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Ethanol Ablation of Thyroid and Parathyroid Tumors 1100.e5

Procedure tissue but does require additional specialized AUTHOR: Richard E. Goldstein, DVM, DACVIM,
equipment.
• The parathyroid or thyroid nodule is defini- • The advantages of heat ablation and PEI over DECVIM
EDITORS: Leah A. Cohn, DVM, PhD, DACVIM; Mark S.
VetBooks.ir • A 25- or 27-gauge needle attached to an surgery include shorter anesthesia time, a Thompson, DVM, DABVP
tively identified and differentiated from the
carotid artery.
more rapid recovery, and less surgical healing
extension set and syringe and filled with
or scar formation.
96% ethanol is carefully advanced into the • There is the potential to fail if the needle
nodule under ultrasound guidance. was not properly inserted or the nodule was
• When the tip of the needle is thought to be not completely destroyed.
in the center of the nodule, a small test dose • Another disadvantage of the two less invasive
of alcohol (<0.1 mL) is given. This should options is that no tissue is obtained; hence
produce a small, white, hyperechoic cloud the tumor cannot be classified histologically.
within the nodule that should not be seen Because almost all parathyroid tumors
dispersing rapidly along tissue planes. If behave in a benign fashion regardless of
there is a doubt that the tip is not in the their histopathologic features, this is not as
nodule, the needle should be removed from severe a disadvantage as it would be in the Procedures and Techniques
the nodule and repositioned and the test case of other neoplasms.
dose repeated.
• If the tip of the needle appears to be SUGGESTED READING
within the nodule, the ethanol should Schaefer C, et al: Canine primary hyperparathyroid-
be injected until all parts of the nodule ism. Compend Contin Educ Vet 31(8):382-390,
become hyperechoic. This may require 2009.
slight repositioning of the needle in a large
nodule. ADDITIONAL SUGGESTED
• Within approximately 10 minutes, the READINGS
injected area will become hypoechoic, so Goldstein RE, et al: Percutaneous ethanol injection for
the decision whether or not the nodule has treatment of unilateral hyperplastic thyroid nodules
been completely filled with ethanol must be in cats. J Am Vet Med Assoc 218(8):1298-1302,
done within that time frame after starting 2001.
the injection. Long CD, et al: Percutaneous ultrasound-guided
• When the filling is complete, the needle is chemical parathyroid ablation for treatment of
removed, and the animal can be recovered. primary hyperparathyroidism in dogs. J Am Vet
Med Assoc 215(2):217-221, 1999. ETHANOL ABLATION OF THYROID AND
Postprocedure Reproduced from the third edition in PARATHYROID TUMORS Anesthetized dog
properly positioned in dorsal recumbency and prepared
• No life-threatening or persistent complica- unabridged form. for percutaneous ethanol injection.
tions have been observed after this procedure
in dogs. Transient unilateral laryngeal swell-
ing/paresis and Horner’s syndrome can occur
and tends to resolve in 1-4 days.
• Bilateral injections should not be attempted
due to the risk of bilateral postprocedure Needle
laryngeal swelling.
• Dogs with PHPTH should be monitored Parathyroid nodule Parathyroid
closely for 5-10 days after ablation for Thyroid nodule
signs of hypocalcemia and should be Needle tip
supplemented as necessary with calcium and
vitamin D.
• Clinical decision making regarding calcium
and vitamin D supplementation, as well as
postinjection calcium monitoring is the A B
same as when surgical parathyroidectomies
are performed for the definitive treatment
of PHPTH.
Alternatives and Their
Relative Merits
• PEI is only one way to definitively treat
PHPTH. Alternatives include surgical
removal of the parathyroid nodule(s) and Ethanol test injection
percutaneous heat ablation, which is per- Parathyroid filled with ethanol
formed in a similar fashion to PEI, but heat
rather than ethanol is used to necrose the C D
tissue via the inserted needle.
• Surgery is still the gold standard and should ETHANOL ABLATION OF THYROID AND PARATHYROID TUMORS Ultrasonographic images of
always be offered as such to the owner. percutaneous ethanol injection (PEI) therapy in a dog with primary hyperparathyroidism. A, Parathyroid nodule
• Heat ablation may be superior to ethanol with the thyroid gland. B, Needle entering the parathyroid nodule, with tip clearly visible within the nodule.
ablation in terms of fewer transient effects of C, Test dose of ethanol being injected and hyperechoic material remaining within the nodule. D, Parathyroid
the leakage of ethanol into the surrounding nodule has been completely infiltrated with ethanol immediately after successful PEI therapy.

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