Axonal neuropathy
Neuropathy is a serious damage to a nerve that greatly interferes with the full functioning of the entire nervous system of a person. This disorder in most cases is extremely difficult to manifest, it has many reasons. Also, the disease is expressed in different manifestations and variations. Despite the fact that all common types of neuropathy have certain symptoms, the disease is difficult to diagnose.
Once the diagnosis has been made, the prognosis for neuropathy is very unclear, since the disorder always manifests itself in different ways. Many patients complain of quite painful and unpleasant sensations in the legs and arms. Such as severe numbness, noticeable tingling, prolonged itching and the unusual effect of sand in the shoes while walking.
There are two types of neuropathies. When a single nerve is damaged, they speak of mononeuropathy. When many or only a few nerves are destroyed, polyneuropathy is diagnosed. As a rule, neuropathy occurs precisely as a result of the destruction of the nerve cells themselves, or their myelin sheath. Peripheral nerves are specialized cell outgrowths called neurites that resemble ordinary electrical wires. Myelin is used as a kind of insulation for these nerve wires.
The clinical picture of axonal neuropathy
If the nerve is severely impaired by compression or stretching, axonal neuropathy is diagnosed. At the same time, there are signs of tingling, numbness, and most patients complain of a burning sensation in the limbs. Sometimes this disease negatively affects the work of some internal organs. Symptoms in the limbs can vary in degree of pain. In exceptional cases, with axonal neuropathy, itching occurs, as well as chronic pain in combination with the main symptoms.
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Typically, severe damage to the axon is a definite consequence of significant nerve injury. The anatomical structure of the nerve will be preserved by stretching or slight compression. The restoration of the functions of such a nerve is possible in a period from a couple of minutes to one month, depending on the severity of the edema and the degree of ischemia. However, more severe injuries, for example, after a strong blow, can severely disrupt the necessary integrity of the axons themselves, but the myelin sheath is not damaged.
Serious distal tearing of many axons often occurs during nerve degeneration. This pathology is called Wallerian rebirth. This regeneration of nerves is characteristic of the growth of axons located within the myelin-preserved sheaths. In this case, the axons grow only in the direction of their immediate terminal ramifications at a rate of 1 mm per day.
With an even more severe injury, neurotmesis is observed, in other words, an anatomical complete break of the entire nerve. This is often followed by the inevitable Wallerian rebirth. It is believed that the necessary regeneration of axons due to severe trauma is always inadequate. Some motor fibers can sometimes replace any sensory fibers or even go to the so-called "foreign" muscles.
Axonal degeneration is a completely different mechanism for the development of axonal neuropathy. It is this degeneration that is caused by a serious violation of the typical metabolism directly in the body of the neuron. As a consequence, the necessary axoplasmic current is further significantly hampered. Always in the first place, the most distant large sections of the nerve are severely affected, after which such a dangerous process consistently spreads in the proximal direction.
This mechanism is considered a major factor in all distal axonal neuropathies. Significant damage to the bodies of motor neurons in motor neuropathies could be attributed to various diseases of the spinal cord, if the clinical picture was due only to damage to the nerves. That is why this type of disease is considered along with axonal neuropathies.
It should be noted that the characteristic symptoms of motor-type axonal neuropathies are fasciculations, atrophy and muscle weakness. With prolonged damage in severe cases, all tendon reflexes are noticeably weakened. Also, the loss of reflexes is often found, as a rule, only at the beginning of the disease. It is noticed that with axonal neuropathies of the sensory type, different zones of sensitivity are often violated, approximately to the same extent.
Schwann cells suffer secondarily in distal axonal neuropathies and Wallerian degeneration. In most cases, their number decreases, or they disappear altogether.
Article author: Mochalov Pavel Alexandrovich | d. m. n. therapist
Education: Moscow Medical Institute. IM Sechenov, specialty - "General Medicine" in 1991, in 1993 "Occupational Diseases", in 1996 "Therapy".
