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What Are the Stages of HIE?

On the Sarnat and Sarnat scale there are three stages of Hypoxic-Ischemic Encephalopathy (HIE): Stage I, Stage II, and Stage III. Stage I is characterized by mild symptoms. Stage II is characterized by moderate to severe symptoms. Stage III is characterized by severe symptoms. 

This information was compiled from government sources, educational non-profits, and medical experts.

To learn more about the stages of HIE, read more.

Stage I Hypoxic-Ischemic Encephalopathy

In Stage I HIE, muscle tone and deep tendon reflexes may be abnormal. The infant may have trouble feeding and appear excessively fussy, crying often and seeming constantly sleepy. Symptoms of Stage I HIE can improve within 24 hours without long term consequences. 

Stage II Hypoxic-Ischemic Encephalopathy

In Stage II HIE, patients exhibit mild symptoms. Seizures may occur within the first 24 hours. Moro reflexes may be poor or absent, and the infant may seem lethargic or less responsive. 

These symptoms can improve over a 1-2 week period of time. However, what may appear to be mild, Stage II HIE can also quickly deteriorate, which can indicate a more serious, ongoing injury brain injury. 

Stage III Hypoxic-Ischemic Encephalopathy

In Stage III HIE, patients are often unresponsive. Infants may require breathing assistance from a ventilator, eyes may not respond to light or stimuli normally, and seizures may set in during the 24-48 hour window. Irregular heart beat and blood pressure may follow.

The Sarnat Staging System

In 1976, Sarnat and Sarnat developed a system for categorizing the stages of HIE. For ease of reference, we have turned that system into an infographic that you can save or refer back to later. 


Hypoxic-Ischemic Encephalopathy Clinical Presentation: History, Physical Examination. (2020). Emedicine.medscape.com. Retrieved 26 February 2020, from https://emedicine.medscape.com/article/973501-clinical#b2

About Brown Trial Firm

Getting help for a child with HIE or Cerebral Palsy can make a big difference. Because early intervention is often key to helping improve a child’s wellbeing, it’s important to act swiftly.

At the Brown Trial Firm, our birth injury attorneys can help you investigate your case, find answers to your questions, and determine whether you are entitled to compensation. 

We offer case reviews at no cost or obligation. Many birth injuries that cause cerebral palsy could have been prevented. Don’t wait, get help today. Call us toll free at +1 (866) 223-7465 or email us a [email protected].

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