To the Editor:—
The palatoglossal arch curves downward and forward from the soft palate to the tongue and forms the lateral part of the isthmus faucium with the palatopharyngeal arch. We experienced difficult laryngoscopy in a patient with an anatomically abnormal palatoglossal arch.
A 15-yr-old boy with mental retardation caused by glycogen-storage disease with frequent hypoglycemic episodes was scheduled for dental treatment during general anesthesia. Premedication consisted of scopolamine and pentazocine. Anesthesia was induced with intravenous midazolam and inhalation of nitrous oxide, oxygen, and sevoflurane. Vecuronium was administered intravenously to facilitate endotracheal intubation. A Macintosh blade was inserted into his mouth and advanced between the right molars and the right side of the tongue. The tongue was about to be displaced to the left to visualize the larynx when the laryngoscopist noticed that it was impossible to displace the base of the tongue with the Macintosh blade. She observed the anatomic relation between the tongue and the pharynx to clarify the reason why the tongue could not be displaced and laryngoscopy was difficult. Her observation of the base of the tongue revealed that the right palatoglossal arch was attached to the dorsal part of the tongue, not to the lateral part (fig. 1).
The palatoglossal arch contains the palatoglossus muscle, which originates in the oral surface of the palatine aponeurosis, extends forward, downward, and laterally in front of the palatine tonsil, and enters the lateral part of the tongue, passing deeply and transversely through the tongue with intrinsic transverse muscle fibers. 1The muscle elevates the posterior part of the tongue and pulls down the soft palate, thus constricting the isthmus of fauces and closing off the oral cavity from the oropharynx. 2During ordinary laryngoscopy with the Macintosh blade, the blade was advanced along the right lingual edge toward the right molars and the base of the tongue, then into the pharynx, while the tongue is displaced to the left. However, in this patient, a laryngoscopist could not displace the tongue to the left while advancing the blade along the right lingual edge because the right palatoglossal arch was attached to the dorsal part of the tongue. This anatomic abnormality prevented the displacement of the tongue to the left, which lead to difficult laryngoscopy using the Macintosh blade. The laryngoscopist tried a different method of laryngoscopy without displacement of the tongue to the left. She inserted the Macintosh blade into the open mouth and advanced it forward along the center of the dorsum of the tongue and pushed the base of the tongue upward without displacing it to the left. This maneuver made arytenoid visualization possible. The palatopharyngeal arch, which was located behind the palatoglossal arch, was normal, and there was no abnormality in the relation between these arches. In general, the so-called Mallampati test is available to predict difficult laryngoscopy. 3However, preoperative intraoral examination was difficult in this patient because of mental retardation. Based on our experience, we propose that the abnormal palatoglossal arch should be described as one of the anatomic factors that make laryngoscopy difficult to perform.