We have performed percutaneous ethanol sclerotherapy (PEI) in more than 500 patients since 1995. It means that we have one of the greatest experience with this relatively new treatment modality. We will discuss the indications, the technique, the advantages and the possible drawbacks of PEI here briefly.
Indications of PEI
The fundamental rule of indications is the following: it is required to meet the criteria of indication of surgery to perform PEI. I do not think that PEI can be a preventive therapy because it may lead to an unacceptable extension of the use of a treatment with side effects.
The indication of surgery is the refilling of a previously aspirated cyst with large enough size to cause cosmetic or compression complaints. Even small-sized cysts may cause aesthetic problems if located in the ventral part of the thyroid. Nevertheless, we only exceptionally treat cysts smaller than 2 cm in maximal diameter. Such small cysts recur only relatively rarely after evacuation. However, cysts larger than 3 cm in maximal diameter recur in more than 2/3 of patients. As a rule of thumb, we offer surgery or PEI instead of surgery to a patient whose cyst refills after 2 evacuations. Naturally, a cyst refilling every five years requires different approach than a lesion refilling within months.
Compared with cystic nodules, the efficiency of PEI in treating solid or dominantly solid nodules is significantly worse. Considering the relatively low side effects of surgery, it may be questioned that PEI may have any role in the therapy of such nodules. Nevertheless, PEI may have significant advantages to surgery under certain circumstances.
Patients with high risk of general anaesthesia
Such patients usually have a poor life expectancy, therefore PEI may solve the problems caused by a large nodule for their entire lifetime.
In such patients a severe hyperthyroidism may last for even months and even extreme doses of thyrostatics may required to control the thyrotoxicosis. Radioiodine therapy is useless in these patients until the iodine depletes from the body; a process that takes 3 to 6 months. Surgery could be the choice of treatment but to reach euthyroid state with a thyrostatic agent may be very difficult and lasts longer. On the other hand, the euthyroid state can be reached within a few weeks with PEI.
Patients with special professions
The risk of permanent palsy of the recurrent nerve is around 1% if operation is performed by an experienced surgeon. These patients are able to talk loudly months after phoniatric therapy but they lose the capability of singing forever. Moreover, temporary palsy may last for months in the case of more than 10% of patients. Also, to save the entire function of the superior laryngeal nerve is a very difficult task. This nerve is responsible for the tone and even a partial impairment of this nerve makes the voice deeper.It means that actors and singers may be candidates for PEI. (Imagine a 65-year-old actor who wishes to work for another ten years. We cannot guarantee that he can avoid surgery later, but we can ensure that this intervention can be postponed.) Similarly kindergarten teachers and singing masters are also candidates for PEI, because the loss of voice of singing means the end of their profession. Teachers and speakers can be included in the indication, as well.
Considering the increased risk of surgery and general anaesthesia during pregnancy, PEI may be the treatment of choice in nodules causing compression signs.
Considering the increased risk of recurrent nerve palsy, PEI may be a treatment of choice in those patients who previously underwent surgery involving the same lobe where the recurrent nodule is located.
The indications and the procedure of PEI is the same in parathyroid and thyroid cysts.
Locoregional recurrence of papillary carcinoma
Nowadays, this is the most popular field in PEI for control of locoregional recurrence of well-differentiated thyroid carcinoma after surgery. The indications are not clear but PEI seems to be a useful alternative of berry picking surgery.
Procedure of PEI
Before PEI treatment
Before PEI treatment is started, a written consent is signed by and obtained from all patients after detailed explanation related to the treatment which is administered once a week as an outpatient procedure.
The patient lies in supine position with extended neck. A pillow with 10 to 15 cm in maximal diameter is placed under the neck as in the case of a thyroid ultrasound examination. We use the ‘free hand'' technique for ultrasound guided needle insertion, i.e. without a guiding device mounted on the US probe, as we find that this technique allows a more accurate positioning of the needle inside the nodule while leaving the probe and the operator the possibility to move freely.
Thyroid function is evaluated in all patients by the measurement of TSH and FT4. All patients undergo ultrasound examinations, except for toxic nodules ultrasound-guided FNA examinations using at least 7,5 MHz stable or 5 to 16 MHz varying linear probe. The nodule size, the proportion of solid internal fluid component, the vascularization are assessed on ultrasound. The three orthogonal diameters of each nodule (the largest diameter and two diameters perpendicular to it) are measured, and the volume of each nodule is calculated as: 3.14xAxBxC/6 (where A and B and C are the diameters).
The PEI session
After skin sterilization, ethanol (96%) is administered in a single injection per session, under direct sonographic control by a 23-gauge needle. No anaesthesia or sedation is given. The average total amount of alcohol administered per patient is around 1 mL/mL nodular volume divided in 3-7 weekly sessions depending on the volume of the nodule. The maximum volume of ethanol injected at one session never exceeds 30% of the volume of the nodule measured before the same session in the event of solid, while 50% in the event or dominantly cystic nodules. Alcohol perfusion within the nodule is monitored as a hyperechoic pattern. We need to be particularly careful to avoid ethanol seepage through the capsule in nodules located near the posterior region of the gland (i.e. near the recurrent laryngeal nerve). We target the ventral half or the ventral 2/3 of the nodule at most in the nodules and we do not move the nodule during the session toward the dorsal part. Patients are always asked to describe the onset of pain in order to stop the alcohol administration if necessary. If it occurs, we stop the ethanol administration until the pain relieves significantly. It may last for 10 to 20 seconds. The patient needs to swallow while we administer the ethanol in many cases. We have to recheck the location of the needle after each swallow. We move the ultrasonography probe with our left hand and the syringe needle with our right hand during the entire procedure. The procedure requires only one operator.
Special considerations in the event of dominantly cystic nodules
We aspirate as much as possible cystic fluid but we do not evacuate the nodule fully in order to avoid difficulties in location of the nodule during administration of ethanol. If we aspirated the cyst completely, it could hinder to find the lesion (for an example click here). A mass with around 5 mm in depth needs to be left in order to ensure a successful targeting. We stick the patient twice, the first time for the aspiration and the second time for the ethanol administration. We do not remove the ethanol after the procedure.
When PEI treatment is completed, the patient is asked to get up and put pressure on a tampon placed on the puncture site which will subsequently be covered with a bandage. We observe the patient for 5 minutes and if he has no significant complaints, he can leave the clinic. We give a phone number to ensure the possibility to communicate with us within minutes if he has any unusual complaints in between two sessions.
They include physical, ultrasound examinations and assays for TSH, FT4 and aTPO were performed during the first 6 weeks after the last PEI, then 3 months later, thereafter 6 months later and thereafter every year.
In around 30% and 90% of sessions, patients feel pain during the ethanol injection in the case of cystic and non-cystic nodules, respectively. The pain may radiate to the jaw and to the teeth. In most cases this squeezing pain decreases significantly in 2 to 3 minutes. The pain lasts for 12 to 24 hours in less than 5% of patients.
Patients feel mild neck discomfort after their sessions that lasts for 24 (35% of cases), 48 (35% of cases), 96 (25% of cases) and 124 hours (less than 5% of cases).
Voice of the patient becomes weaker in around 10% of patients. This complaint resolves spontaneously within 72 hours without any treatment.
A permanent palsy of the recurrent nerve occurred in one of our patients. We suppose that the ethanol provoked a fibrotic reaction. Otherwise, to best of our knowledge, ethanol cannot cause permanent nerve damage.
In around 5% of our patients, characteristically with large nodules, a subacute granulomatous thyroiditis-like reaction develops mainly after an umpteenth session (for an example click here). The lobe which contains the nodule enlarges and becomes painful and hard. Subfebrility or fever is a usual finding in this case too. We administer a short course of steroid therapy which has a prompt effect. We start with 16 to 32 mg methyl-prednisone and administer the steroid with decreasing dose for 10 days. We have never met a patient whose thyroiditis-like reaction recurred as opposed to the de Quervain's thyroiditis. The reaction has a beneficial effect: the nodule decreases in size without further sessions.