Investigation

The diagnosis of temporal bone paraganglioma is made on clinical evaluation, in collaboration with imaging. Biopsy of the tumor is unwarranted, with the undue risk of hemorrhage.

Audiologic function is documented with an audiogram. Screening for urine catecholamine metabolites (vanillylmandelic acid [VMA], normetanephrine, and metanephrine) is recommended only for those patients with hypertension and for those with pheochromocytoma-like symptoms.

When urinary catecholamine levels are elevated, a search should be undertaken for other functional tumors, including pheochromocytomas.28 The search to localize other cate-cholamine-secreting paragangliomas may require comprehensive MRI, 131-metaiodobenzylguanidine nuclear scanning, and selective catheterization for venous samples for plasma norepi-nephrine determination.29

CT scan provides precise evaluation of bony destruction and erosion, which is a hallmark of temporal bone paragangliomas (Table 83-4). Destruction of the infralabyrinthine compartment and the anterolateral base of the skull determines the stage of temporal bone paraganglioma.20'30 Temporal bone CT also provides useful preoperative information about the position of the jugular bulb, and the size and presence of the contralateral sigmoid sinus. Any evidence of erosion into the basal turn of the cochlea allows the surgeon to warn the patient of the attendant high risk of sensorineural hearing loss.

Complementing the CT evaluation of bone destruction, MRI with gadolinium-DPTA enhancement offers superior soft tissue resolution and differentiation. MRI confirms the diagnosis of paraganglioma with a typical salt-and-pepper appearance. MRI is also important in determining the intracranial extension of the tumor (intra- or extradural) and extension into the cavernous sinus.

Angiography confirms the diagnosis with its characteristic rapid vascular blush. It is also important in determining the blood supply and angioarchitecture of the tumor, as well as the integrity of the internal carotid artery and the collateral circulation.

For large temporal bone paragangliomas in which the preoperative imaging indicates encasement or invasion of the internal carotid artery, permanent preoperative balloon occlusion should be considered.22'31'32 This is performed only if an awake temporary balloon occlusion of the internal carotid artery is tolerated by the patient.

Preoperative embolization considerably improves surgical conditions in skull base paraganglioma surgery.22 This technique

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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