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PubMed1989

Spinal muscular atrophy in Brown Swiss calves.

Nineteen Brown Swiss calves affected with spinal muscular atrophy were described. Weakness of the rear legs was the first sign observed at 3 to 4 weeks of age. Terminal stages were characterized by severe muscular atrophy, quadriparesis, and sternal recumbency. Bronchopneumonia was a frequent complicating disease. Microscopic changes consisted mainly of degeneration and loss of motor neurons in the ventral horns of the spinal cord. Neurogenic atrophy of muscles was a constant finding. Electron microscopy revealed accumulation of neurofilaments and mitochondria in affected neurons. The disease shares many features with Werdnig-Hoffmann disease in man and the spinal muscular atrophies of other animals.

Animals↗
PubMed1996

Spinal muscular atrophy in childhood.

Diagnosis and classification of spinal muscular atrophy (SMA) in childhood are based on clinical, electrophysiological, and histological studies. The concept of maturational arrest of motoneurons and their targets (muscle cells in SMA type I) is documented by ultrastructural and immunohistochemical data. The prolongated or markedly delayed process of muscle cell and motoneuron elimination by apoptosis seen in SMA type I is discussed according to the new finding of a gene for a neuronal apoptosis inhibitory protein that is partially deleted in children with spinal muscular atrophy.

Adolescent↗
PubMed1991

Muscle biopsy and the clinical course of infantile spinal muscular atrophy.

Eight infants with severe early infantile spinal muscular atrophy diagnosed by clinical presentation and muscle biopsy were studied. The extent of alterations in muscle histology, histochemistry, and ultrastructure did not reflect the relative severity of the clinical presentation or the course of the illness. In seven biopsies, ultrastructural studies demonstrated empty sleeves of basal lamina projecting from the surface of small myofibers. We conclude that severe infantile spinal muscular atrophy often results in myofiber atrophy similar to that found in other motor neuron diseases, and it is not solely a hypotrophic process. Muscle biopsy findings are important because they help to establish the diagnosis, but they do not help predict the severity of disease among infants with this condition.

Basement Membrane↗
PubMed2004

Characterization of Ighmbp2 in motor neurons and implications for the pathomechanism in a mouse model of human spinal muscular atrophy with respiratory distress type 1 (SMARD1).

Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is caused by recessive mutations of the IGHMBP2 gene. The role of IGHMBP2 (immunoglobulin mu-binding protein 2) in the pathomechanism of motor neuron disease is unknown. We have generated antibodies against Ighmbp2 and showed that low levels of Ighmbp2 immunoreactivity are present in the nucleus of spinal motor neurons and high levels in cell bodies, axons and growth cones. Ighmbp2 protein levels are strongly reduced in neuromuscular degeneration (nmd) mice, the mouse model of SMARD1. Mutant mice show severe motor neuron degeneration before first clinical symptoms become apparent. The loss of motor neuron cell bodies in lumbar spinal cord is followed by axonal degeneration in corresponding nerves such as the femoral quadriceps and sciatic nerve and loss of axon terminals at motor endplates. Motor neuron degeneration and clinical symptoms then slowly progress until the mice die at the age of 3-4 months. In addition, myopathic changes seem to contribute to muscle weakness and especially to respiratory failure, which is characteristic of the disorder in humans. Cultured motor neurons from embryonic nmd mice did not show any abnormality with respect to survival, axonal growth or growth cone size, thus differing from motor neurons derived from, e.g. Smn (survival motor neuron) deficient mice, the model of spinal muscular atrophy (SMA). Our data suggest that the pathomechanism in SMARD1 is clearly distinct from other motor neuron diseases such as classic SMA.

Action Potentials↗
PubMed2004

[Clinical study of 83 cases with spinal muscular atrophy in children].

OBJECTIVE: Spinal muscular atrophy (SMA) is a common autosomal recessive disorder and represents one of the most common genetic causes of death in childhood. The last 10 years have seen major advances in the field of SMA, but no curative treatment is available so far. This study aimed to analyze the clinical characteristics of SMA, improve the clinical diagnosis of SMA, and explore the importance of gene diagnosis and prenatal diagnosis of SMA by gene deletion analysis. METHODS: Totally 83 cases with SMA including 55 males and 28 females were enrolled in this study. The age was between 1 day and 14 years (average 23.7 months). The clinical characteristics and changes of electromyography were assessed in all cases. The muscular biopsy was performed in 2 of 83 cases. The deletion of survival of motor neuron gene (SMN) was detected by PCR and restriction endonuclease spectrum analysis in 13 of 83 cases. RESULTS: The 83 cases were subdivided into three clinical groups based on age of onset of symptom, age at death and achievement of certain motor milestone, 60 cases with type I, 19 cases with type II and 4 cases with type III. They were all characterized by symmetric muscle weakness (more proximal than distal) associated with atrophy, absence or marked decrease of deep tendon reflexes. Electromyographic studies showed a pattern of denervation with neither sensory involvement nor marked decrease of motor nerve conduction velocities in all cases. Muscle biopsy provided evidence of skeletal muscle denervation with groups of atrophy in 2 cases. The SMN detection revealed deletion of exon 7 and exon 8 in 11 of 13 cases, only lacking exon 7 in 1 of 13 cases and lacking exon 8 in 1 of 13 cases. CONCLUSION: SMA is characterized by degeneration of lower motor neuron associated with muscle paralysis and atrophy. The definite diagnosis of SMA will rely on the typical clinical characteristics, changes of electromyogram and muscle biopsy and gene deletion analysis. Gene diagnosis of SMA can provide a basis for prenatal diagnosis which is of great importance in preventing SMA.

Adolescent↗
PubMed1989

Animal models of amyotrophic lateral sclerosis and the spinal muscular atrophies.

The causes of human amyotrophic lateral sclerosis (ALS) and the spinal muscular atrophies (SMA) are, almost without exception, unknown. This ignorance has stimulated the search for animal models to obtain insight into the etiology, pathogenesis and biochemical mechanisms underlying the human disorders. None of the 38 animal models, described in this review, provides an exact animal copy of a specific human motor neuron disease. Most of the models reproduce certain structural or physiological aspects of their human counterparts. The various experimental models can be classified according to the pathogenetic mechanism involved and according to the structural changes observed. Models based on experimentally induced disease, include heavy metals and trace elements (lead intoxication in guinea pigs, rabbits, rats, cats and primates; mercury intoxication in rats; aluminium intoxication in rabbits; swayback in goat kids; calcium and magnesium deficient rabbits and primates and calcium deficient cynomolgus monkeys), toxins (IDPN, vincristine, vinblastine, podophyllotoxin, colchicine, maytansine, maytanprine, L-BMAA, lectins, adriamycin), nutritional factors (ascorbic acid deficient guinea pigs), virus infection (spongiform polioencephalomyelitis, attenuated poliovirus, lactate dehydrogenase-elevating virus), and immunological factors (immunization with motor neurons). Hereditary models comprise hereditary canine spinal muscular atrophy, hereditary neurogenic amyotrophy in the pointer dog, Stockard paralysis, Swedish Lapland dog paralysis, "wobbler" mouse, "shaker" calf, and hereditary spinal muscular atrophy in zebra foals, crossbred rabbits,

Amyotrophic Lateral Sclerosis↗
PubMed2005

The survival of motor neurons protein determines the capacity for snRNP assembly: biochemical deficiency in spinal muscular atrophy.

Reduction of the survival of motor neurons (SMN) protein levels causes the motor neuron degenerative disease spinal muscular atrophy, the severity of which correlates with the extent of reduction in SMN. SMN, together with Gemins 2 to 7, forms a complex that functions in the assembly of small nuclear ribonucleoprotein particles (snRNPs). Complete depletion of the SMN complex from cell extracts abolishes snRNP assembly, the formation of heptameric Sm cores on snRNAs. However, what effect, if any, reduction of SMN protein levels, as occurs in spinal muscular atrophy patients, has on the capacity of cells to produce snRNPs is not known. To address this, we developed a sensitive and quantitative assay for snRNP assembly, the formation of high-salt- and heparin-resistant stable Sm cores, that is strictly dependent on the SMN complex. We show that the extent of Sm core assembly is directly proportional to the amount of SMN protein in cell extracts. Consistent with this, pulse-labeling experiments demonstrate a significant reduction in the rate of snRNP biogenesis in low-SMN cells. Furthermore, extracts of cells from spinal muscular atrophy patients have a lower capacity for snRNP assembly that corresponds directly to the reduced amount of SMN. Thus, SMN determines the capacity for snRNP biogenesis, and our findings provide evidence for a measurable deficiency in a biochemical activity in cells from patients with spinal muscular atrophy.

Animals↗
PubMed1981

Diaphragm pacing in spinal muscular atrophy: case report.

A patient with a diagnosis of intermediate or benign spinal muscular atrophy was severely incapacitated from respiratory complications and alveolar hypoventilation and was confined to mechanical ventilatory support. After extensive diagnostic evaluation of her pulmonary status, including transcutaneous stimulation of the phrenic nerves associated with nasogastric and surface electrode recording of the diaphragmatic response, this patient had a phrenic neurostimulation system implanted bilaterally for diaphragm pacing. Although spinal muscular atrophy has not been previously recognized as an indication for diaphragm pacing, her subsequent social, physical, and psychological improvement indicate that it may be significantly beneficial in selected cases of alveolar hypoventilation due to spinal muscular atrophy or neuromuscular disease.

Adolescent↗
PubMed1996

Spinal muscular atrophies: recent insights and impact on molecular diagnosis.

Spinal muscular atrophies (SMA) are a group of motor neuron diseases characterized by degeneration of anterior horn cells of the spinal cord and by muscular atrophy. Childhood-onset SMA is one of the most frequent autosomal recessive diseases and a leading cause of infant mortality. The underlying biochemical defect of SMA is unknown. Recently two genes have been isolated from the critical region at 5q13, the survival motor neuron (SMN) gene and the neuronal apoptosis inhibitor protein (NAIP) gene. Both genes are frequently deleted in SMA patients. NAIP is deleted in at least 45% of severely affected patients but less frequently in the milder forms. Homozygous deletions of exon 7 of SMN are found in approximately 95% of patients independently of clinical severity. A few point mutations and microdeletions in SMN have also been reported. This high frequency of deletions makes SMN analysis an important molecular diagnostic tool for childhood-onset SMA and greatly facilitates prenatal diagnosis. SMN analysis has also proven useful for the diagnosis of adult-onset SMA and variant forms. Although questions such as phenotype-genotype correlation must still be solved, the isolation of SMN and adjacent genes constitutes an important step towards the understanding of the molecular basis of the disease.

Chromosomes, Human, Pair 5↗
PubMed1998

[X-chromosomal recessive spinobulbar muscular atrophy (Kennedy type). Description of a family, clinical aspects, molecular genetics, differential diagnosis and therapy].

The Kennedy-Syndrome is a X-linked recessive bulbospinal muscular atrophy, in some cases associated with endocrinological disturbances such as androgen resistance and diabetes mellitus. The age of onset is usually between 20 and 40. Presenting symptoms are proximal flaccid weakness, fasciculations, cramps or tremor. Disease progression is usually slow and live expectancy is normal. It is important to distinguish the Kennedy-Syndrome from amyotrophic lateral sclerosis, spinal muscular atrophy, muscular dystrophies and other types of motor neuron disease. Kennedy disease is caused by an expanded trinucleotide repeat in the androgen receptor gene. Genetic analysis allows a precise-diagnosis on an individual basis and reliable genetic counselling. An effective medical treatment does not yet exist.

Diagnosis, Differential↗
PubMed1976

[Clinical electrodiagnostic findings in peroneal muscular atrophy (author's transl)].

43 patients and 27 relatives suffering from a hypertrophic type of peroneal muscular atrophy have been examined. Following the classification of peroneal muscular atrophy by Dyck and Lambert early age of onset and considerable reduction of nerve conduction velocity served as criteria for allotting them to the hypertrophic type. In all patients a typical deformity of the foot developed before the age of 10. Among the relatives there were some without this deformity and with only slight clinical signs. Assessing consistency and thickness of peripheral nerves by palpation proved difficult and unreliable. These findings also varied considerably between members of one family. The motor nerve conduction velocity was less than one half of the normal on average. Even those patients with only minor clinical signs had a nerve conduction velocity reduced by one fifth. In about 60% of the patients there was dominant inheritance, in 3 it was recessive and in about one third nothing was known. 10 of the patients without dominant inheritance had rather severe neurologic disturbance and a kyphoscoliosis. Whether this is hypertrophic neuritis of Dejerine und Sottas is discussed. Data form the literature differ. Another common type of peroneal muscular atrophy is the neuronal type. In contrast to the hypertrophic type it generally begins in adults and nerve conduction velocity is hardly affected.

Adolescent↗
PubMed2004

Histochemical study on the changes in muscle fibers in relation to the effects of aging on recovery from muscular atrophy caused by disuse in rats.

To investigate the effects of aging on the degree of muscular atrophy caused by disuse and its recovery, we evaluated the recovery from muscular atrophy induced in both young and old rats under the same conditions. The soleus was atrophied by immobilization of the foot joint in a hindlimb and unweighting of the bilateral hindlimbs for 2 weeks, and measurement of the wet weight of muscles and biochemical examination were performed 2, 4, and 6 weeks after the removal of unweighting and fixation during the recovery period of 6 weeks. There was no difference in the degree of atrophy in the fixed soleus between the young and old rats. The recovery from atrophy was delayed in the older rats compared to the young rats. In the unfixed hindlimb, the degree of atrophy was low in both the old and young rats, and the recovery was rapid. Because the recovery from disuse muscular atrophy is delayed with aging, it is necessary to avoid unweighting and immobilization, or to reduce the period spent under such conditions.

Age Factors↗
PubMed1983

Chronic asymmetrical spinal muscular atrophy.

The clinical and neurophysiological features of 18 cases of chronic asymmetrical spinal muscular atrophy are described. These were patients presenting with asymmetrical neurogenic atrophy involving one or more limbs who had no evidence of pyramidal tract dysfunction after 3 or more years of symptoms. There were twice as many males as females and the mean age of onset of the disorder was about 32 years. None of the patients had bulbar involvement. The tendon reflexes tended to be depressed. The distribution of muscle weakness in the limbs was very variable, and only slowly progressive. In 5 cases symptoms and signs were confined to the hands and forearms. Motor nerve conduction velocities to wasted muscles were slightly reduced but there was no evidence of generalised neuropathy. A diagnosis of chronic asymmetrical spinal muscular atrophy, as opposed to that of classical motor neurone disease, is favoured by an age of onset under 40 years, an absence of pyramidal signs or bulbar involvement after 3 years or more of symptoms, and depressed or absent tendon reflexes. The 2 conditions appear to be clinically distinct and prognosis is considerably better in chronic asymmetrical spinal muscular atrophy. The aetiology of this condition in unknown; it may be of relevance that 2 patients in this series had close relatives with Werdnig-Hoffmann disease.

Adult↗