What are the main types of myelin sheath disorders. How is myelin sheath destruction diagnosed. What treatment options are available for myelin-related conditions. How does myelin sheath damage impact neurological function. What are the latest research developments in myelin repair therapies.

Understanding the Structure and Function of Myelin

Myelin is a fatty substance that forms an insulating layer around nerve fibers in the central and peripheral nervous systems. Its primary function is to increase the speed of electrical impulses traveling along nerve cells. But what exactly is the structure of myelin, and how does it perform this critical role?

The myelin sheath is composed of multiple layers of cell membrane wrapped tightly around axons. In the central nervous system, specialized cells called oligodendrocytes produce myelin, while in the peripheral nervous system, Schwann cells are responsible for myelination. This multi-layered structure creates insulation around the axon, allowing for faster and more efficient nerve signal transmission.

One of the key structural features of myelin are the nodes of Ranvier – small gaps between adjacent segments of myelin sheath. These nodes play a crucial role in saltatory conduction, a process that allows action potentials to jump from node to node, dramatically increasing conduction velocity compared to unmyelinated fibers.

Key Functions of Myelin

• Electrical insulation of nerve fibers
• Increased speed of nerve impulse transmission
• Protection of axons from external damage
• Facilitation of saltatory conduction
• Support for axonal metabolism and integrity

Understanding the intricate structure and vital functions of myelin provides a foundation for exploring the various disorders that can arise when this protective sheath is compromised.

Inherited Disorders of Myelin: Genetic Causes and Manifestations

Inherited myelin disorders, also known as leukodystrophies, are a group of rare genetic conditions that affect the development or maintenance of the myelin sheath. These disorders can lead to progressive neurological deterioration and often manifest in childhood. But what are the main types of inherited myelin disorders, and how do they impact patients?

Common Inherited Myelin Disorders

1. Metachromatic Leukodystrophy (MLD)
2. Krabbe Disease
3. Pelizaeus-Merzbacher Disease
4. Canavan Disease
5. X-linked Adrenoleukodystrophy

Metachromatic Leukodystrophy (MLD) is caused by a deficiency in the enzyme arylsulfatase A, leading to accumulation of sulfatides in the nervous system. This accumulation causes progressive demyelination, resulting in motor and cognitive decline. Symptoms typically begin in late infancy or early childhood, though adult-onset forms also exist.

Krabbe Disease, also known as globoid cell leukodystrophy, is caused by a deficiency in the enzyme galactocerebrosidase. This leads to accumulation of psychosine, a toxic substance that destroys myelin-producing cells. Infants with the most severe form of Krabbe disease rarely survive beyond two years of age.

Inherited myelin disorders present significant challenges in diagnosis and treatment. Early detection through newborn screening and genetic testing is crucial for implementing supportive care and exploring potential therapeutic options. Research into gene therapies and enzyme replacement strategies offers hope for future treatments of these devastating conditions.

Acquired Myelin Disorders: Autoimmune and Environmental Factors

Acquired myelin disorders encompass a range of conditions where myelin damage occurs due to factors other than genetic mutations. These disorders can be triggered by autoimmune responses, infections, toxins, or other environmental factors. But what are the most common acquired myelin disorders, and how do they differ from inherited conditions?

Major Types of Acquired Myelin Disorders

• Multiple Sclerosis (MS)
• Neuromyelitis Optica (NMO)
• Acute Disseminated Encephalomyelitis (ADEM)
• Guillain-Barré Syndrome (GBS)
• Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)

Multiple Sclerosis (MS) is perhaps the most well-known acquired myelin disorder. It’s an autoimmune condition where the body’s immune system mistakenly attacks the myelin sheath in the central nervous system. This leads to a wide range of neurological symptoms that can come and go in relapsing-remitting patterns or progress steadily over time.

Neuromyelitis Optica (NMO), also known as Devic’s disease, is another autoimmune condition that primarily affects the optic nerves and spinal cord. It can cause severe vision loss and paralysis. Unlike MS, NMO tends to have a more severe and rapid progression.

Acquired myelin disorders often present with acute or subacute onset of neurological symptoms, unlike the typically gradual progression seen in inherited disorders. Diagnosis usually involves a combination of clinical assessment, imaging studies (particularly MRI), and laboratory tests. Treatment strategies often focus on managing symptoms, suppressing the immune system, and promoting remyelination where possible.

The Role of Inflammation in Myelin Destruction

Inflammation plays a central role in many myelin disorders, particularly in acquired conditions. But how exactly does inflammation contribute to myelin destruction, and what are the key cellular and molecular players involved in this process?

In autoimmune demyelinating disorders like multiple sclerosis, the inflammatory process begins when autoreactive T cells cross the blood-brain barrier and recognize myelin antigens as foreign. This triggers an immune cascade involving other immune cells such as B cells, macrophages, and microglia. These cells release pro-inflammatory cytokines, chemokines, and other mediators that directly damage myelin and oligodendrocytes.

Key Inflammatory Mechanisms in Myelin Destruction

1. T cell-mediated autoimmunity
2. B cell activation and antibody production
3. Microglial activation
4. Cytokine and chemokine release
5. Oxidative stress

The inflammatory process not only damages existing myelin but can also impair remyelination efforts by creating an inhospitable environment for oligodendrocyte precursor cells. This ongoing cycle of inflammation and failed repair contributes to the progressive nature of many demyelinating disorders.

Understanding the intricate inflammatory mechanisms involved in myelin destruction has led to the development of various immunomodulatory and anti-inflammatory therapies for conditions like multiple sclerosis. These treatments aim to suppress harmful immune responses and create a more favorable environment for myelin repair.

Diagnostic Approaches for Myelin Disorders

Accurate diagnosis of myelin disorders is crucial for appropriate management and treatment. But what are the key diagnostic tools and techniques used to identify and differentiate various myelin-related conditions?

Common Diagnostic Methods for Myelin Disorders

• Magnetic Resonance Imaging (MRI)
• Cerebrospinal Fluid (CSF) Analysis
• Evoked Potential Tests
• Genetic Testing
• Nerve Conduction Studies
• Muscle and Nerve Biopsies

Magnetic Resonance Imaging (MRI) is a cornerstone in the diagnosis of many myelin disorders, particularly those affecting the central nervous system. MRI can reveal characteristic lesions or patterns of demyelination, helping to differentiate between conditions like multiple sclerosis, neuromyelitis optica, and acute disseminated encephalomyelitis.

Cerebrospinal Fluid (CSF) analysis is another valuable diagnostic tool. In conditions like multiple sclerosis, CSF may show elevated levels of immunoglobulins and the presence of oligoclonal bands, indicating intrathecal antibody production. Genetic testing is crucial for diagnosing inherited myelin disorders, allowing for identification of specific gene mutations associated with various leukodystrophies.

Evoked potential tests measure the electrical activity in the brain in response to specific stimuli, providing information about the function of various sensory pathways. These tests can reveal slowed conduction along nerve pathways, suggesting demyelination even when structural changes may not be visible on imaging.

The choice of diagnostic approach depends on the suspected condition, the patient’s clinical presentation, and the specific questions that need to be answered. Often, a combination of these methods is used to arrive at an accurate diagnosis and to monitor disease progression or treatment response over time.

Treatment Strategies for Myelin Disorders

Managing myelin disorders requires a multifaceted approach, often combining disease-modifying therapies, symptomatic treatments, and supportive care. But what are the main treatment strategies available for different types of myelin disorders, and how effective are they?

Key Treatment Approaches for Myelin Disorders

1. Immunomodulatory Therapies
2. Corticosteroids
3. Plasma Exchange
4. Enzyme Replacement Therapy
5. Gene Therapy
6. Symptomatic Management
7. Rehabilitation and Supportive Care

For acquired autoimmune disorders like multiple sclerosis, immunomodulatory therapies form the backbone of treatment. These medications aim to reduce the frequency and severity of relapses, slow disease progression, and prevent new lesions. Examples include interferon beta, glatiramer acetate, and newer oral medications like fingolimod and dimethyl fumarate.

Corticosteroids are often used to manage acute exacerbations in conditions like multiple sclerosis and neuromyelitis optica. They help reduce inflammation and can speed recovery from relapses. In severe cases or when steroids are ineffective, plasma exchange may be used to remove harmful antibodies from the bloodstream.

For some inherited myelin disorders, enzyme replacement therapy has shown promise. For instance, in Krabbe disease, hematopoietic stem cell transplantation combined with enzyme replacement therapy has demonstrated some success in slowing disease progression when initiated early.

Gene therapy represents an exciting frontier in the treatment of inherited myelin disorders. While still largely experimental, approaches like adeno-associated virus (AAV) vector-mediated gene delivery show potential for correcting underlying genetic defects.

Regardless of the specific disorder, comprehensive management often includes symptomatic treatment (e.g., for pain, spasticity, or cognitive issues) and rehabilitation services to maintain function and quality of life. The development of more targeted and effective treatments remains an active area of research, offering hope for improved outcomes in the future.

Emerging Therapies and Future Directions in Myelin Research

The field of myelin research is rapidly evolving, with new insights into disease mechanisms leading to innovative therapeutic approaches. But what are some of the most promising emerging therapies, and how might they change the landscape of myelin disorder treatment in the coming years?

Promising Areas of Research in Myelin Disorders

• Remyelination Therapies
• Neuroprotective Strategies
• Cell-Based Therapies
• Targeted Immunotherapies
• Nanotechnology-Based Approaches
• Biomarker Development

Remyelination therapies represent an exciting frontier in myelin research. These approaches aim to enhance the body’s natural ability to repair damaged myelin or to introduce factors that promote remyelination. Compounds like clemastine fumarate and biotin have shown early promise in clinical trials for promoting myelin repair in multiple sclerosis.

Cell-based therapies, including stem cell transplantation, are being explored for both acquired and inherited myelin disorders. These treatments aim to replace damaged cells or provide supportive factors to enhance endogenous repair mechanisms. For instance, oligodendrocyte precursor cell transplantation is being investigated as a potential treatment for various demyelinating conditions.

Targeted immunotherapies are being developed to more precisely modulate the immune response in autoimmune myelin disorders. These include monoclonal antibodies targeting specific immune cell subsets or inflammatory mediators, potentially offering greater efficacy with fewer side effects compared to broader immunosuppressive approaches.

Nanotechnology-based approaches offer new possibilities for drug delivery and targeted therapies. Nanoparticles could potentially be used to deliver therapeutic agents directly to areas of demyelination or to cross the blood-brain barrier more effectively.

The development of reliable biomarkers for myelin disorders is another crucial area of research. These could aid in earlier diagnosis, more accurate prognosis, and better monitoring of treatment responses. Advanced imaging techniques, such as myelin water imaging and positron emission tomography (PET) with myelin-specific tracers, are being explored for this purpose.

As research progresses, the hope is that these emerging therapies will lead to more effective treatments, better quality of life for patients, and potentially even cures for some myelin disorders. The complexity of these conditions necessitates continued interdisciplinary collaboration and innovative approaches to unlock new therapeutic possibilities.

Histology, Myelin – StatPearls – NCBI Bookshelf

Jake H. Johnson; Yasir Al Khalili.

Author Information and Affiliations

Last Update: May 1, 2023.

Introduction

Myelin sheath is a fatty product formed from specific neuroglial cells that provides numerous vital supporting functions as well as increases the rate of conduction of action potentials for some central and peripheral nervous system neurons. An axon wrapped in myelin sheath is said to be myelinated fibers, as such, axons not wrapped in myelin are non-myelinated fibers. In the central nervous system, the myelinated fibers have the collective name of white matter, and the nonmyelinated fibers are collectively known as gray matter as they look white and gray respectively on gross inspection of the brain in sagittal cross-section. Myelin is formed via oligodendrocytes and Schwann cells in the central and peripheral nervous systems respectively. Many physiologic complications and clinical symptoms can arise from the malformation and destruction of myelin.

Structure

Myelin is known for having several structural features, most notably, the nodes of Ranvier and myelin incisures (Schmidt-Lantermann clefts). The nodes of Ranvier are the region where two adjacent myelin segments meet and allow for saltatory conduction to occur. Myelin incisures are pouches of Schwann cell cytoplasm, left over from the myelination process, and are believed to play a major role in Wallerian degeneration.[1][2][3]

Function

In both peripheral and central nervous systems, myelin plays a crucial role in the protection and conduction of many neurons. Myelin sheath acts as an insulator allowing for protection of the integrity of the nerve impulse as well as protecting the axon from foreign electrical impulses. Myelin also yields the formation of the nodes of Ranvier which allow for saltatory conduction and faster propagation of action potentials to occur.[4]

Tissue Preparation

Historically, an aldehyde fixation was used to fix the nervous tissue for use in electron microscopy. Today, histological fixing of the nervous tissue is commonly done via a high-pressure freezing technique which yields a better-contrasted specimen as well as better preservation of the nervous tissue with fewer artifacts due to better fixation. However, aldehydes, such as formalin, are still used as a fixation solution for purposes of light microscopy as the decreased contrast, and inferior preservation of the tissue is negligible for use in routine nervous tissue studies.[5][6]

Histochemistry and Cytochemistry

In the central nervous system, myelin can undergo assessment via the use of anti-proteolipid protein and anti-myelin basic protein immunohistochemical stains; this is because both the myelin basic protein and proteolipid protein are present in oligodendrocytes as well as myelin sheath in the central nervous system.[7]

Microscopy, Light

Myelin can be seen using light microscopy using various histological methods, such as but not limited to: hematoxylin and eosin, Luxol fast blue and plastic (paraffin) embedding. These histological methods pronounce myelin and typically makes it appear as peripheral rings surrounding an axon when looking at a transverse section and as long parallel projections when viewing a longitudinal section. The nuclei of oligodendrocytes and Schwann cells are visible on hematoxylin & eosin staining; this presents as circular basophilic nuclei with a perinuclear halo giving a “fried-egg” appearance and as longitudinal basophilic nuclei proximal to an axon respectively. Light microscopy is one of the most commonly used methods used to assess the presence of specific pathology in nervous tissue.[8][9]

Microscopy, Electron

Myelin can be seen on transmission electron microscopy typically as a thick dark outline surrounding myelinated nerve fibers. In research, the use of three-dimensional electron microscopy can be used to view various injuries and disease processes related to the myelin sheath. This technique is typically not used clinically but has prospects to be advantageous to further the understanding of various pathophysiologic processes. [5][10]

Pathophysiology

Myelin sheath formation initiates in the CNS of the human embryo at about four months gestation. Oligodendrocytes can myelinate multiple axons at the same time (up to 50), and as such, any given myelinated neuron in the central nervous system can undergo myelination by several oligodendrocytes. Myelination of neurons in the peripheral nervous system commences between the twelfth and eighteenth week of gestation. Unlike oligodendrocytes, Schwann cells surround only a single axon. Schwann cells also play a role in peripheral neuron regeneration after an injury.

Disruptions of myelin sheath formation and/or autoimmune-related destruction of myelin sheath can often lead to serious neurological complications. These disruptions are commonly referred to as demyelinating diseases. The most common demyelinating disease is multiple sclerosis. Multiple sclerosis is an autoimmune disorder with the patients’ own antibodies directing their efforts against the myelin sheath in their central nervous system. Multiple sclerosis has a prevalence of about one in every thousand persons in the United States with women being affected with the disease two times as much as men. Histologically, multiple sclerosis shows abrupt edges of demyelinated plaque when stained with specific myelin stains. More specifically, light microscopy can view active plaques, in which there is active and progressive demyelination with PAS-stain positive breakdown product and lipid-rich macrophages present, as well as inactive plaques, in which there is no active demyelination taking place, and thus no myelin or myelin degradation products are found. That said, in inactive plaques, there is a reduction of oligodendrocytes nuclei, and there’s an increase in astrocytic proliferation. The third type of plaques seen in multiple sclerosis patients demonstrates non-abrupt borders between the normal and demyelinated tissue. These “shadow plaques” are theorized to be due to oligodendrocytes that did not get destroyed and that partially re-myelinate the damaged tissue.

Multiple sclerosis typically presents clinically with visual disturbances such as diplopia and monocular blindness as well as peripheral symptoms of muscle weakness, sensory deficits, and subsequently ataxia.

The cause of multiple sclerosis remains unknown. However, there has been a higher prevalence of multiple sclerosis in regions more north of the equator than those close or south of the equator; this leads many researchers to believe there’s a genetic and environmental component. Guillain-Barre syndrome is another demyelinating disorder, but unlike multiple sclerosis, there is autoimmune destruction of the myelin sheath in the peripheral nervous system as opposed to the central nervous system.

Guillain-Barre is rarer than multiple sclerosis, only affecting one in every one hundred thousand persons every year and affects males and females equally.[11][12][13] Guillain-Barre syndrome typically presents as an ascending paralysis and muscle weakness, with it’s most severe and life-threatening complication being respiratory depression. The cause of Guillain-Barre disease is also not yet known, but triggers include microbial infection, traumatic surgery, or, very rarely, vaccination.[14][15][16]

Clinical Significance

Demyelinating diseases such as multiple sclerosis and Guillain-Barre syndrome have a progressive and devastating effect on affected patients. There has not been an approved treatment to reverse the demyelinating process in these diseases. However, there is an array of medications that can be used to slow the progression and to treat the symptoms that may arise from them. That said, these medications are not without potential shortfalls and side-effects. For example, beta interferons are commonly prescribed to the patients to help slow the progression of disease in multiple sclerosis. However, the use of beta interferons have been shown to induce flu-like symptoms as well as liver damage, but it is still widely used in many patients due to the therapeutic effects of the drug outweighing its potential adverse side-effects. [17][18]

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Figure

Nerve cell. Image courtesy S Bhimji MD

References

1.

Salzer JL. Clustering sodium channels at the node of Ranvier: close encounters of the axon-glia kind. Neuron. 1997 Jun;18(6):843-6. [PubMed: 9208851]

2.

Small JR, Ghabriel MN, Allt G. The development of Schmidt-Lanterman incisures: an electron microscope study. J Anat. 1987 Feb;150:277-86. [PMC free article: PMC1261681] [PubMed: 3654340]

3.

Ghabriel MN, Allt G. The role of Schmidt-Lanterman incisures in Wallerian degeneration. I. A quantitative teased fibre study. Acta Neuropathol. 1979 Nov;48(2):93-93. [PubMed: 506700]

4.

Nave KA, Werner HB. Myelination of the nervous system: mechanisms and functions. Annu Rev Cell Dev Biol. 2014;30:503-33. [PubMed: 25288117]

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Möbius W, Nave KA, Werner HB. Electron microscopy of myelin: Structure preservation by high-pressure freezing. Brain Res. 2016 Jun 15;1641(Pt A):92-100. [PubMed: 26920467]

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Fix AS, Garman RH. Practical aspects of neuropathology: a technical guide for working with the nervous system. Toxicol Pathol. 2000 Jan-Feb;28(1):122-31. [PubMed: 10668998]

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Mithen FA, Wood PM, Agrawal HC, Bunge RP. Immunohistochemical study of myelin sheaths formed by oligodendrocytes interacting with dissociated dorsal root ganglion neurons in culture. Brain Res. 1983 Feb 28;262(1):63-9. [PubMed: 6187412]

8.

Miko TL, Gschmeissner SE. Histological methods for assessing myelin sheaths and axons in human nerve trunks. Biotech Histochem. 1994 Mar;69(2):68-77. [PubMed: 8204769]

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Daumas-Duport C, Scheithauer BW, Kelly PJ. A histologic and cytologic method for the spatial definition of gliomas. Mayo Clin Proc. 1987 Jun;62(6):435-49. [PubMed: 2437411]

10.

Giacci MK, Bartlett CA, Huynh M, Kilburn MR, Dunlop SA, Fitzgerald M. Three dimensional electron microscopy reveals changing axonal and myelin morphology along normal and partially injured optic nerves. Sci Rep. 2018 Mar 05;8(1):3979. [PMC free article: PMC5838102] [PubMed: 29507421]

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Compston A, Coles A. Multiple sclerosis. Lancet. 2008 Oct 25;372(9648):1502-17. [PubMed: 18970977]

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Anderson DW, Ellenberg JH, Leventhal CM, Reingold SC, Rodriguez M, Silberberg DH. Revised estimate of the prevalence of multiple sclerosis in the United States. Ann Neurol. 1992 Mar;31(3):333-6. [PubMed: 1637140]

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Fact sheet on Guillain-Barré syndrome (updated October 2016. Wkly Epidemiol Rec. 2017 Feb 03;92(5):50-2. [PubMed: 28155266]

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Sharpe RJ. The low incidence of multiple sclerosis in areas near the equator may be due to ultraviolet light induced suppressor cells to melanocyte antigens. Med Hypotheses. 1986 Apr;19(4):319-23. [PubMed: 2940440]

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Levitt P, Veenstra-VanderWeele J. Neurodevelopment and the origins of brain disorders. Neuropsychopharmacology. 2015 Jan;40(1):1-3. [PMC free article: PMC4262917] [PubMed: 25482168]

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Barateiro A, Brites D, Fernandes A. Oligodendrocyte Development and Myelination in Neurodevelopment: Molecular Mechanisms in Health and Disease. Curr Pharm Des. 2016;22(6):656-79. [PubMed: 26635271]

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Jacobs LD, Cookfair DL, Rudick RA, Herndon RM, Richert JR, Salazar AM, Fischer JS, Goodkin DE, Granger CV, Simon JH, Alam JJ, Bartoszak DM, Bourdette DN, Braiman J, Brownscheidle CM, Coats ME, Cohan SL, Dougherty DS, Kinkel RP, Mass MK, Munschauer FE, Priore RL, Pullicino PM, Scherokman BJ, Whitham RH. Intramuscular interferon beta-1a for disease progression in relapsing multiple sclerosis. The Multiple Sclerosis Collaborative Research Group (MSCRG). Ann Neurol. 1996 Mar;39(3):285-94. [PubMed: 8602746]

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Verboon C, van Doorn PA, Jacobs BC. Treatment dilemmas in Guillain-Barré syndrome. J Neurol Neurosurg Psychiatry. 2017 Apr;88(4):346-352. [PubMed: 27837102]

Disclosure: Jake Johnson declares no relevant financial relationships with ineligible companies.

Disclosure: Yasir Al Khalili declares no relevant financial relationships with ineligible companies.

Does the Myelin Sheath Play a Role in MS?

What is the myelin sheath?

Function

Link to MS

Causes of damage

Regeneration

FAQs

Multiple sclerosis (MS) is a disorder in which the body’s immune system attacks healthy parts of the central nervous system — the brain, spinal cord, and optic nerves. This inflammatory attack causes damage to the myelin sheath, a critical part of nerve cells.

What is the myelin sheath?

Nerve cells, known as neurons, are the cells in the nervous system responsible for sending electrical signals that govern body movements and give rise to thoughts and emotions. Each neuron contains a long fiber-like projection, called an axon.

When a neuron “fires,” an electrical current travels from one end of the axon to the other. Once it reaches the end, the electrical impulse triggers the neuron to release chemical messengers called neurotransmitters to pass the signal to other cells (for example, prompting a muscle to contract).

The myelin sheath is a coating surrounding axons, which are the nerve fibers. It is composed mainly of fatty molecules (lipids), as well as a number of specialized proteins. The sheath has a characteristic structure, with regions densely wrapped in myelin interspersed with areas of little to no myelin (referred to as the nodes of Ranvier).

In addition to neurons, the nervous system also is home to a diverse class of cells called glia, which play a number of roles to support neuronal function. Myelin in the central nervous system is primarily made by glial cells called oligodendrocytes.

How does the myelin sheath function?

The most well-characterized role of the myelin sheath is in helping neurons to send electrical signals faster. Conceptually, the myelin sheath wrapped around an axon is a bit like insulation coating a metal wire — just as rubber around a copper wire helps to insulate and direct electricity through the wire, myelin helps insulate and direct electrical signals through nerves.

The biophysics of this process are complicated and not entirely understood, but myelin’s structure is known to play a key role. When an axon does not have myelin, an electrical impulse needs to travel down the entire length of the axon in one go. By contrast, when an axon is wrapped in myelin, electrical signals can “skip” across the segments of dense myelin and travel across the areas with less myelin (the nodes of Ranvier), allowing the signal to travel faster.

It was long thought that this electricity-enhancing effect was the only role of myelin, but in recent years, research has shown that the myelin sheath actually has numerous other functions helping to maintain neuronal health. For example, the myelin sheath helps to support the metabolic activity of nerve cells, and it is important for regulating salt and water levels in the cell.

How is the myelin sheath linked to MS?

In MS, the immune system launches an inflammatory attack in the central nervous system. This inflammation leads to demyelination — the deterioration and loss of the myelin sheath — and causes damage to axons. Consequently, this leads to the development of lesions in the central nervous system where the tissue is damaged and scarred.

These lesions, which can be visualized on MRI scans, are actually how MS gets its name: The disease is characterized by “multiple” areas of scarring, or “sclerosis.”

MS is one of the most common demyelinating disorders that affect myelin in the central nervous system. As a result of this damage, nerve cells are not able to send electrical signals as efficiently; this impaired neuronal activity is mainly responsible for the symptoms of MS.

What causes damage to the myelin sheath?

It is not known exactly what prompts the start of the inflammatory attack that drives MS, and many interconnecting risk factors — including genetics, lifestyle habits, and environmental exposures — are known to contribute to the development of the disease.

The inflammatory attack itself involves the activity of many types of immune cells, including T-cells and B-cells.

• T-cells are immune cells equipped with specific receptors that can recognize a single molecule (usually a piece of a virus or bacteria). MS is commonly characterized by inflammatory T-cells, which are autoreactive against components of myelin.
• B-cells are best known as the cells that make immunological proteins called antibodies or immunoglobulins. It is common for people with MS to have high levels of antibodies in their cerebrospinal fluid (the liquid around the brain and spinal cord), and testing for these antibodies — a procedure called oligoclonal banding — may help in diagnosing MS.

Other immune cells involved in the MS-driving attack include dendritic cells and macrophages, which can secrete signaling molecules that promote inflammation. Dysregulated activity of glial cells, including microglia and astrocytes, also is involved in the attack.

Does the myelin sheath regenerate?

If myelin is damaged or destroyed, it can be repaired or replaced — a process referred to as remyelination.

Remyelination is done mainly by myelin-making oligodendrocytes, including mature oligodendrocytes that reside in the nervous system and new oligodendrocytes generated via the activation of immature cells called oligodendrocyte progenitor cells (OPCs).

While myelin repair in the body is possible, it is not very efficient — remyelination generally decreases with increasing age, and the inflammation that drives MS can further interfere with the process.

Finding therapeutic strategies that can promote remyelination is an ongoing area of research. Dozens of potential remyelinating treatments have shown promise in laboratory studies, and a few medications have shown positive results in early clinical studies in people with MS or other conditions associated with myelin loss.

Some of the potential remyelinating treatments being tested in MS clinical trials include:

• metformin and clemastine
• NVG-291
• CNM-Au8
• PIPE-307

A number of disease-modifying therapies have been developed for MS, mainly to reduce ongoing inflammation. Whether some of these medications also may act to promote myelin repair is still debatable.

Multiple Sclerosis News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

Demyelinating diseases – Neurology with manual therapy – Departments

Demyelinating disease (DZ) is a collective concept that implies the development of pathological processes caused by a violation of the sheaths of myelin fibers. Both trauma and complication of infectious pathology can provoke a disease of such pathogenesis. The negative impact of allergic reactions is not excluded.

The clinical picture includes symptoms of dysfunction of various body systems: gastroenterological symptoms, memory impairment, cognitive impairment, hand tremor, etc. may be present. At the initial stage of the development of the disease, the clinic, as a rule, is absent.

Demyelinating diseases of the nervous system can occur at any age: they are equally diagnosed in children and adults. Diagnosis is carried out by physical examination, laboratory and instrumental research methods. The volume of examinations is carried out in accordance with international standards for the provision of medical care.

Main symptoms:

• headache
• mood swings
• speech disorder
• convulsions
• memory violation
• Urinary incontinence
• decreased vision
• blood pressure fluctuations
• behavior changes
• paralysis
• trembling fingers
• mental impairment
• visual hallucinations
• auditory hallucinations
• difficulty in swallowing
• poor orientation in space
• immobility of the eyeballs
• skin desensitization
• violation of the synchronism of movements.

Etiology

DZ of the brain and spinal cord can be caused by the following etiological factors – alcohol poisoning, psychotropic substances, infectious diseases, multiple sclerosis, and the following pathological processes – infectious and inflammatory diseases with frequent relapses, multiple sclerosis, prolonged bacterial infections, intoxication heavy metals, Phos poisoning, chronic fatigue syndrome, nervous experiences, systemic diseases of various etiologies, against the background of spinal cord injury.

Classification

DZ – the classification of such a disease implies the division of the pathological process into two large groups: myelinopathy , in which the destruction of abnormal myelin occurs, and myelinoclasia – in this case, the destruction of normal myelin. As for localization, the disease can affect the brain, central nervous system, spinal cord.

Symptoms

The nature of the course of the clinical picture will depend on which area of ​​the brain or central nervous system the pathological process develops, and what caused it.

Diagnosis

It is determined by a neurologist, it is impossible to determine DZ only by the nature of the course. First of all, the doctor conducts a physical examination of the patient, uses laboratory and instrumental methods: clinical and detailed biochemical blood tests, magnetic resonance imaging, magnetic resonance imaging using contrast substances.

Treatment is determined by the doctor, self-medication is not allowed.

Prevention

Preventive recommendations are to prevent those diseases that are included in the etiological list, in addition, people who are at risk, that is, have had previous diseases of the central nervous system or the brain / spinal cord, should systematically undergo a medical examination.

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How to identify demyelinating diseases | Directory of medical laboratory Optimum (Sochi, Adler)

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Demyelinating diseases are a group of pathological processes that are characterized by damage to neurons of the spinal cord and brain due to the destruction of their myelin sheath (a specific structure that performs a barrier function and is responsible for the speed of transmission of nerve impulses).

Class

Practitioners divide the processes of demyelination of nerve fibers into:

1. Myelinopathy caused by a congenital anomaly of the biochemical structure of myelin. As a result of such a genetic disorder, the immune system mistakes the abnormal substance for a pathogen and produces specific antibodies aimed at destroying it.
2. Myelinoclasty – in this case, autoimmune antibodies destroy normal myelin under the influence of certain exogenous (external) factors.

Causes of development

Demyelinating process can be caused by:

• poisoning with alcohol, heavy metals, chemical or psychotropic substances;
• multiple sclerosis;
• severe infectious and inflammatory diseases;
• constant psycho-emotional stress;
• systemic pathologies;
• spinal cord injuries;
• chronic fatigue syndrome.

Symptoms and first signs

Clinical manifestations of demyelinating diseases depend on the localization of the pathological process. The collective symptom-complex is characterized by:

• tremor of the upper extremities;
• dizziness;
• blood pressure instability;
• headaches;
• deterioration in visual acuity and memory;
• disorientation;
• impaired speech and movement synchrony;
• visual and auditory hallucinations;
• emotional instability;
• psycho-type change;
• involuntary urination and defecation;
• convulsive attacks;
• paresis;
• decreased sensitivity in certain parts of the body and cognitive abilities.

The progression of the demyelination process leads to the fact that the patient becomes completely helpless, in need of constant nursing care.

Diagnostic methods

For the timely detection of the pathological process occurring in the myelin sheath, the following results are used:

1. Family and personal anamnesis.
2. Careful examination of the patient.
3. Computed tomography and nuclear magnetic resonance imaging to assess the state of the brain.
4. Magnetic resonance imaging with the use of a contrast agent – to determine the nature of neuronal damage and assess the severity of pathological changes.
5. Clinical urinalysis – to assess the state of the urinary capacity of the kidneys.
6. Hemograms – for assessing the state of the hematopoietic system.
7. Serological screening – to detect and quantify autoimmune antibodies.
8. Blood gas analysis.
9. Coagulograms – to determine blood clotting factors.
10. Biochemical blood testing – for measuring the concentration of: electrolyte ions, glucose, total protein and its fractions, digestive enzymes, total and direct bilirubin, thyroid hormones, cholesterol, triglycerides, high and low density lipoproteins.

Treatment

Patients with demyelinating diseases are prescribed:

• taking antibacterial, analgesic and non-steroidal anti-inflammatory drugs, nootropics, muscle relaxants, immunomodulators, corticosteroids, multivitamins;
• physiotherapy exercises;
• manual therapy;
• mud treatment;
• acupuncture;
• reflexology;
• massage.