What is Acute Disseminated Encephalomyelitis (ADEM)?
Acute Disseminated Encephalomyelitis (ADEM) is an inflammatory disease of the central nervous system that causes damage to myelin – the insulating sheath that encapsulates nerve cells. Myelin allows for the efficient transmission of electrical impulses along the nerves. When the myelin is damaged – a process called demyelination – this transmission is affected and the conduction of nerve signals can be disrupted or lost. ADEM can involve the brain and/or spinal cord.
How is ADEM caused?
Although the exact cause of Acute Disseminated Encephalomyelitis is not definitively known, many experience the onset of symptoms following a viral or bacterial infection, or vaccination. The immune system can mistake healthy cells for a foreign threat, and the immune system’s response results in damage to the myelin sheath covering nerves within the central nervous system. Because of the immune system’s aberrant behavior, ADEM is believed to be an autoimmune disorder.
ADEM can occur at any age, although most often it presents in children and affects males slightly more often than females. People can be affected around the world in all ethnic groups, and cases appear more often in winter and spring.
What symptoms are associated with ADEM?
The symptoms can vary depending on the where damage occurs within the central nervous system. The onset of ADEM is generally rapid and intense, and typically begins with encephalitis-like symptoms that can be either mild (i.e. fever, fatigue, headache) or severe (seizures, coma). The affected individual also experiences neurological symptoms, which can include weakness (sometimes to the point of paralysis), confusion, drowsiness, vision problems, and tingling or numbness.
How is Acute Disseminated Encephalomyelitis diagnosed?
A patient may be diagnosed with ADEM after developing multifocal neurologic abnormalities and/or confusion. Unfortunately, there currently is not a definitive test or specific biologic marker used to identify the disorder. As a result, Acute Disseminated Encephalomyelitis is a clinical diagnosis. Medical professionals may diagnose a patient with ADEM after ruling out direct infection of the central nervous system. Physicians may conduct laboratory tests, MRIs, or a lumbar puncture to further rule out potential diagnostic options.
How is ADEM treated?
As there currently is no standard treatment established for ADEM, many physicians use immunosuppressive therapies to prevent further attack on the myelin. This may include corticosteroids, immunoglobulin therapy, or plasmapheresis.
What are the variants of ADEM?
Acute Disseminated Encephalomyelitis shares similarities with, and can be involved in, several illnesses, including Neuromyelitis Optica (Devic disease), Transverse Myelitis, Acute Hemorrhagic Leukoencephalitis (AHL), Multiple Sclerosis (MS), and other demyelinating disorders of the central nervous system.
Living with ADEM
The National Institute of Neurological Disorders and Stroke (NINDS) generally considers the long term prognosis of ADEM to be favorable, often seeing improvement of symptoms within days, and near or total recovery within six months.
Less often, people experience a recurrence of symptoms within the months following initial diagnosis. Patients have also been known to suffer lifelong impairment, including cognitive difficulties, numbness, loss of vision, and weakness. Some Individuals who have recovered from Acute Disseminated Encephalomyelitis have gone on to develop MS, although this is uncommon. Rarely, ADEM can be fatal.