ThyroidectomyMedical editor Lars H. Jørgensen MD
Oslo University Hospital
A total thyroidectomy is ordinarily the primary treatment for differentiated thyroid carcinoma, medullary carcinoma, and anaplastic thyroid carcinoma, based on certain criteria. During the same operation, the pre and paratracheal lymph nodes are removed (central lymph node dissection).
If pathological lymph nodes are found in the lateral neck region before or during the operation, a modified radical lymph node dissection should performed in addition. This involves preservation of nerves, vessels, and muscles in the area.
The next level of treatment for differential thyroid carcinoma is usually ablation with radioactive iodine (131I). The patient will have life-long treatment of thyroid hormone suppression.
A hemithyroidectomy consists of a lobectomy as well as removal of the isthmus and pyramidal lobe, if present.
For papillary thyroid carcinoma, a total thyroidectomy is performed in the following situations:
- tumor diameter > 1 cm
- multifocal disease
- infiltration of thyroid capsule
- incidence of metastases
- previously irradiated neck
- familial accumulation of thyroid cancer
- if the patient will be treated with radioactive iodine
For follicular thyroid carcinoma, a total thyroidetomy is performed in the following situations:
- infiltration of the thyroid capsule, especially in elderly
- minimal invasive follicular thyroid carcinoma with diameter > 4 cm
- follicular thyroid carcinoma with prominent invasive elements
- malignant Hürthle cell tumors (oxyphile)
- if the patient will be treated with radioactive iodine
For medullary thyroid carcinoma, a total thyroidectomy is performed.
For anaplastic thyroid carcinoma, a total thyroidectomy is performed secondary to radiation therapy if there is no metastasis.
A hemithyroidectomy is usually performed when:
- there is a differentiated thyroid carcinoma tumor around 1 cm or less. That is, for low-risk patients.
- the tumor has an ambiguous histology prior to surgery (mostly follicular neoplasia)
- the patient is older with a shorter life expectancy
- the patient is unable to take thyroid hormone replacement regularly
- Cure the disease
- Palliative treatment
Ligasure (if necessary)
Nerve stimulator (if necessary)
Antibiotic prophylaxis in special cases, for example, long surgery, contamination of the surgical field from the tracheaor esophagus.
The patient lies in the supine position with their arms and legs to the side and their head streched back with a pillow under the their knees.
The following principles apply to all thyroid surgery.
- Optimal access to the entire surgical field is important.
- Identification of anatomical structures is very important. It is considered impossible to perform a lobectomy without being able to identify anatomical structures, especially the recurrent laryngeal nerve and the parathyroid gland.
- Bleeding should be minimal. Vigorous use of suction can damage the parathyroid gland or other structures.
- Diathermy should not be used in the vicinity of the recurrent laryngeal nerve. Mild handling of these nerves is important to avoid nerve damage.
- An incision is made in the anterior neck.
Dissection of the thyroid lobes can begin either laterally or cranially. Lateral access facilitates mobilization of the thyroid lobes early in the operation and makes dissection of the upper pole vessels less difficult. This also provides better access to the outer branch of the superior laryngeal nerve. If the tumor is large, it may be difficult to identify the thyroid artery and the recurrent laryngeal nerve, without separating the upper pole vessels first and releasing the upper pole.
- Both polar arteries are separated.
- The lobes are dissected laterally and flipped medially to identify the recurrent nerves.
After the thyroid lobes are rotated medially, the recurrence nerves should be systematically and carefully dissected from the thyroid gland. There are multiple anatomical variations of routes to the recurrent laryngeal nerve, inferior thyroid artery, and the thyroid gland. The nerve can run in front or behind the inferior thyroid artery, and more than 30 variations have been described. There is therefore no "safe" method for manuevering without identifying the recurrent laryngeal nerve.
- The parathyroid gland is dissected.
In some cases, it is impossible to dissect the parathyroid from the thyroid capsule and maintain intact vessel supply. In these instances, the gland is taken out, cut into small pieces, and implanted into surrounding muscle, for example, the sternocleidomastoid muscle. The area is marked with non-absorbable thread for later identification.
- The thyroid is separated and removed.
It is recommended to remove the entire specimen en bloc. That is, after the lobectomy is performed, the surgeon should continue to dissect on the opposite side without separating the isthmus. The thyroid gland is then removed in one piece. If there are metastases in lymph nodes in the central compartment of the throat, these should be removed together with the thyroid gland.
- A vaccuum drain is placed.
- The incision is closed with intracutaneous sutures and a bandage is applied.
A small bandage should be used for easier observation of possible postoperative bleeding.
- The patient must be observed for sign of postoperative hypocalcemia.
- The vaccuum drain is removed when recommended by the surgeon, which is usually when < 50 ml has drained in a day.
- The day after the procedure, treatment with thyroid hormone substitution is started for patients having the entire thyroid gland removed and who is not treated with radioactive iodine.
- The patient is discharged after about one week.
Patients with highly differentiated thyroid carcinoma are usually readmitted after about six weeks for treatment with radioactive iodine.
After ablation treatment with radioactive iodine for follicular and papillary thyroid carcinoma, life-long thyroid suppression treatment is started with thyroxine.
Substitution treatment with thyroxine is given to patients operated for medullary or anaplastic thyroid sarcoma.
The maintenance dose of thyroxine (usually 125-150 µg daily) is managed according to the TSH value, which should lie around 1 mIE/l, and based on physical symptoms. The daily dosage should increase by 25 µg (or less) every 6-8 weeks until the normal TSH level is reached and there are no symptoms.
For medullary thyroid carcinoma, the patient will have a follow-up examination with the surgeon after 6-8 weeks.
Close follow-up is very important for diagnosing recurrence.
Nerve damage rarely occurs with experienced surgeons (often given as 1%). The extent varies depending on which diseases the treatment center usually operates.
Nerve damage which can occur:
Partial recurrent damage
Total or partial paralysis of the ipsilateral vocal cord, which will take on a paramedian or intermediary position. This will lead to incomplete closure of the voice glottal gap, which causes reduced voice quality, ability to cough, and speech and exertion dyspnea.
The patient is encouraged to use their voice and is referred to a speech therapist, if necessary. Less than half of patients will have spontaneous improvement of voice function even if more have improved voice quality. For chronic reduction of voice quality, the patient should be referred for assessment of compensatorical surgery.
Bilateral recurrent damage
If there is bilateral recurrent damage, the symptoms will depend on the position of the vocal cord. The voice is better the closer the voice cords are to the midline, but stridor and dyspnea are simultaneously more significant. For postoperative stridor, reintubation or a tracheotomy should be considered. For lasting bilateral paralysis, a posterior cordectomy (extirpation of posterior part of vocal cord) will reduce dyspnoe, but will also reduce voice function. For these patients, voice training with a speech therapist is indicated.
Superior laryngeal nerve damage
Damage to the superior laryngeal nerve, which innervates the cricothyroid muscle to adduct and tighten the vocal cord, can give rise to a lower tone pitch and reduce the upper part of the tonal register. Sensory fibers are important to protect reflexes, and damage can cause tendency to aspiration.
When the upper pole vessels are cut, they must be carefully isolated while the laryngeal nerve is seen, or at least has been actively looked for, to avoid damage to this nerve. The physical examination and stroboscopic laryngoscopy with detection of an increased glottis wave amplitude are basis for the diagnosis.
Accessory nerve damage
Damage to the accessory nerve causes hanging shoulders and problems lifting the arms over the horizontal plane in a lateral or posterior position, due to paralysis of the trapezius muscle. During a lateral lymph node dissection, the nerve should be identified. Differentiated thyroid cancer is seldom an indication to sacrifice the nerve. Reduced function can still occur and is easily identified immediately after surgery. During extensive scar formation, gradual reduction of function can occur. Shoulder exercises are important to maintain as much shoulder function as possible.
Horner's syndrome consists of hanging eyelids and constant small pupils, thereby impairing vision. Horner's syndrome can occur as a result of nerve damage (sympathetic trunk), or after a modified lateral lymph node dissection.