Anaesthesia in babies with congenital dystrophia myotonica

Regional anesthesia and muscle-wasting diseases in pediatrics: A focused educational review

The muscular dystrophies or muscle-wasting diseases include a diverse group of genetic disorders, which result in progressive degeneration of skeletal muscles, progressive muscle weakness, and comorbid multi-system involvement. Duchenne muscle dystrophy is the most common type of muscular dystrophy with a reported incidence of 1 in every 3500-6000 male live births in the United States. Given the progressive nature of these disorders, skeletal muscle weakness frequently progresses to loss of the ability to ambulate and perform functions of daily life. In addition to affecting the skeletal musculature, many muscular dystrophies have effects on both cardiac and smooth muscles. As respiratory muscles are one of the most frequently affected muscles in patients with muscular dystrophies, progressive respiratory insufficiency may occur with dependance on non-invasive forms of respiratory support. Given the progressive multi-system involvement associated with the muscular dystrophies, perioperative care and the use of general anesthetic agents and opioids may result in postoperative respiratory failure. In an effort to avoid the deleterious effects of anesthetic agents and opioids on hemodynamic and respiratory functions, regional anesthesia may be used as an adjunct to or instead of general anesthesia. This manuscript provides a literature review and educational summary regarding the use of regional anesthetic techniques in pediatric-aged patients with muscular dystrophies.

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.

Malignant hyperthermia and myotonic disorders

Advances in physiology and molecular genetics have promoted greater understanding of the various clinical manifestations of muscle disorders. For example, myotonia or profound weakness may be observed in sodium channel disease (e.g., paramyotonia congenita or hyperkalemic periodic paralysis), depending on the specific channel defect or with slight changes in membrane potential. Observed effects of anesthetic techniques have been essential to elucidating the primary muscular nature of myotonia. Commonly used anesthetic medications have potentially lethal (e.g., MH) or serious (e.g., myotonic dystrophy) adverse effects. Conversely, lidocaine or propofol may have therapeutic benefit for patients with skeletal muscle sodium channel disorders. Additional investigation is required to improve our understanding of how age, gender, or other factors determine the phenotypic expression of malignant hyperthermia. Future research holds the promise for more accurate pre-anesthetic identification of persons with heritable myopathies, especially those who are asymptomatic. Enhanced awareness of multiple organ system involvement in myotonic dystrophy is essential for planning perioperative care. Patients with periodic paralysis require that we know factors that incite or inhibit the development of their attacks. Advances in bench research and detailed clinical studies will further improve our ability to provide optimal care for patients with muscle disorders.

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.

[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.

Postoperative complications of dystrophia myotonica

A 44-year-old man with known mitral stenosis presented for minor surgery. Anaesthesia was induced with fentanyl, droperidol and etomidate and maintained with nitrous oxide, oxygen and vecuronium. Surgery and anaesthesia were uneventful but the postoperative course was stormy, with respiratory arrest, Haemophilus pneumonia, refractory cardiac dysrhythmias and gastrointestinal atony. A diagnosis of dystrophia myotonica was made after 3 weeks in the intensive care unit, and he spent 6 weeks in hospital. A high index of suspicion for this disease must be maintained and intensive care facilities and monitoring should be available for all procedures.

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.

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.