Neurological diseases are becoming more and more common lately. This is due to the aging of the nation, frequent head injuries. A special place among neurological pathology is occupied by sensory and gnostic disorders.
What is meant by these disorders?
Disorders of sensory and gnostic function are failures in the recognition in the brain or peripheral nerve endings of certain stimuli or objects. This happens due to incorrectly constructed neural connections in the brain or in the presence of an obstacle that prevents nerve impulses from penetrating into it. If such a violation is observed in the cerebral cortex, then such a violation is called secondary and referred to as gnostic (because in it, as well as in some other brain structures, all information coming from peripheral neurons is processed).
If at first the peripheral nerve endings or pathways are affected, then in this case there are disorders of sensory synthesis (since the afferent branch mainly suffersspinal nerve, and correctly creating an electrical impulse becomes an impossible task). Since the cerebral cortex and peripheral nerve endings can only function together, disorders are considered as a single unit.
Difference between central and peripheral lesions
Disorders of central genesis, as the name implies, manifest themselves with damage to the brain - the center for processing all incoming information. Brain tissue is extremely sensitive to various factors, which is why gnostic disorders prevail in severity. Since usually all its structures are involved in the pathological process, mental disorders can also develop. In this case, psychosensory disorders take place. Sensory disorders are the cause of damage to the peripheral link of the nervous system - receptors, as well as directly to the trunks of cranial nerves. They develop much more often and usually do not require treatment (neuropathy is an exception).
Combined disorders are most often mixed. Their cause is usually intoxication with psychotropic compounds (not necessarily drugs and alcohol) or systemic diseases of the nervous system.
Types of sensory systems of the human body
The main function assigned to the senses is the perception of stimuli coming from outside. In order to adapt to the environment, nature conceived the creation of special structures designed to receive all information coming from outside.
Due to the fact that all impulses are different in their structure and nature, there are five groups of sensory systems - vision, hearing, smell, touch, taste. Each of them is strictly specific, has its own organs of perception, its own centers in the cerebral cortex responsible for processing incoming information.
Each of these systems has its own receptors located in a certain place (not counting the skin, on which the receptors are located on its entire surface). Receptors differ both in their structure and in the type of influence on them.
Disturbances in the perception of incoming stimuli are strictly specific to each system, and that is why each of them should be analyzed.
Visual agnosia
Visual impairments are usually manifested by fuzzy vision of objects, vagueness, and they are caused by a violation of the function of eye structures. In contrast, a violation of sensory perception lies in the defeat of the pathways (in this situation, the optic nerves) and the cerebral cortex (usually with damage to the occipital lobe of the brain). Visual agnosia is also usually accompanied by damage to long-term memory, in particular, it is associated with remembering and creating images of an object in the mind.
Sensory vision disorder is usually accompanied by a disturbance in the perception of the color gamut of an object. It appears when cones are damaged - receptor cells located on the retina, resulting in color blindness. The disorder may be characterized by a distortion of the shape of an object in consciousness (knowing that an object, for example, a ball, is round, a sick person sees it as oval, with growths - this condition usually develops with hallucinations, especially true ones, and in this situation refers to gnostic disorders). Sensory and gnostic visual disturbances occur with hallucinations of various origins.
Violation of sound perception
Hearing is due to the normal functioning of the conducting system of the ear - the tympanic membrane, the ossicles of the middle ear and the cochlea. Sensory disturbances (deafness) usually develop with damage or underdevelopment of the auditory ossicles (anvil hammer, stirrup). If the pathology lies in the defeat of the hypothalamus (the main center of perception of all impulses from the sense organs), as well as in the temporal lobe of the cerebral cortex, then in this case sensory disorders of the auditory analyzer are implied. Usually, these disorders appear already at an early age, which is why questions about childhood sensory disorders are quite often raised.
Gnostic disorders also occur when there are changes in the temporal lobes. They manifest themselves most often in impaired perception of sound intensity (a quiet sound seems deafeningly loud and vice versa), impaired understanding of what is heard (in parallel with the temporal lobe, Wernicke's area, the center of speech perception, is involved in the process).
Disturbance of smell
Sensory olfactory disorders usuallydevelop as a result of damage to the mucous membrane of the nasal cavity (in particular, its upper third, where the peripheral nerve endings of the olfactory nerve are located). This usually occurs as a result of inhalation of pungent odors, burns of the mucous membrane when hot steam enters, as well as injuries to the nasopharynx. At the same time, the receptors of these endings cannot perceive aromatic molecules, which is why insensitivity to odors develops.
Violation of odor recognition appears with brain injuries, hemorrhage in the hippocampus and limbus, as well as as a result of the formation of a focus of pathological impulses in these areas, which appears due to the use of psychoactive substances - such as LSD, spices, and also on against the background of some psychiatric diseases accompanied by a hallucinatory syndrome (for example, with schizophrenia, some types of encephalopathies).
Sense of touch
Tactile sensitivity is due to receptors located on almost the entire surface of the skin. They are responsible for the perception of an object and some of its characteristics (size, weight, temperature, shape). All this is carried out due to the formation of complex impulse connections coming from all receptors simultaneously. With damage to the peripheral link of the nerves (endings and trunks), only a decrease in sensitivity develops. The image of the object itself is created in the cerebral cortex, usually in the frontal lobe and partially in the temporal lobe. Central damage to these zones (traumatic brain injury, stroke,brain infarction, poisoning with certain poisons) can lead to the formation of a lesion in which all neural connections will be broken, due to which a person will not be able to normally perceive and create an image of an object in his mind. Often, in such disorders, due to restructuring of connections, the image is perceived incorrectly according to one or several criteria (round seems flat, and warm seems hot or cold).
Taste agnosia
Taste buds are located mainly on the tip of the tongue, as well as on its lateral surfaces. Sensory disorders usually develop with burns of the mucous membrane of the tongue, which dulls the sense of taste. A similar condition can also develop when they are blocked by certain substances (for example, the taste is felt weaker after eating cold foods or hot spices). Damage to the trunk of the taste nerve is observed as a result of injuries to the chin muscle area, as well as neuropathy or trauma to the tongue.
Violation of taste recognition usually develops after a stroke, hemorrhage in the thalamus and cerebral cortex, as well as some neuroinfections (meningitis, encephalitis). Gnostic taste disorder (however, taste perversion manifests itself more) can occur in pregnant women against the background of toxicosis or preeclampsia (for example, a nail tastes like an unforgettable and wonderful delicacy).
Combination of different types of sensory disorders
Often, the above sensory disorders can develop independently of each other. However, there isseveral types of diseases leading to their combined development. The most obvious example of such diseases is the sensory disorders in multiple sclerosis.
This disease is characterized by the development of foci of compaction of the brain tissue with a predominance of connective tissue in them. A similar disorder is usually present in people over 50-60 years old, however, there are cases of its development in fairly young people (30-35 years old).
Gnostic disorders appear in cases where such foci develop in places where incoming impulses are processed (that is, in those parts of the brain where the main centers of perception are projected).
Disturbance of recognition and interpretation is eliminated by adequate treatment of multiple sclerosis, started at an early stage of the disease. If timely diagnosis is delayed, the disorders become chronic.
Treatment of sensory and gnostic disorders
There is no specific treatment for sensory disorders. All therapeutic measures are aimed at eliminating the cause (for example, in case of a stroke, it is recommended to limit the focus of hemorrhage as soon as possible (in case of a hemorrhagic form) or reduce pressure to acceptable levels (in ischemic stroke). However, therapy should not be started without first consulting a neurologist and a psychotherapist, since self-medication in such situations can significantly harm he alth.
If the cause of the violationsensitivity are burns, frostbite, then therapy should be carried out according to the severity of the injury (for mild lesions, sensory disorders can be treated at home, and for moderate and severe injuries, only in a hospital or intensive care unit). The function of the receptors will be restored in the process of treatment and physiological renewal of the cellular composition of the tissues of the affected area (since the receptors are mainly located in the mucous membranes or skin, and they, in turn, are tissues with a high regenerative potential).
