RESUMEN
The basic pathologic processes that can affect the peripheral nerve are discussed, with an emphasis on the basic findings seen on nerve biopsy. The indications and usefulness of nerve biopsy are discussed along with a review of the morphologic findings found with a variety of tissue preparation techniques. Advances, such as intradermal biopsies, which may prevent the need for standard nerve biopsies, are discussed.
Asunto(s)
Enfermedades Desmielinizantes/patología , Degeneración Nerviosa/patología , Enfermedades del Sistema Nervioso Periférico/patología , Axones/patología , Biopsia con Aguja , Humanos , Músculo Esquelético/inervación , Regeneración Nerviosa/fisiología , Nervios Periféricos/patología , Sensibilidad y EspecificidadRESUMEN
We have studied the in vitro contractile and fatigue characteristics of extensor digitorum longus (EDL) muscles from 8- and 62-week-old dystrophin-deficient (mdx) and control mice at 20 degrees C and 35 degrees C. There were no differences in fatigability at 20 degrees C, but at 35 degrees C the dystrophin-deficient muscles demonstrated increased fatigability compared to controls, with the older mice exhibiting the greatest fatigue. These results suggest a temperature-related mechanism of myofibrillar fatigue in dystrophin-deficient EDL muscles.
Asunto(s)
Envejecimiento/fisiología , Temperatura Corporal/fisiología , Ratones Endogámicos mdx/fisiología , Fatiga Muscular/fisiología , Músculo Esquelético/fisiología , Animales , Ratones , Ratones Endogámicos C57BL , Contracción Muscular/fisiologíaRESUMEN
To understand how exercise affects the contractile function of dystrophic muscle, we examined the effect of long-term voluntary exercise on mdx mice and related these effects to our findings in sedentary aging mice. Although the mdx mouse is the genetic homolog for Duchenne muscular dystrophy, it does not demonstrate the same progression in limb muscle dysfunction as Duchenne muscular dystrophy as it ages. We postulated that the sedentary lifestyle of this animal plays an important role in its minimal phenotypic expression. To examine the effect of exercise, eight C57BL/10 (C57) and eight mdx mice were allowed to run ad libitum for one year. Forty sedentary mdx mice and 40 sedentary C57 from one month to 18 months of age were used as controls. Contractile characteristics of the extensor digitorum longus and soleus muscles and morphometric characteristics of the mice were examined. The mdx mice ran approximately 45% fewer kilometers per day than C57 mice. Long-term voluntary running had beneficial training effects on both the old mdx mice and their C57 controls. The exercise ameliorated the age-associated loss in tension production that was observed in the soleus of sedentary mdx and sedentary C57 mice. There was a 9% reduction in the fatigability of the extensor digitorum longus muscle of the old mdx mice after the exercise. Despite these improvements, the old mdx mice exhibited significant functional deficits compared with their C57 controls. Our hypothesis, that long-term voluntary exercise would have a beneficial training effect on control mice and a deleterious effect on mdx mice as they aged, was not supported by this study. This study shows that dystrophin-less muscles from sedentary mice display significant signs of muscle damage, yet can respond beneficially to low-level voluntary running in a manner similar to that of the C57 control.
Asunto(s)
Envejecimiento/fisiología , Músculo Esquelético/fisiopatología , Distrofia Muscular Animal/fisiopatología , Carrera/fisiología , Envejecimiento/patología , Análisis de Varianza , Animales , Peso Corporal , Progresión de la Enfermedad , Distrofina/fisiología , Estudios Longitudinales , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos mdx , Actividad Motora/fisiología , Contracción Muscular/fisiología , Fatiga Muscular/fisiología , Músculo Esquelético/patología , Atrofia Muscular/patología , Distrofia Muscular Animal/patología , Tamaño de los Órganos , FenotipoRESUMEN
The effect of mild to moderate arterial occlusive disease on peripheral nervous system conduction was prospectively investigated in 18 subjects and 18 control subjects, aged 40 to 85 years. Experimental and control subjects underwent a thorough history and physical followed by vascular and electrophysiologic studies. The primary outcome measure was the sensory nerve action potential. Although 33% of the subjects with peripheral arterial disease had experienced paresthesias, the clinical evaluation of sensation was relatively unaffected. Sensory conduction studies revealed 30% absent sural responses and 56% absent superficial peroneal nerve responses in subjects with peripheral arterial disease compared with 3 and 14% absent responses in control subjects, respectively (P = 0.044; 0.025). There were no differences in distal latency or sensory amplitude, although the superficial peroneal amplitude did approach significance (P = 0.06). No significant differences were found in motor distal latency, amplitude, or conduction velocity. Age, leg length, temperature, disease severity, presence of paresthesias, cholesterol levels, and past alcohol or tobacco ingestion did not account for the difference in sensory responses. These results support the presence of a mild sensory axonopathy in subjects with peripheral arterial disease. Electromyographers should be cognizant of absent distal responses from peripheral arterial disease so as not to ascribe the findings to an alternative pathology and should not attribute abnormal motor conduction results to the presence of this degree of peripheral arterial disease.
Asunto(s)
Arteriopatías Oclusivas/complicaciones , Axones/fisiología , Neuronas Aferentes/fisiología , Enfermedades del Sistema Nervioso Periférico/complicaciones , Enfermedades Vasculares Periféricas/complicaciones , Potenciales de Acción/fisiología , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Consumo de Bebidas Alcohólicas/fisiopatología , Arteriopatías Oclusivas/fisiopatología , Temperatura Corporal/fisiología , Colesterol/sangre , Electromiografía , Femenino , Humanos , Pierna/anatomía & histología , Masculino , Persona de Mediana Edad , Neuronas Motoras/fisiología , Conducción Nerviosa/fisiología , Evaluación de Resultado en la Atención de Salud , Parestesia/etiología , Parestesia/fisiopatología , Enfermedades del Sistema Nervioso Periférico/fisiopatología , Enfermedades Vasculares Periféricas/fisiopatología , Nervio Peroneo/fisiopatología , Estudios Prospectivos , Tiempo de Reacción/fisiología , Sensación/fisiología , Fumar/fisiopatología , Nervio Sural/fisiopatologíaRESUMEN
Improving quality of life has always been a goal of rehabilitation medicine. However, health care providers often do not know much about the quality of life of individuals with neuromuscular diseases, nor what factors are critical to achieving a good quality of life. Lack of knowledge about subjective quality of life factors can negatively influence expectations and selection of treatments. In the most glaring cases, a physician's subjective but incorrect assessment of a disabled individuals' quality of life may prevent life-sustaining interventions. As a group, the quality of life of individuals with NMD is not much different than nondisabled controls and is substantially better than presumed by the general public and, often times, by health care workers. Nevertheless, their quality of life is reduced in certain areas. Surprisingly, level of disability is not a critical factor that significantly alters life satisfaction. Presumably, this is because physical functioning has been adequately managed. The greatest problems that individuals with neuromuscular disease identified were: lack of information about the disease and services; poor coordination of services; negative attitudes; and a diminished expectation of their potential. In addition, people with severe disabilities had significant problems obtaining, financing, and managing personal care attendants. Factors related to a good quality of life were related to perceived control, perceived health status, but not disability. The more that people could do for themselves, either on their own or with personal care assistants, assistive devices, and use of technology, the better their quality of life.
Asunto(s)
Personas con Discapacidad/psicología , Enfermedades Neuromusculares/psicología , Calidad de Vida , Actitud del Personal de Salud , Curriculum , Educación de Pregrado en Medicina , Humanos , Internet , Enfermedades Neuromusculares/rehabilitación , Satisfacción Personal , Medicina Física y Rehabilitación , Resultado del TratamientoRESUMEN
This article explains how animal models can be utilized to develop rehabilitation approaches to minimize the pathophysiology of neuromuscular diseases (NMD). Homologous animal models can be used to understand the pathogenesis of each NMD and the effect of physical interventions. Much of the current work using animals has been conducted to show how gene therapy could be used to ameliorate these diseases. Although we applaud this work, animal models should also be used to determine how the phenotypic expression of the disease can be modified by such physical interventions as exercise, stretching, and immobilization. Methods that can be experimentally applied to animals but not to humans can be used to determine the underlying causes of the pathologic process and to identify potential therapies for NMD.
Asunto(s)
Modelos Animales de Enfermedad , Enfermedades Neuromusculares/fisiopatología , Enfermedades Neuromusculares/rehabilitación , Medicina Física y Rehabilitación/métodos , Animales , Humanos , Enfermedades Neuromusculares/etiología , Enfermedades Neuromusculares/genética , Fenotipo , Reproducibilidad de los ResultadosRESUMEN
The purpose of this study is to determine whether dystrophin-deficient mdx mice are more susceptible to muscle injury and functional impairment than normal C57 mice when allowed to exercise voluntarily on mouse wheels. The mdx mice were significantly impaired when compared to controls as shown by functional, contractile and morphometric responses. The distance young mdx mice ran was 67-78% of young C57 mice, while adult mdx mice ran 31-48% of adult controls. After exercise the slow, oxidative soleus of young and adult mdx mice exhibited hypertrophy with no changes in strength or fatiguability, while the young C57 mice increased strength and the adults became less fatiguable. In the adult mdx mice the fast EDL, which is primarily glycolytic, exhibits slight hypertrophy with a loss of strength, while the young exhibit no changes. These results indicate that the mdx mouse adapts differently than the C57 mouse to even moderate exercise.
Asunto(s)
Ratones Endogámicos mdx/fisiología , Actividad Motora/fisiología , Músculo Esquelético/fisiología , Adaptación Fisiológica/fisiología , Factores de Edad , Animales , Peso Corporal , Creatina Quinasa/sangre , Ratones , Ratones Endogámicos C57BL , Contracción Muscular/fisiología , Fatiga Muscular/fisiología , Factores de TiempoRESUMEN
This study was designed to define the age-related changes that occur in the F1 cross of the male Fischer 344 and brown Norway rats and to determine if these findings were associated with electrophysiologic abnormalities indicative of motor neuron loss. Contractility, morphologic, and histochemical studies were performed on the tibialis anterior muscles (TA) from 25 male rats at ages 6, 18 and 30-32 months. Tibialis anterior weight was 17% greater in the 18-mo vs 6-mo-old animals, but at age 32 months mean TA weight was 20% less than at 18 months. Other changes at 32 months included a 12% decrease in specific tension and reduced contractile/relaxation velocities of isometric twitches and maximal tetanic tension; findings associated with a 40% decrease in type IIb fiber cross-sectional area. Electrophysiologic studies on 15 rats revealed prolonged H-reflex latencies at 18 and 32 months. Needle electromyography demonstrated abnormal spontaneous activity consistent with peripheral axonal, not motor neuron loss. These findings demonstrate age-related changes in muscle mass and strength that are associated with changes in the peripheral nervous system. These findings are consistent with previous work in homozygous, inbred strains and help to establish the F1 cross of the Fischer 344 and brown Norway strains as a potentially useful rodent model in gerontologic studies of the neuromuscular system.
Asunto(s)
Envejecimiento/fisiología , Músculo Esquelético/fisiología , Nervios Periféricos/fisiología , Envejecimiento/genética , Envejecimiento/patología , Animales , Cruzamientos Genéticos , Electromiografía , Electrofisiología , Masculino , Neuronas Motoras/fisiología , Contracción Muscular/fisiología , Fatiga Muscular/fisiología , Músculo Esquelético/anatomía & histología , Conducción Nerviosa/fisiología , Ratas , Ratas Endogámicas BN , Ratas Endogámicas F344RESUMEN
Bloodless surgical procedures on the extremities are achieved by application of a pneumatic tourniquet. The ischemia produced has deleterious effects on nerve and muscle function. It has been suggested that temporary interruption of ischemia by a reperfusion interval can prevent muscle and nerve injury. We investigated the muscle and nerve response to 3 hours of tourniquet ischemia, with and without a reperfusion interval after the first 2 hours of application, in a rodent model. Morphometric, contractile, and histologic parameters were measured. Tourniquet ischemia, with and without a reperfusion interval, results in muscle injury and a transient depression of muscle function. Introduction of a reperfusion interval reduces the severity of injury and increases the early rate of recovery. However, the later stages of recovery appear to be unaffected by reperfusion.
Asunto(s)
Contracción Muscular/fisiología , Músculo Esquelético/irrigación sanguínea , Daño por Reperfusión/prevención & control , Reperfusión/métodos , Torniquetes/efectos adversos , Animales , Femenino , Miembro Posterior/irrigación sanguínea , Músculo Esquelético/patología , Músculo Esquelético/fisiopatología , Ratas , Ratas Sprague-Dawley , Daño por Reperfusión/fisiopatología , Factores de TiempoRESUMEN
The developmental expression of the alpha, beta, and gamma subunits of skeletal muscle phosphorylase kinase has been examined in regenerating muscle. Rat extensor digitorum longus (EDL) muscles, treated with bupivacaine, promptly undergo a rapid degeneration of the muscle, followed by regeneration and recovery of essentially normal morphology and physiology by 3-4 weeks post-treatment (Hall-Craggs, E. C. B., and Seyan, H. S. (1975) Exp. Neurol. 46, 345-354). Phosphorylase kinase activity dropped to approximately 10% of control within 3 days of bupivacaine treatment and remained at this low level for several days but had attained at least 60% of normal levels by day 21. The pH 6.8/8.2 activity ratio was unusually high during the period of low activity, suggesting that the catalytic activity was not under normal regulation at this time. The subunit mRNAs were readily detected in control EDL but were undetectable at day 3 post-bupivacaine treatment. Very small amounts of message for all three subunits were evident by day 6 and began to approach normal levels by day 12-15. The mRNA for both the alpha and alpha' subunits of phosphorylase kinase exhibited a similar pattern of recovery, as did also the mRNA for phosphorylase. In contrast to both phosphorylase kinase and phosphorylase, actin mRNA exhibited a quite a different pattern, with a nearly full recovery of message levels by day 6 post-bupivacaine. These data indicate that synthesis of phosphorylase and the alpha, beta, and gamma subunits of phosphorylase kinase appears to be coordinately regulated at the level of message accumulation and that the expression of phosphorylase kinase activity is likely to be also regulated post-transcriptionally.
Asunto(s)
Regulación Enzimológica de la Expresión Génica , Músculos/fisiología , Fosforilasa Quinasa/genética , Fosforilasa Quinasa/metabolismo , Regeneración , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Northern Blotting , Bupivacaína/farmacología , Clonación Molecular , ADN/genética , ADN/metabolismo , Sondas de ADN , Femenino , Sustancias Macromoleculares , Datos de Secuencia Molecular , Músculos/efectos de los fármacos , Músculos/enzimología , Oligodesoxirribonucleótidos , Fosforilasa Quinasa/biosíntesis , Reacción en Cadena de la Polimerasa/métodos , ARN Mensajero/genética , ARN Mensajero/aislamiento & purificación , ARN Mensajero/metabolismo , Conejos , Ratas , Ratas Endogámicas , Homología de Secuencia de Ácido Nucleico , Transcripción GenéticaRESUMEN
Freely grafted rat extensor digitorum longus (EDL) muscles were subjected to low-frequency stimulation in an anaerobic environment to determine whether regenerating fast-twitch muscles regain normal glycolytic metabolic capacity. Regenerating muscles were tested at 28, 42, and 76 days after the graft procedure. Stabilized grafts (76 days) produced approximately 60% of the lactate generated by intact, control EDL subjected to the same stimulus paradigm and developed half the estimated increase in H+. The grafts exhibited the same relative decline in force after 5 min of anaerobic stimulation as control EDL but maintained relatively constant levels of ATP while consuming phosphocreatine. This study indicates that regenerating fast-twitch skeletal muscle has a reduced ability to initiate glycolytic activity during exercise. The data also indicate that a small population of regenerating fast-twitch fibers express the slow isoform of myosin heavy chain (beta-MHC) with maximum expression occurring at 56 days postsurgery.
Asunto(s)
Glucólisis , Contracción Muscular , Músculos/metabolismo , Regeneración , Adaptación Fisiológica , Adenosina Trifosfato/metabolismo , Anaerobiosis , Animales , Secuencia de Bases , Peso Corporal , ADN , Sondas de ADN , Femenino , Concentración de Iones de Hidrógeno , Lactatos/metabolismo , Datos de Secuencia Molecular , Músculos/fisiología , Músculos/trasplante , Miosinas/metabolismo , Fosfocreatina/metabolismo , Ratas , Ratas EndogámicasRESUMEN
Despite the lack of a definitive remedy for central nervous system demyelination in multiple sclerosis, certain manifestations of the disease are treatable. Recognition and identification of specific impairments, disabilities, and handicaps faced by the patient afford the physician the best opportunity to provide effective intervention. Impairments are ameliorated with difficulty; however, when comprehensive methods of rehabilitation are applied to the associated disabilities and handicaps, meaningful improvements can be achieved. The goal of rehabilitation in multiple sclerosis is to maximize the patient's physical, emotional, social, and vocational independence. Through the multidisciplinary efforts of numerous health-care workers in close cooperation with the patient and the family, this goal can be attained.
Asunto(s)
Esclerosis Múltiple/rehabilitación , Ataxia/rehabilitación , Equipos de Comunicación para Personas con Discapacidad , Fatiga/rehabilitación , Humanos , Higiene , Esclerosis Múltiple/complicaciones , Espasticidad Muscular/rehabilitación , Parálisis/rehabilitación , Educación del Paciente como Asunto , Charlatanería , Rehabilitación Vocacional , Conducta Sexual , Trastornos de la Visión/rehabilitaciónRESUMEN
Autonomic dysreflexia, a syndrome sometimes occurring in spinal cord injured (SCI) individuals, may be life-threatening. It involves, in varying degrees, hypertension, diaphoresis, headache, bradycardia, anxiety, and flushing and is believed due to unrestricted sympathetic activity below the level of the lesion in individuals with injuries above T4-6. The most frequent causes of the syndrome are urinary infections, rectal impaction, bladder distention, and decubitus ulcers. To our knowledge, medication has seldom been described as causal agent. We report here on an autonomic dysreflexic syndrome following use of an isometheptene combination (Midrin), to treat migraine. The individual involved is a C4-quadriplegic man with a long history of migraines. He was given a standard initial adult dose of the medication. Over a one-hour period, he was initially relieved of the headache, but then noted a new more severe headache, diaphoresis, and flushing. His vital signs showed progressive BP elevation to 210/130 and a relative bradycardia. Treatment over the next three hours was limited to elevation of the head of the bed and observation, during which his vital signs returned to baseline and he became asymptomatic. This experience reinforces the belief that sympathomimetic drugs in general, and isometheptene in particular, should be used in caution in patients with high-level SCI.