Muscle tone in a child is one of the indicators of the state of the nervous system. Despite its low informativeness at first glance, this indicator can really say a lot about the nervous regulation in the baby. This is due to certain features of the structure of the nervous system in newborns.
A newborn child, and especially a premature baby, is a kind of research object that has its own specificity, conditioned by a certain stage in the development of the nervous system. First of all, it concerns the development of the brain, which ensures a unique response to the action of various external and internal factors. Difficulties in analyzing the neurological status are created by appropriate features of the anatomy and physiology of the neonatal nervous system:
- The highest level of integration is the talamopaladar system;
- Most of the responses are closed at the level of the brainstem and subcortical;
- The predominance of inhibition over excitation;
- The dominance of cerebral symptoms over focal symptoms, regardless of the nature of the active pathogenic factor;
- The presence in the neurological status of symptoms, which, unlike adults and older children, have a physiological character;
- Lack of speech and inability to tell about your feelings;
- Presence of peculiar behavioral reactions;
- High neuroplasticity of the CNS and associated increased ability to repair the nervous tissue.
Further, when differentiating the nerve cells of the brain and myelinating the conducting pathways, inhibition of the activity of ancient structures occurs and a change in the nature of the response of the organism to stimuli. In this case, damage to various structures of the brain leads to a disruption of his work as a whole, and the sick kid develops general symptoms, as a reaction to local injuries. Therefore, the violation of the tone can be considered one of such common reactions, signaling those or other problems.
A healthy newborn child has a physiological hypertension of all muscles for up to one month. If this condition is expressed longer or differently from both sides, then it is already a pathological hypertonia, the cause of which must be identified.
Therefore, damage to the central nervous system of a newborn of any nature can cause a general reaction, in this case, hypertonicity. But there are a number of reasons that most often lead to hypertonia. One of these etiological factors is hypoxic or ischemic brain damage. The most sensitive to the effects of hypoxia is the central nervous system, where defense mechanisms are weakly expressed. Nerve cells are the first to suffer in conditions of oxygen starvation. The pathogenesis of hypertension development in this case is the violation of the delivery of oxygen directly to the cells of the brain. But the brain, as the central organ, receives more energy and oxygen, as a priority organ. After all, at the time of onset of oxygen deficiency, the cardiovascular system reacts with the redistribution of blood with the predominant blood supply of vital organs - the so-called "centralization of blood circulation" (brain, heart). This slows the capillary blood flow of the parenchymal organs. Hypoxia of muscles and internal organs leads to the accumulation of lactate and the emergence of metabolic acidosis. Metabolic acidosis leads to an increase in the permeability of the vascular wall, which together with a slowing of blood flow and an increase in concentration leads to a sludge effect and microthrombosis. Diapedemic hemorrhages (point and large in size), cerebral edema, hypovolemia, violations of the function of all organs and systems, including muscles, are secondary. The central inhibition of the regulation of muscle tone under the influence of oxygen deficiency of the brain on the one hand, and the accumulation of lactate in the muscles on the other hand - this all underlies the development of hypertonia, as a reaction to brain damage.
Among other causes of hypertension is often a trauma in the process of childbirth, as an immediate factor in the violation of innervation of muscles. Such traumatization is often observed under the influence of mechanical external factors, as well as with excessive nonphysiological movements due to active labor. In addition, similar injuries can be caused by obstetric interventions, in which the child can be removed from the head with fixed shoulders, and shoulders with a fixed head in the breech presentation, as well as excessive rotation with facial presentation. Rough extraction of the fetus and abnormal turns lead to a violation of the structure of blood vessels, compression of the Adamkiewicz artery, which delivers blood to the spinal cord and above the lumbar thickening. In the case of a minor load, damage can sometimes be accompanied by simple brain swelling or bruising. At the heart of severe forms of trauma are hemorrhages. Trauma of the spinal cord can be accompanied by subluxation, vertebrae and a violation of the carcass of the whole spinal column. As a result of spinal trauma, ischemia of the spinal cord substance develops with the predominant lesion of motor motoneurons and peripheral motor nerve spinal cord fibers of the brain. Sometimes it also damages the pyramidal path located in the lateral parts of the brain. With edemas, transient changes in muscle tone, involuntary contraction of individual muscles, pathological reflexes or asymmetry of physiological reflexes, impaired movement along the periphery of the type at the lesion level, and the central type in the departments located below are clinically manifested. All these types of birth trauma will be accompanied by hypertension, expressed in varying degrees.
, , , ,