Myotonia and neuromuscular blocking agents

A case report of Andersen-Tawil syndrome misdiagnosed with myodystrophy

Andersen-Tawil syndrome (ATS) is a rare periodic paralysis caused by the KCNJ2 gene mutation. Here, we report on an ATS patient misdiagnosed with myodystrophy. A 66-year-old man presented with a 60-year history of episodic weakness in the proximal muscles of the upper and lower limbs. The man has been diagnosed with muscle pathology and has undergone genetic examinations in many hospitals since childhood. We conducted a correct diagnosis in combination with the patient's history, electrical physiology, and genetic analysis and identified a heterozygous KCNJ2 gene variant (c.220A > G; p.T74A). Patients with ATS can develop permanent myasthenia characterized by chronic progressive myopathy. ATS patients should also pay special attention to the risks of anesthesia in surgery, including malignant hyperthermia (MH), muscle spasms affecting tracheal intubation or ventilation, and ventilator weakness. Early diagnosis and therapy could help delay the onset of myasthenia and prevent risks associated with anesthesia accidents.

Myotonic Dystrophy and Anesthetic Challenges: A Case Report and Review

Providing anesthesia to patients with myotonic dystrophy (DM) can be very challenging due to the multisystemic effects of the disease and extreme sensitivity of these patients to sedatives, opioids, and anesthetic agents. Other factors such as hypothermia, shivering, or mechanical or electric stimulation during surgery can precipitate myotonia which is difficult to abolish and can lead to further complications. Generally, local or regional anesthesia is preferred to avoid the complications associated with general anesthesia in this group. However there are several case reports of successful use of general anesthesia (with or without volatile agents and with or without opioids). These general anesthetic cases led to postoperative admission to the regular floor or ICU. We present a case of a woman with a history of DM who underwent robotic assisted laparoscopic hysterectomy under general anesthesia and was discharged home on the same day.

Laparoscopic partial nephrectomy in a patient on simvastatin : Delayed recovery from neuromuscular blockade

Delayed recovery from anesthesia remains a very challenging subject for anesthesiologists. This case report describes the clinical course of delayed recovery from neuromuscular blockade after laparoscopic partial nephrectomy in a patient on simvastatin. The patient was hypertensive on regular treatment with oral captopril 25 mg twice daily and amlodipine 5 mg once daily and hypercholesterolemic on regular simvastatin 40 mg once daily with a normal electrocardiogram (ECG). All preoperative laboratory findings were within normal ranges. The patient was premedicated with midazolam 1 mg and general anesthesia was induced with fentanyl 2 µg/kg body weight, propofol 2 mg/kg and rocuronium bromide 0.6 mg/kg to facilitate tracheal intubation. Anesthesia was maintained with inhalation of isoflurane 1.0-1.5 % in 40 % oxygen-enriched air and 25 µg boluses of fentanyl. The patient did not require any additional rocuronium throughout surgery which was finished after 4 h. The patient most probably had preoperative simvastatin-induced myotoxicity. This potentiated the muscle relaxant effect of rocuronium bromide and was the reason for patient unresponsiveness and delayed postoperative recovery. We can conclude that anesthesiologists should preoperatively identify statin myotoxicity and to avoid neuromuscular blocking drugs for statin-treated patients. Also, preoperative adjustment of statin dosage may be recommended.

A novel mutation in CLCN1 associated with feline myotonia congenita

Myotonia congenita (MC) is a skeletal muscle channelopathy characterized by inability of the muscle to relax following voluntary contraction. Worldwide population prevalence in humans is 1∶100,000. Studies in mice, dogs, humans and goats confirmed myotonia associated with functional defects in chloride channels and mutations in a skeletal muscle chloride channel (CLCN1). CLCN1 encodes for the most abundant chloride channel in the skeletal muscle cell membrane. Five random bred cats from Winnipeg, Canada with MC were examined. All cats had a protruding tongue, limited range of jaw motion and drooling with prominent neck and proximal limb musculature. All cats had blepharospasm upon palpebral reflex testing and a short-strided gait. Electromyograms demonstrated myotonic discharges at a mean frequency of 300 Hz resembling the sound of a ‘swarm of bees’. Muscle histopathology showed hypertrophy of all fiber types. Direct sequencing of CLCN1 revealed a mutation disrupting a donor splice site downstream of exon 16 in only the affected cats. In vitro translation of the mutated protein predicted a premature truncation and partial lack of the highly conserved CBS1 (cystathionine β-synthase) domain critical for ion transport activity and one dimerization domain pivotal in channel formation. Genetic screening of the Winnipeg random bred population of the cats' origin identified carriers of the mutation. A genetic test for population screening is now available and carrier cats from the feral population can be identified.

Myotonic dystrophies type 1 and 2: anesthetic care

Myotonic dystrophy is classified as one of the myotonic syndromes although myotonia is only a minor characteristic of it. It is, in fact, also a multisystem disease with cardiac, digestive, ocular, and endocrine abnormalities. Two subgroups are currently identified with many similarities: DM1 refers to classic dystrophia myotonica (Steinert disease), while DM2, formerly called proximal myotonic myopathy has a later onset. The congenital form is present only in DM1. The genetic causes of DM1 and 2 are different but end up in a similar way of altering RNAm processing and splicing of other genes. The anesthetic risk is increased in case of DM1 type. This review summarizes current knowledge concerning the pathophysiology and anesthetic management of this disease in children and adults.

The effect of rocuronium and sugammadex on neuromuscular blockade in a child with congenital myotonic dystrophy type 1

Myotonic dystrophy type 1 (MD1) is the commonest muscular dystrophy found in adults; however, it may present in the neonatal period with hypotonia, talipes, poor feeding, and respiratory failure. Inheritance is autosomal dominant with a defect in the DMPK gene found on the long arm of chromosome 19 with variable expansion of the cytosine-thymine-guanine (CTG) triplet repeat. A 14-month-old boy with congenital MD type 1 was scheduled for percutaneous endoscopic gastrostomy (PEG) insertion, orchidopexy, and division of tongue-tie. Following induction of anesthesia, acceleromyography was used to monitor neuromuscular function. This revealed a very rapid onset of profound neuromuscular block which lasted significantly longer than would be expected in a child without MD1. Sugammadex reversed the block rapidly. The anesthetic management of children with MD1 has been well described but not the acceleromyographic monitored use of rocuronium and its subsequent reversal with the new cyclodextrin sugammadex.

Pathophysiologic and anesthetic considerations for patients with myotonia congenita or periodic paralyses

Myotonia congenita and periodic paralyses are hereditary skeletal muscle channelopathies. In these disorders, various channel defects in the sarcolemma lead to a severely disturbed membrane excitability of the affected skeletal muscles. The clinical picture can range from severe myotonic reactions (e.g., masseter spasm, opisthotonus) to attacks of weakness and paralysis. Provided here is a short overview of the pathomechanisms behind such wide-ranging phenotypic presentations in these patients, followed by recommendations concerning the management of anesthesia in such populations.

Desflurane anaesthesia in myotonic dystrophy

Myotonic dystrophy (MD) is a rare genetic disorder with multisystem involvement characterised by myotonia and progressive muscle weakness and wasting. These patients pose significant challenges to the anaesthesiologist in view of the muscular and extramuscular involvement and sensitivity to anaesthetic drugs. The literature is replete with reports of postanaesthetic respiratory and cardiovascular complications in these patients. But an ideal anaesthetic technique in MD patients remains to be determined. Rapid recovery is desirable to reduce postoperative respiratory complications. Though there are a few case reports of maintenance of anaesthesia with isoflurane and sevoflurane, there are scanty reports of use of desflurane in these patients. We present successful management of a patient with MD for laparoscopic cholecystectomy using a carefully titrated desflurane-based anaesthesia and discuss the perioperative considerations.

Complications of anaesthesia in neuromuscular disorders

The purpose of this review is to alert non-anaesthesiologists to the various complications from which patients with neuromuscular disorders and those susceptible to malignant hyperthermia can suffer during anaesthesia. The patient's outcome correlates with the quality of consultation between anaesthesiologists, surgeons, neurologists and cardiologists. Special precautions must be taken, since many anaesthetics and muscle relaxants can aggravate the clinical features or trigger life-threatening reactions. Complications frequently occur in these patients, although anaesthetic procedures have become safer by the reduced administration of suxamethonium and the use of total intravenous anaesthesia, new volatile anaesthetics and non-depolarising relaxants. This review provides a synopsis of pre-operative anaesthetic considerations and adverse drug effects on skeletal, cardiac and smooth muscle tissue. It describes the pathogenetic aspects of typical complications and introduces anaesthetic procedures for the various neuromuscular disorders, including regional anaesthesia for patients in whom a restriction of respiratory and/or cardiac function is predicted.

Myotonic dystrophy and paediatric anaesthesia

Myotonic dystrophy is a neuromuscular condition inherited in an autosomal dominant fashion, and is most commonly diagnosed in the neonatal period. With improving levels of care, these patients are now presenting more commonly for anaesthesia. We review the clinical features of the condition, and then discuss the steps in the anaesthetic process, outlining the anaesthetic implications of myotonic dystrophy at each stage.

Anaesthesia and myotonia--an Australian experience

The purpose of this audit was to retrospectively examine the anaesthetic technique and perioperative complications among adult patients with confirmed myotonic dystrophy who presented for surgery at Royal Perth Hospital. A total of 18 general anaesthetics, two spinal anaesthetics, one conscious sedation and six eye blocks were performed. No deaths and no myotonic episodes were described despite the use of a variety of techniques, including the administration of succinylcholine to three patients. The only patient to experience postoperative complications was severely unwell preoperatively and underwent upper abdominal surgery. The audit revealed an overall complication rate of 5.5% of general anaesthetics or 3.8% of all anaesthetics in this patient population.

Continuous propofol anaesthesia for patients with myotonic dystrophy

Myotonic dystrophy, a rare genetic disorder, may pose a serious problem to the anaesthesiologist due to muscular and extramuscular involvement. Thirteen patients, median age 21 yr were anaesthetized by continuous propofol infusion, fentanyl, atracurium and N2O to evaluate this combination in myotonic dystrophy. Intraoperatively, neither exaggerated reactions nor haemodynamic instability was observed. Recovery was smooth and quick. Although there was a significant decrease in mean postoperative vital capacity (965 (349) ml) from the preoperative value (1664 (566) ml, P = 0.0028), there was no change in mean postoperative SpO2 and there were no perioperative respiratory complications. Only two patients complained of nausea and vomiting. Similarly, muscular hypertonia and shivering were not observed. We conclude that the combination of continuous propofol infusion and fentanyl was a successful anaesthetic technique in these young myotonic dystrophy patients undergoing peripheral surgery.

Antenatal and preoperative genetic and clinical assessment in myotonic dystrophy

The antenatal investigation of an obstetric patient with a history of myotonia is described. The smooth and striated muscle dysfunction in myotonic dystrophy renders these patients, as a group, liable to surgical correction and exposure to anaesthesia. A caesarean section is reported to illustrate the preferred timing of diagnosis and peripartum management. While regional anaesthesia is preferred, myotonic dystrophy is not a contraindication to general anaesthesia, provided risks are anticipated and steps taken to minimize complications.

Myotonic dystrophy is a significant cause of idiopathic polyhydramnios

OBJECTIVE

Myotonic dystrophy, the most common form of muscular dystrophy seen in pregnant women, may be a significant cause of middle trimester polyhydramnios. Our purpose was to determine the prevalence of myotonic dystrophy in women with idiopathic polyhydramnios and to characterize the ultrasonographic findings associated with cases.

STUDY DESIGN

We examined the cases of 67 patients who were delivered of infants at the University of Utah between 1992 and 1996 with a diagnosis of idiopathic polyhydramnios (amniotic fluid index >25). Women with diabetes mellitus, hydrops, or fetal anomalies known to cause polyhydramnios were excluded from the study. Amniotic fluid samples or cord blood samples were obtained from 41 patients, and polymerase chain reaction amplification and Southern blot analysis were performed to detect the presence of the myotonic dystrophy mutation. Ultrasonographic findings, prenatal course, and neonatal outcomes were reviewed in all cases.

RESULTS

Four of the 41 patients tested had the myotonic dystrophy mutation, yielding a prevalence in our population of 9.7%. Three of the 4 patients reported a family history of myotonic dystrophy. Ultrasonographic findings associated with a positive result included abnormal posturing of extremities (3/4) and unilateral clubbed foot (3/4). No other structural or growth abnormalities were seen. Two of the patients were delivered before term, 1 at 26 weeks and 1 at 32 weeks. Three of the 4 infants were severely affected, necessitating admission to the intensive care unit, and 1 died on day 11 after birth. One infant, whose myotonic dystrophy mutation consisted of between 800 and 900 triplet repeats, did not require admission to the intensive care unit.

CONCLUSION

Myotonic dystrophy may be seen as idiopathic polyhydramnios and should be considered as part of the differential diagnosis in these cases. Women with a familial history of myotonic dystrophy or ultrasonographic evidence of hypotonia, including positional abnormalities of the extremities, should be offered deoxyribonucleic acid testing for the myotonic dystrophy mutation.

Anaesthesia for caesarean section in a patient with myotonic dystrophy receiving warfarin therapy

A 31-yr-old parturient with myotonic dystrophy and asthma presented for elective Caesarean section. The patient was receiving warfarin having had two previous episodes of thromboembolism. Anticoagulation was subsequently provided by heparin in the weeks prior to delivery. The combination of the patient's medical conditions and the continuing need for anticoagulation presented a considerable anaesthetic problem in planning anaesthesia and analgesia for both elective and emergency delivery. Heparin was discontinued on the day prior to surgery and restarted immediately after surgery. During surgery flowtron anti-embolitic boots were used. Warfarin therapy was recommenced on the seventh postoperative day. Anaesthesia for Caesarean section was provided using a combined spinal epidural technique using a separate needle, separate interspace method. Postoperative pain was relieved by using a continuous epidural infusion, transcutaneous nerve stimulation and diclofenac. No new neurological problems arose despite the use of epidural analgesia in the presence of heparin anticoagulation. This method of providing anaesthesia and postoperative analgesia without the use of opioids in an anticoagulated, asthmatic, myotonic parturient has not been described elsewhere.

The correlation between electrical after-activity and slowed relaxation in myotonia

The correlation between electrical and mechanical after-activity was studied in resealed fiber segments from patients with recessive generalized myotonia (Becker) and in intact fibers from normal muscles which were bathed in 9-anthracene carboxylic acid. The tests were performed in vitro on small bundles of 100 fibers or less. Electromyographic activity and contractile force were measured simultaneously. The relaxation of rested-state twitches and tetani was slowed and accompanied by after-activity in both types of preparations. Often random activity was recorded. In all cases, the contractile force was highly correlated with the electromyographic signs of myotonia. These observations support the hypothesis that electrical after-activity is fully responsible for the slowed relaxation in recessive generalized myotonia.

Obstetric anaesthesia in dystrophia myotonica

Two patients with dystrophia myotonica presented for urgent Caesarean section. Their per- and postoperative courses illustrate the anaesthetic problems posed by this disease. Respiratory difficulties are compounded by pregnancy and there is increased susceptibility to uterine haemorrhage. Choice of anaesthetic agent is discussed. Both had general anaesthetics; muscle relaxation was achieved with vecuronium.

Congenital myotonic dystrophy in children--a review of ten years' experience

A review of the anaesthetic management of children with congenital myotonic dystrophy anaesthetised at the Royal Children's Hospital over the past ten years is presented. Seven children underwent a total of fourteen anaesthetics. Anaesthetic considerations must include the degree of muscle weakness and hypotonia altering muscle relaxant requirements, aspiration risk due to palatopharyngeal dysfunction, and cardiomyopathy. Succinylcholine caused muscle contracture in a patient without clinical myotonia. This drug should be avoided. Although a low threshold to institute postoperative respiratory support must exist when treating neonates and infants, the older children did not clinically exhibit increased sensitivity to respiratory depressant drugs.

Continuous infusion of propofol in dystrophia myotonica

The use of intravenous infusions of propofol and atracurium in a 41-year-old woman, weighing 64 kg, with dystrophia myotonica during major oral surgery is described. Propofol and atracurium, in total doses of 2488 mg and 75 mg respectively, were used during the four-hour procedure. There were no intraoperative problems and operating conditions were excellent. Emergence was rapid and there were no postoperative complications. This technique offers a safe alternative to inhalational anaesthesia for patients with dystrophia myotonica.

[Anesthesia in myotonia]

Myotonia is defined as a persistent contraction of skeletal muscles after their stimulation. This contracture is not prevented or relieved by regional anaesthesia or muscle relaxants. The sensitivity to non-depolarizing muscle relaxants is usually normal. Suxamethonium, neostigmine, hypothermia, a rise in kalaemia should be avoided. There have been case reports of malignant hyperthermia in patients with myotonia congenita. Dystrophia myotonica is the second most frequent of the inherited muscle diseases, after Duchenne's dystrophy. The severity of the disease is due more to the muscular atrophy and the multiple organ involvement than to the abnormal contraction. Atrioventricular heart block and dysrhythmias are more common than heart failure. Prolonged apnoea and pneumonia are the main risks of anaesthesia. In severe cases, exists a restrictive respiratory insufficiency which is preceded by a fall in the maximum expiratory pressure. Dysphagias and inefficient coughing may occur early. An increased susceptibility to hypnotic drugs and opiates is a common feature. Spontaneous sleep apnoeas should be sought before anaesthesia, especially by using pulse oximetry. The anaesthetic implications are reemphasized.

Reversal of prolonged postoperative muscle rigidity by dantrolene: a case report

The use of dantrolene to reverse severe unexplained postanaesthetic muscle rigidity in a previously "healthy" 13-year-old male is described. Anaesthesia was induced with thiopentone. After intubation with pancuronium, the patient had an entirely uneventful nitrous oxide, oxygen and halothane anaesthetic. Immediately following reversal of the relaxant, the patient developed generalized muscle tightness and rigidity involving the trunk and extremities. This was prolonged and severe enough to interfere with adequate ventilation. The patient also had a prolonged recovery from the anaesthetic. After ruling out malignant hyperthermia and some other causes of rigidity, a tentative diagnosis of myotonia was made. The symptoms responded to IV dantrolene in a total dose of 2.0 mg.kg-1. Further testing failed to establish a definite diagnosis. Dantrolene could be a useful drug in treating such unexplained muscle rigidity.

Aspiration pneumonia and coma--an unusual presentation of dystrophic myotonia

A 30-year-old female patient presented in a comatose state with clinical and radiographic signs of aspiration pneumonia 16 hours following elective surgery. Subsequent clinical assessment and investigations revealed the characteristic facies, proximal muscle weakness, lenticular opacities, pulmonary function defects, arterial desaturation and abnormal breathing during rapid eye movement (REM) sleep often associated with myotonia dystrophica. Although these characteristic features were evident on clinical examination postoperatively they were not noted in the preoperative assessment. The aspiration pneumonia and coma were unusual presenting features of this disease. Unsuspected myotonia dystrophica should be considered in the differential diagnosis of unexplained respiratory depression, aspiration or comatose state following surgery. Recognition of the disorder during the preoperative assessment is the key to avoiding complications during the perioperative management of such patients.

Anesthesia for pediatric neurological and neuromuscular diseases

Children with neurological and neuromuscular diseases often present anesthetic problems in the perioperative period. The anesthetic technique can play a significant role in altering the state of the brain during neurosurgical procedures through effects on the cerebral circulation and metabolism. Pre-existing neuromuscular disease may also have specific anesthetic implications such as cardiorespiratory involvement (eg, myotonia dystrophica), the potential for drug interactions (eg, myasthenia gravis) or abnormal responses to commonly used drugs (eg, malignant hyperthermia). In this review, the perioperative anesthetic considerations in a number of common neurological and neuromuscular conditions in the pediatric patient are discussed.

Prolonged neuromuscular blockade with atracurium

During general anaesthesia with oxygen, nitrous oxide and enflurane, a 29-year-old woman received a total of 105 mg (1.78 mg X k-1) of atracurium over a 2.5 hour period. The neuromuscular blockade could not be completely reversed with neostigmine and mechanical ventilatory support was necessary for three hours postoperatively. The patient received succinylcholine without unusual sequelae before and after this episode. This is the first report of a patient who exhibited prolonged weakness after receiving atracurium.

Anaesthetic management of a child with dermatomyositis

A two years, ten months old male with dermatomyositis was anaesthetized with enflurane, nitrous oxide and oxygen by mask followed by intravenous succinylcholine to facilitate endotracheal intubation. The evoked thumb twitch in response to succinylcholine demonstrated an abnormal, short-lived contracture. The depression, duration and return to control of muscle twitch tension and a transient rise in serum potassium concentration followed a normal pattern.

Neuromuscular blockade in dystrophia myotonica with atracurium besylate

The anaesthetic management of a young woman with dystrophia myotonica is described. The use of atracurium and monitoring of neuromuscular block allowed suxamethonium and neostigmine to be avoided, and thereby to reduce the risk of myotonic contractions. No adverse sequelae were observed.

Anaesthesia in babies with congenital dystrophia myotonica

The anaesthetic procedures used in two babies with congenital dystrophia myotonica are described, and the problems of providing anaesthesia in patients with the adult and congenital forms of the condition discussed.

Dantrolene sodium and dystrophia myotonica

A patient with dystrophia myotonica was given dantrolene sodium to try to provide muscle relaxation during a cholecystectomy. Dantrolene was used as it is accepted that the drug has a place in the control of spasticity and also causes muscle relaxation, whereas conventional muscle relaxants are unable to control myotonia of muscle origin. Dantrolene alone did not provide good enough intubating and operating conditions in this subject. Later studies showed that, after dantrolene, EMG recordings from the patient were not significantly altered, although an impression of a slight increase in the myotonic potentials was gained.

[Postoperative respiratory complications of myotonia dystrophica (Steinert's disease)]

Respiratory difficulties have long been recognized to be a major risk in patients with myotonia dystrophica, but postoperative pulmonary complications have only rarely been considered. Two cases of postoperative pulmonary complications which led to the patients's death stressed the severity and difficulty of treatment of these complications. A third case of postoperative respiratory failure revealed the underlying disease. These cases showed all the more the importance of preventing pulmonary complications. Pre-, per- and postoperative measures, chosen with respect to the severity of the myotonia and the seat of the surgical procedure, are suggested.

Alterations of drug toxicity in neuropsychiatric disease states

Potentially adverse alterations in drug response in patients with neuropsychiatric disease can be divided into two categories: those arising from the pathological state itself (e.g., enhanced responsiveness to phenylephrine in patients with chronic autonomic failure) and those arising from interactions with the pharmacological treatment used for such disease (e.g., reversal of the antihypertensive action of guanethidine by imipramine). Sound knowledge of the pharmacological profile of individual compounds and of the pathophysiology of the disease is essential if drug therapy is to be used safely and effectively in these patients.

Case report: intravenous anaesthesia using Althesin in a patient with dystrophia myotonica

A case report of anaesthesia for a patient with dystrophia myotonica undergoing insertion of an endocardial permanent pacemaker is presented. The value of Althesin as the major anaesthetic agent in these patients is outlined, especially with respect to its cardiovascular stability and rapid recovery.

Perioperative hazards in myotonic dystrophy

A 32-year-old man with myotonic dystrophy underwent a thoracotomy for removal of a mediastinal thymoma. Pre-operative examination revealed features of myotonic dystrophy, the only other abnormality was mild restrictive pulmonary disease. Anaesthesia was induced with thiopentone and maintained with enflurane, nitrous oxide, oxygen and curare. Following surgery, the patient was mechanically ventilated for several hours and remained intubated for 9 hours. The anaesthesia and surgery were tolerated well; however, postoperative complications included refractory dysrhythmias, hypoxia, pneumococcal pneumonia and pulmonary emboli. More intensive preoperative pulmonary evaluation and physiotherapy coupled with more aggressive postoperative pulmonary care might have resulted in a smoother recovery phase.