Laryngo fiberscopy-guided suspension procedure for an ectopic lingual thyroid obstructing airway

An ectopic thyroid gland is caused by failure of descent of the thyroid gland anlage early in the course of embryogenesis. The lingual region is the most common ectopic location of the thyroid gland, and this anomaly can cause airway obstruction by compressing the epiglottis. Surgical approaches, such as resection of the mass, are considered for patients with significant airway obstruction, or in those with bleeding or malignancy. Patients in whom the ectopic thyroid tissue is the only functioning thyroid tissue, careful preservation of the secretory function of the ectopic thyroid is required to avoid total loss of thyroid function, particularly in pediatric patients. We report a case of ectopic lingual thyroid in such a pediatric patient in whom a novel laryngo fiberscopy-guided suspension procedure was performed to preserve the ectopic thyroid gland.

The thyroid gland attains its expected normal anatomical position in the pretracheal region by migrating caudally from the foramen cecum at the base of the tongue during the seventh week of fetal life. Ectopic thyroid tissue occurs because of incomplete migration. Clinically, the incidence of lingual thyroid is 1 in 100,000 cases [1]. This anomaly is 4 times more common in women than in men. Although it can occur at any age, it manifests more commonly during childhood, adolescence, and around the time of menopause. This could be attributed to the increased demand for thyroid hormones during these stages, which is met by increase in the level of circulating TSH through growth of ectopic thyroid tissue [2]. In approximately 90% of ectopic thyroid cases, the ectopic thyroid tissue is found at the base of the tongue as a lingual thyroid gland. In 75% of those presenting with a lingual thyroid, no other thyroid tissue is present [3].

Lingual thyroid is usually asymptomatic, unless accompanied by an increase in the size of the gland. Symptomatic patients present with dysphagia, dysphonia, a foreign body sensation in the throat, cough, pain, bleeding, and/or dyspnea [1]. Several previous studies have reported that approximately 33–62% of patients with ectopic thyroid develop hypothyroidism with increased TSH levels [2]. It has been reported that approximately 24% of children with primary nongoitrous hypothyroidism show an ectopic thyroid [4].

There is no consensus regarding the optimal therapeutic strategy for the management of such patients. Asymptomatic patients require a strict follow-up for the early detection of malignancy or the development of other complications [3]. For patients presenting with mild symptoms and a hypothyroid state, levothyroxine replacement therapy may be effective. Administration of a suppressive dose of thyroid hormones decreases TSH levels and can reduce the ectopic glandular volume and consequently reduce symptoms of compression [1, 5, 6]. However, there is no consensus about its dose or the duration. Radioactive iodine therapy has also been reported as a useful non-surgical treatment option for lingual thyroid. However, it should be avoided in children and young adults owing to potential harmful effects on the gonads and other organs [5].

Surgical intervention is warranted in patients with severe symptoms of airway obstruction, bleeding, and/or malignancy [3]. A total excision is the most common surgical procedure performed in such cases. Several surgical approaches have been described, such as transoral, transhyoid, suprahyoid, or lateral pharyngotomy [5]. Transoral CO2 laser excision and transoral radiofrequency ablation have been reported as mini-invasive surgical approaches [4, 7]. However, patients in whom the ectopic thyroid is the only functioning thyroid tissue, total surgical excision needs to be strictly followed by lifelong hormone replacement therapy. Regarding preservation of the patient’s own ectopic thyroid gland, several reports have been published on transposition or autotransplantation of the lingual thyroid instead of its total excision. In those cases, lingual thyroids were transposed or transplanted to the muscles of the neck, floor of the mouth, abdominal or pectoral regions, with or without a vascular pedicle flap. The procedures were performed via a transoral, transhyoidal, or lateral approach [8–13].

Surgical intervention necessitates careful and close attention to airway management because surgical access and excision are associated with a significant amount of edema formation. A preoperative tracheostomy should be considered in high-risk patients [4].

Our laryngo fiberscopy-guided suspension procedure is a novel surgical procedure for the management of a lingual thyroid. It involves suturing and fixation of the ectopic thyroid tissue to the hyoid bone. We adopted this procedure because total excision of the mass would not necessarily release the airway obstruction if laryngomalacia continues to cause the epiglottis to hang over the glottis. Its advantage is that it preserves the ectopic thyroid tissue, which therefore contributes to postoperative hormone replacement therapy and it can resolve an airway obstruction certainly, using intraoperative laryngo fiberscopy. Moreover, the surgical technique of our procedure is easier and simpler than that of other reported transposition or autotransplantation procedures. Pediatric surgeons are accustomed to performing the Sistrunk procedure for thyroglossal cysts via the transhyoidal approach. We developed the idea for present procedure from the Sistrunk procedure itself. Before the operation, we carefully considered the safety of the procedure, especially with respect to the management of the airway. Because we were attempting a minimally invasive surgery based on the Sistrunk procedure, we did not perform preoperative tracheostomy. Vocal function was also discussed and managed carefully. We kept in mind not to invade the hyoid bone laterally so as not to injure the recurrent laryngeal nerve. This procedure is associated with at least 2 disadvantages. Firstly, to our knowledge, no such procedure has been previously reported in the literature; therefore, its clinical response rate and long-term outcome are unknown. Secondly, the procedure is associated with a risk of fistula formation as is common with other surgical procedures performed for lingual thyroid, such as excision via a lateral pharyngotomy technique, because a direct communication is established between the skin of the neck and the pharyngeal cavity [4]. Our patient showed the development of a fistula; however, this resolved within 5 months postoperatively with conservative management.

Our laryngo fiberscopy-guided suspension procedure is a novel surgical procedure for the treatment of a lingual thyroid. Total preservation of the thyroid tissue, certain resolution of an airway obstruction, and ease and simplicity of the surgical technique are the advantages of this novel procedure.