 |
Demyelinating diseases. Degenerative diseases. Pathophysiology of pain. Concept and general characteristics.
|
|
|
|
Demyelinating Diseases
Demyelinating diseases are an important group of neurological disorders which have the pathologic features of focal or patchy destruction of myelin sheaths in the CNS and peripheral nervous system. The true cause of demyelination is not known. There are suggestions the demyelination may be caused by some viral infection or by autoimmune processes.
Multiple or disseminated sclerosis is the most widespread demyelinating disease of CNS. The first symptoms, as a rule, appear at age of 20 to 40 years. The disease is characterized by recurrent attacks with focal neurologic disorders and with lesions of the spinal cord, optic nerve and brain.
Degenerative Diseases
Degenerative diseases are disorders of unknown etiology and pathogenesis, characterized pathologically by progressive loss of CNS neurons. In main causes of degenerative disorders are genetic with dominant or recessive inheritance;
Alzheimer's disease is the most common cause of dementia in the elderly. The condition occurs after 5th decade of life. The exact cause is not known. But a few factors are implicated in its etiology which include positive family history and deposition of Aft amyloid derived from amyloid precursor protein (AFP) forming neuritic 'senile' plaques and neurofibrillary tangles.
Parkinsonism is a syndrome of chronic progressive disorder of motor function and is clinically characterized by , which are most conspicuous at rest and worsen with emotional stress; other features are rigidity and disordered gait and posture. Parkinsonism is caused by several degenerative diseases, the most important being Parkinson's disease. Other parkinsonism causes are trauma, toxic agents, and drugs (dopamine antagonists).
Metabolic diseases of the CNS result from neurochemical disturbances, which are either inherited or acquired. Hereditary metabolic disorders predominantly manifest in infancy or childhood and include genetically-determined disorders of carbohydrate, lipid, amino acid and mineral metabolism. Acquired or secondary metabolic diseases are the disturbances of cerebral function due to disease in some other organ system such as the heart and circulation, lungs and respiratory function, kidneys, liver, endocrine glands and pancreas. Endogenous metabolic diseases may be caused by toxic injuries induced by metals, gases, chemicals, and drugs. The pathologic changes in each of these conditions are quite diverse and include edema, neuronal storage, degenerative changes, and sometimes parenchymal necrosis.
PATHOPHYSIOLOGY OF PAIN
Concept and general characteristics.
Pain is a complex psycho-emotional unpleasant sensation, is realized with a special system of pain sensitivity and the higher parts of the brain. It indicates actions that cause tissue damage, or of existing injuries. . The definition of pain, according to the World Health Organization is: Unpleasant sensory or emotional experience associated with actual or potential tissue damage.
|
|
|
The system of perception and transmission of the pain signal is also called nociceptive system. There are physiological and pathological pain.
Physiological pain is important adaptive defense mechanism. It indicates the action of damaging agents, on the already incurred damage and the development of pathological processes in tissues. Physiological pain activates protective processes and behavioral responses to address the action of pain (algogenic) factors and the consequences of this action. People with congenital or acquired (for example, trauma, infectious lesions) pathology of the nociceptive system, devoid of pain sensitivity, do not notice the damage that can lead to serious consequences.
Pathological pain is maladaptive and pathogenic significance. Various types of pathological pain occur as characteristic for it syndromes and symptoms which are absent at physiological pain. These include causalgia, hyperpathia, primary and secondary hyperalgesia, expansion and new algogenic receptive areas, persistent pain, spontaneous episodes of pain, preservation of pain after the termination of the provoking stimulus and other phenomena. Pathological pain is nociceptive done the same system, but the changes in the conditions of disease. Pathological pain causes the development of structural and functional changes and damage to internal organs, particularly in the cardiovascular system, degeneration of tissues, violation of autonomic reactions, changes in neural activity, endocrine and immune systems, psycho-emotional sphere and behavior.
Extreme pain can cause severe shock, uncontrollable chronic pain can be the cause of disability. Pathological pain becomes pathogenic factor in the development of new pathological processes and acquires the value of self-neuropathological syndrome or disease. Pathological pain is poorly corrected and with it the struggle difficult. If abnormal pain occurs a second time (with severe somatic diseases, malignancies, etc. ), then often it becomes the main target of treatment interventions that aim to reduce patient suffering.
|
|
|
