Right Posterior Retroperitoneoscopic Adrenalectomy (PRA) for Adrenocortical Adenoma

Abstract

Posterior retroperitoneoscopic adrenalectomy (PRA) allows the surgeon to approach the adrenal gland through the back rather than the more traditional laparoscopic transabdominal adrenalectomy (LTA) approach. This technique was popularized in Germany but is being used increasingly throughout the United States. Our institution was one of the early adopters of this technique in the US, and we present such an operation here.

Case Overview

Background

Given their location, deep in the retroperitoneal cavity, the adrenal glands are ideal targets for minimally invasive surgery to avoid the rather large incision an open technique would require. This began first with laparoscopic transabdominal adrenalectomy (LTA), but these also had limitations. As such, it led to the development of the posterior retroperitoneoscopic adrenalectomy (PRA) as an alternative approach, first described in 1995.^1, 2 This approach allows for a direct approach to the adrenal glands without entering the peritoneal cavity, without the mobilization of adjacent organs, and avoiding potential hostile abdominal cavities from previous surgical interventions. Insufflation of the retroperitoneum does not affect a patient’s cardiovascular or respiratory parameters as much as intraperitoneal insufflation. Additionally, this approach allows access to bilateral adrenal glands if necessary, without repositioning.^1, 3, 4

Focused History of Patient

The patient is a 50-year-old female with biochemically unequivocal subclinical hypercortisolism and a right-sided adrenal tumor. She had symptoms of fatigue, palpitations, proximal muscle weakness, abdominal pain, and nausea. Her workup was significant for an AM cortisol level of 9.4 ug/dl (reference range 7.0–25.0 ug/dl). She had two dexamethasone suppression tests performed. After 11 PM administration of dexamethasone, her AM cortisol levels were measured at 8.0 ug/dl and 9.0 ug/dl indicative of a failure to suppress on both occasions. In addition, her ACTH was suppressed with an elevated 24h urine cortisol level. Urine catecholamines were normal.

Preoperative imaging included a CT and MRI of the abdomen. CT revealed a 2.9 x 3.1 x 3.8-cm right adrenal nodule in intracellular fat and characteristics of a benign adrenal adenoma. MRI showed a 3.4 x 3.2 x 0.9-cm right adrenal mass with signal dropout on opposed phase images.

Imaging Studies

CT and MRI are both widely accepted radiologic techniques for imaging normal and abnormal adrenal glands. Adrenal masses are commonly incidentally discovered on abdominal CT. CT densitometry is beneficial in these cases because it can distinguish an adrenal adenoma from metastases based on the attenuation of the masses. MRI is also useful in evaluating the characteristics of adrenal nodules. Specifically, chemical shift MRI is valuable in characterizing these nodules. Relative loss in signal intensity when comparing opposed phase and in phase images helps characterize these masses as benign. These techniques have comparable sensitivity and specificity for diagnosis.^5, 6

We prefer the patient to undergo either adrenal protocol CT or MRI within approximately 3–6 months of planned operative intervention for operative planning. This patient was referred after having both CT and MRI showing a unilateral right adrenal mass with a normal-appearing left adrenal gland. That coupled with the hormonal workup negated the need for any further imaging.

Natural History

With improvements in imaging modalities, what appear to be clinically silent adrenal tumors are found incidentally during cross-sectional imaging for unrelated issues. These adenomas may have autonomous secretion of cortisol only partially blocked by pituitary feedback leading to subclinical hypercortisolism or subclinical Cushing’s syndrome. It is possible that this is also a preclinical Cushing’s syndrome since these patients may progress to overt hypercortisolism.⁷ Since these patients are without overt symptoms, they are at risk for having had chronic exposure to mild cortisol excess, which can lead to classic symptoms of overt Cushing’s syndrome with time.⁸ Studies have shown consistently an association between subclinical Cushing’s syndrome and a manifestation of metabolic syndrome, hypertension, diabetes, and obesity being the most commonly seen.^9, 10

Options for Treatment

Standard practice dictates adrenal nodules that are hormonally active are surgically removed to prevent the consequences of persistent hormone overproduction. Surgical resection of the culprit gland prevents sustained exposure to elevated hormone levels. In subclinical hypercortisolism, the benefit of that resection varies on the level of hypersecretion present. These patients have a higher incidence of hypertension, obesity, decreased bone density, and metabolic syndrome. Adrenalectomy ameliorates the biochemical abnormalities and as such, decreases the cardiovascular risk factors.⁸ In mild cases, observation is an option.¹¹

Rationale for Treatment

The rationale for the surgical treatment of subclinical Cushing’s is to prevent the known sequelae of overt hypercortisolism. Those who have suppressed plasma ACTH and elevated urinary cortisol are close to progressing to overt hypercortisolism and as such, should be managed with surgical resection. Those with a milder disease but evidence of some metabolic syndrome, young age, or symptomatic bone disease should also have surgical management because of the risks of persistent exposure to elevated cortisol levels.¹¹

Discussion

LTA was first described in 1992. The first method described used conventional laparoscopic techniques with a transperitoneal approach. When compared with open surgery, this resulted in reduced postoperative pain, decreased blood loss, fewer wound complications, shorter hospital stays, and shortened recovery times.¹² The PRA was then developed for more direct access to the adrenal glands. It was first described in 1995 and then further developed in Germany through the experience of Walz and his colleagues.^2, 4, 13 Retrospective studies comparing LTA with PRA showed decreased operative times, decreased blood loss, and no difference in long-term outcomes with the posterior approach.

The direct approach into the retroperitoneum allows operators to avoid entering the peritoneum and the complications that could bring including adhesions, postoperative bowel obstructions, injury to intraperitoneal structures, and peritoneal carcinosis.⁴ The higher carbon dioxide insufflation pressures used for this approach have been shown to increase stroke volume, cardiac output, and mean arterial pressure. It also compresses small veins and minimizes bleeding, which aids in operative visualization.¹ There is no distinct tumor size cutoff for PRA, but tumors over 4–6 cm can prove difficult.

This has been our institution’s preferred technique for minimally invasive adrenalectomy. The current patient had no complications following her PRA.

Anesthesia

Since prone positioning is required for this procedure, it is performed under general anesthesia with endotracheal intubation.

Surgical Technique

PRA requires the patient to be placed in the prone jackknife position after induction of general anesthesia and endotracheal intubation. A Cloward table with Cloward Surgical Saddle is used to allow the abdomen to hang anteriorly. That, combined with the jackknife positioning, opens and decreases the pressure of the retroperitoneum. The face, arms, legs, and pressure points are all padded with the elbows, knees, and hips bent at 90 degrees. The external landmarks identified for optimal port placement are the iliac crest, the tip of the 12^th rib, and the edge of the perispinous muscles. The initial incision is placed just inferior to the tip of the 12^th rib. Scissors are used to sharply divide the soft tissue and enter the retroperitoneum. Dissection is just past the mandible, with care being taken not to dissect to superficial penetrating skin. The operator’s finger is then used to bluntly clear a space and guide the placement of 5-mm ports medially and laterally, both angled at about 30 degrees and aimed toward the position of the adrenal gland. A 10-mm balloon port is then placed in the initially placed middle incision. The retroperitoneum is then insufflated with carbon dioxide through high flow tubing with an insufflation pressure of 25 mmHg.

A 5-mm 30-degree scope is inserted in the central port, and a LigaSure device is used to create the retroperitoneal space. Creating the space, the operator then reveals the paraspinous muscles medially and then the kidney. The camera is then moved to the medial port, and the operator uses the LigaSure and a bowel grasper through the lateral and central ports. Dissecting over the superior pole of the kidney and along the paraspinal muscles medially, the adrenal gland is identified. The adrenal gland is mobilized, starting inferiorly, retracting the kidney downward. On the right, this dissection reveals the IVC off which the adrenal must be carefully dissected to reveal the adrenal vein. The vein is clipped and divided. The adrenal gland is mobilized medially and laterally, keeping the superior attachments to suspend the adrenal gland up during dissection. Finally, the superior attachments are taken to completely free the gland from surrounding tissue. It is then placed in an Endo Catch bag and removed through the central port site. The operative bed is inspected for hemostasis after decreased pressure, the ports are removed, and the incision is closed. If visual difficulties occur, other authors have described an additional incision above the hyoid bone, but we have not required this; additional ports do not fit within the vestibulum.

Pathology and Follow Up

Final pathology revealed a 4.0 x 3.8 x 2.7-cm adrenocortical adenoma. Postoperative cosyntropin test performed on postoperative day one showed inadequate cortisol production confirming excess cortisol production. She was temporarily placed on low dose oral steroids and weaned off with recovery of adrenal function.

Equipment

Andrew frame, Cloward Surgical Saddle, LigaSure device, and Endo Catch retrieval bag.

Disclosures

Nothing to Disclose.

Statement of Consent

The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.