21.1 Introduction

Obstructive sleep apnea (OSA) affects 1 to 4% of the US pediatric population. ¹ Traditionally, adenotonsillectomy is the first-line treatment for sleep-disordered breathing or polysomnographic-proven OSA. Although effective, studies have shown that more than 20% of children will have persistent OSA after adenotonsillectomy. Many patients with persistent OSA following T&A have identified risk factors such as obesity, craniofacial anomalies, trisomy 21, and other syndromes with associated hypotonia. In addition, it has been demonstrated that children with OSA have a larger degree of cervical lymph node hypertrophy that extends beyond adenotonsillar hypertrophy. ² Management of children with persistent OSA following is challenging and varies widely by practitioner. Initial interventions and management strategies include weight loss, CPAP, medical treatment (i.e., nasal steroids), and revision sleep surgery.

Choice of second-stage surgery for children with residual OSA following T&A is based on a number of modalities to assess for the site(s) of obstruction. Lateral, soft tissue neck X-ray may be used to assess for adenoid regrowth. CT, MRI, and cine-MRI have been used to assess for lingual tonsillar hypertrophy or palatal involvement. Awake nasendoscopy may be helpful in assessing the presence of lingual tonsillar hypertrophy or base of tongue collapse; however, this may not be helpful in obtaining an accurate assessment in pediatric populations. Drug-induced sleep endoscopy (DISE) is a novel diagnostic tool to assess upper airway obstruction in a pharmaceutically induced sleep state. DISE enables the surgeon to perform a real-time assessment of sites of obstruction to allow for guided interventions accordingly. Studies have demonstrated that airway obstruction sending during DISE correlates with AHI and O2 nadir in children. ³ At our institution, we utilize a validated scale to assess DISE, known as the Chan–Parikh scale. ⁴ This scale assesses five levels of obstruction and grades each on a 4-point scale for minimum and maximum obstruction. The five levels are the adenoid, velum, lateral pharyngeal wall, tongue base, and supraglottis.

21.2 Indications for Surgery

When a child continues to have symptoms of OSA following adenotonsillectomy or in children with small tonsils and adenoids, ⁵ DISE-directed surgery can be employed to identify sites of obstruction and intervene appropriately. Several studies have demonstrated that lingual tonsil hypertrophy is the most common anatomic cause of persistent OSA in children after previous adenotonsillectomy. ^{6 – 8} Lingual tonsillar hypertrophy has been demonstrated using a number of modalities including Cine MRI, CT, and DISE. ^{9 , 10} When identified by DISE, lingual tonsillar hypertrophy can be managed with a lingual tonsillectomy using a number of techniques. Below we describe our standard surgical technique for a patient undergoing DISE-directed surgery with the findings of lingual tonsillar hypertrophy.

21.3 Surgical Technique

Prior to surgery, patients are seen with their family or caregivers and full history and physical examination is carried out, identifying risk factors and potential sites of obstruction. Most patients that are candidates for lingual tonsillectomy have previously undergone T&A or have been found to have small tonsils on physical exam. A discussion of management options is held, including observation, conservative interventions as described above (weight loss, CPAP, etc.), and surgical intervention. Without imaging findings of lingual tonsillar hypertrophy preoperatively, management then proceeds with a discussion of the role of drug-induced sleep endoscopy in identifying sites of obstruction and possible surgical interventions based on findings, including revision adenoidectomy, lingual tonsillectomy, or supraglottoplasty. Risks specific for lingual tonsillectomy include bleeding, damage to the lingual vessels and nerves, pain, scarring, need for revision procedure, and damage to surrounding structures. Informed consent is signed and operative scheduling is initiated.

The patient is brought to the operating room and an IV is placed, typically after induction anesthesia with an inhaled anesthetic. At our institution, drug-induced sleep is initiated with a propofol infusion. Other institutions may favor the use of dexmedetomidine. It is vital to have good communication with the anesthesia provider so that there is mutual understanding of the goals and plan for flexible laryngoscopy and bronchoscopy, as well as contingency plans based on possible findings.

Once a steady plane of anesthesia has been reached, such that the patient is breathing spontaneously, but will not react to the scope being passed, DISE is initiated with evaluation of each of the five subsites in the scoring system, as well as the trachea and proximal bronchi. ▶ Fig. 21.1 demonstrates technique for performing a sleep endoscopy. In patients with identified lingual tonsil hypertrophy, the scope is withdrawn and the patient is nasally intubated to allow for adequate access of the surgical site. ▶ Fig. 21.2 demonstrates varying degrees of lingual tonsil obstruction observed during DISE. This is graded using a validated grading scale, Chan–Parikh, from 0 to 3.

Using either a Lindholm laryngoscope or a McIvor mouth gag, the lingual tonsils are exposed and a 30-degree Hopkins rod is used for visualization. The patient is placed in suspension either utilizing the Mayo stand if using a McIvor or using the Lewy arm and suspension table for a laryngoscope (▶ Fig. 21.3 and ▶ Fig. 21.4). In our institution, a Coblator ProCise wand on the ablate setting is applied to the lingual tonsillar tissue in order to debulk down to the underlying muscle, taking care not to injure the muscle or disrupt the glossoepiglottic ligament, which lies at the midline at the base of the lingual portion of the epiglottis. Dissection is carried laterally being cognizant that the tonsillar tissue is more scarce at the lateral aspects of the base of the tongue than at the midline (▶ Fig. 21.5 and ▶ Fig. 21.6).

Dissection is carried out until all lymphoid tissue has been debulked and hemostasis has been achieved. The patient is taken out of suspension and the mouth gag or laryngoscope is removed. The patient is returned to the anesthesia team and extubated when stable.