Pediatric surgeons are seeing adrenal disease with increased frequency. The objective of adrenal surgery is to completely resect the tumor, resulting in removal of the malignancy and normalization of endocrine function. Surgical approach is based on likely pathology of the adrenal mass, presence of bilateral masses, and the surgeon’s preference. Laparoscopic adrenal resection provides an attractive alternative to the open approach in children.
Laparoscopic adrenalectomy for pediatric patients has only recently been described and the small body habitus of patients makes this surgery more technically challenging (Gagner et al, 1992). Although normally benign in the pediatric population, pheochromocytomas and neuroblastomas are seen with physiologic changes. Neuroblastomas are often large and infiltrative, making laparoscopic removal more difficult. Nevertheless, laparoscopic adrenalectomies have been shown to be successfully performed on the pediatric population with benefits in shorter hospitalization and rapid resumption of diet (Iwanaka et Al, 2001) as well as being more cost effective (Stanford et al, 2002). In adults, laparoscopic adrenalectomy has proven to result in less blood loss and decreased need for transfusion, fewer wound complications, and decreased postoperative pain (Cameron et al, 2011). Most adrenal lesions are small and benign, making laparoscopic surgery both feasible and the appropriate operative choice. Relative contraindications include patients with malignancies that involve lymph nodes, highly vascular pheochromocytomas, and large tumors.
The first anatomic description of the adrenals came in 1563, but it was not until 1805 when the adrenal gland was subdivided into the medulla and the cortex. Later, early animal experimentation uncovered a substance derived from the adrenal medulla that elevated blood pressure. This was subsequently named epinephrine in 1897. Surgical innovation followed with the first surgical removal of adrenal glands performed in Switzerland and the United States by Roux and Charles Mayo respectively. As more information was uncovered regarding the functional capacity of the adrenals, several disorders were identified and subsequently named after those that first described them. Of these, most notable are Addison who characterized adrenal insufficiency, Cushing who described patients with excess cortisol, and Conn who identified Aldosterone and the syndrome resulting from its excess.
The paired adrenal glands sit superior to the kidneys bilaterally. Located in the retroperitoneum, the typical adrenal gland is roughly 5cm at greatest length. By adulthood, the adrenal gland weighs typically four to five grams while at birth the gland weighs just one gram. Each adrenal gland is supplied by three main arterial beds: superior, middle, and inferior. The superior adrenal arteries arise from the inferior phrenic artery and the inferior adrenal arteries arise from the renal artery. The middle adrenal arteries are direct branches off the aorta.
The venous drainage of the adrenal gland is less complex with a single vessel draining the entire gland. The course of the vein varies based on laterality with the right adrenal vein draining directly into the inferior vena cava and the left adrenal vein connecting to the IVC by way of the inferior phrenic vein to the left renal vein.
The adrenal gland is grossly divided into the medulla and the cortex. The cortex is largely comprised of lipids giving it a yellow color. The cortex makes up the exterior portion of the gland and accounts for the large majority of the gland’s volume. It is subdivided into three zones: the zona glomerulosa, the zona fasciculata, and the zona reticularis. The zona reticularis reaches its final maturity late in childhood. The zona glomerulosa produces mineralocorticoid (aldosterone, 11-doxycorticosterone). The zona fasciculata and the zona reticularis produce glucocorticoids (cortisol) and the adrenal androgens (DHEA, androstenedione, testosterone, estrogen). The medulla comprises a smaller area, only 10-20% of the total gland. Its cells are derived from neural crest cells and secrete the catecholamines norepinephrine and epinephrine.
The lymphatics are divided into two plexuses, one in the medulla and one just under the capsule. The left adrenal lymphatics drain to the nodes near the left renal artery while the right adrenal lymphatics drain to the periaortic lymph nodes. Innervation to the adrenal gland is primarily composed of splanchnic nerves to the medulla while the cortex lacks any identifiable innervations.
INDICATIONS/SELECTION OF PATIENTS
Almost all adrenal tumors are treated with surgical removal. Congenital adrenal hyperplasia is the only primary hyperfunctioning disorder for which medical therapy is indicated over surgical excision. Bilateral adrenal hyperplasia is much less responsive to surgery than its unilateral counterpart and selective venous catheterization is used to predict response to surgery. Bilateral hyperplasia is managed medically with spironolactone and unilateral hyperplasia is treated surgically with unilateral adrenalectomy.
Pheochromocytomas are initially treated with alpha-blockers to manage blood pressure prior to surgical intervention, while definitive treatment requires removal of the adrenal gland. In the pediatric patient, extensive adrenocortical carcinoma is often resected en-bloc along with lymph nodes while minimally invasive techniques predominate for less extensive disease.
For adrenal incidentalomas surgery is the treatment of choice if the mass is enlarging or functioning. In adults, resection is typically indicated for masses greater than 5cm but in the pediatric population, some surgeons advocate resection without regard to size. The pediatric population is also unique in that more than 90% of adrenal masses are neuroblastomas. In neuroblastoma, treatment is resection although initially unresectable tumors may become resectable following chemotherapy.
The main techniques for laparoscopic adrenalectomy are the lateral transabdominal and the posterior retroperitoneal approach popularized by Gagner and Walz respectively (Cameron et Al, 2011). Left adrenalectomy and right adrenalectomy are two distinct procedures.
TRANSABDOMINAL LATERAL APPROACH
The transabdominal lateral approach is more commonly used in the pediatric population. It is performed with patient in the lateral decubitus position with the operative side up allowing gravity to assist in exposure of the adrenal glands. Prior to placing the patient on their side, the stomach and bladder are decompressed with an orogastic tube and Foley catheters. A kidney rest is placed in the lumbar area and the bed is flexed at the level of the iliac crest to maximally open the space between it and the costal margin for trocar insertion. The bed is placed in a slight reverse Trendelenberg position. Superior arm supported on pillows on top and opposite arm secured to arm board. An axillary roll is placed and all bony prominences are protected. Next, the bean bag is firmed and the patient is secured, again ensuring appropriated padding of all pressure points. The skin is then prepped and draped in the standard fashion with enough skin exposed to allow open laparotomy if necessary.
Three to four trocars are placed in a subcostal position on the side of the adrenal gland to be extracted. Starting with a 5-mm umbilical port placed under direct vision. The carbon dioxide (CO2) insufflation begins at a low flow rate with maintenance of intraabdominal pressure of 10 -12 mmHg. A 30degree camera should be used if available. Under direct vision, a 3-mm or 5-mm port (depending on facility) should be placed in the upper midline, close to the xyphoid process. A third port (5-mm) should be placed laterally, close to the costal margin. An additional accessory port is often used on the right for either liver retraction or improved exposure.
It has also been described by Cameron et al to use a 10 or 12-mm incision into the flank at the midclavicular line, two fingerbreadths below the left costal margin. Dissection is carried down to the fascia, which is elevated between two Kocher clamps, and the peritoneal cavity is entered with a Veress needle. After a successful leak test, the peritoneal cavity is insufflated and a 10 or 12-mm trocar is placed at the Veress site. The 10-mm cannula is used in order to remove the specimen through the cannula or the incision. A specimen bag is necessary due to the potential of malignancy. Working ports (5mm or 3mm) are placed in a fashion to triangulate the lesion with as much distance between ports as possible depending on the patient’s size. Often, the peritoneal attachments to the colon must be divided in order to place the most posterior cannula.
In a right adrenalectomy, exposure is improved by dividing the right triangular ligament of the liver including the most lateral and posterior attachments to the peritoneum. The fourth trocar should be placed in the epigastrum and be used as a retractor to elevate the right lobe of the liver. During mobilization of the right hepatic lobe, always recognize the proximity of the inferior vena cava (IVC). Laparoscopic ultrasound can assist with this as well as identifying the borders of the liver, kidney, and major vessels to allow for safe and expeditious dissection.
The retroperitoneum is then incised along the IVC allowing exposure to the adrenal gland and its vessels. The medial border of the IVC is carefully exposed, looking for the right adrenal vein at the superior medial border of the adrenal, remembering that this vein is typically broad and short and enters the vena cava slightly posteriorly (Cameron et al, 2011). Three clips should be used, with distal most clip at the edge of the vena cava. Clipping the vein first is especially important in cases of pheochromocytomas.
Once the right adrenal vein has been clipped and divided, dissection continues with use of monopolar hook electrocautery to mobilize the medial portion of the adrenal gland. By dissecting from medial to lateral and inferior to superior, the superior pole of the kidney can be used as a dissection plane through the Gerota fascia, and the dissection can progress in a direction away from any anatomic danger areas (inferior vena cava and renal vein) (Cameron et al, 2011). Visible vessels, including the inferior phrenic vessel which is commonly seen at the superior and lateral border of the gland, are clipped. Before specimen extraction, the operative field is inspected for hemostasis. The adrenal gland is then placed within a bag and extracted without morcellation.
Division of the lienocolic ligament up to the level of the gastric fundus improves exposure of the left adrenal gland by allowing the spleen to fall medially, pulling the tail of the pancreas with it. The left colon is also mobilized medially. Laparoscopic ultrasound can used to verify the borders of the adrenal, kidney, and pancreas. It is important to note that the dissection plane should be relatively avascular and that it is relatively easy to mistake the tail of the pancreas for the adrenal gland.
With small tumors, first dissect the inferior and medial aspect of the adrenal remaining close to the gland until the vein is ligated with endoscopic clips. A right-angle dissector facilitates this exposure. It is important to remember that on the left, this should be done early in the operation after locating it entering the renal vein. Afterwards, the gland is then carefully dissected free form the diaphragmatic attachments superiorly, the kidney on its inferior and lateral aspects, and medially from the midline structures. The inferior phrenic artery is frequently encountered along the superior edge of the adrenal and should be sought and ligated with clips and divided (Cameron et al, 2011).The dissection and extraction then occurs in a similar fashion. For large tumors, early identification of the vein may be difficult and mobilization of the gland inferiorly and laterally is often helpful.
PRONE RETROPERITONEAL ADRENALECTOMY
This can be useful in patients with small tumors and those that are likely to have adhesions from previous abdominal operations. However, due to the small retroperitoneal working space, limitations include large tumors and morbidly obese patients.
The retroperitoneal approach begins by placing the child in a prone position, close to the lateral border of the table on the side of the procedure to allow manipulation of the lateral grasper. The 12th rib, iliac crest, and paravertebral muscles are then marked on the patient. The first incision is made at the lateral border of the laterovertebral muscles, halfway between the 12th rib and the iliac crest (Heloury et al, 2011). According to Heloury, blunt dissection is performed until the retroperitoneal space outside the Gerota fascia is reached. Working space is then created by insertion and distension of a homemade balloon. Heloury uses a finger glove attached to a naso-gastric tube. A 5-mm port is inserted and secured with an external stitch. Insufflation connected and maintained at a pressure between 8 – 12 mmHg. The second port (3 or 5mm) is placed at the tip of the 12th rib and the third port (5-mm) is between the two previously inserted ports. Once inside, the landmarks and dissection are similar to a lateral transperitoneal approach. The specimen is then extracted via a bag without morcellation.
Single-site laparoscopic techniques were devised over 10 years ago. The technique for adrenalectomies was described more recently by Walz et al in 2010. The technique can be performed in a variety of methods including a 10-mm laparoscope with a working port, 2 ports placed in a single incision, or most commonly using a specific device. A case-control study published by Walz et al demonstrated that single site cases for their institution had a conversion rate of 14%, longer operative times, similar instances of complications, and a shorter hospital stay.
Partial or cortical-sparing adrenalectomies have been described for bilateral tumors, hereditary adrenal tumors, and tumors in a solitary adrenal gland (Volkin et al, 2012). During these procedures, a portion of a single gland or portion of bilateral glands are extracted. Early reports that incorporate all patients, including adults and children demonstrate few recurrences and ability to remain corticosteroid independent. Specific operative techniques were previously described by Rogers et al. Tumors were resected with the help of laparoscopic ultrasound aiding the delineation between normal and involved tissues.
Use of the robot in pediatrics remains controversial due to cost, size of the equipment and relatively longer operative times. However, robotic assistance does provide a magnified three dimensional view as well as an improved ability to more precisely dissect structures. Rogers et al in 2008 described their institutions use of a robotically assisted partial adrenalectomy and extra-adrenal pheochromocytomas resection in a pediatric patient with Von Hippel-Lindau Disease. Since this time, robotic equipment has become smaller and single-site robotic surgery has become more prevalent. Further case series are needed in this area.
Most patients are ready for discharge on post-operative day number one. However, pheochromocytomas require close monitoring in the intensive care unit and those with Cushing syndrome require postoperative stress-dose steroids. Patients with aldosterone-producing adenomas often experience a significant diuresis postoperatively and require close monitoring of their fluid balance and electrolytes (Cameron et al, 2011).
Functional adrenal adenoma resection is associated with a 75% cure rate and a mortality rate less than 1%. Early identification of tumors and younger age (< age 5) improves prognosis. In adrenocortical carcinomas, surgical resection is the only chance at a cure. Untreated carcinomas have a mean survival of less than three months with the worse prognosis involving nonfunctional tumors. Complete excision is required, otherwise mortality is high.
Laparoscopic adrenalectomy is associated with typical laparoscopic risks including injury to abdominal structures with trocar and instrument placement. These injuries are even more apparent in the pediatric population where thin pliable abdominal walls are commonplace. Additional concerns related to laparoscopy are complications of insufflation and its cardiopulmonary effects.
Patients who presents with Cushing’s syndrome are more likely to develop thromboses or infectious processes. Conversely, in patients with Cushing’s disease who have bilateral adrenalectomies, they can suffer from Nelson’s syndrome in which the pituitary tumor undergoes progressive growth and leads to increased ACTH, visual disturbances, and hyperpigmentation.
In patients with pheochromocytomas, anesthesia induction can elicit hemodynamic instability requiring further medical intervention intraoperatively. Postoperatively, hypotension is a known risk and patients often stay in the hospital longer for management and to ensure stability prior to discharge.
After bilateral adrenalectomy and less commonly after unilateral adrenalectomy, patients can experience adrenal insufficiency.
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Authors: Craig Wengler, MD, and Heather Nolan, MD, and Joshua Glenn, MD (Editor)