Hypotonic-hyporesponsive episode

Hypotonic-hyporesponsive episode
Synonyms	HHE
Pronounce	N/A
Specialty	N/A
Symptoms	Hypotonia, hyporesponsiveness, pallor
Complications	N/A
Onset	Within 48 hours of vaccination
Duration	Usually less than 24 hours
Types	N/A
Causes	Vaccination, particularly pertussis-containing vaccines
Risks	Infants and young children
Diagnosis	Clinical evaluation
Differential diagnosis	Seizure, anaphylaxis, syncope
Prevention	Monitoring after vaccination
Treatment	Supportive care, observation
Medication	N/A
Prognosis	Generally good, self-limiting
Frequency	Rare
Deaths	N/A

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