Abstract
Adrenalectomy is the therapeutic option for almost all cortical and medullary diseases (Cushing syndrome, hyperaldosteronism, pheochromocytoma, adrenal malignancies). Functional tumors are associated with numerous comorbidities that can affect anesthetic management during adenalectomy. In addition, the surgical approach to the adrenal may result in minor to major vascular or solid organ injury, many of which are preventable by surgical experience. Finally, removal of the adrenals may require steroid replacement in selective cases. Deep venous thrombosis is associated with adrenal surgery and may warrant thromboprophylaxis.
Keywords
adrenalectomy, hypertension, hypotension, laparoscopic, major surgical complications, open, surgical complications
Case Synopsis 1
Pheochromocytoma
A 38-year-old woman presents in the surgical outpatient department with recurrent attacks of palpitations, headache, diaphoresis, occasional right-sided abdominal pain over the last year, and a neck swelling for the last 2 months. On examination she is severely hypertensive (220/130 mm Hg); a 3-cm thyroid nodule is present in the front of the neck. An ultrasound of the abdomen reveals a right-sided suprarenal mass. She is admitted for further evaluation, optimization, and surgical excision of the suprarenal mass.
Case Synopsis 2
Cushing Syndrome
A 45-year-old man presents in the endocrinology outpatient department with a history of progressive proximal muscle weakness, low back pain, and generalized edema for 6 weeks. Investigations reveal bilateral adrenal hyperplasia, elevated cortisol and adrenocorticotropic hormone (ACTH) levels, hypokalemia, and metabolic alkalosis. His condition deteriorates rapidly during hospitalization, and he is scheduled for emergent adrenalectomy.
Case Synopsis 3
Conn Syndrome
A 56-year-old male patient with gallstone disease is found to have asymptomatic hypokalemia ([K + ] 2.0). He is also a hypertensive on treatment. Computed tomography evaluation shows a left adrenal neoplasm measuring 2.7 × 2.4 cm, and he is admitted for diagnosis and possible laparoscopic adrenalectomy combined with cholecystectomy.
Problem Analysis
Definition
Disorders of the adrenal gland can be broadly grouped into those arising from the cortex (producing cortisol and/or mineralocorticoid and/or androgen excess) and those arising from the medulla (producing an excess of catecholamines and their metabolites). Cortex-related disorders are Cushing and Conn syndromes. Cushing syndrome is usually associated with bilateral hyperplasia; Conn syndrome (primary hyperaldosteronism) is usually caused by a single adenoma. Adrenal hyperplasia resulting from pituitary ACTH production is termed Cushing disease and is associated with hyperpigmentation. Cushing syndrome resulting from other sources of ACTH (ectopic ACTH) is accompanied by bilateral adrenal hyperplasia and symptoms of severe cortisol excess. Pheochromocytomas are tumors derived from the neural crest and can arise anywhere in the sympathetic chain and the adrenal medulla. Traditionally, those arising in the adrenal medulla are termed pheochromocytomas and the others are termed paragangliomas. These not only secrete epinephrine, norepinephrine, and dopamine, but elaborate their metabolites metanephrine and normetanephrine through intratumoral catecholamine-O-methyltransferase (COMT). Norepinephrine is methylated by phenylethanolamine-N-methyltransferase (PNMT) to epinephrine. The majority of pheochromocytomas are unilateral. Bilateral tumors are associated with congenital syndromes and found mainly in children. Extraadrenal pheochromocytomas (paragangliomas) rarely produce epinephrine and may be multiple or malignant, and are also associated with genetic mutations in the succinyl dehydrogenase (SDH) gene subunits. Up to 25% of apparently sporadic pheochromocytomas may be genetic or familial. Germ-line mutations have been found in five genes (RET proto-oncogene responsible for the MEN syndrome, VHL gene, NF1 gene, SDH subunits D and B) in patients with pheochromocytoma.
A significant proportion (10%–30%) of pheochromocytomas may present as “incidentaloma.” These patients may be totally asymptomatic, but experience severe blood pressure (BP) and heart rate fluctuations during surgery.
Adrenal malignancies are associated with signs and symptoms of androgen excess, along with cortisol/mineralocorticoid excess and pressure effects of the tumor.
Significant secondary hypertension is a frequent finding in almost all adrenal tumors, regardless of the cause. Excess cortisol/mineralocorticoid production also results in metabolic disorders such as hyperglycemia, hypokalemia, and metabolic alkalosis.
Recognition
Pheochromocytoma
The combination of hypertension with the clinical triad of headache, palpitations, and diaphoresis is strongly suggestive of pheochromocytoma. Hypertension may be sustained or episodic. Pheochromocytomas can present as a variety of hypertensive, cardiac, neurologic, or metabolic crisis and require a high index of suspicion for their diagnosis. Demonstration of catecholamine excess forms the first step in diagnosing pheochromocytoma. Plasma-free metanephrines are associated with the highest sensitivity for detection of pheochromocytoma and their absence reliably excludes the condition. Good correlation has been found between tumor size, location, and plasma metanephrine concentrations. If increase in plasma metanephrine is greater than 15% of combined metanephrine and normetanephrine, the tumor is likely to have an adrenal location. Anatomic location of the tumor is by magnetic resonance imaging and functional localization by MIBG/DOTANOC-PET scans.
Cushing Syndrome
The cortex elaborates glucocorticoids and mineralocorticoids, which govern a variety of metabolic processes including glucose homeostasis and Na + /K + balance. Cushing syndrome may be due to primary adrenal hyperplasia or result from stimulation from an ectopic source of ACTH. Adrenal hyperplasia secondary to excess ACTH from a pituitary microadenoma results in Cushing disease. An ectopic ACTH-producing tumor results in adrenal hyperplasia, hyperpigmentation, and features of cortisol excess.
Clinical features of Cushing syndrome, usually prominent, are truncal obesity, thin skin, easy bruising, abdominal striae, proximal muscle weakness, hypertension, and hyperglycemia. Although clinically obvious, the diagnosis needs to be confirmed by high concentrations of serum cortisol. Identification of Cushing disease requires the dexamethasone suppression test and the corticotropin-releasing hormone test. The former causes ACTH to fall to very low concentrations in the absence of an ACTH-producing tumor. The latter should cause a marked increase in ACTH release with primary pituitary disease, but not in patients with adrenal tumors or ectopic ACTH production.
Conn Syndrome
Primary hyperaldosteronism (Conn syndrome) is associated with hypokalemia, metabolic alkalosis, hypernatremia, severe hypertension, muscle weakness, polyuria, and thirst, and is usually caused by solitary adenoma. Renal dysfunction may occur secondary to hypertension. The diagnosis is confirmed by high serum aldosterone and low plasma renin concentrations. Conn syndrome accounts for 0.5% to 3% of all cases of secondary hypertension.
Adrenal Cancer
Adrenal malignancies are associated with overproduction of sex hormones, cortisol, and aldosterone. Clinical findings including virilizing effects of androgens, signs and symptoms of Cushing syndrome, and aldosterone excess (hypokalemia and hypertension). Diagnosis is usually made by radiologic studies.
The definitive treatment of adrenal cortical and medullary tumors remains adrenalectomy, after initial medical treatment to provide symptom control and metabolic optimization.
Risk Assessment and Implications
Adrenalectomy as a procedure is at high risk of adverse events. Perioperative mortality rates after bilateral adrenalectomy for Cushing syndrome may reach 5% to 10%. The implications of adrenalectomy are related to the individual adrenal lesion, its etiology, and the surgical procedure ( Table 44.1 ) (see later discussion).
| Preoperative Issues | ||
|---|---|---|
| Pheochromocytoma | Cushing Syndrome | Conn Syndrome |
| Hypertension | Hypertension | Hypertension |
| Cardiac involvement | Hyperglycemia | Hypokalemia |
| Vasoconstriction | Metabolic alkalosis | |
| Hypokalemia | ||
| Difficult airway, vascular access | ||
| Osteopenia | ||
| Immunosuppression | ||
| Intraoperative Complications | |
|---|---|
| Related to Disease | Related to Surgical Access/Technique |
| Hemodynamic instability: hypertension/hypotension/pulmonary edema/congestive heart failure | Pneumoperitoneum-related hemodynamic changes |
| Arrhythmias | Vascular injury and hemorrhage |
| Hypokalemia | Solid organ injury |
| Metabolic alkalosis | Diaphragmatic injury, pneumothorax |
| Glucose homeostasis | Bowel injury |
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