How To: Transoral Endoscopic Vestibular Approach to the Sistrunk Procedure

Introduction

Thyroglossal duct cysts (TGDCs) are the most common congenital neck masses, with an incidence of 7%. During the seventh week of fetal development, the thyroid descends from the pharyngeal floor through the thyroglossal duct. The duct obliterates around the eighth to 10th week, and the foramen cecum and the pyramidal lobe of the thyroid gland are left as remnants (Otolaryngol Clin North Am. 2015;48:15-27). Through some undefined mechanism, cysts may arise in these remnants of the thyroglossal duct tract. Although this is primarily considered a pediatric diagnosis, it may also be first present in adults (Ann Otol Rhinol Laryngol. 2020;129:1239-1242). The cyst is generally painless and asymptomatic, commonly presenting after a respiratory infection as a midline mass with vertical movement on swallowing (Otolaryngol Clin North Am. 2015;48:15-27). In some patients, cysts may become infected and present with pain or a draining sinus.

The Sistrunk procedure is routinely performed through an anterior transcervical incision, with excision of the cyst, tract, and the central portion of the hyoid bone to reduce the risk of recurrence (Ann Otol Rhinol Laryngol. 2020;129:1239-1242). However, this traditional approach leaves patients with a permanent visible scar. Using a transoral endoscopic vestibular approach to the Sistrunk procedure results in an improved cosmetic outcome while achieving all objectives of the traditional approach (see supporting video).

Method

A 51-year-old female with no past medical history presented to the otolaryngology–head and neck surgery clinic with symptoms consistent with an upper respiratory infection, as well as the sensation of a lump in her throat. She denied respiratory distress, compressive symptoms, dysphagia, odynophagia, or constitutional symptoms. She denied tobacco or alcohol use.

A neck and thyroid ultrasound revealed multiple bilateral nodules, including a 1.6-cm nodule in the right posterior thyroid lobe and a 2.1-cm thin-walled rounded structure in the midline neck extending from the superior aspect of the thyroid gland to the hyoid bone. A fine-needle aspiration biopsy of the thyroid nodule was consistent with benign goiter (Bethesda II). A computed tomography scan of the neck with intravenous contrast showed a septated, cystic mass measuring 2.3 cm within the midline anterior strap musculature just below the level of the hyoid bone. These findings were most consistent with a TGDC. Thyroid function tests were within normal limits.

Using a transoral endoscopic vestibular approach to the Sistrunk procedure results in an improved cosmetic outcome while achieving all objectives of the traditional approach.

Description of Surgery: The patient was brought to the operating room and intubated with a reinforced endotracheal tube. Three incisions were marked and infiltrated with 1% lidocaine in 1:100,000 epinephrine: a central gingivobuccal incision 1 cm anterior to labial frenulum of the lower lip measuring 1.5 cm, and two stab incisions near the oral commissure (Figure 1). Mucosal incisions were made using a 15 mm blade, and a Crile clamp and Kelly clamp were used to develop the subplatysmal flap plane in the midline incision. Hegar dilators were used in the central pocket to dilate the subplatysmal tract to 12 mm. An 11 mm trocar was then placed in the central incision, and two 5 mm ports were placed in the lateral incisions. The subplatysmal plane was developed under direct visualization using a Harmonic device,  and the pocket was insufflated with CO₂ to 6 mmHg. The location of the incisions, as described earlier, the length of the central incision not exceeding 1.5 cm, and an angle between the central and lateral ports of less than 45° are all critical in avoiding a mental nerve injury.

Throughout the procedure, 0°, 30°, and 45° endoscopes were used. Dissection was performed to identify the thyroid notch, thyrohyoid membrane, and hyoid bone. The cyst was visualized and a needle aspiration was performed using a 21-gauge spinal needle. The cyst was then carefully dissected off the thyroid notch using the Harmonic device and Maryland dissector. The hyoid bone was identified, and the dissection was carried out to the lateral hyoid to plan bone cuts to obtain a 1.5 cm piece of hyoid bone adjacent to the specimen. Careful dissection was performed with the Harmonic to the suprahyoid musculature. The suprahyoid musculature was carefully transected using the LigaSure as well as a laparoscopic L-hook bovie. Once the suprahyoid musculature was released from the hyoid, bone cuts were made using the SONOPET ultrasonic aspirator at a power of 100%, suction of 50%, and irrigation of 15 mL/min. The undersurfaces of the hyoid and cyst were then visualized, and the Harmonic scalpel was used to ligate and cut a cuff of the base of tongue to ensure that the cyst was completely removed. Once completely freed, the cyst was retrieved with an Endo Catch bag and removed through the central incision.

Five milliliters of EVICEL were placed under direct visualization. The trocars were removed and the incisions were closed with running locking sutures using 4-0 chromic. Fluffs and Tensoplast were placed over the cervicomental angle as a pressure dressing.

Postoperatively, the patient had an expected amount of subcutaneous emphysema due to CO₂ insufflation, as well as mild routine postoperative pain. She was observed in the hospital overnight. The pressure dressing was removed after 24 hours, and the patient was discharged home on the first postoperative day. Discharge medications included standing Tylenol and a few-day course of opioid medications for breakthrough pain. Additionally, the patient was instructed to follow a soft diet until her first postoperative visit. At her postoperative visit, her intraoral incisions were healing well, and she was without pain or any complications. The final pathology was consistent with a TGDC.

Results

The TGDC was successfully excised, and the patient experienced no surgical complications. The risk of TGDC recurrence in patients undergoing a Sistrunk procedure with this novel approach is an outcome measure that needs to be established. Thus, moving forward, long-term follow-up will be critical to delineate this risk. Experience with the transoral endoscopic vestibular approach can be applied to the transoral approach for additional procedures such as the Sistrunk, but more reports are needed to build the literature base for this novel technique.

View the video of the technique described here.