A case of a difficult airway due to large sublingual dermoid in a rural medical college.

Sir,

Giant size sublingual dermoid cysts are extremely rare and pose considerable technical challenges to the anesthesiologists. We report a case posted for marsupialization of cyst with a tentative diagnosis of congenital ranula and ectopic thyroid as differential diagnosis.

A 29-year-old patient complained of a slow growing swelling inside the mouth, first noticed in childhood. The patient complained of pain in the swelling, dysarthria, dysphagia, and mild respiratory distress on lying supine after needle aspiration biopsy. Airway examination revealed a smooth tender immovable mass 3 × 4 cm on the floor of the mouth occupying the entire oral cavity and displacing the tongue against the hard palate making visualization of the tongue difficult. There was limited temporomandibular joint movement and normal thyromental distance. Lateral X-ray of neck in the standing position revealed narrowing of the oropharynx [Figure 1]. Preoperative indirect laryngoscopy was attempted by the otolaryngologist; however, glottic structures were not visualized.

Figure 1

Lateral X-ray of neck in standing position

Consent for fiberoptic nasal intubation under general anesthesia was obtained and the patient was premedicated with injection Glycopyrolate 0.2 mg i.v. and injection Metoclopramide 10 mg i.v. 30 min before procedure. Emergency invasive airway access was kept ready in the case of failed intubation. Pulse oximeter, electrocardiogram, and end tidal carbon dioxide monitors were connected and baseline parameters recorded. Injection Fentanyl 100 μgm i.v. was given and nasal mucosa anaesthetized with cotton pledgets soaked in 3 ml 4% lignocaine and 0.5 ml xylometazoline.

After preoxygenation with 100% oxygen for 3 min, anesthesia was induced with halothane in oxygen and nitrous oxide (33:67%). Mask-assisted ventilation was possible during spontaneous breathing. Fiberoptic bronchoscopy through the nasal cavity was performed under spontaneous breathing. The fiberoptic view was poor, epiglottis was not visible, hence jaw thrust was provided and vocal cords were visualized. Lignocaine 4% was sprayed onto vocal cords. Adequacy of inhalational and local anesthesia was verified, scope was advanced under the epiglottis through the vocal cords till the carina was visualized. A 6.0 mm cuffed endotracheal tube was advanced into the trachea over the scope. Oxygenation was adequate throughout intubation. Anesthesia was maintained with halothane, oxygen, nitrous oxide, and vecuronium bromide as necessary.

An intraoperative diagnosis of dermoid was made [Figure 2]. At the completion of surgery, direct laryngoscopy showed laryngeal grade 2 view (Cormack and Lehane classification). As supraglottic edema was not anticipated, patient was extubated when fully awake. Postextubation vital parameters were within normal range and patient maintained oxygen saturation (SpO2) of 97-98% in room air.

Figure 2

Maximum mouth opening achieved under general anaesthesia with muscle relaxation

Sublingual dermoid cysts account for less than 1% of cystic intraoral lesions and fewer than 225 cases have been reported in the literature.[1] Various airway management strategies have been suggested such as blind nasotracheal intubation, fiberoptic endoscope-guided intubation and preliminary tracheostomy. Blind nasotracheal intubation requires extensive practice prior to use and carries the risk of bleeding and trauma. Preliminary tracheostomy significantly increases morbidity.

Excision under local anesthesia with monitored anesthesia care carries significant risk of intra operative pulmonary aspiration. Decompression of dermoid cyst by aspirating its contents prior to intubation to facilitate intubation has been reported.[2] This was not attempted in our case as a preoperative diagnosis was not made and surgical procedures in the airway preceding a definitive diagnosis have the potential for converting an anticipated difficult airway into a dangerously difficult airway.[345]

Nasal fiberoptic intubation was chosen as it was not possible to pass both scope and tube in the highly limited oral cavity. As the patient refused bronchoscope placement while awake, general anesthesia using volatile anesthetic agents was chosen. When spontaneous ventilation is maintained, the changes in depth of anesthesia and associated respiratory and cardiovascular effects occur gradually and can be easily reversed with the use of volatile anesthetic agents.[6]

Fiberoptic nasotracheal intubation while maintaining spontaneous breathing under inhaled anesthesia is one of the recommended methods of securing the airway in uncooperative patients with large sublingual dermoid.