Anesthetic Consideration of Patient With Myotonic Dystrophy Type 1: A Case Report and Review of Literature

ABSTRACT

Myotonic dystrophy type 1 (DM1) presents significant anesthetic challenges. A 46‐year‐old woman with DM1 underwent emergent exploratory laparotomy. This case highlights the importance of conservative neuromuscular blocker dosing, quantitative neuromuscular monitoring, clinically‐guided timing of sugammadex administration, careful airway planning, and use of opioid‐sparing multimodal analgesia in a patient with DM1.

Key Clinical Message

Myotonic dystrophy type 1 requires individualized anesthetic management due to multisystem involvement and heightened sensitivity to anesthetic agents and neuromuscular blockers. Conservative dosing, quantitative neuromuscular monitoring, opioid‐sparing analgesia, and clinically guided timing of sugammadex administration are essential to minimize perioperative complications and ensure safe recovery.

1. Introduction

Myotonic dystrophy type 1 (DM1) is a progressive, multisystemic neuromuscular disorder characterized by myotonia, muscle weakness, cardiac arrhythmias, gastrointestinal dysfunction, and other complications. The pathogenesis of DM1 involves an RNA gain‐of‐function from a CTG trinucleotide repeat expansion in the 3′ untranslated region of the DMPK gene, leading to sequestration of MBNL proteins and disruption of RNA splicing [1, 2, 3].

Patients with DM1 experience increased sensitivity to anesthetic agents, muscle relaxants, and opioids, placing them at increased risk for perioperative complications such as cardiac arrhythmias, respiratory failure, residual neuromuscular blockade, and delayed recovery from anesthesia [4, 5, 6, 7]. Gastrointestinal dysmotility is also common in DM1, ranging from delayed gastric emptying to rare cases of intestinal pseudo‐obstruction [8].

In DM1 patients, the use of succinylcholine is contraindicated due to the risks of hyperkalemia and rhabdomyolysis [9, 10]. If neuromuscular blockade is necessary, nondepolarizing neuromuscular blockers (NDMB) are preferred, but quantitative neuromuscular monitoring is recommended for careful titration. Shorter‐acting agents, such as rocuronium or cisatracurium, are recommended due to the lower risk of prolonged neuromuscular blockade. For neuromuscular blockade reversal, neostigmine is not recommended in patients with myotonic dystrophy, as it may exacerbate myotonia. Instead, sugammadex offers a safer and more effective alternative in this patient population [11, 12]. In relation to analgesia, multimodal non‐opioids and applicable regional blocks are recommended due to the high risk of opioid‐induced respiratory depression, especially in patients with severe muscular impairment [13].

In this case, we describe the anesthetic management of a 46‐year‐old woman with DM1 and history of an acute sepsis‐induced cardiomyopathy with resolved reduced ejection fraction (HFrEF), who required emergent exploratory laparotomy due to possible bowel ischemia and/or perforation. Written informed consent and HIPAA authorization were obtained from the patient for case publication.

2. Case Presentation

2.1. Preoperative

The patient is a 46‐year‐old female (Height: 5′3″, Weight: 56.7 kg) with medical history including DM1, resolved acute HFrEF (Ejection Fraction 55%–60% at time of procedure), Gastroesophageal Reflux Disease (GERD), gastritis, chronic kidney disease, and a history of sigmoid colectomy for diverticulitis, prior bowel obstructions, who presented with 1 day of multiple episodes of vomiting and generalized abdominal pain. CT abdomen and pelvis with contrast revealed moderate gastric pneumatosis consistent with emphysematous gastritis/ischemia, portal venous gas, and a high‐grade small bowel obstruction with dilated loops measuring up to 5.5 cm. A multidisciplinary team recommended emergent diagnostic laparoscopy with possible conversion to exploratory laparotomy.

The patient presented as acutely ill‐appearing, with ongoing hemodynamic instability requiring frequent intensive interventions. Clinically, the patient was confused, experiencing severe generalized abdominal pain, nausea, and recurrent vomiting. Physical exam revealed a Mallampati class IV airway, retrognathia, mouth opening limited to 2 cm, thyromental distance < 3 fingerbreadths, short neck, and limited neck range of motion. Her exercise tolerance was less than 4 metabolic equivalents of task (METs).

Pertinent laboratory results included elevated white blood cell count at 12.5 × 10⁹/L, hyponatremia (133 mmol/L), hypokalemia (3.2 mmol/L), elevated blood urea nitrogen (33 mg/dL) with normal creatinine (0.70 mg/dL), and mildly elevated transaminases (Aspartate Aminotransferase [AST] 70 U/L, Alanine Aminotransferase [ALT] 65 U/L). Lactate was 2.01 mmol/L, and procalcitonin was elevated at 2.90 ng/mL. EKG demonstrated a normal sinus rhythm with left axis deviation, an incomplete right bundle branch block, and a T wave abnormality. Prior transthoracic echocardiogram demonstrated moderately reduced left ventricular systolic function with an estimated ejection fraction of 35%–40% and moderate diffuse hypokinesis.

2.2. Intraoperative

Upon arrival at the operating room, ASA standard monitors were applied along with arterial blood pressure monitoring and processed EEG monitoring (SedLine, Masimo, Irvine, CA, USA). The pre‐induction blood pressure was 111/94 mmHg, and the heart rate was 74 bpm. Rapid sequence intravenous induction anesthesia was performed with fentanyl 50 μg, lidocaine 80 mg, propofol 100 mg, etomidate 6 mg, and rocuronium 30 mg. Intubation was performed uneventfully with video laryngoscopy (GVL 3; Verathon Inc., Bothell, WA, USA).

Anesthesia was maintained with propofol titrated to SEDLine (Masimo, Irvine, CA) Patient State Index (PSI), with fentanyl administered for analgesia. After intubation, the patient was started on norepinephrine infusion to maintain blood pressure and titrated throughout the case. Acetaminophen IV was given for multimodal analgesia, and dexamethasone and ondansetron were administered for postoperative nausea and vomiting prophylaxis.

To monitor neuromuscular block, we performed continuous train‐of‐four (TOF) and post‐tetanic count (PTC) monitoring throughout the procedure. After we administered the single dose of rocuronium 30 mg at intubation, we did not give any additional neuromuscular blocking agents. TOF responses remained absent (0/4 twitches) when checked at 45, 60, and 90 min after administration of rocuronium. PTC was 0 at both 45 and 60 min and increased to 4 at 90 min after rocuronium administration.

At the time of surgical incision, an arterial blood gas was obtained to assess the patient's physiologic status. The results demonstrated a pH of 7.478, PaCO₂ of 39.5 mmHg, and a bicarbonate level of 29.3 mmol/L, consistent with a primary metabolic alkalosis. Base excess was +6, and arterial oxygen saturation was 100%, with a PaO₂ of 171 mmHg. Fentanyl 50 μg was also administered at incision for pain management.

Thirty‐three minutes after incision, the procedure was converted to an exploratory laparotomy. Intraoperative findings included diffusely dilated small bowel without adhesive disease, scar tissue, or obstructive bands. The bowel was examined from the ileocecal valve to the ligament of Treitz and revealed no gross pathologic abnormality. The postoperative diagnosis was diffusely dilated small bowel consistent with pseudo‐obstruction, with no evidence of gross intra‐abdominal pathology. The total case duration was 2 h and 13 min, and no additional neuromuscular blocking agents were given other than at intubation.

2.3. Postoperative

After the surgical procedure, the patient was transported to the intensive care unit (ICU) intubated. Sugammadex 200 mg was administered in the ICU 143 min after the induction dose of rocuronium due to prolonged neuromuscular blockade. Because train‐of‐four recovery remained incomplete, an additional 200 mg was given, resulting in complete return of neuromuscular function and adequate spontaneous ventilation.

Throughout the postoperative course, the patient remained hemodynamically stable without the need for vasopressor support. Multimodal pain management included acetaminophen 1000 mg every 8 h, lidocaine patch daily, methocarbamol 500 mg three times a day as needed, and gabapentin 100 mg three times a day. Following successful extubation, the patient was downgraded from the ICU to a step‐down unit for continued recovery. The patient was discharged from the hospital on POD 7 in stable condition.

3. Discussion

Anesthetic management of patients with myotonic dystrophy presents unique challenges due to delayed muscle relaxation that affects many organ systems, requiring a highly individualized approach to balance adequate surgical anesthesia while minimizing the risk of cardiopulmonary complications, opioid‐related respiratory depression, and heightened neuromuscular sensitivity to anesthetic agents, neuromuscular blockers, and opioids. Perioperative concerns in patients with DM1 and the corresponding anesthetic management strategies are summarized in Table 1.

TABLE 1.

Perioperative concerns in myotonic dystrophy type 1 and corresponding anesthetic management.

Complication/concern	Anesthetic intervention/management
Airway difficulty and high aspiration risk (pharyngeal weakness, limited mouth opening, delayed gastric emptying)	Rapid sequence induction Video laryngoscopy to optimize first‐pass success
Cardiac conduction abnormalities and reduced ejection fraction	Etomidate for hemodynamic stability during induction Propofol co‐administered to reduce etomidate‐induced myoclonus Invasive arterial monitoring
Contraindication to succinylcholine (risk of hyperkalemia, rhabdomyolysis)	Rocuronium used for neuromuscular blockade
Unpredictable response to nondepolarizing neuromuscular blockers	Reduced rocuronium dose (0.5 mg/kg) Continuous quantitative TOF and PTC monitoring
Unsafe reversal with neostigmine (exacerbates myotonia)	Sugammadex used for prolonged neuromuscular blockade reversal
Increased sensitivity to opioids and risk of respiratory depression	Limited fentanyl dosing Multimodal, opioid‐sparing analgesia: IV acetaminophen; postoperative acetaminophen, lidocaine patch, gabapentin, methocarbamol

Abbreviations: DM1, myotonic dystrophy type 1; IV, intravenous; TOF, train‐of‐four.

Given the increased risk of aspiration in DM1 due to pharyngeal and laryngeal muscle weakness, dysphagia, and delayed gastric emptying, we elected to perform rapid sequence induction [14]. We selected rocuronium as the neuromuscular blocking agent due to its intermediate duration of action, predictable pharmacokinetics, and the availability of sugammadex for reversal. Several published cases have also demonstrated the safe and effective use of rocuronium and sugammadex in DM1 [15, 16, 17, 18]. Although some reports describe successful anesthetic management in DM1 patients without the use of neuromuscular blockade, we determined that significant abdominal muscle relaxation would be required for this exploratory laparotomy to allow safe bowel handling and decrease the risk of organ injury [19]. For intubation, we selected video laryngoscopy due to the known anatomic challenges identified during preoperative evaluation. Video laryngoscopy is associated with improved first‐pass success and fewer intubation attempts, which is particularly important in DM1 patients to minimize the risk of triggering a myotonic crisis or respiratory compromise [20].

DM1 is associated with cardiac conduction abnormalities and sudden cardiac death. Given this patient's DM1 and reduced ejection fraction (EF), we chose to use etomidate in combination with propofol for induction. We selected etomidate for its hemodynamic stability and minimal cardiovascular depression, while propofol was co‐administered to mitigate the risk of etomidate‐induced myoclonus [21, 22]. An arterial line was placed for real‐time blood pressure monitoring and arterial blood gas sampling for rapid detection and management of hemodynamic instability or electrolyte abnormalities.

Patients with DM1 may exhibit heightened and unpredictable sensitivity to nondepolarizing neuromuscular blockers, placing them at risk for prolonged paralysis even after reduced induction doses [17, 23, 24, 25]. In this case, we administered a lower‐than‐standard induction dose of rocuronium (approximately 0.5 mg/kg), which resulted in deep neuromuscular blockade lasting over 2 h despite no additional dosing. Continuous quantitative monitoring demonstrated absent TOF responses at 45, 60, and 90 min, with gradual recovery of PTC to 4 by 90 min, highlighting the prolonged and variable duration of blockade in this patient population. This case adds to existing reports demonstrating variability in the duration and depth of neuromuscular blockade following rocuronium administration, even at reduced doses. Reports describe persistent absence of train‐of‐four responses 45–60 min after doses ranging from 0.7 to 1.0 mg/kg, as well as delayed recovery following lower doses near 0.4 mg/kg [17, 23, 24, 25]. These findings highlight the importance of quantitative neuromuscular monitoring and individualized clinical assessment when managing neuromuscular blockade and reversal in this population. Although sugammadex is frequently administered intraoperatively in patients with DM1, there are no established guidelines regarding the optimal timing or setting for reversal.

DM1 patients are also highly sensitive to the respiratory depressant effects of opioids [13, 26]. Intraoperatively, we limited the total fentanyl dose to 100 μg and optimized analgesia with non‐opioid IV acetaminophen. Postoperatively, opioid use was not required. Multimodal analgesia consisted of acetaminophen, lidocaine patch, gabapentin, and methocarbamol.

Gastrointestinal involvement is common in DM1 and is primarily attributed to smooth muscle damage and possible abnormalities of the enteric neural pathways [8]. Common symptoms include dysphagia, reflux, and constipation, and in rare cases, intestinal pseudo‐obstruction. When not recognized promptly, intestinal pseudo‐obstruction can progress to bowel ischemia or perforation. Although most cases respond well to conservative measures, pseudo‐obstruction can present emergently and mimic surgical emergencies, creating diagnostic and anesthetic challenges.

In this case, the patient's CT findings of gastric pneumatosis and portal venous gas raised concern for ischemia or perforation, and pseudo‐obstruction was not initially suspected. The multidisciplinary team determined that urgent operative exploration was needed to exclude life‐threatening pathology. Only after surgical inspection and confirmation of the absence of mechanical obstruction or ischemic injury was the diagnosis of diffuse small‐bowel pseudo‐obstruction established. Importantly, gastrointestinal dysmotility in DM1 patients can be worsened by opioids, anticholinergic agents, and electrolyte abnormalities such as hypokalemia and hyponatremia [27]. This unanticipated finding highlights the extent of gastrointestinal involvement in DM1 and underscores the importance of minimizing medications that impair gastrointestinal motility and optimizing fluid and electrolyte status perioperatively.

This patient had mildly elevated transaminases preoperatively. Elevated liver enzymes are a common finding in DM1 [28]. Although overt liver failure is uncommon in DM1 patients, elevated transaminases may reflect subclinical hepatic involvement [29]. The clinical significance of these abnormalities remains uncertain, but they may serve as early indicators of potential organ dysfunction. Although the elevations in this patient did not alter anesthetic management, recognizing these findings is important when selecting medications that depend on hepatic metabolism.

4. Conclusion

This case highlights the importance of individualized anesthetic planning in patients with myotonic dystrophy type 1 undergoing emergent surgery. In addition to airway management, conservative neuromuscular blocker dosing, and opioid‐sparing analgesia, this case emphasizes clinically guided timing of sugammadex administration rather than routine intraoperative reversal. Prolonged and variable duration of neuromuscular blockade can occur in DM1 patients even at reduced rocuronium doses, reinforcing the importance of quantitative neuromuscular monitoring. The intraoperative finding of small‐bowel pseudo‐obstruction further highlights the multisystem involvement of myotonic dystrophy and the challenges these patients present.

Author Contributions

Yun Chin Lin: conceptualization, data curation, investigation, methodology, visualization, writing – original draft, writing – review and editing. Sallie Canumay: conceptualization, methodology, writing – review and editing, visualization, project administration. Leonard Soloniuk: conceptualization, investigation, writing – review and editing, methodology, visualization, resources, project administration, supervision. Benjamin Kuo: conceptualization, investigation, writing – review and editing. Wendy Hitt: conceptualization, methodology, investigation, writing – review and editing. Ioana Pasca: conceptualization, methodology, investigation, visualization, writing – review and editing, project administration, resources, supervision. Juan Liuzzi Stamerra: conceptualization, investigation, writing – review and editing. Blake Han: conceptualization, methodology, visualization, writing – review and editing, project administration.

Funding

The authors have nothing to report.

Ethics Statement

Our institution does not require ethical approval for reporting individual cases or case series.

Consent

Written informed consent was obtained from the patient for their anonymized information to be published in this article.

Conflicts of Interests

The authors declare no conflicts of interest.

Data Availability Statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.