The consequence of defeat, disruption of peripheral motor neurons (spinal cord cells, motor fibers of the spinal and cerebral nerves) is a dangerous peripheral paralysis. In this paralysis, there is a significant loss of ordinary reflexes, hypotension, degenerative muscle atrophy, accompanied by a transformation reaction. The loss of reflexes (or dullness with partial damage) is clarified by recalling that a function of the peripheral motor neuron is a specific transmission of information on a reflex arc. If there is a failure in such a transmission, then the reflected reflex is unrealizable or, at a brief interruption, rather weakened.
Laxiness or hypotonia of muscles also indicates inactive intervals of the reflex arc. In this case, the muscles lose their invariable tone, characteristic of them, which is preserved in the norm by the same reflected arc. In addition, it can significantly increase with the onset of atrophy of muscle mass.
Atony of muscles
Relaxed muscles in palpation are flabby, apathetic, inert movements are unnecessary, “loose joints”. Because of this condition of the muscles, peripheral paralysis is also called sluggish or atopic.
Muscular depletion is due to an imbalance with the anterior horn cell, because it is from there that the motor nerve fibers transmit to the muscles the necessary nerve impulses that clearly stimulate the natural metabolism of muscles. When nerve motor fibers degenerate and die, the “denervation” of the muscle occurs, resulting in the loss of muscle.
As a result, in the nerves from the site of the impairment, motor fibers disappear, and a specific degeneration process is formed in the muscle mass. It is caused by the transformation of muscles, their disappearance, the development of connective, adipose tissue. Appear typical of the peripheral paralysis of electrical interactions of the affected nerves, muscles, the so-called degeneration reaction.
With degeneration, the nerves lose the function of the current conductor to the muscle in connection with the death of motor centrifugal fibers. The muscle inevitably loses certain reduction skills when stimulated by Faradic current, it reacts exclusively to the galvanic current. However, such a contraction is made slow. This is a transformation reaction that occurs 12 to 15 days after the infringement or death of the anterior horn cells.
The absolute transformation reaction is not yet a bad prognostic sign. If the nerve fiber is to be regenerated, it is possible to replace the phase of the incomplete response with ordinary electroexcitability. But with denervation of the muscle for more than 12-14 months, the complete destruction of its fibers occurs, followed by a fatty tissue. A dangerous muscle cirrhosis begins, the reaction to galvanic current is lost, that is, an irreversible process occurs in the muscles.
Other processes of muscle exhaustion (inactivity, muscular disease) are not accompanied by a degeneration reaction. Clinical studies make it possible to carry out a differential diagnosis of muscle depletion in various forms. In addition, the study of electroexcitability provides a unique opportunity to determine in advance the diagnosis of pathologies of nerve conduction, the ability to contract muscles. Based on the results of such a modern study, one can see a noticeable dynamics of the process.
In the course of the investigation of the electrical excitability of nerve fibers, it was found that the usual contraction is easier and better coming out of specific areas of muscles and nerves – irritation points.
The reflex of the change, characteristic for peripheral paralysis, is classed as a group of qualitative transformations of electroexcitability. Myotonia and myasthenia gravis also belong to this group. Myotonia – the sensuality of the nerve is typical, the muscles get weakened quite slowly after the reduction is received. Myasthenia gravis is characterized by quite severe muscle fatigue, which is also traced in the active depletion of their ability to contract with repeated stimulation by current. Chronaximetry
Chronaximetry is a newer and more noticeable more susceptible way of studying the electrical excitability of nerve fibers and muscles. This method allowed us to establish new and interesting regularities in the pathologies and physiology of nerve endings and the system as a whole. Chronaximetry is considered to be a very delicate method of study, especially in the case of peripheral nervous system damage.
In specific clinical studies, in addition to electric excitability of nerves and muscles, a mechanical one is also studied, which in certain diseases may be overestimated or underestimated. The contraction of the muscles is always checked by hitting it hammer. The mechanical sensuality of the nerve endings is studied either with the help of the same hammer or by palpation, rolling the nerve trunk where it can be easily probed and pressed against the bone.
The level of mechanical excitability of nerve fibers determines, due to certain contractions of the innervated muscles.