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At least 19 recordsLinked to original sources
PubMed2026

Treatment updates in myotonic disorders.

Myotonia is delayed muscle relaxation after forceful contraction. It is due to hyperexcitability of the skeletal muscle membrane. It can arise from primary skeletal muscle ion channel dysfunction, involving chloride or sodium channels, but is also a prominent clinical feature in myotonic dystrophies where altered RNA splicing leads to secondary ion channel dysregulation amongst other systemic manifestations. Clinically, myotonia can range from delayed eye opening to a disabling symptom causing impaired mobility, functional difficulty and sometimes pain. It can also be a "hidden disability" with many patients feeling socially embarrassed by "looking healthy", yet being unable to do everyday physical tasks or to do them as effortlessly as their peers. It is a symptom that almost always indicates a genetic diagnosis, although it can occur in acquired conditions, including metabolic and drug-induced causes. To experience myotonia without knowing what it is can be baffling. To receive a genetic diagnosis associated with it can be life changing. Although there is no cure, there are many effective and available symptomatic treatments for myotonia and currently we are in an exciting era of clinical trials for new molecular disease-modifying therapies for myotonic dystrophy type 1. In this review, we consider recent developments in the treatment of myotonic disorders and how they may change clinical practice.

Humans↗
PubMed1992

[Central nervous system disorders in myotonic dystrophy--with special reference to neuron-specific enolase, S-100b protein and creatine kinase BB isoenzyme levels in CSF].

In order to evaluate central nervous system disorders in myotonic dystrophy (MyD), neuron-specific enolase (NSE), S-100b protein and creatine kinase BB (CK-BB) isoenzyme were measured using enzyme immunoassay in MyD. Intelligence quotient (IQ) test (WAIS, 17 cases), electro-encephalography (17 cases) and brain computed tomography (18 cases) were examined. In patients with MyD, NSE level was significantly elevated in comparison with 25 age-sex matched control subjects. In some cases of MyD levels of S-100b protein and CK-BB in CSF were elevated. IQ test disclosed intellectual impairment in 70.6% of the patients examined and EEG study demonstrated slowing of basic rhythm in the majority of the cases. On brain CT both enlarged ventricles and dilated sulci were commonly found. The results of the present study suggest that in MyD the CNS is involved not only functionally but structurally as well. Since NSE, S-100b and CK-BB are localized in neuronal and glia cells, their elevated levels in CSF indicate existence of organic lesions in the central nervous tissue in patients with MyD.

Adult↗
PubMed1992

Hyperproinsulinaemia in patients with myotonic dystrophy.

Hyperinsulinaemia is a reported feature of the inherited multisystem disorder myotonic dystrophy. This phenomenon has been attributed to a compensatory beta cell response to tissue insulin resistance. In this study, circulating concentrations of insulin, proinsulin, and split proinsulin molecules were determined after an overnight fast in ten patients with myotonic dystrophy using two-site monoclonal antibody-based immunoradiometric assays. Results were compared with ten healthy control subjects matched for age, gender, and body mass index. Oral glucose tolerance (75 g), as defined by World Health Organization criteria, was normal in all subjects. Fasting plasma immunoreactive insulin concentration, as determined using a conventional radioimmunoassay, was almost three times higher (p < 0.005) in the myotonic dystrophy patients than the healthy control subjects. By contrast, fasting concentrations (mean +/- SEM) of C-peptide (0.75 +/- 0.09 vs 0.52 +/- 0.03 nmol/l, p = 0.07) and immunoradiometrically-determined insulin (60 +/- 12 vs 38 +/- 4 pmol/l, p = 0.09) were not significantly different between the groups. Fasting concentrations of proinsulin (10.3 +/- 2.9 vs 1.6 +/- 0.3 pmol/l, p < 0.01), and 32-33 split proinsulin (7.8 +/- 2.5 vs 2.9 +/- 0.4 pmol/l, p < 0.05) were significantly elevated in the patients with myotonic dystrophy. Accordingly, the mean fasting proinsulin:insulin ratio, expressed as a percentage, was significantly increased in the myotonic patients (20 +/- 5 vs 4 +/- 1%, p < 0.01). The overall C-peptide response to the oral glucose challenge was significantly greater in the myotonic patients compared with the healthy control subjects (p < 0.001). These results provide corroborative evidence of increased beta-cell secretion in myotonic dystrophy.(ABSTRACT TRUNCATED AT 250 WORDS)

C-Peptide↗
PubMed1975

Study of sensitivity to curare in certain neurological disorders using a regional technique.

A regional technique for the study of curare sensitivity has been applied to patients with Duchenne type muscular dystrophy, myotonic disorders, certain lower motor neurone disorders, to patients with weakness in the arm after hemiplegia, to patients with hyper-reflexia and hypertonia without weakness, and to Parkinsonism. In the dystrophy patients, sensitivity to curare differs from normal controls in that the neuromuscular block persists. The possibilities that this latent defect of neuromuscular transmission is the result of acetylcholine deficiency due to a prejunctional defect or the result of alterations in the property of the postjunctional membrane are discussed. In the myotonic and lower motor neurone disorders, curare sensitivity was similar to that of normal controls. After hemiplegia, the affected side shows resistance to curare when compared with the unaffected side. In states of hyper-reflexia and hypertonia, however, the sensitivity to curare is greater than in normal controls. In Parkinsonism, sensitivity is similar to that of the controls. The results in upper motor neurone lesions are discussed in relation to the dependence of neuromuscular transmission upon the motor neurone, which, in turn, is dependent upon descending impulses.

Action Potentials↗
PubMed1992

Molecular genetics and clinical aspects of inherited disorders of nerve and muscle.

Rapid progress has been made in elucidating the molecular genetic basis of several neuromuscular disorders in the past year. Candidate genes have been identified or analysed in hereditary motor and sensory neuropathy (HMSN) type I, X-linked bulbospinal neuronopathy and non-dystrophic myotonic disorders, and further mutations causing amyloidosis have been identified. A familial amyotrophic lateral sclerosis (ALS) locus maps to chromosome 21 in some families, and the chronic childhood spinal muscular atrophy (SMA), facioscapulohumeral muscular dystrophy (FSHD) and malignant hyperthermia loci have been localized more precisely.

Amyloidosis↗
PubMed1979

Myopathies.

This paper reviews the recent advances in our knowledge of muscle disease. The use of muscle biopsy for diagnosis is discussed. The etiology, pathogenesis, and treatment of polymyositis/dermatomyositis are considered. The author discusses the clinical patterns, inheritance, and pathogenesis of progressive muscular dystrophies, especially Duchenne muscular dystrophy; myotonic disorders; glycogen storage diseases; disorders of lipid metabolism; mitochondrial diseases; and congenital muscle diseases. (Neurosurgery, 5: 747--758, 1979).

Dermatomyositis↗
PubMed1977

Weakness in myotonic syndromes.

Muscle weakness occurs in a number of myotonic syndromes, including those in which muscle bulk is preserved. The possible causes of muscle weakness may be considered in terms of the different stages of the electromechanical activation process and defects in the contractile machinery. In individual myotonic disorders the ability to identify the origin of the muscle weakness (whether neurogenic or myogenic) and the functional level at which the defect occurs would assist the choice of rational treatment.

Action Potentials↗
PubMed1977

The declining electrical response of muscle to repetitive nerve stimulation in myotonia.

The electrical response of muscle to repetitive nerve stimulation was studied in patients with various myotonic disorders. A decrementing response was common but not invariable finding, and was unrelated to the severity or diagnosis. The decrement either continued throughout the period of stimulation or "leveled off", sometimes being followed by an increment. If it occurred at low rates of stimulation, a greater decrement occurred at higher rates, usually after a shorter latent period. It was not related consistently to the presence of weakness, but in patients with myotonia congenita it was more conspicuous and elicited by lower rates of stimulation when transient weakness was a feature of the history.

Adolescent↗
PubMed1992

Treatment of myotonia with antiarrhythmic drugs.

The effects of disopyramide, phenytoin, mexiletine, and tocainide were compared in 30 patients with myotonic disorders. The severity of myotonia was assessed by clinical and electromyographic criteria at the end of each treatment phase lasting four weeks. Mexiletine (MXT) and tocainide (TCD) were found to be the most potent antimyotonic agents. The antimyotonic efficacy of MXT and TCD is explained by their fast-blocking effect on voltage-dependent sodium channels in the muscle membrane. The benefits of myotonia control with pharmacological agents must be weight against the risk of therapy in the individual patient. Because of the risks of hematologic problems, TCD is not recommended by us for the treatment of myotonia.

Adolescent↗
PubMed1975

Muscle hypertonus after intravenous suxamethonium: A clinical problem.

Hypertonus of masseter and chest wall muscle in one patient following intravenous suxamethonium is reported. Subsequent investigations including electromyography and muscle biopsy with in vitro pharmacological testing failed to reveal any abnormality to account for the response. The clinical problems presented to the anaesthetist when suxamethonium-induced hypertonus occurs are discussed. The relationship between a hypertonic reaction to suxamethonium and neuromuscular disease (including myotonic disorders and the malignant hyperpyrexia myopathy) is considered.

Adult↗
PubMedDate not supplied

[Pharyngo-esophageal motility disorders in Steinert's myotonic dystrophy. Description of a case presenting with dysphagia].

In Myotonic Dystrophy symptoms of gastrointestinal dysfunction may dominate the clinical picture or they may be manifested long before the musculoskeletal disturbances become apparent. A case of Myotonic Dystrophy in a 26-year-old woman with dysphagia as the symptom of clinical presentation is reported. Manometric investigations demonstrated motor dysfunctions in pharynx and in proximal, middle and distal portions of the esophageal body, indicating both striated and smooth muscle involvement. The pathophysiology of the esophageal motility disorders in Myotonic Dystrophy and the related therapeutic problems are briefly discussed.

Adult↗
PubMedDate not supplied

Recessive congenital myotonia and pregnancy.

There is a group of genetic disorders of muscle associated with myotonia. Congenital myotonia, usually a benign disorder and myotonic dystrophy, potentially a serious disorder, belong to this group. Uterine recordings during labor in patients with congenital myotonia have not been previously reported. These records have been abnormal in patients with myotonic dystrophy which has been associated with serious obstetric complications. A case of congenital myotonia in pregnancy is reported. The record of uterine contractions was normal. Although the patient delivered a stillborn male, the etiology of the intrauterine fetal demise is obscure.

Adolescent↗
PubMed1992

[Central nervous system disorders in patients with myotonic dystrophy--in relation to respiratory dysfunction].

Although central nervous system (CNS) involvement, such as intellectual impairment simulating dementia, in myotonic dystrophy (MyD) has been well documented, the cause of this condition remains unclear. In has been reported that the progressive cases of MyD are often accompanied with respiratory disturbance and sleep apnea syndrome (SAS). We studied the relation between CNS involvement and respiratory disorders in 15 MyD patients. They consisted of 10 males and 5 females with ages ranging from 21 to 58 years (average 46 +/- 8.4 years old). Arterial blood gas (ABG) analysis, respiratory function test, and monitoring of arterial oxygen saturation (SaO2) during sleep were carried out. In some cases abnormal respiration during sleep was analyzed with polysomnography. For an assessment of CNS involvement the following examinations were performed; intelligence quotient (WAIS-IQ); electroencephalography (EEG); brain computed tomography (CT); and cerebrospinal fluid (CSF) levels of neuron-specific enolase (NSE), S-100b and creatine kinase BB isoenzyme (CK-BB) which were estimated by using enzyme immunoassay. ABG analysis demonstrated the presence of hypercapnia (PaCO2 > 45 torr) during wakefulness in MyD patients. During sleep 14 of the 15 patients showed frequent desaturation phenomenon (SaO2 < 90%), indicating the episodic hypoxemia. Polysomnographic study revealed the occurrence of SAS of both obstructive and central types in all the cases examined. IQ test disclosed intellectual impairment in 80% of the 15 patients, and EEG showed slowing of basic rhythm in the majority of the cases. On brain CT both enlarged ventricles and dilated sulci were commonly observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Molecular analysis for the myotonic dystrophy mutation in neuromuscular disorders.

A variable expansion of an unstable CTG repeat has been identified as the causal mutation for myotonic dystrophy. Standard molecular genetic techniques can now supplement traditional assessment protocols in a variety of clinical neurological situations where diagnostic uncertainty prevailed. Southern analysis using DNA probes which identify the expanded sequence, supplemented by direct PCR analysis for repeat number, provides a specific sensitive diagnostic test for myotonic dystrophy.

Adult↗
PubMed1975

[Heterochronia of nerve fibers in man. Diagnostic value: initial results].

A classical physiological observation not usually apparent with methods used for detecting nerve potential in man, heterochronia of the nerve fibres is often found in extraordinary circumstances with considerably higher than normal frequence : mainly in muscular disorders, in particular myotonic dystrophy ; more incidentally in disorders of muscle tone. The authors draw attention to certain sources of error which could lead to wrong diagnosis of heterochronia and emphasize that these are only the initial results of research which needs to be pursued further.

Electric Stimulation↗