vitamin E deficiency neuropathy
Introduction
Introduction to Vitamin E Deficiency Neuropathy The main active ingredient of vitamin E in the human body is -tocopherol (tocopherol), which is an important fat-soluble antioxidant nutrient in the body. Vitamin E includes 8 tocopherols, and the most powerful one is D (dextrorotatory) -fertility. Phenol (-tocopherol). Vitamin E deficiency is caused when plasma D (dextrorotatory) -tocopherol levels are lower than normal for various reasons. Vitamin E deficiency can cause neuronal axonal membrane damage, resulting in peripheral nerves, spinal ganglia, posterior root and Axonal degeneration of the posterior column of the spinal cord. basic knowledge The proportion of illness: 0.002% Susceptible people: no special people Mode of infection: non-infectious Complications: atherosclerosis cataract
Cause
Vitamin E deficiency neuropathy
Absorption barrier (30%):
Malabsorption, fat metabolism disorders, depression into the liver circulation, alpha-tocopherol-operating protein (-TTP) mutations, -lipoprotein deficiency and other metabolic stages can cause vitamin E deficiency.
Disease factors (25%):
The following patients are prone to vitamin E deficiency: hypolipoproteinemia, hepatic pancreatic lesions, gallbladder fibrosis and primary biliary occlusion, -TTP deficiency, familial vitamin E deficiency, cholestasis caused by other causes, etc. Plasma vitamin E levels are elevated, but immature children have less adipose tissue, insufficient storage of vitamin E and vitamins through placental dysfunction, and low levels of vitamin E.
Genetic factors (45%):
Most patients with severe vitamin E deficiency have severe malabsorption since childhood and rare familial vitamin E deficiency. Autosomal recessive familial vitamin E deficiency is caused by mutations in the -TTP gene located on chromosome 8. - TTP deficiency, which hinders the combination of vitamin E and very low density lipoprotein.
Pathogenesis
Vitamin E is absorbed in the small intestine and chylomicron, and enters the liver through the portal vein. Vitamin E regenerated in the liver is combined with low-density and very low-density lipoprotein under the action of -tocopherol-operating protein (-TTP). Vitamin E It is mainly stored in fat, liver and muscle. It exerts physiological effects through anti-oxidation, regulation of immunity and anti-platelet action. Vitamin E protects cell membrane from damage by preventing free radical oxidation, and prevents oxidation of low-density lipoprotein. Prevent arteriosclerosis.
Vitamin E deficiency leads to axonal membrane damage, which in turn causes axonal degeneration of peripheral nerves, spinal ganglia, posterior root and posterior column of the spinal cord. From the surface, pathological changes of the spinal cord caused by vitamin E deficiency and subacute caused by vitamin B12 deficiency The combined degeneration is similar, but in fact the vitamin B12 deficiency is caused by the loss of the posterior column and the lateral cord spongy myelin, while the vitamin E deficiency causes the posterior column of the spinal cord, the axons of the spinal ganglia and the axons of the Clark column to swell. Malnutrition and astrocyte proliferation.
Harding et al. (1982) reported that two adults had progressive fat neuropathy due to fat malabsorption for more than 20 years, mainly showing spinal cord cerebellar degeneration and peripheral neuropathy, and were effective with vitamin E. Rosenblum et al reported 6 cases of chronic bile duct obstructive liver disease. In children, their serum vitamin E was decreased. Two of them had neuropathological findings and found axonal dystrophia in the spinal cord. The axon terminal or terminal anterior thickened into a spindle-shaped swell, silver-plated staining. The display is clearer, in addition, the loss of myelin and the disappearance of large and myelinated fibers in the peripheral nerves, Saito et al. (1982) describe a neuropathology of a neuromuscular disorder in a girl who died of familial intrahepatic cholestasis, and found that sensory ganglion cells The central and peripheral axons are damaged at the distal end, the sensory nucleus in the brainstem and the ocular nucleus, the basal nucleus, the Clark column, the posterior horn and the nerve cells in the spinal nerve root segment are lost. Most studies consider human or animal In the absence of vitamin E, the center of the sensory nerve cells and the surrounding fibers appear dying back, and the central branch fiber degeneration is more severe than the surrounding fibers. The vitamin E in the food is absorbed in the form of micelles in the middle part of the small intestine. Its absorption is similar to the absorption of dietary fat. It must be dissolved in the bile to reach the surface of the intestinal absorption cells, and passively diffuse into the intestinal mucosal cells. Under normal circumstances The absorption rate of tocopherol is 20% to 25%. The medium chain triacylglycerol can promote the absorption of vitamin E, while the polyunsaturated fatty acid inhibits its absorption. The vitamin E in the blood can be combined with various lipoproteins and transported. Through red blood cell transport, vitamin E is present in the fat droplets of fat cells. The cell membrane of all cells and the circulating lipoprotein are mainly stored in adipose tissue, muscle and liver. Vitamin E is mainly excreted from the feces, and a small amount is excreted in the urine.
The main physiological function of vitamin E is anti-oxidation, which protects polyunsaturated fatty acids in cell membranes, sulfhydryl and cytoskeletal and other proteins in the cell from free radical attack, and vitamin E deficiency causes intracellular antioxidant mechanism. Dysfunction, causing cell damage, this function and vitamin E against arteriosclerosis (reducing lipid peroxides in the arterial wall), anti-cancer (destroying nitroso ions, blocking nitrosamine production), improving immune function protection Eye vision (reducing retinal lipid peroxide accumulation and lens circulation) and delaying the aging process (reducing lipofuscin content), followed by vitamin E to promote protein synthesis by promoting nuclear RNA synthesis, thereby promoting the synthesis of certain enzyme proteins, experimental animals In the absence of vitamin E, oxidative phosphorylation disorder occurs, and the utilization rate of oxygen is lowered. Vitamin E can regulate the adhesion and aggregation of platelets, protect the integrity of red blood cells, cause hemolytic anemia when lacking, and maintain the normal function of reproductive organs. Experiments have shown that when vitamin E is deficient, sperm cannot be produced, and fertilized eggs cannot be implanted into the uterus. Wait.
Prevention
Vitamin E deficiency neurological prevention
The recommended intake of daily dietary vitamin E recommended by the Chinese Nutrition Society (developed in 2000) is: 3 to 4 mg for infants (an international unit of vitamin E is defined as the activity of 1 mg of all-race alpha-tocopherol acetate), school age The former child is 5mg, the school age is 7-10mg, from 14 years old to 40mg for adults, and 14mg for pregnant women, nursing mothers and the elderly.
The intake of vitamin E is related to the intake of polyunsaturated fatty acids. Since polyunsaturated fatty acids are prone to lipid peroxidation, the demand for vitamin E is also increased when the intake of polyunsaturated fatty acids is increased. Adults have suggested that about 0.4 mg of vitamin E is needed per gram of polyunsaturated fatty acids.
Complication
Vitamin E deficiency neuropathy complications Complications atherosclerosis cataract
The effects of normally low vitamin E nutritional status on atherosclerosis, cancer, cataract formation, and other degenerative processes involving aging are currently being investigated. Studies suggest that supplementation with vitamin E and antioxidants may reduce the incidence of these diseases.
Symptom
Vitamin E deficiency neuropathy symptoms Common symptoms Vitamin E deficiency cerebellar ataxia night blind eye muscle eyeball tremor cognitive dysfunction arrhythmia erythrocytosis dysarthria thrombocytopenia
Vitamin E deficiency has not been recognized as a well-defined syndrome. Adults have vitamin E storage in their bodies. Even if the diet is lacking or malabsorbed, it will take several years to reduce plasma vitamin E levels to a lack of scope and adulthood. The mature nervous system is more tolerant to vitamin E deficiency, and neurological abnormalities often occur after 5 to 10 years.
Patients gradually developed sputum reflexes, disappearance, cerebellar ataxia, skin sensory disturbances, abnormal position and vibration, night blindness, a few patients with extraocular tendons, skeletal muscle weakness, nystagmus, drooping eyelids and dysarthria, Late blindness, cognitive dysfunction, arrhythmia, erythrocytosis and pigmented retinopathy are mainly seen in -lipoprotein deficiency. The phenotype of familial vitamin E deficiency and Friedreich ataxia are difficult to identify.
In children, on the contrary, if there is vitamin E malabsorption in infancy, it is prone to severe vitamin E deficiency. If not treated in time, neurological symptoms can occur rapidly, mainly affecting the posterior spinal cord and spinal cord cerebellum. Deep muscle reflex disappears, proprioception, abnormal vibration, ataxia, ophthalmoplegia (eye movement disorder), visual field disorder, muscle weakness, especially in premature infants, less vitamin E storage, lower intestinal absorption capacity, growth rate Fast, more prone to deficiency, often hemolytic anemia, thrombocytosis, intraventricular hemorrhage, edema, fibrous tissue formation after lens and increased risk of pulmonary bronchial dysplasia.
Examine
Vitamin E deficiency neurological examination
1. Determination of plasma levels of vitamin E
Plasma vitamin E concentration can accurately reflect the content of vitamin E in the body.
2. Red blood cell hemolysis test
The amount of hemoglobin hemolyzed by mixing red blood cells with 2% to 2.4% hydrogen peroxide is compared with the amount of hemoglobin dissolved after mixing with distilled water, expressed as a percentage, and the vitamin E is undernourished by 10% to 20%. The lack is greater than 20%.
3. Electrophysiological examination: The amplitude of sensory nerve potential is decreased, the conduction velocity is slowed down, and the somatosensory evoked potential is abnormal.
Diagnosis
Diagnosis and identification of vitamin E deficiency neuropathy
Mainly based on medical history and clinical manifestations, serum vitamin E levels and the ratio of vitamin E to serum lipids are helpful in the diagnosis of vitamin E deficiency. The average value of normal serum vitamin E is 1 mg/dl, and 0.5 to 0.7 mg/dl is insufficient. <0.5mg/dl is a deficiency, vitamin E/cholesterol <2.2 also has diagnostic value, and the red blood cell hemolysis test has diagnostic reference value.
The phenotype of familial vitamin E deficiency needs to be differentiated from Friedreich's ataxia.
