Phenomenon that causes the disappearance of the myelin sheaths of nerve fibers and which can be the basis of various diseases, including multiple sclerosis
I am here to tell you that unfortunately I have been found a health problem, fortunately with great timing, which involves a path. An important path that I will have to take and that I feel I can tell. Not now, not in this moment when I need to hold on to my family, my children. But which I feel like telling in the future because when I discovered what I discovered, reading other people’s stories gave me comfort. Fedez, 32, shared on social networks the concern for the disease she suffers from. He did not specify which pathology he is dealing with but in December 2019, a guest in The Confession on the Ninethe singer had said: I have been found something called demyelination in the head, I am at risk of multiple sclerosis.
Myelin sheaths
What is demyelination? It is a pathological process that leads to the disappearance of the myelin sheaths of the nerve fibers and to the reactive proliferation of cells of the neurlia (supporting tissue located inside the brain and spinal cord). Demyelination often occurs when there are pathologies of the nervous system: in all lesions of the white matter, or the part of the brain that contains nerve fibers (heart attacks, hemorrhages, tumors), and especially in the so-called demyelinating diseases. Myelin surrounds the axons, or extensions of neurons, and is divided into central and peripheral. Central myelin is that of the central nervous system (CNS) and consists of oligodendrocytes. Peripheral myelin is that of the peripheral nervous system (PNS) and produced by the so-called Schwann cells.
Multiple sclerosis
Demyelination can also be central or peripheral. The most famous of the demyelinating diseases of the CNS is multiple sclerosis. It was once said that in this disease only the myelin sheath is altered due to inflammatory processes, while the axons are little affected or initially remain intact. It was believed that only after so many years of myelin destruction did the axons begin to suffer. Today it is known instead that there is an early axonal degeneration that involves the death of the neuron due to the propagation of the lesion, up to the cell body. An outbreak of demyelination causes a decrease in the speed of conduction and if there is also damage to the axon, the conduction is altered or blocked. At the onset of multiple sclerosis, myelin swells and fragments due to acute inflammatory phenomena. At this stage of the disease there is minimal axonal damage.
Progressive course
Over time, the lost myelin is replaced by proliferation of astrocytes (constituent elements of neurlia), with scarring that leads to stretching and fragmentation of the axons. When the axon is not yet damaged, repair is possible as myelin can regenerate. At the beginning of the disease the number of degenerated axons is not high, so there are moments with functional deficits due exclusively to myelin inflammation. When the inflammation subsides, the patient recovers. Gradually, due to the axonal damage, it accumulates, until it exceeds a certain threshold: at that point the patient no longer recovers as before, and the disease takes on a so-called progressive course.
Schilder’s disease
Another example of a demyelinating pathology is Schilder’s disease (or diffuse cerebral sclerosis). The demyelination process can manifest itself with different symptoms in relation to the area of the nervous system affected, but these are symptoms related to the loss of function of the axons without the myelin sheath. Also in leukodystrophies there are alterations of myelin: these pathologies are linked to congenital enzymatic alterations, which determine alteration of the synthesis or metabolism of myelin. As for the demyelinating diseases of the PNS, an example is the Guillain-Barr syndrome.
March 17, 2022 (change March 17, 2022 | 21:35)
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