Pheochromocytoma medical therapy: Difference between revisions

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Revision as of 15:30, 5 July 2017

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ahmad Al Maradni, M.D. [2]

Overview

Treatment with alpha blockers (example: phenoxybenzamine) followed by beta blockers (example: atenolol) is required before surgery. Adjunctive chemotherapy and radiation are used in metastatic disease.

Medical Therapy

Preoperative medical therapy:

All patients doing surgery need preoperative treatment to control hypertension during surgery and hypotension after it. There are three medical regimens for treatment; Combined alpha and beta-adrenergic blockade, calcium channel blockers, and metyrosine^[1]:

Aalpha adrenoceptor blocker (phenoxybenzamine) are used to counteract hypertension and the beta-1 adrenoceptor antagonist atenolol to reduce cardiac output. They can block sudden release of adrenaline during surgery and prevent hypertensive crisis. Patient is ready for surgery in 10 to 14 days after initiation of alpha-adrenergic blockade. Patients should take high sodium diet to antagonize orthostatic hypotension of alpha blockers.After adequate alpha-adrenergic blockade has been achieved, beta-adrenergic blockade is initiated 3 days before surgery. Beta-adrenergic blocker should never be started first because unopposed alpha-adrenergic receptor stimulation can lead to brisky increase in blood pressure. It should be used with caution due to risk of heart failure, pulmonary edema and asthma.

Second line of treatment is calcium channel blocker which is used to control blood pressure preoperatively and intravenous injection intraoperatively.

Its main use is controlling blood pressure in case of failed alpha and beta blockers regimen or unaccepted side effects in the that regimen.

Metyrosine is the last medical line of treatment. It inhibits catecholamine synthesis. It is used in case of failure of other medical lines of treatment or in patients who cannot tolerate them. Additionally, clinicans use combined treatment in difficult cases and if radiofrequency ablation for metastatic foci will be used. Metyrosine side effects include: crystaluria , extrapyramidal manifestations and high cost.

Management of hypertensive crisis

Sodium nitroprusside is the first line of treatment because of its rapid onset of action and short duration of effect. The rate of a prolonged infusion should be no more than 3 mcg/kg per minute to avoid cyanide toxicity.
Phentolamine is nonselective alpha-adrenergic blocker. The response to phentolamine is maximal in two to three minutes after starting of initial dose.
Nicardipine is calcium channel blocker and the last line of treatment after failure of previous two lines.

Chemotherapy

Metastatic pheochromocytoma is treated with Averbuc protocol which is a combination of cyclophosphamide, vincristine, and dacarbazine.^[2]

Radiation

¹³¹I-MIBG radiation therapy has been used for the treatment of MIBG-avid metastases.^[2]

Contraindicated medications

Pheochromocytoma is considered an absolute contraindication to the use of the following medications:

References

↑ Tauzin-Fin P, Sesay M, Gosse P, Ballanger P (2004). "Effects of perioperative alpha1 block on haemodynamic control during laparoscopic surgery for phaeochromocytoma". Br J Anaesth. 92 (4): 512–7. doi:10.1093/bja/aeh083. PMID 14766711.
↑ ^2.0 ^2.1 National Cancer Institute. Physician Data Query Database 2015. http://www.cancer.gov/types/pheochromocytoma/hp/pheochromocytoma-treatment-pdq#link/_179_toc

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[pmid14766711-1] Tauzin-Fin P, Sesay M, Gosse P, Ballanger P (2004). "Effects of perioperative alpha1 block on haemodynamic control during laparoscopic surgery for phaeochromocytoma". Br J Anaesth. 92 (4): 512–7. doi:10.1093/bja/aeh083. PMID 14766711.

[cancergov-2] 2.0 ^2.1 National Cancer Institute. Physician Data Query Database 2015. http://www.cancer.gov/types/pheochromocytoma/hp/pheochromocytoma-treatment-pdq#link/_179_toc

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[2]

@@ Line 18: / Line 18: @@
 <u>[[Metyrosine]] is the last medical line of treatment</u>. It  inhibits catecholamine synthesis. It is used in case of failure of other medical lines of treatment or in patients who cannot tolerate them. Additionally, clinicans use combined treatment in difficult cases and if radiofrequency ablation for metastatic foci will be used. Metyrosine side effects include: [[crystaluria]] , [[Extrapyramidal symptom|extrapyramidal]] manifestations and high cost.
-== Surgical therapy ==
-'''Adrenalictomy:''' Laparoscopic transabdominal and retroperitoneal approaches have been used successfully for non-metastatic abdominal pheochromocytmas. Complicationa are less in laparoscopic than open surgery. Catecholamine secretion falls to normal level within a week.
-Major intraoperative complications include: intraoperative tumor capsule rupture, hypertensive crisis, myocardial infarctions, or cerebrovascular haemorrhages.
-Hyperdynamic instability after tumor resection is poosible. Hypoglycemia can occur after tumour resection due to unopposed insulin effect after decline of catecholamines levels.
-'''''Prognosis'''''
-Good prognosis pateints include: small tumor size, short duration of surgery, systolic blood pressure less than 160 mmhg, and low levels of urinary catecholamines.Postoperative hypotension can be avoided by adequate fluid replacement. Recurrence is more in patients with familial pheochromocytoma and extraadrenal tumors.
-Familial pheochromocytoma  have a high incidence of bilateral disease. partial adrenalectomy is recommended for these patients with bilateral pheochromocytomas to prevent permanent glucocorticoid deficiency. Complete bilateral adrenalectomy is recommended for MEN2 patients. There is highrt rate of reccurence than in sporadic cases. Follow up for long duration after surgery is needed. Most patients should have annual biochemical screening.
-neck paragangliomas may be in the carotid sheath or in the carotid body and thus require proximal and distal vascular control for resection. Preoperative embolization may simplify carotid body tumor resection and reduce blood loss [24]. Most chest paragangliomas require a median sternotomy and may involve the heart and great vessels with cardiac bypass, although videoscopic removal may be possible in some cases [25].
 == Management of hypertensive crisis ==