What is the Sistrunk procedure for treating thyroglossal duct cysts?

The Sistrunk Procedure for Thyroglossal Duct Cysts

What is the Sistrunk Procedure?

The Sistrunk procedure is the definitive surgical treatment for thyroglossal duct cysts, involving excision of the cyst, the central portion of the hyoid bone (approximately 10mm), and a core of tissue extending superiorly through the suprahyoid muscles to the foramen cecum at the base of the tongue. 1, 2

This procedure was established as the gold standard in 1920 and achieves recurrence rates of only 3-5% when performed correctly 1. The key anatomical principle is that thyroglossal duct remnants can extend from the foramen cecum (at the tongue base) down through the hyoid bone to the thyroid gland, and incomplete removal of this tract leads to recurrence 3.

Surgical Technique Components

The complete Sistrunk procedure includes three essential elements:

• Excision of the entire cyst and any associated fistulous tract 2, 4
• Resection of the mid-portion of the hyoid bone (approximately 10mm of the central body), as the thyroglossal duct passes through or immediately adjacent to this bone 2, 4
• Removal of a core of suprahyoid tissue extending to the foramen cecum, which requires dissection through the geniohyoid and genioglossus muscles to ensure complete tract removal 2, 3

Preoperative Evaluation

Before proceeding with surgery, specific workup is required:

• Ultrasound imaging must document normal thyroid gland anatomy to confirm the patient has functioning thyroid tissue elsewhere, as the cyst may rarely contain the only thyroid tissue present 1
• Fine-needle aspiration should be performed if malignancy is suspected, based on characteristics including a hard, fixed mass with rapid growth or vocal cord paralysis 1

Clinical Outcomes and Recurrence

The procedure demonstrates excellent outcomes when performed correctly:

• Recurrence rates are 3-5% with proper technique 1, compared to significantly higher rates (up to 50%) with simple cyst excision alone 3
• All recurrences typically present within 12 months and occur at the same location as the primary cyst 5
• Perioperative infection (either preoperative or postoperative) increases recurrence risk, with 71% of recurrent cases in one series having infection at the time of primary surgery 5
• Multiple duct tracts are found in 71% of recurrent cases, emphasizing the importance of complete initial resection 5

Modified vs. Standard Sistrunk

A modified approach has been described:

• The modified Sistrunk involves hyoid bone resection with suprahyoid dissection only when duct epithelium is macroscopically visible 4
• Both standard and modified approaches show zero recurrence rates in properly selected cases 4
• However, the complete classic Sistrunk procedure is recommended for all cases to ensure the lowest failure rate 3

Critical Surgical Pitfalls and Complications

Several serious complications can occur with improper technique:

Airway Injury

• The thyroid cartilage can be mistaken for the hyoid bone, particularly in young children where the hyoid may override the thyroid notch, leading to catastrophic airway injury 6
• If airway injury occurs, urgent laryngotracheoplasty with cartilage grafting is required, typically necessitating tracheotomy for an average of 4.5 months 6
• Voice outcomes are poor in 75% of patients with airway injury, though aspiration can be avoided 6
• Prevention requires meticulous attention to midline cervical anatomy and proper identification of the hyoid bone before resection 6

Inadequate Surgery Leading to Recurrence

The direct causes of recurrence include:

• Misdiagnosis of the lesion 3
• Inadequate hyoid bone resection (failing to remove the central portion through which the tract passes) 3
• Persistent infrahyoid or suprahyoid tract remnants from incomplete dissection 3

Perioperative Management

• General anesthesia is required for adequate exposure and patient comfort 2
• Blood transfusion is not typically needed 2
• Average hospital stay is 3 days 2
• Postoperative imaging follow-up is not required if clinical evolution is favorable, but ultrasound or CT with contrast may be indicated if there is clinical suspicion of recurrence 1

Management of Recurrent Cases

For patients with recurrent thyroglossal duct cysts after inadequate initial surgery:

• The "extended" Sistrunk procedure is highly effective and safe, even when multiple duct tracts are present 5
• No further recurrences occur after proper extended Sistrunk revision in reported series with follow-up ranging from 6 months to 8 years 5
• The extended approach involves more aggressive dissection of the suprahyoid tissue to ensure complete tract removal 5