Acute flaccid myelitis

A rare but serious neurological illness of sudden onset, usually in children.

It presents with localized limb weakness and visible changes on MRI.

The cause is currently unknown.

May be correlated with enterovirus-D 68. respiratory disease.

Predominately affects children, with the median age of approximately six years, male slightly more than females, anymore than 80% of cases is preceded by a prodromal illness that occurs a median of five days before onset, and typically includes fever and respiratory or gastrointestinal symptoms.

No effective treatment for the condition is known.

A polio-like syndrome.

Increases occurred in the late summers of 2014, 2016, and 2018.

Incidence has spiked in recent years.

Many patients have neck, back, or extremity pain, but otherwise those affected generally had normal sensation in their limbs.

Not associated with mental changes, or seizures.

Associated with severe arm flaccidity, but sensation is generally intact.

A flaccid paralysis of one or more limbs, often following a viral illness.

Has a temporal association between respiratory enteroviral illness, particularly with enteroviruses D 68 and A71.

Estimated incidence of AFM is less than one per million, and htypically affects previously healthy children with a slight male preponderance.

Spine MRIs showing gray matter involvement.

MRI images and symptoms closely mimic polio.

MRIs show a signal increase in the ventral horns of the spinal cord, exactly the same region of the spinal cord affected in polio.

In most cases, MRI lesions spanned more than one level of the spinal cord.

Some patients have acute cranial nerve dysfunction with correlating nonenhancing brainstem lesions on MRI.

Spinal magnetic renaissance imaging shows a longitudinal area of increased T2 and FLAIR signal predominately involving the gray matter, localizing to the anterior horns over days to weeks.

There were no cortical, subcortical, basal ganglia, or thalamic lesions on MRI.

Almost all patients have an increase in their white blood cells in the cerebrospinal fluid.

Some of the patients have brainstem findings and cranial-nerve findings.

CSF pleocytosis is present in morethan 80% of cases, with a median cell count of approximately 100 cells.

80% of patients had a preceding respiratory illness and 75% reported fever in the days leading up to limb weakness, the onset of which was generally abrupt.

Symptoms/clinical findings include:

Difficulty moving the eyes or drooping eyelids

Facial droop or weakness

Difficulty with swallowing or slurred speech

Sudden arm or leg weakness

Causes suggested: viruses, environmental toxins, and genetic disorders, with poliovirus, non-polio enteroviruses, West Nile Virus, and adenoviruses among the potential causes.

Diagnosis is by history and physical examination in combination with reviewing images of the spinal cord.

Diagnosis requires acute onset limb paralysis and at least one gray-matter spinal-cord lesion. CSF should show pleocytosis.

Paralysis is of rapid onset from hours to days, and is frequently asymmetrical, and may involve any combination of limbs with the predilection for the upper extremities.

The pattern of weakness is consistent with the lower motor neuron process and includes hyporeflexia or areflexia and hypotonia.

Cranial nerve dysfunction seen in approximately 30% of patients, while bowel and bladder dysfunction are variable present.

Sensory involvement is not common, and if present that is usually mild and transient.

Cannot currently be prevented with a vaccine.

CDC advises to prevent infections in general, persons should stay home if they are ill, wash their hands often with soap and water, avoid close contact with those who are ill, and clean and disinfect frequently touched surfaces.

No treatment for the disease is known.

Whether steroids were helpful or harmful is not established.

Physical therapy and occupational therapy may be beneficial.

Thus far intravenous immunoglobulins, corticosteroids, plasmapheresis, and fluoxetine have not improved outcomes.

Recovery is often incomplete, with motor deficits and muscle atrophy persisting in most affected children at one year.

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