Operations on the adrenal glands are performed for primary hyperaldosteronism, pheochromocytoma, hypercortisolism (Cushing disease or Cushing syndrome), and adrenocortical carcinoma. These conditions are usually characterized by hypersecretion of one or more of the adrenal hormones. Less commonly, surgery may also be performed for nonfunctioning tumors or metastases.
ANATOMY & SURGICAL PRINCIPLES
The normal combined weight of the adrenals is 7-12 g. The right gland lies posterior and lateral to the vena cava and superior to the kidney (Figure 35–1). The left gland lies medial to the superior pole of the kidney, just lateral to the aorta and immediately posterior to the superior border of the pancreas. An important surgical feature is the remarkable constancy of the adrenal veins. The right adrenal vein, 2-5 mm long and several millimeters wide, connects the anteromedial aspect of the adrenal gland with the posterolateral aspect of the vena cava. The left adrenal vein is several centimeters long and travels inferiorly from the lower pole of the gland, joining the left renal vein after receiving the inferior phrenic vein. Variant venous drainage (multiple or anomalous veins) occurs in about 9%-17% of glands and is more common for pheochromocytomas and larger tumors. The adrenal arteries are small, multiple, and inconstant. They usually come from the inferior phrenic artery, the aorta, and the upper pole branch of the renal artery.
Anatomy of the adrenals, showing venous return.
With the exception of rare nonsecreting cancers, indications for adrenal surgery result from hypersecretory states. Diagnosis and treatment begin with confirmation of a hypersecretory state (ie, measurement of excess cortisol, aldosterone, or catecholamines in blood or urine). To determine whether the problem originates in the adrenal, levels of the trophic hormone in question (ie, adrenocorticotropic hormone [ACTH] or renin) must be measured. If levels of the trophic hormone are suppressed but hormone secretion is excessive, autonomous secretion by the adrenal is proved. The next step, except in pheochromocytoma, is to determine the degree of autonomy, a process that usually distinguishes hyperplasias (which respond to most but not all controlling mechanisms) from adenomas and adenomas from cancers. In general, cancers are under little, if any, feedback control. If the primary problem is not in the adrenal, as in Cushing disease, treatment must be directed elsewhere when possible.
The major principles of adrenal surgery are as follows:
Whenever possible, the surgeon must be certain of the diagnosis and the location of the lesion before undertaking the operation.
The patient must be thoroughly prepared so he or she can withstand any metabolic problems caused by the disease or by the operation.
The surgeon and consultants must be able to detect and treat any metabolic crisis that occurs during or after the operation.