What are the anesthesia considerations for a patient with GNE (Glycogenosis Nonaka distal myopathy) myopathy undergoing surgery?

Anesthetic Management for GNE Myopathy

Avoid succinylcholine absolutely and use total intravenous anesthesia (TIVA) with propofol and short-acting opioids as the safest approach for patients with GNE myopathy, while maintaining vigilant perioperative respiratory monitoring.

Critical Drug Contraindications

Succinylcholine is absolutely contraindicated in all patients with myopathies, including GNE myopathy, due to the risk of acute rhabdomyolysis, hyperkalemia, and cardiac arrest. 1 This applies universally to myopathic conditions and is non-negotiable. 2, 3

• Volatile anesthetic agents (halothane, isoflurane, sevoflurane) should be avoided or used with extreme caution, as patients with myopathies have increased risk of rhabdomyolysis and anesthesia-related complications similar to other muscular dystrophies. 1, 3
• While the evidence specifically addresses other myopathies, the anesthetic implications of GNE myopathy do not differ from other myopathies in terms of drug sensitivities. 1

Recommended Anesthetic Technique

Total intravenous anesthesia (TIVA) using propofol with short-acting opioids (remifentanil or fentanyl) is the safest documented approach. 1, 4 This technique avoids triggering agents while providing adequate anesthesia depth.

• Regional anesthesia (spinal, epidural, peripheral nerve blocks) or local anesthesia should be strongly considered as first-line options when surgically appropriate. 1, 3
• If neuromuscular blocking agents are required, use non-depolarizing agents (such as rocuronium) at significantly reduced doses with careful neuromuscular monitoring. 1, 4 Patients with myopathies demonstrate increased sensitivity to these agents. 1

Preoperative Assessment and Optimization

Conduct a focused evaluation targeting cardiopulmonary function and muscle involvement:

• Measure forced vital capacity (FVC), maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP), and peak cough flow (PCF). 4 Patients with FVC <50% predicted require assisted ventilation during all phases of anesthesia. 1, 4
• Obtain cardiology consultation to assess for cardiomyopathy, as GNE myopathy can involve cardiac muscle. 4, 3
• Assess baseline respiratory function and secretion management capabilities, as these patients may have limited respiratory reserve. 1, 2
• Screen for history of rhabdomyolysis, which is more common in myopathic patients. 1

Intraoperative Monitoring

Standard monitoring must be enhanced with specific attention to neuromuscular and respiratory parameters:

• Continuous SpO₂ monitoring is mandatory throughout the procedure. 1, 4
• Monitor end-tidal or blood CO₂ levels continuously whenever possible. 1, 4
• Use objective neuromuscular monitoring if any neuromuscular blocking agents are administered. 4, 2, 3
• Monitor core temperature continuously to detect early signs of metabolic complications. 3

Respiratory Support Strategy

Patients with FVC <50% predicted should receive assisted or controlled ventilation during induction, maintenance, and recovery from anesthesia. 1, 4

• Consider extubation directly to non-invasive positive pressure ventilation (NPPV) for patients with baseline FVC <50% predicted or those using NPPV preoperatively. 1
• Delay extubation until respiratory secretions are well controlled and SpO₂ is at baseline in room air. 1
• Options for respiratory support include endotracheal intubation with planned NPPV transition, laryngeal mask airway, or mechanical ventilation via face mask. 1

Postoperative Management

Continue SpO₂ monitoring for a minimum of 24 hours postoperatively due to high risk of delayed respiratory compromise. 4, 2, 3

• Have ICU bed availability for postoperative care, particularly for patients with FVC <50% predicted or significant muscle weakness. 1, 4
• Monitor closely for respiratory insufficiency, as delayed muscle weakness can occur hours after anesthesia. 5
• Maintain vigilance for metabolic complications including rhabdomyolysis (check CK if clinically indicated). 2, 3

Anesthesia Workstation Preparation

If avoiding volatile agents completely (recommended approach):

• Remove vaporizers from the anesthetic workstation. 1
• Change the breathing circuit, reservoir bag, and CO₂ absorbent to uncontaminated equipment. 1
• Flush the circuit with oxygen at maximum flow for the workstation-specific time (typically 90 seconds minimum). 1
• Alternatively, use activated charcoal filters on inspiratory and expiratory limbs if rapid preparation is needed. 1

Common Pitfalls to Avoid

• Never assume GNE myopathy is "mild" based on ambulatory status alone—these patients can have significant respiratory muscle involvement that becomes apparent only under anesthetic stress. 2, 3
• Do not use standard dosing for neuromuscular blocking agents; always reduce doses significantly and monitor objectively. 1
• Avoid premature extubation before ensuring adequate respiratory muscle strength recovery and secretion clearance. 1
• Do not discharge patients with significant muscle involvement to unmonitored settings in the first 24 hours postoperatively. 4, 2