What Are the Anesthesia Risks for Patients With MPS I?

For individuals with Mucopolysaccharidosis type 1 (MPS I)—whether children with severe Hurler syndrome or adults with attenuated forms—receiving anesthesia for any procedure carries significant risks. It is never a “routine” process ^[1]. Because of the unique anatomical changes caused by the condition, anesthesia must be handled by experienced anesthesiologists at specialized medical centers equipped with an intensive care unit (ICU or PICU) ^[2]. While this can sound intimidating, with the right multidisciplinary team and careful preparation, these procedures are successfully and safely performed.

The Danger of Pre-operative Sedation

Before surgery, it is common for hospitals to give patients mild relaxing medications (sedation) in the holding area. However, for individuals with MPS I, pre-operative sedation carries a severe risk. Even mild sedatives can cause a sudden loss of muscle tone in the throat, leading to immediate airway collapse before the patient even reaches the operating room ^[1][3]. Routine pre-operative sedation should generally be avoided, or given only under the direct, immediate supervision of the anesthesiologist with emergency airway rescue equipment ready.

Why is Intubation So Difficult?

Due to the buildup of complex sugars (glycosaminoglycans) in tissues, individuals with MPS I have narrowed and thickened airways ^[4]. When an anesthesiologist places a breathing tube (intubation), they often encounter a dangerous “cannot intubate, cannot ventilate” scenario. Specific challenges include:

• Macroglossia: A larger-than-normal tongue takes up extra space in the mouth and throat, obstructing the view of the vocal cords ^[5].
• Enlarged tonsils and adenoids: These can physically block the airway ^[5].
• Jaw stiffness: Reduced flexibility in the jaw makes it hard to open the mouth wide, which is necessary for inserting a breathing tube ^[6].
• Tracheobronchial malacia: The cartilage rings that hold the windpipe open can become soft and floppy, leading to airway collapse even after a tube is successfully placed ^[7].

It is crucial to know that even if a patient is receiving enzyme replacement therapy (ERT) or has undergone a stem cell transplant (HSCT), these specific airway issues do not completely resolve and remain a lifelong risk ^[8][3].

The Risk of Neck Instability

Many individuals with MPS I have cervical spine instability, meaning the bones in their neck are loose or not formed correctly ^[9]. During normal anesthesia, doctors tilt the patient’s head backward to place a breathing tube. In someone with MPS I, tilting the head back can compress the spinal cord, potentially causing permanent neurological damage or paralysis ^[10].

Anesthesiologists must use specialized techniques to secure the airway. This includes keeping the neck completely still in a neutral position (manual in-line stabilization) and using a thin, flexible camera (fiberoptic intubation) to safely place the tube without moving the neck ^[10][11]. Before any surgery, dynamic X-rays (where the patient looks up and down) or MRI scans are often required to check the stability of the neck bones ^[12].

Heart Considerations

MPS I can cause the heart valves to become thick and stiff (valvular heart disease) and lead to other structural cardiac abnormalities ^[13][14]. A thorough evaluation by a cardiologist is essential before anesthesia to ensure the heart can handle the stress of being put to sleep and waking up, as cardiovascular complications can arise suddenly during surgery ^[1].

The Importance of Specialized Care and Emergency Preparedness

Because of this “perfect storm” of airway, skeletal, and heart issues, planned anesthesia should never be performed at an outpatient clinic or community hospital. It requires a multidisciplinary team at a specialized center ^[1][2]. These hospitals have access to advanced airway equipment and an Intensive Care Unit (ICU or PICU). Close monitoring in an ICU as the patient wakes up is critical. Removing the breathing tube (extubation) must only happen when the patient is completely awake and breathing strongly on their own, because there is a high risk of severe breathing problems—such as a dangerous fluid buildup in the lungs (negative pressure pulmonary edema)—immediately after the tube is removed ^[15][16].

For emergency situations where you cannot choose your hospital, it is highly recommended to wear a medical alert bracelet and carry an “Anesthesia Alert Letter” from your metabolic geneticist. This provides immediate, life-saving instructions to emergency room doctors about your specific airway and neck risks.