Difficult intubation due to ossification of the anterior longitudinal ligament.

Abstract

Ossification of the anterior longitudinal ligament (OALL) is occasionally seen among elderly people. OALL is usually clinically asymptomatic and no therapy is needed, unless symptoms such as dysphasia or hoarseness are severe. We would like to report a case of difficult intubation due to asymptomatic OALL. A 62 year-old man presented for cholecystectomy. Four months previously he had acute cholecystitis and was scheduled for surgery twice in another hospital. On both occasions surgery was cancelled because tracheal intubation was impossible. After another episode of cholecystitis he was referred to our hospital for surgical treatment. Following endoscopic removal of stones in the common bile duct, laparoscopic cholecystectomy was scheduled. His neck movements were not grossly restricted and on examination his pharyngeal view was Mallampati Class I. To determine the cause of the failed intubation, laryngofibrescopy was performed by an otolaryngologist, which showed a protruded posterior pharyngeal wall. A lateral cervical spine radiograph showed OALL from C3 to C7 (Fig. 2), which was considered to be the cause of difficult intubation. After insertion of an epidural catheter, a propofol infusion 2 mg.kg−1.h−1 was started and fibreoptic intubation performed. Except for the lump in the posterior pharyngeal wall, no airway stenosis was found. He was extubated at the end of surgery and there were no postoperative airway complications. Ossification of the anterior longitudinal ligament. OALL along at least four contiguous vertebral bodies is one of the major radiographic characteristics of diffuse idiopathic skeletal hyperostosis (DISH) [1]. There are a number of reports of difficult intubation associated with DISH [1-6]. In several cases, standard bedside tests were unable to predict difficult intubation and the diagnosis of DISH was not made prior to the operation [2, 3]. Although we were able to intubate the patient without difficulty using an awake fibreoptic technique, standard bedside tests did not suggest difficult intubation. Without the previous failed intubations, we would have encountered an unexpected difficult intubation. The intubating laryngeal mask has been used successfully [1], although this is not available in our hospital. Difficulty in inserting a laryngeal mask airway has also been reported [4]. The mechanism by which DISH leads to difficult intubation is not clear at present. Difficulty in elevating the epiglottis during direct laryngoscopy may be important [5], possibly die to the effect of DISH on the ligaments around the larynx. Routine radiological evaluation of the cervical spine is not recommended because OALL is a relatively common condition and only occasionally associated with difficult intubaton [2].