Subacute combined degeneration of spinal cord

The Funicular Funicular myelosis or spinal cord disease such as multiple sclerosis belongs to the demyelinating diseases. The English term is Subacute combined degeneration of the spinal cord (SACD ). It is caused by a deficiency of vitamin B12 and is treated by the intake of the vitamin. Prominent symptoms of the disease are loss of motor function and sensitivity, which may worsen to a paraplegia. The disease underlying damage to the spinal cord. You may under certain circumstances a pernicious anemia, which is also caused by vitamin deficiency, run ahead.

Etiology

The disease is causally based on a vitamin B12 deficiency. The most common cause is a lack of intrinsic factor. This glycoprotein is produced in the parietal cells of the stomach and binds vitamin B12. Only the bound form of the vitamin is not decomposed by digestive enzymes, and can be absorbed in the ileum. Thus, the parietal cells can be damaged by auto-immune antibodies. Patients after surgical removal of the stomach may also not produce intrinsic factor. In alcohol dependence often occurs on a chronic gastritis, which brings the production of the factor to a halt. Less common causes include intake disorders in the small intestine and relative vitamin deficiency in pregnant women. Likewise, a B12 deficiency can be caused by medication. Described as triggering are phenobarbital, cytostatics or anesthesia with nitrous oxide.

Other possible causes of the deficiency state are infestations with the fish tapeworm, which consumes the vitamin for themselves. Also can use up the gas supplied through the food vitamin pathological bacterial colonizations of the gut. A vegan diet style can also lead to vitamin B12 deficiency, as for humans usable vitamin occurs almost exclusively in animal foods.

Pathogenesis

Prominent in the disease are patches of demyelination in the spinal cord in the posterior funiculus that mediate tactile perception and proprioception, the lateral cerebellar pathways, which also serve the proprioceptive perception, and the pyramidal tract, mediates the movement stimuli. In the demyelination first go the myelin sheaths around nerve fibers based. This is followed also the sinking of the nerve cells themselves in the final stage of the destroyed tissue is replaced by scar tissue from glial cells. As a rule, the disease affects the spinal cord remains limited, but they may also consider the myelin sheaths of peripheral nerves affected. It occurs most frequently in the cervical and thoracic region of the spinal cord. The mechanism by which vitamin deficiency damages the myelin sheaths of nerve fibers is not yet known.

Symptoms

The first sign of the disease are perceived as burning sensations, which first occur on the hands and feet. This may spread the disease progresses to the respective limbs from. On the sensory symptoms follow paralysis of the legs and ataxia, which is due to the failure of the sensory paths. The paralysis can also go to the arms. And disorders of the bladder function are described. If left untreated, the disease leads to paraplegia. Since the vitamin B12 stores of the body holds up about two years, the symptoms occur on a delay.

In the neurological examination shows a diffuse weakness of the muscles of the legs and / or arms without a preference circumscribed muscle groups. The tone of the muscles is reduced thereby. The reflexes are increased only in the course, to then decrease in intensity. Pathological reflexes are triggered in many patients with funikulärer myelosis. Just as often, are sensory disturbances and the position sense and vibration sense. Less common are failures of the eye muscles and psychiatric symptoms such as psychosis, delirium or depression.

Diagnostics

In a measurement of nerve conduction velocity, these shows typically reduces the motor and sensitive nerve. In laboratory studies it is shown in one third of patients have a typical pernicious anemia. It is noteworthy that the myelosis of anemia precede and thus may be the first symptom of deficiency state. In 40 to 50 percent of cases, enlarged erythrocytes show no signs of anemia. Furthermore, conspicuous in the blood picture hypersegmented granulocytes. The measurement of the blood level of vitamin B12 is of limited diagnostic value. Proving a deficiency is the measurement of the metabolites in the urine methylmalonate and homocysteine ​​, which are increased in the disease. To distinguish a lack of intrinsic factor faced with a shortage of supply of vitamin B12 of the Schilling test is recommended. This radiolabeled vitamin is given with and without intrisischem factor. From the urine of the patient results in the absorption of the vitamin.

In addition, the exclusion of gastric cancer or chronic gastritis recommended a gastroscopy.

Treatment and prognosis

The disease can be treated by the substitution of vitamin B12. This is administered by intravenous or intramuscular injections. In the initial phase they are conducted daily. Thanks to the high storage capacity in the liver can be reduced in the later stages of one injection per month or quarter. In early cases, the symptoms returned without permanent damage. However, this can take several months. Case of severe anemia iron supplements should be reconsidered, as the body for the increased formation of red blood cells requires large amounts of iron.

Through the administration of vitamins, a further aggravation of the symptoms definitely can stop them. If the disease is detected at an early stage, they regress completely. Not only are the myelin sheaths destroyed in the affected areas, but also the Axonzylinder, the effects are irreversible, and there remain residual symptoms.