Did you know about PEI?
Ethanol has been the first agent to be proposed for thyroid ablation. Soon it was clear that ethanol is indicated in thyroid cystic rather than in solid thyroid nodules.
Ethanol injection causes irreversible tissue damage through:
- Direct coagulative necrosis
- Local small vessels thrombosis
- Eventual tissue sclerosis
Percutaneous ethanol injection (PEI) had broadly been used for the treatment of hepatocellular carcinoma, adrenal adenoma and parathyroid adenoma or hyperplasia. Then PEI was introduced for the treatment of thyroid lesions in 1990.
In a fist time, Ethanol was used as an alternative to open surgery or radioiodine administration in the management of autonomous functioning nodules. Then thyroid interventional procedures went through many evolutions, and PEI has been replaced by other technical approaches (such as RFA or Laser) to treat the most part of thyroid nodularities.
Possible applications of PEI in thyroid are: Thyroid cysts, Autonomous Functioning Thyroid Nodules (AFTN) and Cold Solid Thyroid Nodules (controversial).
HOW TO DO IT
Disposable echoic needles are inserted into the cyst through a little sterile inserting supportive needle device. Sterility is ensured by sterile gloves for operators, a sterile cover for the US probe and sterile gel.
Through a syringe connected to the needle, the cystic fluid is extracted. After the extraction, 95% sterile ethanol is injected into the cysts, through the same needle.
Infused ethanol will be seen on Ultrasound as a hyperechoic signal refilling the cyst. The amount of ethanol injected id variable: often is about 60% of cystic fluid extracted.
Before needle extraction, it is washed by normal saline fluid, in order to minimize the spread in of ethanol in subcutaneous tissues during the extraction of the needle, that would cause pain.
Based on the operatore, the ethanol may be or may be not left into the cysts after the procedure. Data does not show any result differences.
If performed by experienced operators, major drawbacks are rare.
10-20% of patients complain about pain at the injection site, which may irradiate to the ears and jaw. it usually last less than a couple of minutes. This is most frequently due to a leakage of ethanol in subcutaneous tissues during rising of the needle: that's why the use of small amount of saline as described above. Local anesthesia may be use to minimize this annoying feeling.
Pain may be followed by neck muscular stiffening, lasting few hours.
More severe complications are rare. Cord paralysis, due to irritation of the recurrent laryngeal nerve is ofter transitory. Jugular vein thrombosis or facial dysesthesia are very rare.
Due tu the fibrotic capsule, the procedure is even safer in cystic lesions than in solid ones.