Denervation is the loss of the neural supply irrespective of the cause. If the nerve is lost because denervation is part of the neural communication to a specific function in the body then a change or loss of physiological function can occur. Denervation can be caused by injury or symptoms of disorders such as ALS and post-polio syndrome. In addition, this can be a useful surgical technique to reduce major negative symptoms, such as in renal denervation. Denervation can have many harmful side effects such as increased risk of infection and tissue dysfunction.
Video Denervation
Cause
Loss of nerve supply may be caused by injury, disturbance, or result of surgical procedure.
Injuries
Denervation may be caused by a nerve injury. The three main types of nerve injury are neurapraxia, axonotmesis and neurotmesis. These three types distinguish between the severity of nerve damage and the potential for recovery after damage. After an injury in which some of the nerves are damaged, the brain has demonstrated the ability to rewiring or rearrange the neural circuitry. This plasticity allows the brain to compensate for the loss of neural communication caused by injury.
Disorders
The denervation process has a strong association with symptoms seen in post-polio syndrome. Those with post polio syndrome are undergoing a constant process of denervation and re-conservation. This process occurs after acute poliomyelitis and leads to an increase in the area of ​​motor units over time. The area of ​​the motor unit immediately increases to the point where re-conservation is no longer likely to lead to the denervation of uncompromising motor units leading to muscle atrophy and loss of muscle strength. After symptoms of diagnosis of acute polio infections such as fatiguability, general weakness and pain are believed to be correlated with muscle denervation.
Much like post-polio syndrome, amyotrophic lateral sclerosis also has similar symptoms of motor neuron degeneration leading to generalized weakness and in some cases paralysis. The type of symptoms experienced may depend on a particular area of ​​the body that has a loss of nerve supply. This denervation process is however different from post-polio syndrome because it only involves the degeneration of upper and lower motor neurons and does not undergo a constant process of reinnervaiton and denervation.
Surgical procedure
In addition to peripheral nerve injuries, denervation is used as a medical procedure for the various benefits resulting from the removal of the nerve supply to the specific area of ​​the body. In renal denervation, the procedure involves the use of radio frequency or ultrasound to eliminate the supply of sympathetic nerves to the kidney wall in order to reduce blood pressure and treat chronic hypertension. However, renal denervation is used less frequently in recent years as new evidence suggests that blood pressure does not decrease significantly after the procedure and there are even recommendations for not using the procedure as there is little evidence to suggest that renal denervation leads to a blood drop. pressure.
Another common surgical procedure involves deliberately reducing the supply of nerves to treat various disorders. In sympathectomy, sympathetic ganglion is surgically removed to treat hyperhidrosis, or excessive sweating. In the vagotomy, the vagus nerve is surgically removed to treat peptic ulcer disease through acid reflux reduction. In rhizotomy, the nerve fibers in the spinal cord are removed in the hope of relieving chronic muscular pain.
Maps Denervation
Physiological differences
In relation to skeletal muscle denervation there are two different diagnoses: traps and compressive neuropathy or non-trap neuropathy. Entrapment and compressive neuropathy syndromes occur because of compression and/or constriction at specific locations for a single nerve segment or some nerve sites. This deprivation or compression can be diagnosed based on several factors including physical examination, electrodiagnostic tests and clinical history.
After denervation, muscle atrophy and degeneration occur within the affected skeletal muscle tissue. In skeletal tissue a noticeable decrease in observed muscle weight of denervation is observed and a reduction in the size and quantity of muscle fibers. These muscles show a slowdown in contraction speed, reduced tension developed, and twitch strength.
Magnetic resonance imaging (MRI) and high-resolution ultrasonography (US) are two clinical imaging studies performed to classify different diagnoses. Ultrasound is advantageous with evaluation of peripheral nerve resolution while Magnetic Resonance Imaging is more sensitive in terms of changes in signal intensity than muscle.
Denervation affects the process of muscle activation caused by the development and spread of potential action and subsequent calcium release. It was found that there was an increase with reuptake of calcium due to changes in morphology and the structure of the sarcoplasmic reticulum. Consequently there is a decrease in the amplitude and speed of the impulse conduction by increasing the duration of muscle spikes.
In clinical and experimental studies there is an observed increase in muscle stimulation in electric currents involving chemical action, while there is a decrease in current-induced stimulation with electrical induction in the denervated muscles. Potential membrane break changes that involve denervated muscles present mild depolarization when muscle contraction stimuli are present. Although there is no immediate change involving rest and action potential, there is an increase with membrane resistance. After prolonged denervation, it is revealed that the membrane's potential breaks over time decreases while the action potential decreases and becomes slower. Acetylcholine is a neurotransmitter that becomes supersensitive in the presence of a denatured muscle. After the injection of acetylcholine, the slower contractile response, which is drastically below the action potential threshold, is obtained.
Possible reinnervation
Damaged muscles have shown the ability to survive after the denervation period or in the case of damaged nerves. The nerve size and functional ability can be maintained if electrically stimulated immediately after denervation, in clinical trials. Home-based functional electrical stimulation has been shown to save muscles that have undergone severe atrophy as a result of denervation. This process involves electrical stimulation of nerves that conserve affected parts of the body, using electrodes placed on the skin.
For muscles that can not be saved through home functional electrical stimulation, an Italian study shows that, at some point in the future, the following techniques may apply: they must first have the induction and separation of autologous miogenic cells. This can be accomplished either by in vivo marcaine infiltration of muscle tissue which can then be grown in vitro, or have induced in vitro autologous adipose tissue followed by selection of myogenic stem cells that can be recreated in vivo. New autologous myogenic stem cells will be injected, proliferate and differentiate into new adult muscle fibers. The functional properties of these newly created muscle fibers will be induced through surface electrodes and external neuromodulators.
References
Source of the article : Wikipedia
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