The Modified Sarnat Exam for Neonatal Encephalopathy

Dr. Courtney Wusthof, a pediatric neurologist at Stanford University, provides a comprehensive guide on performing the Modified Sarnat Exam. This exam is essential for diagnosing neonatal encephalopathy, particularly hypoxic-ischemic encephalopathy (HIE). The Modified Sarnat Exam evaluates six categories, each with criteria for normal, mild, moderate, or severe encephalopathy.

Key Categories of the Sarnat Exam: 

1. Level of Consciousness

The level of consciousness is crucial for the Modified Sarnat Exam. A healthy newborn should be calm and awake, responding appropriately to stimulation. Signs of normal alertness include spontaneous crying, reacting to touch, and maintaining visual attention. In contrast:

• Moderate Encephalopathy: The infant may be lethargic and less responsive.
  
• Severe Encephalopathy: The infant may be comatose and unresponsive.
   

2. Spontaneous Activity

Observing spontaneous movements helps assess the infant's neurological status. A healthy term baby shows spontaneous movements in all extremities and the trunk. In cases of encephalopathy:

• Moderate Encephalopathy: There may be reduced spontaneous movements.
• Severe Encephalopathy: The infant may exhibit no spontaneous movements.
   

3. Posture

Assessing the infant's resting posture provides insights into their neurological health. A normal infant's posture includes ams and legs drawn towards the torso with flexed elbows and knees.

• Moderate Encephalopathy: The infant may show distal flexion in the extremities.
• Severe Encephalopathy: The infant may have a flaccid posture with extended limbs.
   

4. Tone

Evaluating muscle tone involves several maneuvers to assess resistance to movement:

• Extremity Tone: Lift the infant's leg or arm and observe resistance and flexion.

• Trunk and Neck Tone: Support the infant's head and neck, lifting them to check for resistance.
  
  
• Moderate Encephalopathy: Reduced resistance and diminished effort to maintain head position.
• Severe Encephalopathy: No resistance or effort.
   

5. Reflexes

Key reflexes include the suck and Moro reflexes:

• Suck Reflex: A normal infant will reflexively suck on a pacifier or gloved finger.
  
• Moro Reflex: A normal infant will have a symmetric response to stimulation.
  
  
• Moderate Encephalopathy: Weak suck reflex and incomplete Moro reflex.
• Severe Encephalopathy: No reflex response.
   

6. Autonomic Responses

Assessing autonomic function involves checking heart rate and pupillary response:

• Heart Rate: Normal, bradycardia (moderate), or variable (severe).
  
• Pupillary Response: Reactive to light (normal), sluggish (moderate), or fixed and nonreactive (severe).
   

Consideration of medications like opiates is essential as they can affect these responses.

Scoring and Diagnosis

The Modified Sarnat Exam uses the findings from these six categories to determine the presence and severity of encephalopathy. An infant must have at least three abnormal findings to be classified as having abnormal encephalopathy. The majority of findings dictate the overall severity:

• Moderate Encephalopathy: Majority of findings are moderately abnormal.
• Severe Encephalopathy: Majority of findings are severely abnormal.
   

Dr. Courtney Wusthof's demonstration emphasizes the importance of a thorough and methodical approach to the Modified Sarnat Exam. By carefully assessing level of consciousness, spontaneous activity, posture, tone, reflexes, and autonomic responses, healthcare providers can accurately diagnose and determine the severity of neonatal encephalopathy.