Anaesthetic considerations in Hurler syndrome (MPS I-H)
People with Hurler syndrome (severe MPS I) face a heightened risk of complications around sedation, anaesthesia, and recovery. Upper airway narrowing, cervical spine pathology, and cardio-respiratory involvement reduce physiological reserve, so even seemingly minor procedures can become high-risk without careful preparation.
This resource brings together key peri-anaesthetic considerations for clinicians, covering structured pre-assessment, airway and cervical spine protection, intra-operative planning, and post-anaesthetic care within a multidisciplinary framework.
Why anaesthesia is high risk in MPS I-H
Multiple organ systems are commonly affected, and these risks often coexist. As a result, any exposure to sedation or general anaesthesia should be approached as potentially high-risk and planned with senior anaesthetic input.
- Airway anatomy: enlarged tongue, adenotonsillar hypertrophy, thickened soft tissues, narrowed upper airway, and tracheobronchial involvement.
- Cervical spine and skeleton: atlanto-axial or cervical instability, kyphosis/gibbus, reduced neck mobility, and altered spinal canal dimensions.
- Cardio-respiratory disease: valve pathology, cardiomyopathy, pulmonary hypertension, restrictive/obstructive lung disease, sleep-disordered breathing.
- Reduced physiological reserve: limited tolerance of hypoxia, hypotension, and prolonged procedures.
- Frequent procedures: ENT, orthopaedic, dental, imaging, and transplant-related interventions.
Structured pre-operative evaluation
Purpose: identify risk early and plan the right setting, team, and monitoring.
History and examination
- Airway/ENT: snoring, noisy breathing, witnessed apnoea, prior difficult airway, previous airway imaging.
- Respiratory: baseline work of breathing, age-appropriate exercise tolerance, infections, home CPAP/BiPAP.
- Cardiac: known valve disease, cardiomyopathy, pulmonary hypertension, syncope; date/findings of last echo.
- Neurological/skeletal: neck pain, limb weakness, gait change, sphincter symptoms; deformity and positioning limits.
- General: previous anaesthetic records (airway difficulty, unplanned ICU), HSCT/ERT status, infection history.
Investigations (per local policy)
- Recent echocardiogram and ECG.
- Pulmonary assessment (sleep study, lung function where age-appropriate).
- Cervical spine imaging (X-ray and/or MRI) if instability or cord compression is suspected.
- Laboratory tests guided by procedure and comorbidity (e.g., FBC, coagulation, organ function).
Anticipating and managing a difficult airway
Most individuals with MPS I-H should be presumed to have a potentially difficult airway. Planning and airway management should involve a senior clinician with paediatric and difficult-airway expertise.
- Approach GA and deep sedation as difficult airway scenarios.
- Define primary and backup airway strategies appropriate to local expertise and policies.
- Where feasible, preserve spontaneous ventilation during airway instrumentation in high-risk cases.
- Minimise neck flexion/extension due to potential cervical instability.
- Prepare size-appropriate equipment and anticipate limited laryngeal views.
- Ensure immediate access to advanced airway tools and skilled assistance.
- Record airway findings clearly to inform future procedures.
Protecting the cervical spine
Cervical canal narrowing and atlanto-axial instability may be silent. Excessive neck movement risks spinal cord injury.
- Review any existing cervical imaging before procedures.
- If imaging is unavailable and concern is high, manage the neck as unstable and avoid extremes of movement.
- Position carefully for theatre or imaging with appropriate supports and padding.
- Communicate cervical precautions to the entire peri-procedural team.
Conduct of anaesthesia – general considerations
Apply within local protocols and formularies.
- Location and team: favour centres with paediatric complex-airway expertise and HDU/ICU access.
- Monitoring: standard monitoring at minimum; consider invasive or advanced monitoring for major cases.
- Ventilation: plan for restrictive/obstructive physiology and airway collapse tendencies.
- Haemodynamics: avoid sustained hypotension and tachyarrhythmia given limited reserve.
- Temperature/positioning: prevent hypothermia; protect joints, spine, and pressure points.
- Duration/complexity: where appropriate, combine necessary procedures while balancing total anaesthetic time.
Recovery and post-operative monitoring
Post-anaesthetic complications may include airway obstruction, respiratory compromise, cardiac decompensation, and delayed recovery.
- Post-op location: consider HDU/ICU or prolonged PACU for higher-risk cases.
- Airway/breathing: close observation for obstruction or hypoventilation, especially with OSA.
- Non-invasive support: early CPAP/BiPAP when part of baseline care and aligned with local practice.
- Analgesia: multimodal strategies with attention to respiratory status and organ function.
- Fluids/haemodynamics: continued monitoring in those with cardiac disease.
- Documentation: record airway difficulty, complications, and guidance for future anaesthetics.
Sedation versus general anaesthesia
Even minimal sedation can precipitate airway obstruction in MPS I-H. In higher-risk patients, a secured airway under GA may be safer than deep sedation.
- If sedation is used, ensure full monitoring and immediate access to skilled airway support.
- Avoid regimens that cannot be promptly reversed or escalated in the event of airway compromise.
- Have a clear plan to convert to GA if required, with appropriate backup available.
- Consider non-sedated imaging where feasible and combining procedures to reduce repeat sedations.
Emergency airway and anaesthetic risk outside theatre
- Call for senior help early; involve paediatric anaesthesia and/or intensive care where possible.
- Use structured difficult-airway responses adapted to anticipated anatomy.
- Prioritise oxygenation using techniques familiar to the responding team.
- Limit repeated attempts by inexperienced operators; escalate promptly to the most experienced clinician available.
- Where time allows, involve teams familiar with the patient and use any existing emergency summaries.
Anaesthesia in the wider treatment pathway
Peri-anaesthetic planning should be embedded within the overall care plan, particularly around HSCT and major orthopaedic or cardiac surgery.
- Align elective procedures with HSCT timing, conditioning, and engraftment phases.
- Coordinate with ERT schedules, especially for patients travelling long distances.
- Reassess surgical indications as cardio-respiratory or neurological risk evolves.
Making information visible across teams
- Maintain an up-to-date anaesthetic summary highlighting airway, cervical spine, cardiac/respiratory status, and prior complications.
- Use pre-operative checklists that explicitly flag MPS-specific risks.
- Ensure robust handover between theatre, ICU/HDU, wards, and community teams.
- Encourage families to keep copies of key letters for non-specialist settings.
Key anaesthetic messages for professionals
- Approach all sedation and anaesthesia in MPS I-H as higher-risk, especially for airway, cervical spine, and cardio-respiratory issues.
- Undertake structured pre-assessment and plan care in appropriately resourced centres.
- Anticipate a difficult airway, protect the cervical spine, and work closely with ENT, respiratory, cardiac, and metabolic teams.
- Plan enhanced recovery monitoring and early escalation for respiratory or haemodynamic instability.
- Use clear documentation and checklists so learning from one anaesthetic informs future care.
Emergency information
High-risk scenarios and practical notes
Multisystem management
Organ-specific care and MDT coordination
HSCT & ERT guidance
Indications, timing, and treatment roles
Multidisciplinary care
Clinic structure and surveillance
Clinical overview of Hurler syndrome
Pathophysiology, presentation, and natural history
Living with Hurler syndrome
Patient- and family-facing information