease in the middle ear or around the ICA, external auditory canal preservation is not possible and some kind of facial nerve mobilization is required. Preservation of lower cranial nerves is facilitated by intrabulbar dissection, previous extradural ligation of the sigmoid sinus. Management of large intracranial involvement is controversial, although most authors advocate resection of the tumour in a single stage. Surgical control of the tumour can be expected in 70-85% of the patients and is clearly dependent on the tumour stage. Tumour size determines success in hearing and lower cranial nerves preservation.