Diagnosing multiple sclerosis (MS) can be difficult, in part because so many diseases mimic it. Multiple sclerosis is an autoimmune disease in which the conductive fat (myelin) that covers nerve fibers is eroded away, largely by inflammation. This process is called demyelination. Demyelination interrupts communication within the central nervous system (the spinal cord and brain), leading to the symptoms of MS.
However, other diseases work similarly in the body and can mimic multiple sclerosis. These include neurological autoimmune diseases, infectious diseases, and others. Working with a health care provider who is familiar with these conditions can help you receive the correct diagnosis.
There are neurological autoimmune diseases other than MS in which the body attacks its own central nervous system. Some of these diseases may cause symptoms found in MS.
Acute disseminated encephalomyelitis is a brief but widespread attack of inflammation in the brain and spinal cord. Fatigue and physical impairments characterize both multiple sclerosis and acute disseminated encephalomyelitis, particularly in children.
Chronic idiopathic demyelinating polyradiculoneuropathy is a rare neurological and autoimmune disorder in which inflammation causes nerve damage in the nerve roots and peripheral nerves. Destruction of myelin also occurs, as with MS. Symptoms include muscle weakness and impaired motor function, generally affecting both sides of the body.
Despite its shared features with multiple sclerosis, it does differ in some specific inflammatory biomarkers found within cerebrospinal fluid. The acute form of this condition is called acute inflammatory demyelinating polyradiculoneuropathy and it also falls under the umbrella of Guillain-Barre syndrome. This condition can also mimic the symptoms of MS or an MS exacerbation.
Neuromyelitis optica is a nervous system disorder that primarily affects the optic nerves and the spinal cord. Neuromyletis optica and multiple sclerosis are both autoimmune demyelinating diseases of the central nervous system, but they do have distinct symptoms and responses in the body.
Posterior reversible encephalopathy syndrome mainly affects white brain matter, and it can result from high blood pressure, kidney failure, severe infections, certain medications, some autoimmune diseases, and pre-eclampsia. Symptoms include headaches, seizures, altered mental status, and visual loss. This disorder can both mimic and occur alongside multiple sclerosis.
Susac syndrome describes immune-mediated lesions of the vascular system, typically involving small vessels in the brain, eye, and ear. In Susac syndrome, MRI findings can be mistakenly identified as demyelinating lesions like those seen in MS.
Several infectious diseases may be mistaken for multiple sclerosis because of how they attack the central nervous system.
Epstein-Barr virus is a form of herpes that results in progressive immunodeficiency. In fact, this virus has been associated with a higher risk of multiple sclerosis and may even play a causal role in progression to MS.
Cytomegalovirus is another form of herpes that mimics multiple sclerosis. This virus may also contribute to MS development.
Lyme disease is an infection caused by bacteria called Borrelia burgdorferi. Lyme disease symptoms can mimic signs of multiple sclerosis. People with multiple sclerosis also tend to have the antibodies in their blood for Borrelia (which means that they previously had Lyme disease), suggesting that MS and Lyme disease may be associated.
Progressive multifocal leukoencephalopathy (PML) is also a neurological disorder that causes infection in the white matter of the brain, thus mimicking multiple sclerosis. In this case, neurodegeneration is caused by a virus known as the John Cunningham or JC virus.
Like PML, many types of leukoencephalopathies mimic multiple sclerosis. This classification of diseases all involve damage to the white matter (the myelinated nerve cords) in the brain.
Alexander’s disease is a rare genetic disorder that demyelinates the brain. It may cause clumsiness, trouble speaking (dysarthria), or trouble swallowing (dysphagia).
Adrenoleukodystrophy is another genetic disorder that is linked to brain demyelination.
Metachromatic leukodystrophy is a progressive metabolic disease characterized by demyelination of the central nervous system.
Other mimics of multiple sclerosis include vasculitis and vitamin B12 deficiency. Vasculitis involves inflammation of the blood vessels, including those that supply the central nervous system. Vitamin B12 deficiency results in some symptoms similar to multiple sclerosis symptoms, as the vitamin is essential for neurologic function.
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