Electromyographic analysis in spinal progressive muscular atrophy, juvenile unilateral muscular atrophy, neural progressive muscular atrophy and myeloradiculoneuritis.
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Adolescent↗
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Results for “Muscular Atrophy, Spinal”
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Motor unit behavior in canine motor neuron disease.
Hereditary canine spinal muscular atrophy (HCSMA) is an autosomally dominant disease of motor neurons that shares many pathological features with human motor neuron disease. A particularly striking feature of the affected, accelerated phenotype (homozygous HCSMA) is that profound weakness develops before appreciable motor neuron cell death occurs (Cork et al., 1989a), implying that motor unit functional defects occur initially. The purpose of this study was to identify the site of these defects and characterize their nature. In most young homozygotes (2-3 months postnatal), motor neurons were encountered that could support orthodromic action potential propagation to the muscle but did not activate muscle fibers. The tetanic forces of innervated motor units in young homozygotes tended to be smaller than those in closely age-matched clinically normal animals. In older homozygotes (approximately 4.5 months, postnatal), all motor neurons sampled were capable of activating muscle fibers, but many motor units displayed abnormal behavior including an inability to sustain force output during high frequency activation. Motor units exhibiting tetanic failure also showed proportionately greater twitch potentiation than nonfailing units of similar unpotentiated twitch amplitude. Tetanic failure and large potentiation tended to occur in motor units that possessed the slowest contraction speeds. These results indicate that motor neuron functional defects in HCSMA appear initially in the most distal parts of the motor axon and involve defective neurotransmission. The possible roles of distal nerve degeneration, motor terminal sprouting, and synaptic transmission in causing these deficits are considered.
Action Potentials↗
[Double discharges of motor unit -- importance in electromyographic diagnosis].
The prevalence of double-discharge motor unit potentials (DD) in patients with neuromuscular disorders was analysed. Concentric needle electromyography was performed in 29 cases of spinal muscular atrophy (SMA), 25 cases of amyotrophic lateral sclerosis (ALS), 30 cases of Duchenne muscular dystrophy (DMD) and in 20 healthy controls. The DD were recorded only in the patients with neurogenic lesion, mainly in the ALS group. The diagnostic yield of DD in early detection of neurogenic lesion is discussed.
Amyotrophic Lateral Sclerosis↗
A likelihood approach to calculating risk support intervals.
Genetic risks are usually computed under the assumption that genetic parameters, such as the recombination fraction, are known without error. Uncertainty in the estimates of these parameters must translate into uncertainty regarding the risk. To allow for uncertainties in parameter values, one may employ Bayesian techniques or, in a maximum-likelihood framework, construct a support interval (SI) for the risk. Here we have implemented the latter approach. The SI for the risk is based on the SIs of parameters involved in the pedigree likelihood. As an empirical example, the SI for the risk was calculated for probands who are members of chronic spinal muscular atrophy kindreds. In order to evaluate the accuracy of a risk in genetic counseling situations, we advocate that, in addition to a point estimate, an SI for the risk should be calculated.
Female↗
Effects of 4-aminopyridine on muscle and motor unit force in canine motor neuron disease.
Hereditary Canine Spinal Muscular Atrophy (HCSMA) is an autosomal dominant disorder of motor neurons that shares features with human motor neuron disease. In animals exhibiting the accelerated phenotype (homozygotes), we demonstrated previously that many motor units exhibit functional deficits that likely reflect underlying deficits in neurotrans-mission. The drug 4-aminopyridine (4AP) blocks voltage-dependent potassium conductances and is capable of increasing neurotransmission by overcoming axonal conduction block or by increasing transmitter release. In this study, we determined whether and to what extent 4AP could enhance muscle force production in HCSMA. Systemic 4AP (1-2 mg/kg) increased nerve-evoked whole muscle twitch force and electromyograms (EMG) to a greater extent in older homozygous animals than in similarly aged, symptomless HCSMA animals or in one younger homozygous animal. The possibility that this difference was caused by the presence of failing motor units in the muscles from homozygotes was tested directly by administering 4AP while recording force produced by failing motor units. The results showed that the twitch force and EMG of failing motor units could be significantly increased by 4AP, whereas no effect was observed in a nonfailing motor unit from a symptomless, aged-matched HCSMA animal. The ability of 4AP to increase force in failing units may be related to the extent of failure. Although 4AP increased peak forces during unit tetanic activation, tetanic force failure was not eliminated. These results demonstrate that the force outputs of failing motor units in HCSMA homozygotes can be increased by 4AP. Possible sites of 4AP action are considered.
4-Aminopyridine↗
SMA type 2 unrelated to chromosome 5q13.
We describe two brothers with clinical and histological findings of type 2 spinal muscular atrophy (SMA) associated with small head circumference (<2%) and normal cognitive development. No survival motor neuron (SMN) or neuronal apoptosis-inhibitory protein (NAIP) deletions were detected in these sibs, and they were discordant for the haplotypes determined by DNA markers flanking the 5q13 SMA locus. These findings support the presence of a distinct anterior horn disease unrelated to 5q13. This entity may have either autosomal recessive or X-linked inheritance.
Child, Preschool↗
Lipid disturbances associated with spiral muscular atrophy. Clinical, electromyographic, histochemical, and lipid studies.
Twelve patients with juvenile- and adult-onset spinal muscular atrophy have been studied. Eleven of the twelve patients had either type II, type IV, or borderline abnormal phenotypes, suggesting a possible relationship between serum lipid abnormalities and neuronal degeneration in the spinal muscular atrophies. Muscle enzyme histochemical studies provided valuable diagnostic information. Extensor toe signs and talipes cavus were common clinical observations.
Adenosine Triphosphatases↗
Rehabilitative operation for motor neuron disease: tendon transfer for segmental muscular atrophy of the upper extremities.
Segmental spinal muscular atrophy of adolescence is a clinical syndrome that can be distinguished from the more common forms of motor neuron disease. A patient with this syndrome who was no longer able to care for herself is described. After selective tendon transfers in her right upper extremity, she has been able to perform many of the activities of daily living. This improved function has been maintained for more than 2 years. We suggest that transfer of tendons and muscles may be indicated in selected patients with slowly progressive muscular atrophy.
Activities of Daily Living↗
Motoneuron death in normal and spinal muscular atrophy-affected human fetuses.
The onset and sequence of motoneuron death in the lumbar part of spinal cord of seven control and five affected fetuses carrying deletion of exon 7 in the SMN gene were studied by light and electron microscopy. Naturally occurring motoneuron death in control fetuses was detected between 8 and 13 weeks of gestation. In affected fetuses motoneuron death was prolonged and also observed at 16 and 20 weeks of gestation. In addition, motoneurons in the affected fetuses displayed nuclear abnormalities as early as 16 weeks of gestation and the changes progressed as the affected fetuses developed and can be considered first signs of motoneuron degeneration.
Apoptosis↗
Benign monomelic amyotrophies of upper and lower limb are not associated to deletions of survival motor neuron gene.
Benign monomelic amyotrophies (BMAs) are rare conditions in which neurogenic atrophy is restricted either to the upper or lower limb. BMAs are usually sporadic, have insidious onset and slow progression followed by stabilization, are clinically confined for many years to a single limb and lack of sensory, bulbar, and pyramidal signs. Although the aetiology and pathogenesis of BMAs are unknown they are considered variants of spinal muscular atrophy with focal emphasis and a benign course. We studied 7 patients with BMAs to investigate whether they present alterations of the survival motor neuron gene (SMN) which has been found deleted or disrupted in proximal spinal muscular atrophy. All 7 patients showed the presence of both exon 7 and 8 of SMN gene. These findings indicate that deletions at the SMN locus are not present in BMA of upper and lower limb and suggest that these disorders are not only clinically but also genetically separate entities from proximal spinal muscular atrophies.
Adult↗
[Somatic mosaicism of expanded CAG trinucleotide repeat in spinal and bulbar muscular atrophy (SBMA)].
The CAG repeat in spinal and bulbar muscular atrophy (SBMA) is relatively stable in mitotic and meiotic processes as compared with other CAG repeat diseases. Previous reports indicate that SBMA does not manifest somatic mosaicism. However, detailed analysis in various tissues from 20 SBMA including 4 autopsied patients revealed the presence of the tissue-specific pattern of mosaicism. The prominent somatic mosaicism was observed in the cardiac and skeletal muscles, which are predominantly composed of postmitotic cells, and in the skin, prostate, and testis. The central nervous system (CNS) tissues, liver, and spleen showed smallest mosaicism. Such tissue-specific pattern of somatic mosaicism in SBMA is not explained by cell composition with different cell turnover rates. Other cell specific factors are likely more important for the somatic mosaicism in SBMA.
Humans↗
The "split hand" phenomenon: evidence of a spinal origin.
The clinical phenomenon of a split hand, dominant muscle atrophy in the thenar as compared to the hypothenar complex, has been used to support the theory of primary cortical degeneration in amyotrophic lateral sclerosis. However, the same phenomenon, both clinically and electrophysiologically, was observed in three diseases with a second but not first motor neuron affection: autosomal dominant spinal muscular atrophy, spinocerebellar ataxia type 3, and juvenile muscular atrophy. Neurogenic loss in a split hand distribution points to a spinal instead of cortical origin.
Adult↗
[Chronic spinal amyotrophy involving the upper limbs in young adults (O'Sullivan and McLeod syndrome). MRI study of the cervical spinal cord].
In 5 cases of sporadic spinal muscular atrophy in young adults the muscular atrophy was localized in the hands and forearms. Age at onset ranged from 7 to 20 years. The duration of the disease was less than 5 years in 3 patients and more than 15 years in 2. Electromyography showed neurogenic anomalies in all wasted muscles, denervation potentials being also present in the proximal muscles of the upper limbs and distal muscles of the lower limbs in 2 patients. Motor nerve conduction velocity and sensory nerve action potentials were normal. Advantages of a topographic classification of the distal form of chronic spinal muscular atrophy are discussed. Spinal cord MRI was performed in 4 patients with a 0.5 Tesla superconducting magnet using surface coils, using a T1-weighted spin-echo technique (ET 26 ms; RT 500 ms) and a T2-weighted spin-echo technique (ET 90, 180 ms; 2,000 ms). With the T1 technique, axial MRI sections 7 to 9 mm thick of spinal cord showed a normal image between C1 and C4, and a flattened image between C5 and T1. This was considered as a possible spinal cord segmental atrophy.
Adolescent↗
[Noncompressive myelopathy and dysglobulinemia. A fortuitous association? Discussion of 3 new cases].
Three new cases of myelopathy without compression associated with paraproteinemia are reported. The neurologic picture was that of spinal muscular atrophy in one case and chronic spinal combined sclerosis in two. The nature of the paraproteinemia is discussed: all three patients seem to have had benign monoclonal dysglobulinemia. One patient died from cardiovascular disease five years after onset, and another from complications related to decubitus seven years after onset. Postmortem examination was not possible in either case. Spinal muscular atrophy has been reported in certain carcinomas (lung, stomach, breast) and, less frequently, in macroglobulinemia. As benign dysglobulinemia is common after sixty, coincidental association cannot be outruled. However, data from the literature and the response to cancer chemotherapy in two patients suggest an original pathologic association. Recent demonstration of demyelinating neuropathies associated with benign paraproteinemia provide further evidence in support of such an association.
Aged↗
[Chronic distal spinal amyotrophy localized to the both upper limbs (O'Sullivan and McLeod type)].
A case of sporadic spinal muscular atrophy affecting the upper limbs and with a chronic course over 19 years is reported, features of the affection being similar to the rare cases reported in the literature. Distinguishing aspects of these cases are those of a particular topographical form of chronic spinal muscular atrophies: onset in adolescents or young adults, symmetrical weakness and atrophy of the small muscles of the hands sometimes extending to the forearms, a progressive and slow course, absence of sensory or pyramidal signs, normal findings on cervical cord examinations neurogenic electromyogram recordings and normal nerve conduction rates.
Arm↗
Molecular pathogenesis of spinal and bulbar muscular atrophy.
Studies of the molecular pathogenesis of spinal and bulbar muscular atrophy, as well as of the other polyglutamine repeat diseases, has led to an understanding of the role of protein accumulation in disease pathogenesis. Aggregation of the expanded repeat androgen receptor (AR), rather than playing a pathogenic role, likely reflects the insoluble nature of the misfolded AR. Proteolytic processing of the expanded AR at various stages of its metabolism may contribute to cellular toxicity through the enhancement of AR insolubility, and potentially through the disruption of normal proteolytic degradation processes. The finding that molecular chaperones not only promote solubility, but also enhance the degradation of expanded polyglutamines as well, make them promising targets for therapeutic development. Understanding the role of ligand binding in expanded AR metabolism may provide additional avenues of therapeutic manipulation as well.
Humans↗
Mutations in dynein link motor neuron degeneration to defects in retrograde transport.
Degenerative disorders of motor neurons include a range of progressive fatal diseases such as amyotrophic lateral sclerosis (ALS), spinal-bulbar muscular atrophy (SBMA), and spinal muscular atrophy (SMA). Although the causative genetic alterations are known for some cases, the molecular basis of many SMA and SBMA-like syndromes and most ALS cases is unknown. Here we show that missense point mutations in the cytoplasmic dynein heavy chain result in progressive motor neuron degeneration in heterozygous mice, and in homozygotes this is accompanied by the formation of Lewy-like inclusion bodies, thus resembling key features of human pathology. These mutations exclusively perturb neuron-specific functions of dynein.
Animals↗
[Type II spinal proximal muscular atrophy associated with modified plasma and urinary concentration of various amino acids].
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Amino Acids↗