Chapter 40 Radiofrequency tongue base reduction in sleep-disordered breathing
Sleep-disordered breathing is caused by collapse or obstruction of the upper airway during sleep. This obstruction may occur at any site along the upper airway passages to include the nasal cavity, oropharynx, hypopharynx and larynx. Once the presence of sleep-disordered breathing is documented by a nocturnal polysomnogram and the patient is intolerant of medical therapy, the presurgical evaluation preceeds. The preoperative evaluation includes a comprehensive head and neck physical examination, fiberoptic nasopharyngoscopy and an optional lateral cephalometric radiograph to determine the site or sites of upper airway obstruction. Other diagnostic avenues, such as sleep endoscopy, may also be performed by the surgeon in directing surgical therapy in a site-specific approach. If the base of tongue is determined to be a causative factor in the upper airway collapse, then adding radiofrequency tongue base reduction to the therapeutic regime is contemplated. Numerous surgical procedures have been developed to address each of the sites of obstruction and have offered the surgeon an armamentarium of options, each with its own set of advantages, disadvantages and success rates.
Radiofrequency tissue volumetric reduction (RF) was developed to reduce the size of upper airway tissues (nasal turbinate, soft palate and tongue base) as an outpatient, minimally invasive procedure using local anesthesia causing minimal discomfort with a low complication rate. The technique works by using radiofrequency at 460 KHz, by a high-frequency alternating current flow into the tissue creating ionic agitation, resulting in protein coagulation and tissue necrosis. This is followed by chronic inflammation, and fibrosis and tissue volume reduction from scar contracture. The scar contracture causes a decrease in the volume of the tongue, enlarges the diameter of the posterior airway space, and thus, should decrease the amount of upper airway obstruction. The physics behind this technique using the medical RF device (Gyrus ENT LLC, Memphis, TN) enables optimal energy delivery to generate larger yet more consistent lesion volumes. The submucosal lesions created using temperature control features in the probe prevent superficial mucosal injury by controlling the temperature at the mucosa to <40°C.
Patients diagnosed with obstructive sleep apnea in whom the preoperative evaluation confirms or suggests tongue base collapse as the cause of the hypopharyngeal obstruction are candidates for RF. Patients need to be in stable medical condition, understand that the procedure may be a multiple stage process, and appreciate the potential complications. Patients with preoperative complaints of dysphagia or dysarthria should undergo a modified barium swallow and/or a speech therapy evaluation prior to considering these therapeutic options, so as not to exacerbate these complaints post treatment. Those patients with underlying diabetes mellitus should be counseled regarding the increased risk of tongue abscess formation.
The technique can be performed as an outpatient or as an inpatient. Depending on the severity of the patient’s sleep-disordered breathing, post-treatment airway monitoring and/or protection with nasal continuous positive airway pressure (CPAP) or a tracheotomy may be considered.
First, the oral cavity is prepped by the patient gargling with approximately 30 ml of 0.12% oral chlorhexidine (Peridex). Oral or parenteral cephalexin is administered prior to placing the electrode. If under local anesthesia, the tongue may be sprayed with 20% benzocaine as a topical anesthetic. In addition, a local anesthetic as a gel (2% lidocaine) may be placed on a sterile cotton tipped applicator at the tongue injection sites. A 25-gauge needle injects 5.0 ml of local anesthesia such as 0.25% bupivacaine (Marcaine) with 1:200,000 epinephrine into each site. A different sterile needle is used at each site of injection. Lingual nerve blocks may be used, but are not necessary. The author does not inject saline into the treatment area. There is an increased risk of infection with each additional injection at the lesion site by bringing potential superficial tongue debris and bacteria into the area to be ablated.
Currently, a dual 22-gauge RF needle electrode with a10 mm active length and a 10 mm protective sheath in a custom-fabricated device allows placement of the electrode under the superficial tongue musculature in the area selected for treatment. Potential sites of treatment include the midline and paramedian dorsal base of tongue areas and the anterior ventral tongue areas (Figs 40.1 and 40.2). Treatment sites should be spaced a minimum of 1.5 cm apart if a single needle probe is used or at least 2.5 cm using the dual needle probe device (Fig. 40.3). Continual pressure on the electrode and visualization that the insulation sheath is not retracting out of the tongue tissue reduce the risk of superficial tissue injury. Using the most current Gyrus radio frequency generator machines and a dual probe at 85°C, 600 joules (J) of rapid energy radiofrequency is delivered to two base of tongue sites with a total of 1200 J delivered. Treatment sessions may be repeated every 4–6 weeks.
Fig. 40.1 Tongue cross-sectional view. Note that the probe should be seated firmly against the dorsal tongue tissue to prevent withdrawal of the probe and injury to the superficial tissue. Also, the hypoglossal neurovascular bundle is located approximately 2.0–2.5 cm deep from the dorsum and should be safe from injury if the probe is placed no more lateral than the paramedian position.
Fig. 40.2 Tongue dorsum view. Note the position of the probe is at the midline or paramedian position of the dorsal tongue. The probe can be placed at the base of tongue, middle tongue area or ventral surface of the tongue to achieve tongue reduction.
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