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Hunter, disease or syndrome
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(Mucopolysaccharidosis type II) Rare: 0.3 to 0.7/100,000. Deficiency in iduronate-2-sulfatase in lysosomes. Transmission of a mutation of the I2S gene on Xq27-28 but some female (severe) cases have been described. Normal phenotype at birth.
- severe form (IIA): phenotype similar to Hurler disease but without corneal opacities; it appears between 2 and 4 year of age
- crude form (IIB): clinical manifestations appear in childhood or early adolescence. Slower progression; no mental retardation.
In summary:
- coarse facies from 3 years
- respiratory tract: macroglossia, hypertophied tonsils and adenoids, chronic rhinorrhea, narrow trachea, sometimes tracheomalacia; gradual onset of a restrictive pulmonary syndrome
- first conductive and later sensory deafness
- umbilical and inguinal hernias
- heart: thickening and sclerosis of the mitral and aortic valves in childhood: stenosis and/or regurgitation
- painful and destructive arthritis: deformation of the hands, hips, carpus and stenosis of the spinal canal in the neck by thickening of the cervical dura mater (risk of myelopathy)
- hepatosplenomegaly
- episodes of watery diarrhea
- decrease in growth from 3-4 years
- beaded and papular rash at the level of the shoulder blades
- severe form: often aggressive and hyperactive behavior
Substitutive enzyme therapy with recombinant iduronate-2-sulfatase (0. 5 g/kg weekly IV) is available and effective if started early.
Bone marrow or stem cell transplantation does not improve the course of the disease and is not proposed anymore .
Anesthetic implications:
difficult intubation and narrow cervical canal with stiffness of the cervical spine. Obstructive sleep apnea. Recent echocardiography: valvular function ? Progressive coronary stenosis by thickening of the intima. Technique of intubation: inhalation induction, laryngeal mask and use of the laryngeal mask as a conduit for intubation with a fiberscope. There is still a risk of intubation failure. Emergence of anesthesa: risk of obstruction of the airways and of low pressure pulmonary edema.
Risk of tracheal stenosis and/or tracheomalacia: an endotracheal tube of a diameter smaller than estimated for the child's age should be preferred. Enzymatic treatment does not improve the intubation conditions because it is, at present, usually started after the age of 2 years.
An airway assessment score has been developed for adolescent and adult (even treated) patients with mucopolysaccharidosis: the Salford score (table). It comprises 15 parameters graded from 0 to 3. Parameters 1-6 are based on clinical examination, 7-10 on nasal endoscopy, 11-13 on chest CT and 14-15 on respiratory function tests (if feasible).
A total score of 0-15 indicates minor, 15-30 moderate and 30-45 severe involvement of the airways. A score of ≥ 25 means that difficult airway management should be considered.
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Nr |
parameter |
measures |
score |
|
1 |
mouth opening |
> 5 cm 4-5 3-4 < 3 |
0 1 2 3 |
|
2 |
teeth protrusion (profile) |
none minor moderate severe |
0 1 2 3 |
|
3 |
mobility /stability
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non limited 60-90° flexion 30-60° flexion < 30° or instable |
0
|
|
4 |
tongue bulkiness |
normal light (< 1/3 of the floor) moderate (1/3 to ½ of the oral cavity) severe (> 1/2 of the oral cavity) |
0 1 2 3 |
|
5 |
Mallampati score |
1 2 3
|
0
|
|
6 |
Thyromental distance |
> 6 cm 5-6 4-5 < 4 |
0 1
|
|
7 |
larynx height - epiglottis/ soft palate |
> 4 cm 3-4 2-3 < 2 |
0
|
|
8 |
epiglottic bulkiness |
normal (filling < 1/3 of the oropharynx) mild (1/3 to ½ of the oropharynx) moderate (1/2 of the oropharynx) severe (filling the entire oropharynx) |
0
|
|
9 |
supra-glottis bulkiness |
normal (filling < 1/3 of the laryngopharynx) mild (1/3 to ½ ) moderate (1/2 ) severe (filling the entire laryngopharynx) |
0 1
|
|
10 |
glottis bulkiness |
normal (filling < 1/3 of the glottis) mild (1/3 to ½ ) moderate (1/2 ) severe (filling the entire glottis) |
0
|
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11 |
sub-glottis or cricoid diameter |
> 7 mm 6-7 5-6 > 5 |
0
2 3 |
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12 |
tracheomalacia
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no stenosis decrease of 50-75 % decrease of 75-99 % complete obstruction |
0
|
|
13 |
Tracheal tortuosity |
none present |
0 3 |
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14 |
Expiratory volume max 1 sec |
> 80 % 60-79 40-59 < 40 |
0 1 2 3 |
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15 |
Vital capacity |
> 80 % 60-79 40-59 < 40 |
0 1 2 3 |
Epidural block is usually difficult to perform (vertebral malformations) and carries an increased risk of complications (narrow spinal canal).
Given the risk of neurological complications even after surgery that does not involve the spine, it is useful to rely on the intraoperative monitoring of the evoked sensory and the motor potentials:
- in case of kyphosis > 60° and an estimated surgical duration of > 60 min
- in case of kyphosis < 60° and an estimated surgical duration of > 90 min
The basic values must be established with the patient supine and then in the position needed for surgery. Any change in amplitude > 50 % and/or increase in latency > 10 % of the evoked sensory potential, or any change in the polyphasic aspect of the evoked motor potentials must lead to a therapeutic reaction: check the BP, the depth of anesthesia, the hemoglobin level, the temperature, the position of the patient.
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EXPERT CONSENSUS for MANAGEMENT:
Surgical morbi-mortality is higher than in the normal population and the risk of anesthetic complications is very high: these patients must therefore be managed in facilities where care of those complications can be taken. It is why : - a full neurological examination is necessary before general or locoregional anesthesia - imaging (MRI or CTscan) of the full spine is recommended - a flexion/extension MRI of the cervical spine is necessary if there is any concern about its stability - polysomnography, respiratory functional tests (restrictive or obstructive syndrome) and cardiac evaluation (echocardiography) must be considered before an anesthesia - morphological and functional anomalies of the upper airway, a decrease in mobility of the cervical spine and bronchial airway anomalies increase the morbidity and mortality of anesthesia - a sedative premedication can be administered before anesthesia - for intubation, a videolaryngoscope and a intubating fiberscope must be immediately available - tracheostomy can be extremely difficult in those patients, particularly in emergency; it is crucial to identify the position of the cricothyroid membrane (XRays, echography) before anesthesia - extubation must be preferably done in the operating room; if this may not be the case, an experienced team must be present - in patients in whom a fragility of the spinal cord is suspected (concept of spinal cord at risk : significant cyphosis, risk of hypotension, long lasting surgery, difficult surgical positioning), neurological monitoring must be done during the whole procedure, and it is better to avoid epidural anesthesia Reference:
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References :
- Hishitani T, Wakita S, Isoda T, Katori T, Ishizawa A.
Sudden death in Hunter syndrome caused by complete atrioventricular block.
J Pediatr 2000; 136; 268-9.
- Wraith JE, Scarpa M, Beck M, Bodamer OA, De Meirleir L, Guffon N, Lund AM, Malm G, Van der Ploeg AT, Zeman J.
Mucopolysaccharidosis type II (Hunter syndrome): a clinical review and recommendations for treatment in the era of enzyme replacement therapy.
Eur J Pediatr 2008; 167: 267-77.
- Walker RWM.
The laryngeal mask airway in the difficult paediatric airway: an assessment of positioning and use in fiberoptic intubation.
Paediatr Anaesth 2000; 10: 53-8.
- Gross ER, Lemmens HJM.
Hunter syndrome in an adult : beware of tracheal stenosis (letter).
Anesth Analg 2010 ; 110 ; 642-3.
- Frawley G, Fuenzalida D, Donath S, Yaplito-Lee J, Peters H.
A retrospective audit of anesthetic techniques and complications in children with mucopolysaccharidoses.
Pediatr Anesth 2012; 22: 737-44.
- Kumar KR, Kumar H, Baidya DK, Arora MK..
Successful use of spinal anesthesia for inguinal hernia repair in a child with Hunter syndrome with difficult airway.
J Clin Anesth 2016; 30: 99-100.
- Kloesel B, Holzman RS.
Anesthetic management of patients with inborn errors of metabolism.
Anesth Analg 2017; 127: 822-36
- Kandil AI, Pettit CS, Berry LN, Busso VO, Raeskey M et al.
Tertiary pediatric academic institution’s experience with intraoperative neuromonitoring for nonspinal surgery in children with mucopolysaccharidosis based on a novel evidence-based care algorithm.
Anesth Analg 2020; 130: 1678-84.
- Gadepalli C, Stepien KM, Sharma R, Jovanovic A, Tol G, Bentley A.
Airway abnormalities in adult mucopolysaccharidosis and development of Salford mucopolysaccharidosis airway score.
J Clin Med 2021;10: 3275. doi.org/10.3390/jcm10153275
Updated: February 2024