TY - JOUR
AU - Williams, Mark
AB - Lingual nerve injury is an uncommon complication of laryngoscopy. We report a case of isolated unilateral lingual nerve injury that occurred during suspension microlaryngoscopy. The injury was transient, with complete return of sensation within 3 months after surgery. Several mechanisms have been proposed to explain the occurrence of lingual nerve injury during laryngoscopy, including direct compression of the nerve caused by the laryngoscope, stretching of the nerve caused by cricoid pressure or instrumentation, and compression of the nerve between the medial and lateral pterygoid caused by manipulation of the mandible. The precise mechanism of injury in this case was not obvious, but stretching of the lingual nerve caused by pressure of the suspended laryngoscope on the tongue or retrolingual region was likely. The transient nature of the injury and the rapid return of the nerve to baseline function in this case are consistent with a neurapraxic injury.Lingual nerve injury is a rare but well-recognized complication of laryngoscopy and orotracheal intubation. The resulting sensory deficits are usually transient, with complete recovery occurring within weeks. Forceful laryngoscopy, with compression or stretching of the lingual nerve, has been implicated in this type of injury.Anterior displacement of the mandible, mandibular retraction, and cricoid pressure have also been cited as possible causes of lingual nerve injury.Closely related to the pterygoid muscles, tongue, and mandible, the anatomic course of the lingual nerve places it at risk during laryngoscopy and related maneuvers.REPORT OF A CASEA 37-year-old, 105-kg man presented for elective excision of a right true vocal fold cyst after several months of persistent hoarseness. His medical history was significant only for severe gastroesophageal reflux, which had been treated with omeprazole, and for an emergent appendectomy approximately 20 years earlier. At that time, he tolerated oral intubation without difficulty or complications. Physical examination revealed no head, neck, or intraoral abnormalities. The patient's airway was assessed as Mallampati class I.Intraoperatively, a face mask was used to preoxygenate the patient. Anesthesia was then induced with succinylcholine chloride to facilitate intubation. Tracheal intubation was successful on the first attempt under direct visualization using a No. 4 Macintosh blade and a No. 6.5 endotracheal tube. During intubation, the laryngoscope rested on the right side of the tongue. No cricoid pressure was applied. The tube was secured at 22 cm to the left side of the patient's mouth. General anesthesia was continued with isoflurane, nitrous oxide, oxygen, and fentanyl. Rocuronium was administered to produce muscle relaxation.Following endotracheal intubation, a Dedo laryngoscope was introduced and the patient's true vocal folds were again visualized. The laryngoscope was then suspended from a Mayo tray and the operating microscope brought into position. Excision of the cyst proceeded without difficulty. Eight milligrams of dexamethasone was administered intraoperatively. The patient was extubated uneventfully in the operating room; at that time, no obvious tongue, mouth, or oropharynx trauma was noted. The total operative time was approximately 45 minutes. In the recovery room, the patient complained of tongue numbness that was localized to the right anterolateral aspect of the tongue and floor of the mouth. He also reported decreased taste sensation on the right side. His tongue mobility was normal and there were no other cranial nerve deficits. By 3 weeks after surgery, he reported resolving intraoral numbness. At his next appointment, 3 months after surgery, his touch and taste sensation had returned to normal.COMMENTThe lingual nerve provides tactile sensory innervation of the ipsilateral aspect of the tongue, the lower lingual gingivae, and the floor of the mouth. It also provides taste sensation of the anterior two thirds of the tongue via the chorda tympani branch of the facial nerve and secretomotor innervation to the submandibular ganglion via preganglionic parasympathetic fibers. It arises from the posterior trunk of the mandibular nerve in the pterygomandibular fossa and initially courses between the tensor veli palatini and the lateral pterygoid muscles, where it receives the chorda tympani branch of the facial nerve. It then passes between the lateral and medial pterygoid muscles, proceeding anteriorly and inferiorly on the surface of the medial pterygoid muscle to lie medial to the body of the mandible opposite the third molar (Figure 1). Here, at its most superficial point, the lingual nerve lies just beneath the gingival mucosa on the medial surface of the mandible. The lingual nerve then passes anteriorly and medially, across the styloglossus muscle and lateral to the hyoglossus and genioglossus muscles, before coursing upward to divide into terminal branches that supply the lingual mucosa.Figure 1.Course of the lingual nerve and its relationship to the medial and lateral pterygoid muscles and to the mandible. Arrowheads indicate possible sites of injury.Several mechanisms for lingual nerve injury during laryngoscopy have been proposed. Direct compression of the nerve along its superficial course may occur. This compression may occur as a result of forceful use of the laryngoscope (Figure 2) or, less commonly, from positioning of the endotracheal tube.Direct lingual nerve compression has also been implicated in several reported cases of hypesthesia following the use of the laryngeal mask airway.Figure 2.Possible mechanisms of lingual nerve injury during laryngoscopy. The laryngoscope may compress the nerve against the mandible and injure the nerve directly or compress the tongue and result in stretching of the nerve (arrow).Cricoid pressure, applied during laryngoscopy, results in anterior displacement of the tongue, while the hyoid bone remains immobile. This maneuver may result in stretching of the lingual nerve as it crosses the hyoglossus.The use of instruments on the tongue may produce a similar stretch injury by providing tongue compression and/or anterior displacement of the tongue. The use of a tongue retractor was implicated in a case of bilateral lingual nerve injury following tonsillectomy.It is possible that laryngoscope suspension could result in similar pressure on the tongue or retrolingual region. This pressure could stretch and injure the lingual nerve (Figure 2).The lingual nerve is also vulnerable to compression between the medial and lateral pterygoid muscles or between the medial pterygoid muscle and the medial surface of the mandible (Figure 1). Bilateral anterior pressure at the mandibular angles to maintain airway patency has been associated with lingual nerve injury, and mandibular retraction was implicated in a case of combined lingual and buccal neuropathy.In both maneuvers, compression of the lingual nerve between the medial and lateral pterygoid muscles was cited as the likely cause of injury.The sensory deficits in our patient almost certainly represent a lingual nerve injury, as direct injury to the tongue would be unlikely to affect sensation of the entire distribution of the lingual nerve. Neither cricoid pressure nor mandibular manipulation was used in this case. Thus, the likely cause of injury was either direct compression of the lingual nerve by the laryngoscope or stretch injury caused by excessive pressure on the tongue or tongue base when the laryngoscope was suspended. Visualization of the vocal folds was accomplished easily and without obvious trauma. Still, the possibility of a compression injury cannot be completely eliminated. Tongue compression or pressure on the retrolingual region during suspension of the laryngoscope may have stretched the lingual nerve. However, lingual nerve injury is a rare complication of suspension laryngoscopy. This raises the possibility that additional anatomic or technical factors may have contributed to the injury in this patient.The time course for the return of normal lingual nerve function in our patient is typical, with complete recovery occurring within weeks. Other reports of lingual nerve injury resulting from laryngoscopy describe complete recovery times of between 1 and 6 weeks.This course of recovery is consistent with neurapraxia, an injury to the nerve fiber that may result from compression or, more commonly, stretching. In contrast to other types of injury in which nerve regeneration must occur, neurapraxia is characterized by rapid, spontaneous, and complete recovery of nerve function.Experimentally, this distinction has been documented in the lingual nerve of cats, where crush injuries have exhibited faster and more complete recovery than that of sectioned lesions.The deleterious effects of stretching on physiologic function has been well studied in peripheral nerves. Ischemia, due to disruption of blood flow, is thought to be partially responsible for this type of injury. Lundborg and Rydevikshowed alterations of in vivo intraneural venular flow patterns with as little as an 8% increase in length in rabbit tibial nerves. Complete cessation in arterial blood flow occurred with 15% elongation. Compromise of nerve conduction with stretching has also been demonstrated, albeit in motor nerves. Brown et alshowed that while an 8% stretch in rabbit tibial nerve over a 2-hour period did not affect the amplitude of compound motor action potentials, a 15% stretch over the same period resulted in an amplitude decrease of 99%, with a 32% recovery after 1 hour.CONCLUSIONSWe describe a case of temporary unilateral lingual nerve injury that occurred during suspension microlaryngoscopy. The prognosis for such an injury is excellent, with complete recovery of sensation to be expected within weeks to months. Like other reported cases of lingual neurapraxia following laryngoscopy, recovery of nerve function in our patient was rapid and complete, with no lingering deficits. The precise mechanism of injury in this case is not obvious. However, possible causes include direct compression of the lingual nerve by the laryngoscope or, more likely, excessive tongue base pressure with subsequent lingual nerve stretching. As has been proposed by other investigators, the rarity of lingual nerve injury suggests that the cause may be multifactorial, with anatomic or technical factors contributing to its occurrence.Nevertheless, careful attention to placement of the laryngoscope and minimization of the amount of tongue base pressure applied by the laryngoscope are considerations that can help to reduce the already low incidence of lingual nerve injury.RLTeichnerLingual nerve injury: a complication of orotracheal intubation.Br J Anaesth.1971;43:413.ELoughmanLingual nerve injury following tracheal intubation.Anaesth Intensive Care.1983;11:171-172.DASilvaKAColingoRMillerLingual nerve injury following laryngoscopy.Anesthesiology.1992;76:650-651.BCJonesLingual nerve injury: a complication of intubation.Br J Anaesth.1971;43:730.FMJamesHypesthesia of the tongue.Anesthesiology.1975;42:359.RWinterMMunroLingual and buccal neuropathy in a patient in the prone position: a case report.Anesthesiology.1989;71:452-454.MBerryCHBannisterSMStandringThe nervous system.In: Williams P, Dyson M, Bannister L, et al, eds. Gray's Anatomy. 38th ed. New York, NY: Churchill Livingstone Inc; 1995:901-1398.CHLaxtonRKiplingLingual nerve paralysis following the use of the laryngeal mask airway.Anaesthesia.1996;51:869-870.SMajumderPMHopkinsBilateral lingual nerve injury following the use of the laryngeal mask airway.Anaesthesia.1998;53:184-186.AJVartanianAAlviLingual nerve palsy following tonsillectomy.J Otolaryngol.1997;26:389-391.AMFerdousiAJMacGregorThe response of the peripheral branches of the trigeminal nerve to trauma.Int J Oral Surg.1985;14:41-46.PPRobinsonThe effect of injury on the properties of afferent fibres in the lingual nerve.Br J Oral Maxillofac Surg.1992;30:39-45.GLundborgBRydevikEffects of stretching the tibial nerve of the rabbit: a preliminary study of the intraneural circulation and the barrier function of the perineurium.J Bone Joint Surg Br.1973;55:390-401.RBrownRPedowitzBRydevikEffects of acute graded strain on efferent conduction properties in the rabbit tibial nerve.Clin Orthop.1993;296:288-294.Accepted for publication December 3, 1999.Reprints: Mark Williams, MD, Department of Otolaryngology–Head and Neck Surgery, Johns Hopkins Bayview Medical Center, 4940 Eastern Ave A5W-595A, Baltimore, MD 21224.
TI - Lingual Nerve Injury During Suspension Microlaryngoscopy
JO - JAMA Otolaryngology - Head & Neck Surgery
DO - 10.1001/archotol.126.5.669
DA - 2000-05-01
UR - https://www.deepdyve.com/lp/american-medical-association/lingual-nerve-injury-during-suspension-microlaryngoscopy-AvZ0gB2FvA
SP - 669
EP - 671
VL - 126
IS - 5
DP - DeepDyve
ER -