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PubMed2005

Origin of ICU acquired paresis determined by direct muscle stimulation.

BACKGROUND: Acquired diffuse paresis in an intensive care unit (ICU) can result from critical illness myopathy or polyneuropathy. Clinical examination and conventional neurophysiological techniques may not distinguish between these entities. OBJECTIVE: To assess the value of direct muscle stimulation (DMS) to differentiate myopathic from neuropathic process in critically ill patients with diffuse severe muscle weakness. METHODS: 30 consecutive patients with ICU acquired diffuse motor weakness were studied. Responses of the right deltoid and tibialis anterior muscles to DMS and to motor nerve stimulation (MNS) were studied and compared with results of conventional nerve conduction studies and concentric needle electromyography (EMG). An original algorithm was used for differential diagnosis, taking into account first the amplitude of the responses to DMS, then the MNS to DMS amplitude ratio, and finally the amplitude of the sensory nerve action potentials recorded at the lower limbs. RESULTS: Evidence of neuropathy and myopathy was found in 57% and 83% of the patients, respectively. Pure or predominant myopathy was found in 19 patients. Other results were consistent with neuromyopathy (n = 5) and pure or predominant neuropathy (n = 2). Four patients had normal results with stimulation techniques, but spontaneous EMG activity and raised plasma creatine kinase suggesting necrotic myopathy. CONCLUSIONS: A neurophysiological approach combining DMS and conventional techniques revealed myopathic processes in a majority of ICU patients. Reduced muscle fibre excitability may be a leading cause for this. The diagnosis of myopathy in ICU acquired paralysis can be established by a combination of DMS, needle EMG, and plasma creatine kinase.

Adolescent↗

PubMed1999

[A case of motor and sensory polyneuropathy with retinitis pigmentosa and diffuse idiopathic skeletal hyperostosis].

We here report a 53-year-old man who presented with motor and sensory polyneuropathy, retinitis pigmentosa and diffuse idiopathic skeletal hyperostosis (DISH). He had a 15-year history of diabetes mellitus (DM). Visual impairment appeared at 17 years of age. Since age 47, he showed a slowly progressive sensory impairment and muscle weakness of the extremities. On neurological examination, retinitis pigmentosa and severe muscle atrophy, muscle weakness and sensory disturbance of all modalities in the distal portions of all four extremities were observed. Deep tendon reflexes were absent. A plain X-P showed diffuse ossification of the spinal and extraspinal ligaments. The motor nerve conduction velocities were severely reduced and no sensory nerve action potentials were evoked. The CSF examination revealed an increased protein level without pleocytosis. The sural nerve biopsy showed a marked onion bulb formation and a loss of the myelinated nerve fibers, which could not be solely explained by DM. As the phytanic acids levels, beta-lipoprotein, lactate and pyruvate in the sera were within the normal ranges, Refsum disease, Bassen-Kornzweig syndrome and mitochondrial diseases were unlikely in this patient. The presence of demyelinating and axonal polyneuropathy in this patient may have been caused by a common metabolic disturbance which produced both retinitis pigmentosa and DISH.

Diabetes Complications↗

PubMed1989

Fiber type disproportion in nemaline myopathy.

A 21-year-old female with nemaline myopathy and concomitant dysmorphism characteristic of elongated face, high arched palate, scoliosis and pes cavus is reported. Neurological examination revealed mild bilateral facial weakness, moderate proximal muscle weakness, and generalized absence of deep tendon reflexes in all limbs. Electromyography disclosed a moderate amount of fibrillations and positive, and short duration polyphasic waves. A biopsied specimen, obtained from the vastus lateralis muscle, showed abundant nemaline bodies from pathological study, and electron dense particles on Z-line by electron-microscopic examination. In addition, a twin-peaked population curve in fiber diameter, selective type 1 muscle fiber atrophy (34.3 um +/- 8.7 um in diameter) as well as type II fiber hypertrophy (117.0 +/- 55.8 um in diameter), and type 1 fiber grouping were observed. We report the case and raise another important clue of fiber type disproportion in the diagnosis of nemaline myopathy.

Adult↗

PubMed1987

Pathophysiology of cough.

Mucous secretions are normally removed by ciliary beating. When this defense mechanism is impaired or overwhelmed by increased secretions, cough then becomes an important means of secretion removal. For cough to be effective, the linear velocity of gas traveling through the airways should be high. Since the linear velocity of gas is related to flow and the cross-sectional area of the airways, cough is most effective when expiratory flows are great (effort independent) and dynamic compression (effort dependent) leads to a reduction of the cross-sectional area of the larger downstream airways. Cough failures may be related to either inadequate generation of expiratory flow rates (that is, in obstructive lung disease or inspiratory muscle weakness), failure to dynamically compress the airways (that is, in expiratory muscle weakness or increased collapsibility), alterations in airway geometry (that is, in bronchiectasis), or abnormal quantity or quality of mucous production (that is, in chronic bronchitis).

Cough↗

PubMed2002

[From gene to disease; the dystrophin gene involved in Duchenne and Becker muscular dystrophy].

Duchenne and Becker muscular dystrophy (DMD and BMD) are progressive disorders, which almost exclusively affect males. DMD is the more severe type with an onset at 2-3 years of age. Patients become wheelchair-bound before the age of 13 and often die due to cardiac arrest or respiratory insufficiency. BMD, a more varying phenotype which may overlap with limb girdle muscular dystrophy (LGMD), has a less severe muscle weakness which starts later than in DMD patients. DMD carriers may show some muscle weakness. The dystrophin gene (2.4 Mb), known to be involved in DMD/BMD, codes for a 427 kilodalton muscle-specific protein named dystrophin as well as several tissue-specific isoforms. Dystrophin, as part of a membrane-bound complex of proteins, connects the cytoskeleton of the muscle cell to the extracellular matrix. Since 1985, when highly reliable carrier detection and prenatal diagnosis at the DNA level became possible, over 250 prenatal tests have been performed. Molecular genetic analysis, highlighted a phenomenon called germinal mosaicism, which explains the recurrence of de novo mutations and led to the discovery of the so-called reading-frame rule, which helps to discriminate between DMD and BMD. Fifteen years after the discovery of the dystrophin gene, mutations can be detected in 95% of the patients, while the remaining 5% are still hiding within this very large gene.

Chromosome Mapping↗

PubMed1988

Myopathies caused by disorders of lipid metabolism.

Myopathies due to abnormalities in fatty acid oxidation fall into several clinical categories. Rhabdomyolysis occurring with prolonged stress on the muscle is frequently found to be caused by carnitine palmityl transferase deficiency. The association of systemic metabolic derangements and muscle weakness is seen with defects in long-chain acyl-CoA dehydrogenase, medium-chain acyl-CoA dehydrogenase, or short-chain acyl-CoA dehydrogenase. The latter three are often associated with low muscle carnitine concentrations. In patients who present with only muscle weakness and triglyceride storage, muscle carnitine concentrations may be either normal or reduced.

Fatty Acids↗

PubMed1993

Ocular myasthenia gravis. A critical review of clinical and pathophysiological aspects.

Myasthenia gravis (MG) is probably the best studied autoimmune disease caused by autoantibodies against the acetylcholine receptor (AChR) at the neuromuscular junction, subsequently leading to abnormal fatigability and weakness of skeletal muscle. Extraocular muscle weakness with droopy eyelids and double vision is present in about 90% of MG patients, being the initial complaint in about 50%. In approximately 20% of the patients the disease will always be confined to the extraocular muscles. The single most important diagnostic test is the detection of serum antibodies against AChR which is positive in 90% of patients with generalized MG, but only in 65% with purely ocular MG. Electromyographic studies and the Tensilon test are of diagnostic value in clear-cut cases, but may be equivocal in purely ocular myasthenia, especially the latter not rarely producing false-positive results. Treatment response to corticosteroids and anti-cholinesterase agents is satisfactory in many patients with ocular MG, however other immunosuppressive drugs may also be needed. Pathogenetically relevant steps of the underlying autoimmune process have been elucidated during the last few years; nevertheless a number of questions remain open, especially what starts off the autoimmune process, and why are eye muscles so frequently involved in MG?

Autoantibodies↗

PubMed2000

Phenotypic and genetic study of a family with hereditary sensory neuropathy and prominent weakness.

We report the clinical and electrophysiological features of six members of a French family with a dominantly inherited motor and sensory neuropathy. Mean age at onset was 33.6 +/- 9.1 years. Mean age at examination was 55.5 +/- 13.3 years. Clinical presentation combined symptoms of hereditary sensory and autonomic neuropathy type I (HSAN-I) with prominent distal muscle weakness. Five male patients presented with sensory symptoms involving the distal part of the limbs, especially the legs. All but one had histories of trophic alterations, consisting of poorly healing foot ulcers. Muscle weakness and wasting were always present, often severe, and mainly affected dorsiflexion of the toes and feet. One obligate female carrier aged 65 was clinically asymptomatic. Electrophysiological findings were consistent with a distal axonal motor and sensory neuropathy. Results of linkage analysis excluded the Charcot-Marie-Tooth 2A (CMT2A) and CMT2B loci and suggested the possibility of a linkage to HSAN-I locus on 9q22.1-q22.3.

Adult↗

PubMed2004

[Two children seriously weakened by myasthenia].

Two boys, aged 2 and 11 years, presented with fever and muscle weakness that resulted in respiratory insufficiency. A physical examination and additional tests confirmed the diagnosis 'myasthenia'. Acetyl cholinesterase-inhibitor therapy had a favourable effect. Myasthenia is a diagnosis that should be considered for every child presenting with muscle weakness of unknown origin.

Child↗

PubMed1999

Electroneurophysiological studies in rats of acute dimethoate poisoning.

In order to investigate the mechanism of muscular weakness in the intermediate myasthenia syndrome (IMS) following acute organophosphate poisoning, the effect of dimethoate on the neuromuscular transmission was studied in rats by using the electrical stimulation single fiber electromyography (SSFEMG) and repetitive nerve stimulation (RNS). The results showed that there was a prolongation of mean consecutive difference (MCD) of the latencies of single fiber potential shown by SSFEMG in dimethoate intoxicated rats during the presence of muscle weakness when the stimuli were given at 10 or 20 Hz, and there was a remarkable decrement of compound muscle action potential (CMAP) of gastrocnemius muscle evoked by RNS on the sciatic nerve at 20 Hz in some rats with myasthenia. The frequency of neuromuscular transmission abnormalities detected by SSFEMG was significantly higher than those detected by RNS. This study demonstrates that the SSFEMG is a more sensitive electrophysiological method in the detection of neuromuscular transmission block occurred in rats of acute organophosphate poisoning with muscle weakness.

Acute Disease↗

PubMed1991

Asymmetrical weakness in polymyositis associated with neuropathic involvement.

Peripheral nerve involvement is rare in polymyositis and dermatomyositis. We describe a patient in whom the clinical appearance was suggestive of a markedly asymmetrical presentation of polymyositis. Nerve conduction studies, however, were consistent with multiple neuropathies and suggest that neurological involvement may have been the basis of the asymmetrical weakness. Both the muscle weakness and the neurological abnormalities resolved with corticosteroid therapy. This case illustrates a previously undescribed neurological complication of polymyositis.

Humans↗

PubMed2003

CBA/J mice infected with Trypanosoma cruzi: an experimental model for inflammatory myopathies.

Idiopathic inflammatory myopathies are inflammatory disorders of unknown origin, characterized by muscle weakness. The aim of our study was to establish and characterize an animal model for chronic inflammatory myopathy which would permit investigations of the role of T-cells in chronic myositis as well as of the mechanisms for muscle weakness in chronic inflammatory muscle disorders. CBA/J mice were infected with the protozoan parasite Trypanosoma cruzi. Immunohistochemistry was used to characterize the distribution and composition of inflammatory infiltrates, and demonstrated a chronic focal inflammation comprised mainly of T-cells and macrophages in infected mice. The inflammatory infiltrates were predominantly found in the endomysium and, to a lesser extent, in perivascular areas. CD8(+) T-cells were found to have invaded nonnecrotic muscle fibers. Degenerating muscle fibers were also found, as well as an increased number of central muscle nuclei. The murine model described in this article may be useful in studying certain aspects of idiopathic inflammatory myopathies such as the role of T-cells in chronic muscle inflammation and chronic myocytotoxicity.

Animals↗

PubMed2001

[A patient with myopathy due to preclinical Cushing syndrome].

A 57 year-old man with a history of diabetes mellitus was admitted to our hospital for the complaint of slowly progressive muscle weakness involving proximal limbs and head dropping. His serum CK level was within normal range, and muscle biopsy showed no inflammatory changes. To rule out myasthenia gravis, computerized tomography was done for the detection of thymoma, and detected an adrenal tumor in stead. He was not over-weighted, and his morning plasma levels of ACTH and cortisol were within normal ranges. Additional hormonal examinations revealed daily autonomous hypersecretion of cortisol. He received diagnosis of preclinical Cushing syndrome. After resection of the tumor, muscle weakness improved and his diabetes mellitus was controlled better. The muscle symptoms seem to be related with steroid myopathy. Preclinical Cushing syndrome should be included as a differential diagnosis for myopathy of unknown etiology.

Adrenal Gland Neoplasms↗

PubMed2004

Hypoglycosylation of alpha-dystroglycan in patients with hereditary IBM due to GNE mutations.

Hereditary inclusion body myopathy (HIBM) is an adult onset neuromuscular disorder associated with mutations in the gene UDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine kinase (GNE), whose product is the rate limiting bi-functional enzyme catalyzing the first two steps of sialic acid biosynthesis. Loss of GNE activity in HIBM is thought to impair sialic acid production and interfere with proper sialylation of glycoconjugates, but it remains unclear how such a defect would lead to muscle destruction and muscle weakness. Hypoglycosylation of alpha-dystroglycan, a central protein of the skeletal muscle dystrophin-glycoprotein complex, results in disturbed interactions with extracellular matrix proteins. This has recently been identified as the pathomechanism involved in several congenital muscular dystrophies. We examined the glycosylation status of alpha-dystroglycan in muscle biopsies of four HIBM patients of non-Iranian Jewish origin (one American, two Indians, and one Greek). Two of these patients carry novel compound heterozygous GNE mutations on exon 2 and exon 9. All four muscle biopsies showed absent or markedly reduced immunolabeling with two different antibodies (VIA4 and IIH6) to glycosylated epitopes of alpha-dystroglycan. Normal labeling was found using antibodies to the core alpha-dystroglycan protein, beta-dystroglycan, and laminin alpha-2. These findings resemble those found for other congenital muscular dystrophies, suggesting that HIBM may be a "dystroglycanopathy," and providing an explanation for the muscle weakness of patients with GNE mutations.

Adult↗

PubMed2001

[Two adult cases of nemaline myopathy presenting different clinical symptoms and CT findings].

We report herein two cases of nemaline myopathy which showed peculiar muscle involvement and clinical symptoms. Case 1: A 44-year-old woman had developed gradual woresening of muscle weakness. Neurologically, only flexion of her neck was found to be weak. Her muscular CT revealed mild atrophy of four extremities and the sternocleidomastoid muscles. Histological examinations with Gomori-trichrome staining revealed tiny structures whose form was compatible with nemaline rods. Moreover, electronmicroscopic examination demonstrated the lattice pattern of electron-dense structures, and they also appeared to possess structural continuity with the Z-band. Case 2: A 56-year-old woman visited our department because of neck pulsations. Neurological examinations revealed bilateral hearing disturbance, marked atrophy of neck muscles, muscle weakness in four extremities and hypoactive deep tendon reflexes. She also exhibited steppage and waddling gaits. Her muscular CT demonstrated degenerative processes in the neck muscles(splenius muscles and semispinal muscles), trapezius muscles, para-spinal muscles, deltoid muscles and gluteal muscles. Among them, the para-spinal muscles and extensor muscles of the lower limbs showed marked degeneration and had been partly replaced by fatty tissues. A muscle biopsy was performed, and the presence of nemaline rods was confirmed by Gomori-trichrome staining. Although these two cases could be diagnosed as nemaline myopathy, the clinical symptoms and muscular CT findings were not quite the same. Whether these differences might simply indicate different clinical phases during the disease progression or be of further pathogenic significance still remains unclear. Additionally, since long-term follow-up studies of nemaline myopathy are quite rare, further follow-up examinations of these cases are necessary in order to understand the clinical and pathological alterations of nemaline myopathy.

Adult↗

PubMed1982

Motor dysfunction in spontaneous thymoma rats, Buffalo/Mna.

The muscle responsiveness of rats of Buffalo/Mna strain with spontaneous thymoma (Mna rats) was investigated in vivo electrophysiologically and pharmacologically in order to determine the principal cause of the muscle weakness and fatigability. Hindlimb muscles of these rats exhibited a lesser contractility and a greater fatigability during repetitive nerve stimulation than those of rats of another strain, ACI. Nevertheless, there was no difference in the time course of amplitude of evoked electromyograms between Mna and ACI rats. According to the test of drug sensitivity, Mna rats were much less sensitive to curare than ACI rats. Sensitivity to 4-aminopyridine was normal. In conclusion, Mna rats showed an increased fatigability and weakness of the muscle. The principal cause seems to be involved in contractile mechanisms subsequent to muscle cell membrane. The reduced sensitivity to curare suggests a possibility of some change at the site of neuro-muscular junction.

Animals↗

PubMed2007

Muscle strength and muscle training after stroke.

For many individuals who have experienced a stroke, muscle weakness is the most prominent impairment. Both the theoretical and statistical relationships between muscle weakness and performance at functional activities suggest that weakness may be an appropriate target for therapeutic interventions. Researchers investigating the outcomes of strengthening regimens after stroke have routinely shown that resistance exercise leads to increased muscle strength, but that strength is typically measured using the same maneuvers that were used in training. Evidence supporting the use of strengthening regimens to reduce limitations in functional activity is equivocal.

Activities of Daily Living↗

PubMed2005

Progressive scoliosis in central core disease.

Central core disease (CCD) is a rare congenital myopathy with autosomal dominant inheritance. Here, we report on two cases of progressive scoliosis in CCD, pointing out the value of a muscle biopsy to establish the correct diagnosis. The first case involves a 13-year-old boy with severe progressive scoliosis and joint contractures. The patient was initially diagnosed with arthropgryposis multiplex congenita. The second case involves a 45-year-old man with severe scoliosis that had slowly progressed over the years. Both patients suffered from unexplained muscle weakness and severe restriction of pulmonary function. The correct diagnoses were established through muscle biopsies taken from the paravertebral musculature during scoliosis surgery. Correction of the spinal deformities was achieved through posterior instrumentation in both patients, with prior anterior release in one patient. Although scoliosis is a common feature in CCD, the correct diagnosis can be missed in scoliosis patients. Therefore, we recommend a muscle biopsy in patients with scoliosis, unexplained muscle weakness and multiple joint problems.

Adolescent↗