How To: Induced Paresis for Awake Laryngoscopy Procedures

INTRODUCTION

Advances in endoscopic techniques have spurred the growth of awake in-office outpatient laryngeal procedures. Targeted applications of local anesthesia need to be effective because the common limiting factor for performing these procedures is patient tolerance (J Voice. 2019;33:732-746). For many patients who require multiple interventional treatments of the larynx and especially those at risk of being put under general anesthesia, awake in-office procedures may be the preferred treatment method.

The posterior larynx, characterized by a rich network of sensory endings, is a problematic area to anesthetize and treat. Sensory reactions of the laryngeal adductor reflex result in laryngospasm, which decreases precision and increases complications or failure of the awake operation. One reason may be related to dual innervation by sensory fibers from the recurrent laryngeal nerve and the superior laryngeal nerve forming the interneural communications of the arytenoid plexus and Galen’s anastomosis (Laryngoscope. 2012;122:865-867). Also, the range of motion and velocity of the posterior larynx in the region of the arytenoid and interarytenoid is significantly greater than the anterior commissure. Treatment of the posterior glottis, such as laser ablation and therapeutic injection, is challenged by patient tolerance and limits the application of in-office awake procedures. In addition to standard patient preparation and anesthetization, we describe direct injection of local anesthetic into the posterior glottis to induce a temporary selective unilateral adductor vocal cord paresis allowing for increased patient tolerance of awake in-office treatment.

There are several methods of achieving local or regional anesthesia for awake laryngeal procedures. Topical anesthesia methods include a nebulized anesthetic, gargles, dripping of anesthetic superior to the larynx through the working nasolaryngoscope channel, and transtracheal lidocaine injection. Unilateral and bilateral superior laryngeal nerve blocks are also common local and regional anesthesia methods for laryngeal procedures.

METHOD

We describe an anesthetic technique using direct intramuscular lidocaine injection to induce temporary adductor paresis and sensory loss. We most commonly use this method for patients with recurrent disease near the interarytenoid and arytenoid regions.

Operative Technique

The patient is seated in the upright position, and lidocaine hydrochloride (HCl) 2% and oxymetazoline HCl 0.025% spray are administered to the nasal cavity for topical anesthesia and vasoconstriction. The oropharynx and larynx are further anesthetized with a laryngeal gargle of lidocaine HCl 4% 40 mg/mL (4% lidocaine) and/or butamben-tetracaine-benzocaine 2%–2%–14% 200 mg/sec (cetacaine). A supplemental 2 cc of 4% lidocaine is often delivered via transtracheal approach using a 23-gauge needle.