Friday, January 18, 2008

A case report of prolonged laryngeal oedema after posterior cranial fossa surgery

Sangram Patil1

Madhu Gowda2

1. Specialist Registrar in Anaesthetics, Morriston Hospital Swansea, SA6

6PU, UK.

2. SHO in ITU, Morriston Hospital Swansea, SA6 6PU, UK.

Case report:

A 62 yrs lady was transferred to our neurosurgical unit to assess and investigate the cause for hydrocephalus. Her presenting complains were difficulty in swallowing and walking for last 3 months, worsening paraesthesia & numbness of left upper limb and worsening memory for last few weeks. She was non-smoker.

Her background history was hypertension, hypothyroidism, hiatus hernia, basal cell carcinoma of face and duodenal perforation operated in the past. Her preoperative examination showed normal higher functions, cranial nerves, unsteady gait and reduced left upper limb power. CT scan of head showed distortion of ventricles, suspicion of posterior fossa mass. Her thyroid functions were normal.

She underwent excision of ependymoma 4th ventricle, resection of tonsils and insertion of ventricular drain. The operation was performed in prone position and lasted 6 hours. She was extubated at the end of operation and transferred to neuro ICU. On neuro ICU she developed increasing stridor and needed reintubation.

Laryngoscopy showed grade 1 view and laryngeal inlet was swollen & appeared crescent shaped. Only size 6.5 cm endotracheal tube could pass through the cords due to laryngeal oedema. She subsequently developed chest infection. On ventilator she was moving all 4 limbs and obeying commands. CT scan of head showed expected postoperative findings.

On day 8 she was reviewed in view for extubation. On deflation of endotracheal tube cuff there was good leak around the tube and she ventilated well spontaneously. Fibre optic scopy showed slightly oedematous vocal cords. On extubation patient developed stridor, difficulty in speaking and needed intubation again (awake fibre optic nasal intubation).

She underwent elective tracheostomy in theatre. Meanwhile, she became drowsier and developed weakness in proximal muscles. CT scan head showed chronic SDH of increasing size.

She subsequently settled and could breathe spontaneously with tracheostomy mask with speaking valve and later minitrach.

Neurological review after 3 weeks of admission showed left facial weakness with nystagmus, weakness in the distribution of 9th & 10th cranial nerves. She had a husky voice with evidence of incomplete closure of vocal cords.

ENT surgeon opined that her soft palate on left was normal and on right the function was diminished. Left vocal cord was immobile, arytenoid cartilage displaced anteromedially. Left cord was in paramedian position and there was incomplete right cord compensation.

The patient was discharged to rehabilitation ward after a month of ICU stay. The issues at discharge were bulbar palsy, left upper limb weakness and unsteady gait. Minitracheostomy was removed before discharge.

Discussion:

Prone position in posterior fossa surgery requires substantial flexion of neck to facilitate surgical access. This causes reduction of anterior-posterior dimension of hypopharynx, compression ischemia of base of tongue, soft palate, posterior wall of pharynx (against ETT or oral airway). The consequence of this can be post-extubation airway obstruction of rapid onset as a result of macroglossia caused by accumulation of oedema. Macroglossia after prone position surgery has been well described.1 An unusual case of massive oropharyngeal swelling and macroglossia occurring after cervical spine surgery performed on a patient in the prone position has been described.2

Posterior fossa is relatively small space; relatively little swelling can result in disorders of consciousness, respiratory drive and cardio-motor function. Irritation and injury of posterior fossa structures that may have occurred during surgery need to be taken into account when planning extubation and postoperative care. Procedures involving dissection on the floor of 4th ventricle entail possibility of injury to cranial nerve nuclei or postoperative swelling. Injury of 9th, 10th & 12th cranial nerves can result in loss of control/patency of upper airway

The intubation trauma can lead to tears in mucosa of larynx, trachea, and arytenoid cartilage dislocation causing hoarseness. Pressure effects due to shape of ETT may exert substantial pressure on arytenoid cartilages. Pressure effects of cuff can cause nerve injury due to pressure on braches of recurrent laryngeal nerve.

Post intubation laryngeal oedema is commonly symptomatic in children as their small airway size is more severely reduced by oedema and is usually subglottic. The possible causes could be large ETT, trauma from laryngoscopy and intubation, excessive neck manipulation during intubation and surgery, coughing and bucking on tube and recent upper respiratory tract infection.

Long-term intubation can cause trauma, ulceration, healing with fibrotic scar tissue causing stenosis, granuloma and web formation. The incidence of laryngeal complications after prolonged intubation is between 4% and 13%. Benjamin has described several stages of injury and the resultant chronic laryngeal changes that may be seen after prolonged intubation.3 The earliest of these changes are non-specific hyperaemia and oedema due to mucosal irritation. Oedema within the submucosa in the subglottis at the level of the cricoid may increase slowly leading to delayed airway obstruction hours after the removal of the endotracheal tube.

V Narayan et al has reported a case of unilateral tongue, face and neck swelling after prolonged operation in lateral position with extreme neck flexion.4

We think the causes for prolonged laryngeal oedema in our case were prolonged posterior cranial fossa surgery and neck flexion in prone position.

Conclusion:

From the literature and our case report we conclude that following factors need to be kept in mind for post-operative laryngeal oedema -

Prolonged surgery

Prone position

Posterior cranial fossa surgery including resection of cerebellar tonsils

Hypothyroidism

Traumatic intubation

Extreme neck positioning during operation

Anaesthetist & surgeon need to interact to make decisions regarding whether extubation is appropriate and the location for postoperative observation.

References:

1. McAllister RG. Macroglossia: a positioning complication. Anesthesiology 1974; 40:199–200.

2. Sinha, Ajay; Agarwal, Anil; Gaur, Atul; Pandey, Chandra Kant. Journal of Neurosurgical Anesthesiology. 13(3):237-239, July 2001.

3. Benjamin B. Laryngeal trauma from intubation: endoscopic evaluation and classification. In: Cummings CW, et al., ed., Otolaryngology-Head&Neck Surgery, 3rd ed., St. Louis: Mosby, 1998:2013-35.

4. Bhadri Narayan, MD and G. S. Umamaheswara Rao, MD. Unilateral Facial and Neck Swelling After Infratentorial Surgery in the Lateral Position. Anesth Analg 1999;89:1290

No comments: