An isthmusectomy is a rare type of thyroid surgery. It involves removing a structure called the isthmus, which connects the left and right halves, or “lobes,” of the thyroid gland.

Doctors may recommend an isthmusectomy to treat benign nodules (small tumors) on the isthmus. Surgeons may carry out an isthmusectomy alone or in addition to other types of thyroid surgery.

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Doctors may recommend an isthmusectomy to help treat benign nodules on the isthmus. The isthmus is the central part of the thyroid gland, connecting the left and right lobes.

A 2021 case report quotes older research that indicates nodules isolated to the isthmus are uncommon compared with nodules in the right or left lobe. For this reason, isthmusectomy is a rare procedure.

In some cases, doctors may perform an isthmusectomy alone. In other cases, they may recommend performing one alongside other thyroid procedures.

The American Thyroid Association describes other thyroid surgeries as follows:

Total thyroidectomy

A total thyroidectomy involves removing the entire thyroid gland. Afterward, individuals will take medication for the rest of their lives to replace the thyroid hormones their body no longer makes naturally.

Doctors typically only recommend a total thyroidectomy if a person has:

  • a high risk form of thyroid cancer
  • Graves’ disease, an autoimmune condition that causes the thyroid to produce too much thyroid hormone
  • a large goiter, which is a large lump or swelling in the neck due to thyroid enlargement

Thyroid lobectomy

A thyroid lobectomy, also called a hemithyroidectomy, involves removing half of the thyroid gland.

In some individuals who undergo a thyroid lobectomy, the remaining lobe continues to produce all the thyroid hormone their body needs. In others, the remaining lobe does not produce enough thyroid hormone, and the person will require lifelong thyroid hormone supplements.

The British Thyroid Association (BTA) states that an isthmusectomy involves the following steps:

  1. A healthcare professional administers general anesthesia.
  2. The surgeon makes an incision in the lower part of the neck.
  3. Some surgeons use a procedure called intraoperative nerve monitoring to help them intermittently or continually assess the function of important nerves, such as those that supply the voice box, to ensure they preserve them.
  4. Before removing the thyroid gland, the surgeon carefully seals off the surrounding arteries to reduce bleeding.
  5. They remove the isthmus along with any other parts of the thyroid, if necessary.
  6. The surgeon closes the wound using stitches, clips, staples, or a medical adhesive. Some stitches require follow-up removal, while others gradually dissolve.
  7. Finally, the surgeon may place small drainage tubes in the neck to help drain away any excess fluid over the next 24 to 48 hours.

As the BTA explains, individuals who are due to have thyroid surgery will first undergo a pre-operative assessment.

During this assessment, doctors will order blood tests to check thyroid function and calcium levels. These tests may also check the following:

Doctors may also perform a laryngoscopy to check vocal cord functioning. This procedure involves using a long, thin, flexible tube with a light and camera at one end to assess the vocal cords and other internal structures in that area.

Other tests a doctor may recommend include the following:

Individuals who undergo only an isthmusectomy are usually able to go home on the same day, provided there are no complications.

Following the surgery, a person may experience:

  • temporary mild pain or discomfort in their neck
  • increased tiredness and reduced energy levels for up to a month

Doctors will arrange follow-up blood tests for around 6 to 8 weeks after surgery to check the person’s thyroid function and calcium levels.

Individuals who undergo an isthmusectomy alongside other types of thyroid surgery may require lifelong thyroid medication to ensure their body receives the correct amount of thyroid hormone.

Isthmusectomy and other types of thyroid surgery are associated with certain risks, including:

Hoarseness

Thyroid surgery can irritate the recurrent laryngeal nerves, which control the vocal cords. When this happens, the nerves stop sending signals to the vocal cords, resulting in a hoarse voice.

Thyroid surgery carries a 5 to 7% risk of temporary hoarseness that recovers without treatment, and a 0.5% risk of permanent nerve injury that requires surgery to reverse the hoarseness.

Other vocal changes

Thyroid surgery can also cause other vocal changes, including:

  • Reduced yelling ability and changes to singing voice: These changes may occur following injury to the external branch of the superior laryngeal nerves. This branch controls a muscle that helps with voice projection and reaching a high pitch.
  • Deeper voice: Surgical scarring on the muscles and nerves on the outside of the voice box may cause the voice to deepen.
  • Wound infection: As with all surgeries, isthmusectomy and other thyroid surgeries carry a risk of wound infection. However, the risk is low, affecting fewer than 1% of individuals who undergo thyroid surgery. Antibiotic treatment can clear most infections, though surgical drainage may be necessary in severe cases.
  • Neck hematoma: Rarely, bleeding in the 1 to 2 days following thyroid surgery can lead to a collection of blood in the area, called a neck hematoma. Mild cases may cause localized swelling and bruising. Severe cases may disrupt breathing and require emergency surgery.

For individuals who undergo isthmusectomy as part of a total thyroidectomy, there is a small risk that the surgeon may accidentally damage or remove the parathyroid glands. These are four tiny glands that sit above the thyroid and make parathyroid hormone, which controls calcium levels.

Damaging or removing these glands can lead to low calcium levels and an underactive thyroid (hypothyroidism). Both conditions are treatable with lifelong supplements and medication.

When to contact a doctor

A person should contact a doctor if they experience any of the following signs or symptoms around the surgical site after their procedure:

  • increased warmth
  • discoloration of the skin
  • pus or other drainage
  • swelling
  • a bad odor

It is also important to seek medical help if the following occur:

  • numbness, twitching, or tingling around the mouth, fingertips, or toes
  • a fever of 100.5 °F (38 °C) or higher
  • difficulty breathing
  • chills

The Thyroid Cancer Survivor’s Association lists some useful questions a person may want to ask their doctor before undergoing thyroid surgery:

  • Do I need a total or partial thyroidectomy in addition to the isthmusectomy?
  • What are the risks and possible complications of the surgery?
  • Where will the surgical incision site be, and how large will the scar be?
  • How long will I need to remain in hospital after the surgery?
  • How long will it be before I can safely return to work?
  • Should I seek a second opinion before surgery?

An isthmusectomy is a rare type of surgery to remove a structure called the isthmus, which connects the left and right lobes of the thyroid gland. Doctors may recommend this to treat benign nodules on the isthmus. A person may undergo an isthmusectomy on its own or in addition to other types of thyroid surgery.

Thyroid surgeries carry certain risks, such as vocal changes, wound infection, and neck hematoma. Most of these complications are temporary or treatable. Individuals who undergo an isthmusectomy as part of a total thyroidectomy are at increased risk of calcium or thyroid hormone deficiency, which are both treatable with lifelong supplementation.

A person can talk with a doctor about the relative risks and benefits of an isthmusectomy before undergoing the procedure. A doctor can also answer any questions they may have about surgery preparation and recovery and their outlook following the procedure.