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Petrosal Sinus Sampling (PSS)...

Patient information from Canterbury Health Limited Endocrine Services

INFERIOR PETROSAL SINUS SAMPLING WITH CRH STIMULATION

Introduction
Procedure
Risks

Introduction

You have been diagnosed with Cushing's syndrome which results from excessive production of the hormone cortisol, made by the adrenal glands. In your case, the adrenal glands are being driven by excessive amounts of another hormone called ACTH. This test is to determine where that ACTH is coming from. Constant high levels of ACTH are usually caused by a tumor. Approximately 80% of cases are tumors of the pituitary gland while the remainder may occur in the lung, pancreas and other sites (known as "ectopic" sites).

This test relies on the fact that if the source of your high ACTH is the pituitary gland blood levels taken from very near the gland will be higher than the blood level in an arm vein. Pituitary gland tumors are often tiny and can't be seen even with the most modern scanners. This test will help your endocrinologist to know with almost 100% certainty whether the pituitary gland is the source or if a search is needed elsewhere (for example in the lungs or abdomen). This guides treatment, for example the recommendation for Pituitary surgery.

Procedure

You are allowed water only from midnight the night before (nothing else to eat or drink). You will be given a light sedative, but will be awake during the procedure. You will be taken to the Radiology Department where the procedure will take place. The radiologist will place some local anesthetic into the groin on each side over the main vein that drains blood from each leg. Then a fine bore catheter will be passed up the vein, past the heart and into the major vein in the neck (the jugular vein). From there it is passed into a smaller vein that drains blood directly from the pituitary gland, known as the inferior petrosal sinus. The procedure is repeated for the other side. X-ray screening guides the radiologist to know where the catheters are positioned. A small butterfly needle is inserted into an arm vein.

Once the catheters are in place, blood samples will be taken from the right and left petrosal sinus, and an arm vein at exactly the same time. After two baseline samples, a hormone called CRH is injected into the arm vein. This increases ACTH when a pituitary gland tumor is present, but has no effect on ectopic ACTH production. Further blood samples are taken for another 10 to 15 minutes, then the catheters are withdrawn. Pressure is applied to the groins to minimize bruising. Often sampling is continued from the arm vein only, for a total of 90 minutes. You will have to remain lying on your back for at least 2 hours afterwards.

Risks

This procedure is very safe when performed by an experienced radiologist. Rarely, there have been reports of people having a stroke at the time of this procedure but this was related to a catheter of faulty design which is now no longer used. Bruising, which is common in Cushing's syndrome, may occur after the catheters are pulled out. Some people notice flushing of the face after the CRH and rarely it can result in a fall in blood pressure.


From: http://www.pituitarycenter.com/html/article1.html

INFERIOR PETROSAL SINUS SAMPLING

Patients who are suspected of having a pituitary tumor resulting in Cushing's syndrome may be referred for inferior petrosal sinus sampling if findings on MRI examination of the pituitary did not reveal a tumor or are inconclusive.

The inferior petrosal sinus sampling procedure is performed in the radiology department. With the patient on the angiography table both groin regions are partially shaved, sterilized, and a local anesthetic is injected into the skin to provide pain relief. A tiny incision is made within the skin and a needle is inserted to puncture the femoral vein which drains blood from the leg. A small catheter is then inserted into the vein and flushed with an intravenous solution. Longer catheters are passed into the shorter catheters and advanced through the large veins traversing the torso into the neck and then into the base of the skull. Thereafter, a microcatheter is advanced through each of these larger guiding catheters and threaded into the inferior petrosal sinuses which lie along the internal aspect of the skull base and drain blood from the pituitary gland. Once these microcatheters have been positioned, contrast dye is injected and X-rays are taken to verify their position in the inferior petrosal sinuses. Next, blood samples are collected from both catheters in the inferior petrosal sinuses and from a peripheral (usually arm) vein. Thereafter, corticotropin-releasing hormone is administered through the peripheral vein. Repeat blood samples are drawn 2, 5, and 10 minutes after the injection. Additional X-rays are taken to confirm that the catheters were not dislodged from their site during the sampling procedure. Thereafter, the catheters are removed and direct pressure is applied to the groin region to decrease the likelihood of bruising. Patients are observed for 4 hours following the procedure to ensure that no bleeding from the femoral vein puncture sites will occur. Normal non-strenuous activity may be resumed 48 hours after the procedure.

Sedatives and pain relievers may be administered during the procedure as necessary. A blood thinner might be used depending on the patient's anatomy and the clinical suspicion of developing a blood clot. If a blood thinner is used, this may be counteracted with medication at the conclusion of the procedure to ensure that normal blood clotting resumes while removing the catheters. Overall, the inferior petrosal sinus sampling procedure involves minimal discomfort. The risks of the procedure are small. X-rays are used but the radiation doses are minimized. Infection is controlled by using sterile technique. Some patients might have an unexpected allergic reaction to the dye used during the study. A bruise may develop within the groin. Although rare, blood clots have developed in the groin veins following this procedure. Again, steps are taken to minimize the likelihood of each and every one of these complications.

ACTH levels are measured in each of the blood samples obtained during the procedure. The ratios between the petrosal sinus sampling and the peripheral vein samples are compared. The results are used to determine whether ACTH production is due to either a pituitary or a non-pituitary source.


From: http://www.mc.vanderbilt.edu/pituitarycenter/html/article1.html

Patients who are suspected of having a pituitary tumor resulting in Cushing's syndrome may be referred for inferior petrosal sinus sampling if findings on MRI examination of the pituitary did not reveal a tumor or are inconclusive.

The inferior petrosal sinus sampling procedure is performed in the radiology department. With the patient on the angiography table both groin regions are partially shaved, sterilized, and a local anesthetic is injected into the skin to provide pain relief. A tiny incision is made within the skin and a needle is inserted to puncture the femoral vein which drains blood from the leg. A small catheter is then inserted into the vein and flushed with an intravenous solution. Longer catheters are passed into the shorter catheters and advanced through the large veins traversing the torso into the neck and then into the base of the skull. Thereafter, a microcatheter is advanced through each of these larger guiding catheters and threaded into the inferior petrosal sinuses which lie along the internal aspect of the skull base and drain blood from the pituitary gland. Once these microcatheters have been positioned, contrast dye is injected and X-rays are taken to verify their position in the inferior petrosal sinuses. Next, blood samples are collected from both catheters in the inferior petrosal sinuses and from a peripheral (usually arm) vein. Thereafter, corticotropin-releasing hormone is administered through the peripheral vein. Repeat blood samples are drawn 2, 5, and 10 minutes after the injection. Additional X-rays are taken to confirm that the catheters were not dislodged from their site during the sampling procedure. Thereafter, the catheters are removed and direct pressure is applied to the groin region to decrease the likelihood of bruising. Patients are observed for 4 hours following the procedure to ensure that no bleeding from the femoral vein puncture sites will occur. Normal non-strenuous activity may be resumed 48 hours after the procedure.

Sedatives and pain relievers may be administered during the procedure as necessary. A blood thinner might be used depending on the patient's anatomy and the clinical suspicion of developing a blood clot. If a blood thinner is used, this may be counteracted with medication at the conclusion of the procedure to ensure that normal blood clotting resumes while removing the catheters. Overall, the inferior petrosal sinus sampling procedure involves minimal discomfort. The risks of the procedure are small. X-rays are used but the radiation doses are minimized. Infection is controlled by using sterile technique. Some patients might have an unexpected allergic reaction to the dye used during the study. A bruise may develop within the groin. Although rare, blood clots have developed in the groin veins following this procedure. Again, steps are taken to minimize the likelihood of each and every one of these complications.

ACTH levels are measured in each of the blood samples obtained during the procedure. The ratios between the petrosal sinus sampling and the peripheral vein samples are compared. The results are used to determine whether ACTH production is due to either a pituitary or a non-pituitary source.


Good info on Petrosal Sinus Sampling for doctors and medical personnel may be found at http://neurosurgery.mgh.harvard.edu/e-f-932.htm. The information includes test and normal values, as well as diagrams and pictures.

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