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.     

Multiple thymoma with myotonic dystrophy

A case of multiple thymoma associated with myotonic dystrophy is reported. The patient was a 42-year-old man who had two separate encapsulated thymoma in the anterior mediastinum, at 3 cm in diameter on the right side, and at 4 cm in diameter on the left. Extended thymo-thymomectomy was performed. Microscopically, the tumor in the right thymic lobe was predominantly mixed type, and that in the left predominantly epithelial type. Neuromuscular disease appeared to develop, with severe sputum retention in the larynx and he was referred to neurology at 6 months after surgery. On examination, he presented a characteristic hatchet face, muscle atrophy, muscle weakness, percussion myotonia and grip myotonia, and diagnosis was revised to be multiple thymoma associated with myotonic dystrophy. This association is extremely rare. It is difficult to clarify whether this association was a syndrome or coincidence.     

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.     

Laparoscopic cholecystectomy in a patient with Steinert myotonic dystrophy. Case report

Myotonic dystrophy (MD) is a serious multi-systemic autosomal dominant disease. The estimated incidence is 1 in every 8000 births, with an estimated prevalence of between 2.1 and 14.3 cases per 100,000 inhabitants. Signs and symptoms vary from a severe form of congenital myopathy, present from birth and often fatal, to a classic form and a delayed form, which generally presents after the age of 50 and in which the only sign is a cataract and life expectancy is completely normal. We describe the clinical case of a 40-year-old woman with Steinert myotonic dystrophy who underwent laparoscopic cholecystectomy (under general anesthesia) for symptomatic gallbladder stones. The conduct of anesthesia in such patients must be carefully considered, as hypothermia, shivering, electrical and mechanical stimulation, and the drugs used can all trigger myotonia.     

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.     

Intra- und postoperative Analgesie mit Kaudalkatheter bei einem Kind mit Schwartz-Jampel-Syndrom

The Schwartz-Jampel syndrome, also known as myotonia chondrodystrophica, is a rare autosomal recessive disorder characterized by bone dysplasia, growth retardation and generalized myotonia. Laryngoscopy and intubation may be difficult because of micrognathia and limited mouth opening due to myotonia of the masseter muscles. As regional anaesthesia reduces myotonic contractions and avoids administration of opioids causing respiratory depression, it appears to be the ideal method for postoperative analgesia. We report on a 5-year-old girl who underwent osteotomy of both hips and received intraoperative and postoperative analgesia via a caudal catheter. Excellent analgesia without myoclonic episodes could be achieved by continuous infusion of ropivacaine.     

Comparison of mechanomyography and acceleromyography for the assessment of rocuronium induced neuromuscular block in myotonic dystrophy type 1

We measured acceleromyography and mechanomyography simultaneously with monitoring of rocuronium‐induced neuromuscular block in four patients with myotonic dystrophy type 1. Furthermore, we compared neuromuscular block measures from these patients with those from normal controls from previous studies. In myotonic dystrophy type 1 patients, the dose‐response curve obtained with acceleromyography was steeper and right‐shifted compared with that obtained using mechanomyography. However, the effective doses to produce 95% neuromuscular block determined with both acceleromyography and mechanomyography were similar to each other and to values found in normal patients. In the three myotonic dystrophy type 1 patients with mild to moderate disease, times to recovery from block were similar to those observed in normal controls. In both patients and normal controls, neuromuscular block recovered faster with acceleromyography. However, in one patient with severe muscle wasting, recovery of neuromuscular block was prolonged. We conclude that mechanomyography and acceleromyography cannot be used interchangeably to monitor neuromuscular block in myotonic dystrophy type 1 patients.     

Multiple pilomatrixomata and myotonic dystrophy: a familial association.

The association of pilomatrixoma and myotonic dystrophy has been described in the past in 13 publications in the English literature. The association seems to involve the development of pilomatrixomata before signs of myotonic dystrophy. Myotonic dystrophy is the commonest adult dystrophy and is an autosomaldominant disease with a variable phenotypic penetrance. The disease is determined by a genetic locus on chromosome 19q and can be diagnosed using methods of DNA testing. We describe the 25th case of a patient with both conditions together with a review of the literature. To our knowledge, no other patient has had such a large number of histologically proven pilomatrixomata.     

THE MYOTONIC RESPONSE TO SUXAMETHONIUM

A survey of the reported responses of myotonic patients to depolarizingrelaxants reveals the variable incidence and extent of inducedmyotonia. Generalized myotonia due to suxamethonium is describedin a patient with myotonia congenita and, from subsequent investigationsduring a second operation, the action of the drug is clarified.Such a myotonic response is attributed to fasciculation, anda normal depolarizing block was demonstrated with continuedadministration of the drug. Suggestions are made for the anaestheticmanagement of such patients. Present address: Cairns Base Hospital, Queensland, Australia.     

ARE MYOTONIAS AND PERIODIC PARALYSES ASSOCIATED WITH SUSCEPTIBILITY TO MALIGNANT HYPERTHERMIA?

Excised muscles from patients with myotonia or periodic paralysiswere subjected to the in vitro contracture test for susceptibilityto malignant hyperthermia (MH). In a group of 44 patients, thisstandard test gave four positive, 10 equivocal and 30 negativeresults. The results for 27 control muscles from normal subjectswere negative. When the test was performed with less than normalconcentrations of contracture-triggering substances (caffeine< 2 mmol litre^–1, <2% halothane), 70 % of the musclesfrom the patients and only 15% of the controls responded withsmall contractures (< 0.2 g). These results should not betaken to indicate that the patients have the genetic trait forMH. The positive and equivocal test results, in addition tothe slight contractures, may be accounted for by the electricalafter-activity in the cases of pure myotonia, and by increasedresting myoplasmic [Ca²⁺] in myotonic dystrophy. This showsthat the in vitro contracture test lacks specificity. Present Address: Department of Anesthesioogy, University ofMinnesota, Minneapolis, Mn, U.S.A.     

A 5-year follow-up study of an atypical case of myotonic dystrophy

This study presents 5-year follow-up data on NG, a woman with adult onset myotonic dystrophy and progressive cognitive decline who was first described by Wilson et al. The extent of the cognitive impairment is atypical of symptom-onset in adulthood and of paternal inheritance, both of which apply to this case. Together, the present and earlier studies report the results of regular neuropsychological assessments over a 16-year period. Severe impairment in executive functioning, episodic and semantic memory were apparent early in the history, while visuospatial skills and working memory were only mildly impaired after 16 years of follow-up. There was also a progressive dyslexia, initially characterized by the regularization errors typical of surface dyslexia, but subsequently dominated by visual/phonological reading errors. This pattern of impairment is not typical of myotonic dystrophy but resembles semantic dementia. Whilst the deficits may be attributable wholly to myotonic dystrophy pathology, the co-existence of a form of semantic dementia is also possible. It is noted that the aggregation of tau protein is a neuropathological feature common to both diseases.     

Sleep hypoxia in myotonic dystrophy and its correlation with awake respiratory function.

BACKGROUND--Tiredness and daytime respiratory failure occur frequently in myotonic dystrophy. Sleep hypoxaemia was studied in 12 patients with myotonic dystrophy and correlations were sought with their daytime lung and respiratory muscle function. METHODS--All patients underwent overnight sleep studies, clinical assessment, measurement of flow-volume loops and carbon monoxide transfer factor, arterial blood gas analysis, and physiological assessment of both thoracic muscle function and upper airways obstruction. RESULTS--The mean nadir of oxygen saturation during sleep was 75% (95% confidence interval 69% to 81%). A mean of 3.4% of total sleep duration was spent at an oxygen saturation level below 85%. Five of the 12 patients had an apnoea index of > 5, the group mean apnoea/hypopnoea index being 15.8 events/sleep hour. The mean awake arterial oxygen tension (PaO2) was 10.7 kPa. There was a trend to hypercapnoea with a mean awake arterial carbon dioxide tension of 6.1 kPa; carbon dioxide retention worsened during sleep. Respiratory muscle dysfunction was mainly evident as a low maximum expiratory mouth pressure. Upper airway obstruction assessed by physiological criteria was found in four of the 12 patients. The proportion of total sleep duration with oxygen saturation levels below 85% was directly related to body mass index (weight/height2) and inversely related to the awake PaO2. Body mass index was inversely related to the overnight nadir of oxygen saturation. CONCLUSIONS--Patients with myotonic dystrophy are often hypoxic during sleep and the subgroup that are obese, or have symptoms of sleep apnoea, or both, are particularly at risk. Sleep studies should be considered in this subgroup of patients with myotonic dystrophy.     

Anaesthetic management of the child with myotonic dystrophy: epidural anaesthesia as an alternative to general anaesthesia

An 11-year-old boy with myotonic dystrophy required anaesthesia for a lower extremity orthopaedic procedure. The management of patients with myotonic dystrophy is discussed including the use of epidural anaesthesia with a continuous chloroprocaine infusion as an alternative to general anaesthesia.     

Anesthetic management of a patient with myotonic dystrophy for a Nissen fundoplication and gastrostomy

A 16-month-old baby with myotonic dystrophy underwent an open Nissen fundoplication and gastrostomy insertion under general anesthesia with an epidural. Postoperative care was managed on the pediatric intensive care unit for the first 6 h. She was then discharged to the ward, where she continued to make an uncomplicated recovery. Other anesthetic management that has been used in children with myotonic dystrophy is discussed.     

Isoflurane anesthesia for a child with myotonic dystrophy

A 5 year-old boy with myotonic dystrophy was anesthetized with isoflurane for bilateral orchiopexy. Intubation was easily done without muscle relaxants, following slow induction using isoflurane, nitrous oxide and oxygen. Myotonia was not observed perioperatively and postoperative course was uneventful. It is concluded that isoflurane is an anesthetic of choice for a patient with myotonic dystrophy.     

Thin muscle capillary basement membranes in myotonic dystrophy.

Muscle capillary basement membrane width (MCBMW) was measured in 18 myotonic dystrophy patients and compared with that in age- and sex-matched normal and diabetic subjects. The MCBMW in myotonic dystrophy patients (773 +/- 258 A) was significantly thinner than in normal subjects (925 +/- 181 A, P less than 0.05) or in diabetics (1224 +/- 614 A, P less than 0.01). An increase in MCBMW with advancing age was present in all groups but was greatest in the myotonic dystrophy groups (r = +0.59, P less than 0.01). There was no relation between MCBMW and either the degree of glucose intolerance or insulin hypersecretion in the myotonic dystrophy group, though none had fasting hyperglycemia. This is the first report of a condition associated with thinner-than-normal capillary basement membrane.     

Myotonic dystrophy. Part II. A clinical study of 96 patients

To demonstrate the widespread manifestations of myotonic dystrophy the clinical features of 96 patients are reviewed. The study includes 24 children, 6 of whom have congenital myotonic dystrophy.     

Three times of anesthetic management in a patient with myotonic dystrophy

A 38-year-old female, at 38-week gestation, was scheduled for cesarean section under epidural anesthesia. After the delivery, it was found that she had been diagnosed as myotonic dystrophy by the other physician and the neonate was a floppy infant indicating hereditary neuromuscular diseases. In her case, myotonic dystrophy had not been advanced and symptoms had been mild. We previously had given her general anesthesia for two times with nitrous oxide, isoflurane and vecuronium for her to undergo emergency operations, left salpingectomy under laparoscopy due to unruptured tubal pregnancy at 34 years of age and cesarean section due to liver function disorder indicating HELLP syndrome at 36 years of age. Although many problems have been described about the perioperative management in patients with myotonic dystrophy, she was safely managed for each operation.     

Scoliosis in Steinert syndrome: a case report.

BACKGROUND CONTEXT: Steinert syndrome is described as an autosomal dominant condition characterized by progressive muscular wasting, myotonia, musculoskeletal manifestations and rare spinal defects. Little is reported about spinal deformity associated with this syndrome. PURPOSE: We present a patient with Steinert syndrome complicated by scoliosis. In the literature on muscular dystrophy, other than Duchenne, little mention is given to the problem of scoliosis in general and its treatment in particular. STUDY DESIGN: A case report of a patient with Steinert syndrome associated with thoracic scoliosis and hypokyphosis is presented. METHODS: A 17-year-old boy presented with King type II right thoracic scoliosis (T5-T11, Cobb angle of 40 degrees) and hypokyphosis--10 degrees. He was treated with posterior stabilization and instrumentation at level T3-L2 with a postoperative correction of the scoliotic curve to 20 degrees. Histopathologic examination of the muscles confirmed the diagnosis of Steinert myotonic dystrophy. RESULTS: At 30-month follow-up, the patient was clinically pain free and well balanced. Plain radiographs showed solid spine fusion with no loss of deformity correction. CONCLUSIONS: Scoliosis in Steinert syndrome shares the characteristic of an arthrogrypotic neuromuscular curve and demands the extensive soft tissue release for optimal surgical correction. Intraoperative observations included profound tissue bleeding, abnormally tough soft tissues and a difficult recovery from anaesthesia.     

Anesthetic management of three patients with myotonic dystrophy in a family

Case-1: A 24-year-old woman was admitted because of pressing hydramnion. She was treated by ritodrine hydrochlorides leading to rhabdomyolysis, and she was diagnosed as myotonic dystrophy. She underwent cesarean section because of urgent premature birth. The surgery was performed with spinal anesthesia using tetracaine. Case-2: A 1-year-old boy, the son of Case 1, underwent orchiopexy. He showed respiratory distress at birth and needed respiratory support for 140 days. The surgery was performed under general anesthesia combined with caudal anesthesia. Anesthesia was induced with nitrous oxide-oxygen-sevoflurane. He was intubated without muscle relaxants. Since he recovered consciousness soon after the surgery, he was extubated and returned to the ward. Case-3: A 30-year-old woman, the sister of Case 1, underwent tonsillectomy. At the age of 27 she underwent salpingectomy under general anesthesia with nitrous oxide-oxygen-halothane, after which she was diagnosed as myotonic dystrophy. She was anesthetized with propofol and fentanyl. Because severity of the myotonic dystrophy varies among the patients, the strategy for anesthesia should be planned on each patient. Generally speaking, regional anesthesia including spinal and epidural anesthesia is preferable.