Diseases Relating to Myelin Sheath
Nerve cells send signals along long wires called axons, which are insulated with a fatty substance called myelin. The myelin sheath allows signals to be transmitted rapidly from the nervous system to the rest of the body. When myelin is destroyed -- called demyelination -- nerve signals are slowed or stopped. In the central nervous system -- the brain and spinal cord -- myelin cannot repair itself after it is damaged. However, in the peripheral nervous system -- the nerves that travel to the arms and legs -- myelin can often regrow. A number of diseases affect the myelin sheath in the central and peripheral nervous system.
Multiple Sclerosis
Multiple sclerosis is the most common chronic disabling disorder of the central nervous system in young adults, according to a November 2014 article in "American Family Physician." MS is an autoimmune demyelinating disease, which means that a person’s immune system attacks his own body -- in this case the myelin sheath in the brain and spinal cord 13. MS can follow a relapsing-remitting course -- with attacks of worsening symptoms that are followed by partial or complete recovery. It can also follow a progressive course, in which the disease steadily worsens.
- Multiple sclerosis is the most common chronic disabling disorder of the central nervous system in young adults, according to a November 2014 article in "American Family Physician."
Other Autoimmune Disorders of the Myelin Sheath
Epstein-Barr Neurological Symptoms
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Guillain-Barre syndrome, or GBS, occurs when the body's immune system attacks the myelin sheath in the peripheral nervous system -- the nerves outside the brain and spinal cord 4. GBS usually begins with muscle weakness in the legs that spreads up the body. The muscles of breathing may become involved. GBS can also affect the nerves involved in unconscious body functions -- leading to abnormal heart rhythms, blood pressure fluctuations and difficulties with passing urine. The cause of GBS is not known, though it sometimes happens after vaccinations or surgery.
- Guillain-Barre syndrome, or GBS, occurs when the body's immune system attacks the myelin sheath in the peripheral nervous system -- the nerves outside the brain and spinal cord 4.
- GBS can also affect the nerves involved in unconscious body functions -- leading to abnormal heart rhythms, blood pressure fluctuations and difficulties with passing urine.
Genetic Disorders of the Myelin Sheath
In certain inherited diseases, the myelin sheath does not develop properly, or it becomes damaged with time. One of the best-known of these disorders is X-linked adrenoleukodystrophy, or X-ALD, which more severely affects males. In X-ALD, an abnormal fatty substance accumulates in the brain, causing damage to the myelin sheath. Symptoms include progressive loss of thinking skills, muscle weakness and seizures. The disease also affects the adrenal gland, which regulates blood pressure and the body's ability to respond appropriately to stress.
- In certain inherited diseases, the myelin sheath does not develop properly, or it becomes damaged with time.
- One of the best-known of these disorders is X-linked adrenoleukodystrophy, or X-ALD, which more severely affects males.
Other Disorders of the Myelin Sheath
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Progressive multifocal leukoencephalopathy, or PML, is an often fatal demyelinating disease of the brain caused by the John Cunningham, or JC, virus 6.cause:
- Progressive multifocal leukoencephalopathy
- or PML
- is an often fatal demyelinating disease of the brain caused by the John Cunningham
- or JC
- virus 6
PML occurs in people with severely weakened immune systems, including those with HIV. It has also been seen in people with autoimmune diseases -- like MS or psoriasis -- who take a type of medication known as a monoclonal antibody.
Related Articles
References
- American Family Physician: Multiple Sclerosis: A Primary Care Perspective
- Pharmacy & Therapeutics: Multiple Sclerosis Review
- National Multiple Sclerosis Society: Types of MS
- American Family Physician: Guillain-Barre Syndrome
- Basic Neurochemistry: Molecular, Cellular and Medical Aspects, 6th Edition: Genetic Disorders of Myelin; Richard H. Quarles et al.
- The Lancet Neurology: Beyond Progressive Multifocal Leukoencephalopathy: Expanded Pathogenesis of JC Virus Infection in the Central Nervous System
- American Association of Neurological Surgeons. Multiple sclerosis.
- Haines JD, Inglese M, Casaccia P. Axonal damage in multiple sclerosis. Mt Sinai J Med. 2011;78(2):231-43. doi:10.1002/msj.20246
- Mehndiratta MM, Gulati NS. Central and peripheral demyelination. J Neurosci Rural Pract. 2014;5(1):84-6. doi:10.4103/0976-3147.127887
- Awad A, Stüve O. Idiopathic transverse myelitis and neuromyelitis optica: clinical profiles, pathophysiology and therapeutic choices. Curr Neuropharmacol. 2011;9(3):417-28. doi:10.2174/157015911796557948
- Perlman SJ, Mar S. Leukodystrophies. Adv Exp Med Biol. 2012;724:154-71. doi:10.1007/978-1-4614-0653-2_13
- Harlow DE, Honce JM, Miravalle AA. Remyelination therapy in multiple sclerosis. Front Neurol. 2015;6:257. doi:10.3389/fneur.2015.00257
- Green AJ, Gelfand JM, Cree BA, et al. Clemastine fumarate as a remyelinating therapy for multiple sclerosis (ReBUILD): a randomised, controlled, double-blind, crossover trial. Lancet. 2017;390(10111):2481-9. doi:10.1016/S0140-6736(17)32346-2
- Harlow DE, Honce JM, Miravalle AA. Remyelination therapy in multiple sclerosis. Front Neurol. 2015;6:257. doi:10.3389/fneur.2015.00257
- Fox RJ, Coffey CS, Conwit R, et al. Phase 2 trial of ibudilast in progressive multiple sclerosis. N Eng J Med. 2018;379(9):846-55. doi:10.1056/NEJMoa1803583
- Matute-Blanch C, Montalban X, Comabella M. Multiple sclerosis, and other demyelinating and autoimmune inflammatory diseases of the central nervous system. Handb Clin Neurol. 2017;146:67-84. doi:10.1016/B978-0-12-804279-3.00005-8
Writer Bio
Colleen Doherty has been a medical writer since 2012. Her work has appeared in national online publications. Doherty graduated from Duke University with a Bachelor of Science in psychology. She received a medical degree and completed her residency program at the University of Chicago. She is board-certified in internal medicine.