Sample Case Card · De-identified · Real case, identifiers removed
Laparoscopic cholecystectomy — patient with myotonic dystrophy type 1
42 yo M, DM1 (mild proximal weakness, no cardiac involvement on recent echo), elective lap chole. TIVA-based GA with sugammadex-reversible NMB, planned avoidance of volatiles given MH-like sensitivity reports.
Clinical Insights
Volatile-free TIVA with rocuronium reversed by sugammadex avoided prolonged weakness and myotonic crisis in a DM1 patient undergoing lap chole, with awake extubation only after sustained TOF and clinical strength.
Key Decisions
DM1 patients have reported MH-like reactions and prolonged weakness with volatiles; propofol provides predictable offset.
Avoids succinylcholine (myotonic contracture risk) and avoids neostigmine (can precipitate myotonia).
Cold and shivering are potent triggers for myotonic contracture.
Risk Drivers
DM1 carries progressive AV block risk — recent ECG and echo required; pads on if any conduction abnormality.
Baseline restrictive pattern, blunted CO2 response — high risk for delayed respiratory depression with opioids/benzos.
Increased aspiration risk; consider RSI and prokinetic prep.
Alternative Approaches
Reduces postoperative opioid need but adds time and not feasible for upper-abdominal laparoscopic exposure alone.
Hofmann elimination is reliable but no rapid reversal — sugammadex strategy preferred when available.
What To Watch For
- Delayed emergence and prolonged respiratory depression even with normal TOF.
- Shivering on emergence — pre-warm and consider low-dose meperidine cautiously.
- Postop monitored bed with continuous SpO2 and capnography for at least 24h.
Teaching Points
- Avoid succinylcholine in myotonic dystrophy — contracture, not malignant hyperthermia, is the issue.
- Sugammadex is preferred over neostigmine in DM1 — anticholinesterases can precipitate myotonia.
- Even mild DM1 patients can have severe perioperative respiratory and cardiac events disproportionate to baseline exam.
Oral-board Prompts
- 1.How would your plan change if this patient developed third-degree AV block intraoperatively?
- 2.Walk me through your extubation criteria in a DM1 patient.
- 3.What is the mechanism of myotonic contracture with succinylcholine, and why doesn't dantrolene treat it?
Reflect On
Consider preoperative pulmonology consult and baseline PFTs in any DM1 patient — would have changed PACU disposition planning.
References
- "Anesthetic management of patients with myotonic dystrophy" · BJA Education. Reviews volatile avoidance, NMB choice, and extubation criteria.
- "Sugammadex versus neostigmine in neuromuscular disorders" · Anesthesiology. Supports sugammadex preference in myotonic disorders.
Pearls
- 01Pre-warm aggressively. The OR is the most controllable variable.
- 02Sugammadex is not optional — verify availability before induction.
- 03Document a true sustained TOF + clinical strength check before extubation. Don't rely on TOF alone.