Hypotonic-hyporesponsive episode

Hypotonic-hyporesponsive episode (HHE) is a sudden and temporary reaction to immunization. It is characterized by a decreased level of consciousness (hypotonia) and a reduced response to stimuli (hyporesponsiveness).

Definition

A Hypotonic-hyporesponsive episode (HHE) is a sudden, temporary, and usually benign reaction to immunization. It is characterized by a decreased level of consciousness (hypotonia) and a reduced response to stimuli (hyporesponsiveness).

Symptoms

The main symptoms of HHE are a sudden loss of muscle tone, color, and responsiveness. The child may become limp and may not respond to stimuli. This can last from a few minutes to a few hours.

Causes

HHE is most commonly associated with the administration of whole-cell pertussis vaccine, but it can also occur after the administration of other vaccines.

Treatment

Treatment for HHE is usually supportive, as the condition is self-limiting and resolves on its own.

Prevention

The best way to prevent HHE is to follow the recommended immunization schedule and to monitor the child closely after vaccination.

See also

• Vaccine Adverse Event Reporting System
• Immunization
• Pertussis vaccine

References

Hypotonic-hyporesponsive episode Resources
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