Neurological Disorders: Acute Disseminated Encephalomyelitis

Introduction

Acute Disseminated Encephalomyelitis (ADEM) is a demyelinating condition of the central nervous system. Central nervous system means the brain & spinal cord together.

A demyelinating condition is one where damage to the myelin tissue takes place. Myelin is the substance (a complex of fat & protein) that wraps around axons and enables faster conduction of neuro impulses (electrical signals) along these nerve fibers. If myelin is damaged these electrical conduction suffers and this will manifest as disease conditions characterized by weakness, numbness, visual problems etc depending upon the area of the central nervous system damaged.

It is mostly a monophasic illness, means a patient develops just one attack in life although rarely more than one attack in the same individual is possible.

Who gets this diseases?

ADEM is predominantly a disease of childhood although no age is spared. Both genders and all races/ethnicity are affected too.

What causes ADEM?

It is thought be an autoimmune disease where your immunity instead of protecting your body paradoxically attacks it. In this case the confused immune system attacks the myelin tissue.

Preceding viral infection is common. There may be history of vaccination too. Somehow these events trigger the immune system of the body, make it confused and precipitate an attack on the myelin tissue of the CNS.

Clinical Presentation

The following manifestations are seen (not all patients will experience ach and every below mentioned manifestations);

• Focal limb weakness (paralysis)
• Facial drooping
• Numbness over the extremities
• Seizures
• Headache
• Altered sensorium
• Obtundation
• Coma etc

Diagnosis

A CT or preferably an MRI of the brain will show multiple white matter lesions. There is also edema (swelling) around these lesions most of the times. They may be seen in the spinal cord as well.

A CSF (cerebrospinal fluid) analysis may be done with a spinal tap, provided lot of brain swelling is not seen (if seen that is a contra indication for spinal tap). The spinal fluid will show some elevated cells, protein, red blood cells etc. The fluid helps in ruling out meningitis, encephalitis etc if there is a doubt.

Treatment

Patients are typically admitted to the hospital and treated with steroids like intravenous methylprednisolone (solumedrol). Intravenous immunoglobulins, other immunosuppressive agents, plasmapheresis are few other choices.

Prognosis

Mortality rate is around 5% for these patients. There is a variant of ADEM called as acute hemorrhagic encephalomyelitis and it carries higher mortality rate.

Generally majority of the ADEM patients fully recover either without any deficits or only with minor deficits. Some are left with moderate to severe neurological deficits. These patients will require long term rehabilitation treatment including physical, speech and occupational therapy.

Seizures if present are treated with anti seizure medications.

A pediatric and or adult neurologist is generally involved in the care of Acute Disseminated Encephalomyelitis patients.

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