What anesthesia approach is recommended for patients with myotonic dystrophy?

Anesthetic Management for Myotonic Dystrophy

Use total intravenous anesthesia (TIVA) with propofol and short-acting opioids (remifentanil or fentanyl), avoid succinylcholine completely, and use volatile anesthetics with extreme caution or not at all. 1, 2

Critical Drug Contraindications and Cautions

Absolute Contraindication: Succinylcholine

• Succinylcholine is contraindicated due to risk of acute rhabdomyolysis, massive potassium release, and hyperkalemic cardiac arrest, similar to Duchenne muscular dystrophy 1
• Cardiac arrest can occur immediately after injection, even in previously undiagnosed cases 1

Volatile Anesthetics: Use with Extreme Caution

• While patients with myotonic dystrophy type 2 (DM2) tolerated volatile anesthetics without obvious complications in one series 3, the safer approach is to avoid them given the risk profile similar to other muscular dystrophies 4, 1
• If volatile agents must be used, prepare the anesthetic workstation by removing vaporizers, changing breathing circuits, and flushing with oxygen at maximum flow 4
• Maintain trigger-free anesthesia whenever possible to minimize risk 4

Recommended Anesthetic Technique

Primary Approach: Total Intravenous Anesthesia (TIVA)

• Induction and maintenance with propofol infusion plus remifentanil or fentanyl is the safest documented approach 1, 5, 2
• Multiple case series demonstrate smooth, quick recovery with this combination without respiratory complications 2
• One case report successfully used propofol, remifentanil, and rocuronium with epidural anesthesia, achieving fast recovery without respiratory depression or muscle spasm 5

Muscle Relaxation Strategy

• Non-depolarizing agents (rocuronium, atracurium) can be used cautiously with careful neuromuscular monitoring 1, 5, 2
• Use minimal dosing: start with 5 mg rocuronium and titrate while monitoring train-of-four (TOF) ratio continuously 5
• Expect normal response to non-depolarizing relaxants and neostigmine in DM2 patients 3
• Recovery of TOF ratio to 80% may take 90 minutes; avoid supplemental doses if surgery permits 5

Regional Anesthesia Consideration

• Regional or local anesthesia is preferred when feasible to avoid general anesthesia complications entirely 4, 6
• Combined epidural-general anesthesia has been used successfully, reducing opioid and anesthetic requirements 5, 7

Essential Perioperative Monitoring

Respiratory Monitoring

• Continuous SpO₂ monitoring intraoperatively and for minimum 24 hours postoperatively 1, 8
• Monitor blood or end-tidal CO₂ levels continuously during the procedure 4, 1
• Use supplemental oxygen cautiously as it can mask hypoventilation 1, 8

Neuromuscular Monitoring

• Continuous train-of-four monitoring is mandatory when using muscle relaxants 5
• Watch for prolonged effects of neuromuscular blockers despite normal responses 5

Critical Preoperative Assessment

Pulmonary Evaluation

• Measure forced vital capacity (FVC), maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP), and peak cough flow (PCF) 1
• Patients with FVC <50% predicted require assisted ventilation during all phases of anesthesia 1
• Consider preoperative training in noninvasive positive pressure ventilation (NPPV) for high-risk patients 4

Cardiac Evaluation

• Mandatory cardiology consultation before any anesthetic as myotonic dystrophy causes cardiomyopathy and conduction abnormalities 1, 7
• Assess for autonomic dysfunction-related cardiac abnormalities 8

Postoperative Management and Disposition

Monitoring Duration

• Continue SpO₂ monitoring for at least 24 hours postoperatively 1, 8
• Have ICU bed available for postoperative care, especially for patients with FVC <50% predicted 1
• Delayed respiratory or neurological complications can occur up to 24-48 hours postoperatively 8

Respiratory Support

• Patients with baseline FVC <50% should continue NPPV postoperatively 1
• Despite one case report of same-day discharge after robotic hysterectomy 6, this should not be routine practice given the high risk of delayed complications

Common Pitfalls to Avoid

• Do not use shivering or hypothermia prevention carelessly: mechanical or electrical stimulation can precipitate myotonia that is difficult to abolish 6
• Avoid excessive sedation: patients show extreme sensitivity to sedatives, opioids, and anesthetic agents 6
• Do not assume DM2 is identical to DM1: while DM2 patients showed normal responses to standard anesthetics in one series 3, err on the side of caution and follow DM1 precautions
• Never discharge early without extended monitoring: postoperative respiratory depression is a major risk even with smooth initial recovery 2, 6