Management Surgery

Surgery has been established as the principal primary treatment of temporal bone paraganglioma.21-23'34-36 Surgery offers the only chance of cure. With the modern microsurgical techniques and advances in anesthesia and interventional radiology, temporal bone paragangliomas are currently removed with minimal morbidity, excellent control rate, and good quality of life23,24 In contrast, radiotherapy may, at best, arrest tumor growth with a significant side effect profile. For this reason radiotherapy is reserved when resection of the tumor is impossible or incomplete.37-39

In planning treatment, the objective—whether cure or palliation—is determined by a balance of patient, tumor, and treatment factors. Of these considerations, tumor stage is the most important in surgical planning. Tumor stage alone dictates the surgical approach. The infratemporal approach provides the necessary exposure to remove paragangliomas up to Fisch class C4De2Di123 (Fig. 83-2).

Surgery is contraindicated when the tumor is deemed unre-sectable or the risk of associated morbidity is unacceptably high. Surgery is contraindicated in Fisch class C and CD temporal bone paragangliomas when there is carotid involvement and the collateral cerebral circulation is poor. In patients who have a contralateral vagal palsy, surgery that compromises the only functional vagus is also contraindicated.

Class A Tumors Class A temporal bone paragangliomas are removed with a conventional transmastoid approach with hearing preservation. They tend to be more extensive than anticipated on preoperative imaging.

Class B Tumors As in Fisch class A, Fisch class B temporal bone paragangliomas may prove to be larger than indicated on preoperative imaging. In this case, both the surgeon and the patient must be prepared to progress from a conventional trans-mastoid approach to a subtotal petrosectomy, should there be extension into retrofacial air cells or deep infiltration of the spon-giotic bone in the infralabyrinthine compartment of the temporal bone. If the tumor is found to invade the jugular bulb or the carotid foramen, an infratemporal type A approach is indicated.

Class C Tumors Fisch C class lesions are resectable via a infratemporal type A approach. The Fisch type A approach is a cran-iotemporocervical approach. It exposes the infralabyrinthine and apical compartments of the temporal bone, the mandibular fossa, and the posterior infratemporal fossa. It does so by subtotal pet-rosectomy and by anterior transposition of the facial nerve.23 Dissection of the superior neck permits proximal and distal control

Figure 83-2 Schematic view of type A craniotemporocervical exposure for the removal of temporal paragangliomas class C.

of the jugular and carotid systems, essential for success in resection of these tumors.

More advanced temporal bone paragangliomas growing along the horizontal segment of the internal carotid artery to the foramen lacerum (Fisch class C3) require more extended infratemporal approaches. Removal of the most anterior portion of Fisch class C4 lesions within the foramen lacerum and cavernous sinus necessitates a combined Fisch type A and B approach. Extension into the cavernous sinus requires a switch from the Fisch type A to the Fisch type C approach.

Class D Tumors The intradural extension of a glomus tumor can only be removed at the same time as the main tumor mass, if the extension is < 2 cm (class Di1). Otherwise, a planned two-stage procedure is advisable, as intracranial intradural extension of > 2 cm may be strongly attached to the pons and medulla. Removal of tumor from this region often results in bleeding from the pontomedullary veins. Second-stage removal of large intracranial intradural tumors avoids serious complications, including sizable cerebrospinal fluid (CSF) leaks due to the persistent cough and aspiration that may arise when swallowing is affected at both a central and peripheral neurologic level.

After incomplete resection of a Di2 lesions, patients do not require an immediate two-stage procedure. These patients are first followedup with regular imaging every year, to monitor the progression of the residual tumor. Only 25% of residual intradural tumors require irradiation or neurosurgical intervention because of clinical or radiologic progression.

For class Di3 tumors, selected patients may benefit from removal of the extradural component of the tumor. This decompresses the posterior cranial fossa and devascularizes the rest of the tumor. Postoperative irradiation can be started 4 weeks after surgery.

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