Failed Fibreoptic Intubation in a Patient with a Large Mandibular Fibreosseous Lesion

Summary

A case is presented of a 25 year old patient with a 15 year history of a lesion in the oral cavity, the histology of which showed it to be fibrous dysplasia. Conventional laryngoscopy and intubation were not possible as the lesion filled the entire oral cavity. Attempted awake fibreoptic intubation failed as the lesion extended into the nasopharynx and oropharynx, making it impossible to pass the fibreoptic scope beyond the nasopharynx. A tracheostomy was performed under local anaesthesia and surgery proceeded uneventfully. Although fibreoptic intubation has proved to be extremely useful in difficult intubations, there are a number of situations where fibreoptic intubation is not possible.

Introduction

In our sub-region, patients with jaw tumours often present late when the lesions have grown to very large sizes. This poses problems with the airway as one is unable to fit a face mask on the patient and also the large lesion makes intubation difficult. In many of these, after pre-oxygenation and an induction dose of propofol, we have been able to insert a laryngeal mask airway and after confirming that ventilation of the patient is possible via the laryngeal mask airway, suxamethonium is given and the patient is intubated with the aid of a bougie. In a few patients, on preoperative assessment, it has been realized that the insertion of an LMA would be difficult or impossible and an awake fibreoptic intubation is planned. This case report illustrates that even fibreoptic intubation may not be the answer to such an airway problem.

Case Report

A 25 year old farmer presented at the Maxillofacial Surgery Unit of the Korle Bu Teaching Hospital, with a 15 year old history of swelling of the lower jaw. His delayed presentation was due to lack of funds for his medical expenses. On examination the lesion was found to be a hard bony swelling that filled the whole mouth, extended extra-orally and made the lips incompetent. There was a small gap inferiorly through which he could protrude his tongue (Figure 1). It was impossible to examine every aspect of the oral cavity. However, it appeared that the lesion arose from the right posterior alveolar bone of the mandible from the premolar region. Incision biopsy histopathological report indicated that the lesion was ‘Fibrous Dysplasia’ (FD).

Figure 1.

Patient with lesion filling entire mouth

During pre-anaesthetic assessment it was decided that conventional laryngoscopy and intubation would be impossible as the lesion filled the whole of the oral cavity and therefore awake fibreoptic nasotracheal intubation was planned. Plain radiographs and CT scan that had been done previously were not available to be reviewed at the pre-anaesthetic visit.

In preparation for the fibreoptic intubation the patient was given 0.6mg of atropine intravenously as an anti-sialogogue, 30 minutes prior to the procedure. Once in theatre, after attaching pulse oximetry, electrocardiography and blood pressure monitors, the patient was given oxygen through one nostril. 2mg of midazolam was given intravenously for sedation and a bilateral superior laryngeal nerve block was done using 1.5ml of 2% plain lignocaine on each side. During the procedure of fibreoptic intubation however, it was impossible to pass the fibrescope beyond the nasopharynx due to an obstruction.

At this point, a review of the plain radiographs and CT scans, showed that the lesion filled the whole of the naso- and the oropharyngeal spaces thus obstructing the passage of a flexible fibreoptic scope (Figures 2 and 3). A tracheostomy was therefore performed under local anaesthesia and surgery proceeded uneventfully following general anaesthesia.

Figure 2.

Axial CT scan showing lesion extending to posterior pharyngeal wall

Figure 3.

Sagittal CT scan showing very compressed airway (as indicated by arrow))

The lesion was sectioned into four, in the sagittal and transverse planes, to facilitate its delivery out of the oral cavity. Figure 4 shows the oral cavity after excision of the lesion. The patient did well postoperatively and was discharged from hospital after one week. This case illustrates a situation of difficult intubation where the use of the fibreoptic technique was not successful.

Figure 4.

A view of the oral cavity after excision of the lesion.

Discussion

Flexible fibreoptic laryngoscopy has been a major advance in the management of difficult intubation.¹ In our own institution we have found flexible fibreoptic laryngoscopy particularly useful in the management of patients for surgery to release temporo-mandibular joint (TMJ) ankylosis², large oral tumours and known failed intubation using conventional techniques. Flexible fibreoptic laryngoscopy features prominently in the algorithm for difficult intubation. However there is evidence that in some patients it may prove unsuccessful.

In a review of 423 fibreoptic nasal intubations over a 5 year period, Ovassapian et al found that in 10 cases, narrow nasal passages did not allow the insertion of either the nasotracheal tube or the fibreoptic scope. Of the remaining 413 intubations, 5 were unsuccessful for reasons other than narrowing of nasal passages. One was due to an undiagnosed posterior pharyngeal wall tumour, three to inability to thread the endotracheal tube over the fibreoptic scope, although the scope was in the trachea, and in one case the vocal cords could not be visualized.

Presumably we failed with fibreoptic intubation in our patient due to two reasons. Firstly, the nasal passages themselves were clear but we failed to appreciate the size and extension of the tumour posteriorly to occupy and obstruct the naso-and oropharyngeal spaces. Secondly we failed to insist on the availability and review of the radiographs and CT scans on the preoperative visit. It was after failure with the fibreoptic scope to intubate that a careful review of the patient's radiographs and CT scans alerted us to the problem.

Fibrous dysplasia (FD) is said to be a common benign developmental disorder of bone.⁴ It may involve one bone (monostotic) or multiple bones (polyostotic), occurring throughout the skeleton with a predilection for long bones, ribs and craniofacial bones. Most lesions are monostotic, asymptomatic and identified incidentally. When polyostotic, it is sometimes associated with abnormal skin pigmentation and endocrine abnormalities5, known as McCune Albright's syndrome. This patient had the monostotic type since he did not have multiple lesions or abnormal skin pigmentation but was not investigated for endocrine abnormalities.

Aetiology of FD is unknown, has uncertain pathogenesis and diverse histopathology.⁶ It has been linked to an activating mutation in the gene that encodes the alpha subunit of stimulatory G protein (G(s) alpha) located at 20q13.2–13.3.⁴ FD is characterized by substitution of normal bone with immature tissue embedded in a fibrous stroma.⁷ Ozek et al⁶ found that the maxilla was the most commonly involved as compared with mandible. In our patient the mandible was the site of the lesion.

In craniofacial FD, jaw involvement often causes facial asymmetry/deformity, occlusal cant and loss of teeth as seen in our patient.⁸ Ocular, masticatory, respiratory or auditory functional alterations are some of the consequences.⁷ Lesions can grow to huge sizes extending to fill the entire oral cavity as was seen in this patient being reported. The marked deformity and functional disturbance were the major indications for treatment as suggested by Ozek.⁶

Surgery is also indicated for confirmatory biopsy, correction of deformity, prevention of pathologic fracture and/or eradication of symptomatic lesions.⁴

In cases where surgery has been chosen as the treatment of choice there could be difficulty with intubation under general anaesthesia. This was clearly demonstrated in our patient by our failure to intubate using the flexible fibreoptic scope although fibreoptic nasal intubation is said to have a high success rate.¹

Conclusion

We have reported a case of a large fibre-osseous lesion of the right mandible in whom attempted flexible fibre-optic intubation failed. We failed because we did not appreciate the extent and size of the lesion. We also failed to review the radiographs and CT scans prior to initiation of anaesthesia. We propose that in circumstances where specialized imaging techniques, such as CT scans, are not available and where clinical judgment favours fibreoptic intubation, such as in this case, one should always be prepared for tracheostomy.