Anesthesia and myotonic dystrophy type 2: a case series
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Myotonic dystrophy type 2 (DM2) is a genetically distinct disorder that shares some phenotypical features of myotonic dystrophy type 1 (DM1). However, anesthetic management of patients with DM2 has not been described. The purpose of this study is to report the anesthetic management of a series of patients with DM2 and to describe their response to anesthesia.
We performed a computerized search of the Mayo Clinic medical records database looking for patients with DM2 who underwent general anesthesia. The medical records were reviewed for anesthetic technique, medications used, and postoperative complications.
We identified 19 patients with DM2 who underwent 39 general anesthetics, 17 monitored anesthetic care cases, and two regional anesthetics. The patients exhibited normal responses to succinylcholine, nondepolarizing neuromuscular blockers, neostigmine, induction agents, and volatile anesthetics. Serious postoperative complications related to DM2 did not occur.
In our series, patients with DM2 tolerated commonly used anesthetics without obvious complications, and they exhibited normal responses to muscle relaxants. These observations suggest that these medications may be used safely in patients with DM2.
Anesthésie et dystrophie myotonique de type 2: une série de cas
La dystrophie myotonique de type 2 (DM2) est un trouble génétiquement distinct qui partage certaines caractéristiques phénotypiques avec la dystrophie myotonique de type 1 (DM1). La prise en charge pour l’anesthésie de patients souffrant de DM2 n’a cependant pas été décrite. L’objectif de cette étude est de rendre compte de la prise en charge pour l’anesthésie d’une série de patients souffrant de DM2 et de décrire leur réponse à l’anesthésie.
Nous avons réalisé une recherche informatisée dans la base de données des dossiers médicaux de la Clinique Mayo pour identifier les patients souffrant de DM2 et ayant subi une anesthésie générale. Les dossiers médicaux de ces patients ont été révisés et l’on a noté la technique anesthésique et les médicaments utilisés ainsi que les complications postopératoires.
Nous avons identifié 19 patients souffrant de DM2 et ayant subi 39 anesthésies générales, 17 cas de sédation consciente, et deux cas d’anesthésie régionale. Des réponses normales à la succinylcholine, aux curares non dépolarisants, à la néostigmine, aux agents d’induction et aux agents anesthésiques volatils ont été observées chez ces patients. Il n’y a pas eu de complications postopératoires graves associées à la DM2.
Dans notre série de cas, les patients souffrant de DM2 ont toléré les anesthésiques fréquemment utilisés sans complication évidente et ont montré des réponses normales aux curares. Ces observations suggèrent que ces médicaments peuvent être utilisés de façon sécuritaire chez des patients souffrant de DM2.
Myotonic dystrophy type 2 (DM2) is a rare autosomal-dominant multisystem disorder characterized by proximal muscle weakness, myotonia, precocious cataracts, muscle pain, and muscle stiffness.1,2 Though it shares some phenotypical features of classic or type 1 myotonic dystrophy (DM1), it is a genetically distinct disorder and recognized as a separate entity.1, 2, 3, 4, 5, 6 Anesthetic management of patients with DM2 has not been described, and it is unknown if these patients may have similar abnormal responses to anesthetic agents as do patients with DM1, for example, myotonic responses to succinylcholine,7, 8, 9, 10 increased sensitivity to nondepolarizing muscle relaxants,3 myotonic responses to neostigmine,3 or increased sensitivity to anesthetic agents.11, 12, 13, 14 To determine if patients with DM2 have similar atypical responses to anesthesia, we used the Mayo Clinic medical records database to identify patients with DM2 who underwent anesthesia, and we reviewed their anesthetic course.
After obtaining Mayo Clinic, Rochester, Minnesota, Institutional Review Board approval, a manual and computerized search of the Mayo Clinic Rochester medical records database from 2000 through 2008 was conducted to identify patients who were diagnosed with DM2 by Mayo clinic neurologists and who underwent anesthetic care at Mayo Clinic, Rochester, Minnesota. The medical records of these patients were then reviewed to determine if they had received anesthetic care. The anesthetic records were reviewed by one of the authors (R.E.H.); data were entered into a standardized data collection form, and all questionable entries were discussed with the senior author (T.N.W.). We reviewed demographics (age, gender), anesthetic techniques, responses to neuromuscular blocking agents and neostigmine, hemodynamic variability (blood pressure and/or heart rate episodes above or below 30% measured before anesthesia induction), hemodynamic instability (need for any pressor/chronotropic drugs), the occurrence of significant arrhythmias (new onset atrial fibrillation/flutter, tachycardias, complete heart block, etc.), and intraoperative body temperature. We also reviewed the records of the postoperative period for signs of delayed anesthetic recovery, myotonia, residual muscle weakness, need for prolonged ventilatory support or tracheal reintubation, and any note of postoperative respiratory or other complications. Only descriptive statistics were used.
Demographic and other characteristics of patients with DM2
Age at surgery (yr)*
56 (41, 60)
Duration of symptoms (yr)*
3 (1, 11)
Otolaryngological and oral procedures
Associated co-morbid conditions (n)
Heart conduction abnormalities
Prior aspiration pneumonia
All adult patients were assigned ASA physical status II or III. Seventeen of the adult patients had proximal muscle weakness, and in seven of these patients, the weakness was moderate. Eleven patients had mild clinical signs of myotonia, and in five of these patients, myotonia was moderate. Two of the patients with moderate myotonia and weakness also had flaccid dysarthria, while another patient with moderate myotonia had a history of aspiration pneumonia. Only one patient had decreased left ventricular function with an ejection fraction of 25%, but rather than DM2-associated cardiomyopathy, this decreased function was attributed primarily to the presence of significant coronary artery disease and prior chemotherapy to treat non-Hodgkin’s lymphoma. Five patients (26.3%) had abnormal conduction patterns on their electrocardiograms: one chronic atrial fibrillation, two right bundle branch blocks, one non-specific intraventricular conduction delay, and one left anterior fascicular block. Four patients (21%) in this series had diabetes mellitus. Cognitive function, as assessed clinically by a Mayo clinic neurologist, was fully preserved in 16 adult patients and they all lived independently. One patient, a 60-yr-old female with co-morbid Parkinson’s disease, had severe psychiatric disorders requiring electroconvulsive therapy and nursing home care. Cataracts were common (n = 9, 47.4%).
Surgical and anesthetic characteristics of patients with myotonic dystrophy type 2 undergoing anesthesia
Age @ surgery
Age @ diagnosis
Type of surgery
Anesthetic duration (min)
Induction agent, dose (GA only)
SUX use, dose (mg)
NDMR type, dose (mg)
Neostigmine use, dose (mg)
Maintenance agent, dose (% or mcg·kg−1·min−1)
PACU stay duration (min)
1. P, 200
1. Vec, 8
1. Not used
1. Sev, 2.3
2. P, 150
2. Vec, 5
2. Des, 6.0
4. P, 180
4. Roc, 7
4. Not used
4. P, 120
5. P, 200
5. Cis, 12
5. P, 100, Sev, 0.8
1. P, 200
1. Miv, 6
1. Not used
1. Iso, 1.0
2. P, 70
2. Vec, 5
2. Sev, 1.3
3. P, 120
3. Sev, 1.2
4, all cases
1. P, 200
1. Vec, 8
1. Iso, 1.2
2. P, 140
2. Vec, 14
2. Not used
2. Iso, 0.7
1. P, 200
1. Vec, 5
1. Not used
1. P, 25
4. P, 200
4. Iso, 1.1
1. P, 10
2. STP, 300
2. Cis, 26
2. Not used
2. Iso, 0.5
P, 40 mg bolus
1. STP, 150
1. Roc, 25
1. Sev, 2.9
2. P, 90
2. Ata, 2
2. Not used
2. Iso, 1.5
4. P, 30
5. P, 50
5. Sev, 2.2
7. P, 10
9. Sev, 2.6
The ten-yr-old female presented for surgical management of a ruptured appendix that required general anesthesia for two exploratory laparotomies as well as seven radiologic procedures, i.e., sonogram, requiring monitored anesthesia care. The patient had normal responses to anesthesia care, including the administration of propofol for induction, rocuronium and atracurium for muscle relaxation, and reversal with neostigmine. She developed postoperative hyperglycemia (484 mg·dL−1) and was subsequently diagnosed as having diabetes mellitus type 1. Her plasma insulin level was low normal (4.4 UIU·mL−1; range 1.4–14 UIU·mL−1), which suggested that her diabetes was due to low insulin production rather than insulin resistance. From her evaluation for hyperglycemia, it was learned that she had a family history of “mild” myotonic dystrophy. She underwent genetic testing and was found to have DM2. However, save for her diabetes, she was asymptomatic for DM2.
Comparison of characteristics between DM1 and DM2
DMPK (Protein kinase)
ZNF9 (Zinc finger protein 9)
birth, childhood, or adult onset
Congenital form: mental retardation25
Posterior subcapsular iridescent cataracts common
Posterior subcapsular iridescent cataracts common2
Diabetes (Insulin Resistance)
Mild to severe
Mild to moderate
Distal > Proximal
Proximal > Distal
Less prominent or absent
Elevated creatine kinase
Responses to Anesthetic Medications
Inadequate reversal and myotonic reactions3
Our DM2 patients tolerated commonly used anesthetic medications satisfactorily and exhibited normal response to a variety of muscle relaxants, including succinylcholine and several nondepolarizing relaxants. Also, reversing the effects of muscle relaxants with neostigmine was uneventful. With the exception of the ten-yr-old female developing hyperglycemia, our patients’ intraoperative and postoperative periods were unremarkable. The cases where recovery room stay was prolonged were the result of factors other than excessive sensitivity to anesthesia. From our limited series, it appears that these medications are tolerated well in patients with DM2 and, thus, may be used safely. This is in contrast to patients with classic DM1 where various adverse effects due to muscular and extramuscular involvement were reported, including an exaggerated response to sodium pentothal11,14 and propofol,12,13 a myotonic reaction to succinylcholine,7, 8, 9, 10 unpredictable and inadequate muscle relaxant reversal, increased muscle weakness and myotonia to neostigmine,3 and prolonged apnea following sodium pentothal.14
Diabetes mellitus is common in DM2 and is a result of altered insulin receptors on skeletal muscle that contribute to insulin resistance in this disorder.16 In our series, diabetes mellitus was present in four adult patients. There were no clinically significant elevated plasma glucose levels among non-diabetic adult patients in this series; however, perioperative glucose levels were not obtained consistently, and hyperglycemia may have been unrecognized in these cases. The manifestation of diabetes in the ten-yr-old female in the postoperative period may have been coincidental, as she had low levels of plasma insulin, which suggests her diabetes was not secondary to insulin resistance. Regardless, because of the propensity of these patients to have insulin resistance, anesthesiologists should monitor glucose levels closely during the perioperative period.
Cardiac involvement appears to be more benign in DM2 patients compared with DM1 patients, although a case of severe cardiomyopathy has been reported.17 The most frequent cardiac symptoms in DM2 patients are palpitation, intermittent tachycardia, and syncopal spells.2 Conduction abnormalities and intraventricular and atrioventricular blocks were also described,2 and were present in five of our patients. It is well established that sudden death can occur as a consequence of cardiac-conduction abnormalities in the DM1 patients.18 However, it is not known whether the same risk applies to DM2 patients. In one series of 297 DM2 patients, sudden death occurred in four patients. Three of the patients had no prior cardiac symptomatology, and one patient had a history of heart failure.19 Cardiac histopathology showed dilated cardiomyopathy in all four patients and conduction system fibrosis in two patients with pathogenetic DM2-specific ribonuclear inclusions demonstrable in cardiomyocytes.19 In DM2 patients without overt cardiac disease, magnetic resonance spectroscopy of the left ventricular myocardium has found evidence of the existence of subclinical cardiomyopathy.20 In our series, only one patient had clinically significant cardiomyopathy, which was attributed to chemotherapy and coronary artery disease. In retrospect, however, DM2-associated cardiomyopathy cannot be excluded. While cardiac rhythm disturbances have been described in patients with DM2, these patients do not have major abnormalities of cardiovascular autonomic function.21 We still have limited knowledge in assessing the cardiac risk of DM2 patients undergoing anesthesia, and it is unclear whether their risk of a perioperative cardiovascular event differs from the general population.
Gastrointestinal symptoms are highly prevalent in DM2 patients.22 Dysphagia for liquids and solid food, abdominal pain, and constipation were significantly more common among DM2 patients than among healthy controls and were comparable with DM1 patients. When present, dysphagia in DM2 patients is generally mild but becomes more severe with age.22 Our 40-yr-old patient who had a history of aspiration pneumonia had more severe symptoms compared with other patients in our series. Since advanced myotonic conditions may increase the risk for aspiration, preemptive measures need to be implemented perioperatively.
Clinical presentation of DM2 with body stiffness and muscle pains may resemble fibromyalgia. One study found that 3.2% of patients with fibromyalgia were tested positive for DM2 mutation.23 Physicians, especially anesthesiologists evaluating these patients in a pain clinic, should be aware of possible overlap in the clinical presentation of these two distinct disorders and should focus their attention on subtle signs and symptoms that may indicate the presence of DM2.
In one series, 21% of women had the initial symptoms of DM2 during pregnancy and worsening of symptoms in subsequent pregnancies.24 Thirteen percent of 96 pregnancies ended as early miscarriages, and 4% ended as late miscarriages. Preterm labour occurred in 50% of the pregnancies resulting in 27% preterm deliveries in women with overt DM2.24 Presently, there is no evidence that regional anesthesia or labour epidural analgesia can affect outcomes of pregnancy in patients with DM2.
Since DM2 is a very rare disorder, it is impossible to conduct large-scale studies to assess the safety of anesthesia in these patients. Thus, we must rely on experience gained from reports of individual cases or case series. Our case series has all the inherent limitations of a retrospective observational study, with the possibility that subtle complications or abnormal responses to anesthetic medications may not have been captured by our electronic medical records. It is also unclear whether our favourable results were secondary to a modification of typical anesthetic management by the attending anesthesiologist to account for the fact that the patients had DM2. In the instance of the patient who underwent multiple electroconvulsive treatments, there was a clear deviation from standard anesthetic care at our institution. In that case, the treating anesthesiologists used atracurium as the muscle relaxant rather than succinylcholine, which is the norm. Though speculative, the decision to use a nondepolarizing muscle relaxant was probably secondary to concerns about the use of succinylcholine in a patient with myotonic dystrophy. However, the diagnosis of DM2 in six patients was made following the surgery, so it can be assumed that these patients received standard care. Therefore, our results should be interpreted with a degree of caution, and further observational studies of patients with DM2 are necessary to make definitive conclusions regarding the safety of anesthesia.
In conclusion, in our series of 19 patients and 58 anesthetics, we could not detect anesthetic complications that could be attributed to DM2. Thus, it appears that commonly used anesthetic induction agents, i.e., succinylcholine, nondepolarizing muscle relaxants, and neostigmine are well tolerated in patients with DM2 and may be used safely. Although the clinical course of DM2 is more benign than that of DM1, anesthesiologists should be aware that patients with DM2 have a propensity to develop diabetes mellitus, dysphagia, cardiac conduction abnormalities, and cardiomyopathies.
The authors would like to thank Drs. Jasper Daube and Nathan Young for their assistance in identifying patients with DM2.
This work was entirely supported by the Department of Anesthesiology, Mayo Clinic, Rochester, MN. The authors have no commercial or non-commercial affiliations or other associations that present or could be construed to present a conflict of interest.
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