HIHARS

Posted on
October 6, 2023
Let's learn all the facts about a brain pattern called

HIHARS

!
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Hyperventilation induced high amplitude rhythmic slowing is described just as the name implies. This is a very high amplitude rhythmic slowing of the EEG induced by the provocation method of hyperventilation. The classic EEG response to HV consists of bilateral generalized synchronous slowing that is more prominent in patients exerting great effort, a low blood sugar, and of a younger age. Although HIHARS is considered normal it can sometimes be associated with an altered awareness in children.

Question:
Hyperventilation is an activation procedure aimed to bring out focal slowing or epileptiform activity on the EEG. During a 3-Hz spike-and-wave absence seizure (an abnormal response to HV), which of the following is NOT a clinical manifestation typically observed?
A
Brief myoclonic jerk
B
Behavior arrest
C
Blank stare
D
Blinking
E
Correct Answer: 
A

Brief myoclonic jerks will often occur in adolescents with JME. Absence seizures are generalized and typically have no preceding aura or prodrome. The seizure usually lasts for only a few seconds to minutes. There is a sudden interruption of consciousness, staring, 3-Hz blinking, and less frequent automatisms. There is no postictal confusion.

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