Morquio–Brailsford syndrome or mucopolysaccharidosis IV is an inborn error of metabolism in which an enzyme deficiency causes excessive storage of mucopolysaccharides in cartilage, soft tissue and bone.1 Airway management is challenging due to infiltration and altering of the oropharyngeal structures, vocal cords and trachea. Distinctive features include macroglossia, hypertrophic adenoids and tonsils, bulgy soft tissue prone to bleeding, tracheomalacia with position-dependent obstruction, sleep apnoea, deformity of joints with limited mouth opening, hypoplasia of the odontoid process causing atlanto-axial instability and cervical subluxation, skeletal dysplasia with a significant kyphoscoliosis and pectus carinatum. The accumulation of abnormal mucopolysaccharide in the coronary arteries, heart valves and myocardium is also seen leading to cardiomyopathy, myocardial ischaemia and valve dysfunction.2 Thoracic deformities result in restrictive pulmonary disease, reduced alveolar capacity and recurrent infections.3
Estimates of the incidence differ from one in 450 000 to as high as one in 10 000 live births.4 Life sustaining surgery and improved medical treatment has increased life expectancy and recommendations about prophylactic stabilising cervical fusion5 suggest that more patients will undergo general anaesthesia.
We obtained written consent from the patient to report this case. A 42-year-old woman with Morquio–Brailsford syndrome and progressive cervical instability was admitted to the Department of Neurosurgery for elective occipito-atlanto-axial fusion. Skeletal deformities were significant with a distinct kyphoscoliosis and a barrel-shaped thorax. Her height was 111 cm and weight 26 kg. Cervical instability caused the patient to depend largely on muscle tone in her neck to prevent atlanto-axial subluxation, with her head appearing loosely placed directly on the thorax without a neckline. Pulmonary function tests, ECG and echocardiography revealed no significant abnormalities. Blood tests and vital parameters were generally normal. MRI of the airway showed tracheal stenoses and multiple strictures with the lumen reduced to 4 mm in the narrowest part, located 4 cm below the laryngeal inlet (Fig. 1). The Mallampati score was four and cervical extension was impossible.
As the patient refused awake fibreoptic intubation, the planned technique was oral fibreoptic intubation after induction of general anaesthesia. A size 6.0 mm spiral tracheal tube was shortened using scissors and ensuring smooth edges so that 1 cm of the tube remained below the cuff. It was intended that the 1 cm of tube below the cuff would lie proximal to the strictures. To reduce airway resistance and because of increased ventilation pressure in the prone position, we did not use a narrower or an uncuffed tube.
After preoxygenation, anaesthesia was induced intravenously and surprisingly large doses of thiopental (10 mg kg−1) and remifentanil (1 μg kg−1) were required. Manual in-line stabilisation of the head was used. Mask ventilation was uncomplicated and neuromuscular blockade was induced with rocuronium (0.6 mg kg−1) with sugammadex immediately available as an emergency antidote. Maintaining in-line stabilisation, the fibrescope was inserted orally, but visualising the laryngeal inlet was impossible due to malformation of the oropharyngeal structures. Nasal intubation was performed easily and the tracheal tube was placed in the trachea proximal to the strictures. However, as visualising and verifying the position of tube was uncertain in this rather high position, and to prevent accidental extubation, it was decided to gently advance the tube further and the cuff passed unhindered through the strictures. Invasive blood pressure, additional intravenous access, a urinary catheter and a stomach tube were placed and a near infrared oximetry to monitor cerebral oxygen saturation was commenced. A four-point rigid head frame was fixed to the cranium and the patient was placed in the prone position, requiring additional support for the lower body due to the deformed thorax. Anaesthesia was maintained with sevoflurane and remifentanil and rocuronium for neuromuscular blockade was maintained at the surgeon's request due to the proximity of the spinal cord to the site of surgery. Surgery lasted 3 h and was uneventful. Hydrocortisone was administered to prevent tracheal and spinal cord oedema. The patient was kept sedated and intubated for 24 h in the ICU. She was then weaned off the ventilator and extubated over a tube-exchanger without complications. She returned to the ward and was discharged on the 9th postoperative day.
Patients with Morquio–Brailsford syndrome often undergo surgery – particularly heart valve replacement, occipito-atlanto-axial fusion, orthopaedic and ear-nose-throat procedures. Airway management is described mainly in paediatric cases.6 However, accumulation of mucopolysaccharides continues with age, particularly in the tracheal rings, thus further complicating airway management in adult patients. Tracheal intubation has been described by means of direct laryngoscopy, oral or nasal fibreoptic intubation and video-intubation laryngoscopy.7 No standardised recommendations exist and the choice of airway management and anaesthetic drugs seems to rely on case reports and personal opinion.
Maintaining spontaneous ventilation during induction would seem obvious. However, this carries the risk of inadequate respiration in an insufficiently anaesthetised patient, compromising manual ventilation at a critical point when intubation is not yet possible. Thus, we chose to induce anaesthesia intravenously, securing an adequate depth of anaesthesia in order to establish sufficient manual ventilation before intubation. Limited mouth opening and a small oropharyngeal cavity rendered the use of a laryngeal mask airway impossible. Some authors argue that neuromuscular blockade should be avoided in patients dependent on muscle tone to keep their airway open. Others argue for optimising the difficult conditions and ensuring relaxation of the infiltrated vocal cords as long as uncomplicated mask ventilation has been established. The pronounced macroglossia in our patient was an issue. The tongue occupied the hypopharynx (Mallampati IV) and neuromuscular blockade might cause it to fall backwards leading to further obstruction of the airway. Our inability to visualise the laryngeal inlet via the orally inserted fibrescope was due to the deformed anatomical structures and limited space. It is argued by some that nasal fibreoptic intubation is difficult due to adenoid hyperplasia and infiltration of the nasopharynx. However, in our case, there was no alternative and there were no complications. There was sufficient space to insert the fibrescope via the nasopharyngeal cavity without damaging the mucosa. A vasoconstrictor might have been used to prevent bleeding.
Both the intubation and surgery were high-risk procedures. Because of the patient's abnormal anatomy, there was no possibility of performing an emergency tracheostomy and, without cervical extension, there was no alternative to the use of the fibreoptic scope. In spite of thorough information, the patient refused awake intubation. Furthermore, she was a Jehovah's Witness and was informed of the increased risk as well as the immediate termination of surgery if there was excessive bleeding. In the light of her poor prognosis without surgery, she agreed to undergo the procedure.
In conclusion, different strategies have been described for airway management in patients with Morquio–Brailsford syndrome. Regardless of the technique chosen, meticulously planning is of paramount importance.
Assistance with the letter: none declared.
Financial support and sponsorship: none declared.
Conflicts of interest: none declared.
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