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Difficulty: EasyPediatric Neurologic Disorders

A 7-year-old boy is brought to the pediatrician by his parents because of declining academic performance. His teacher reports that he frequently "stares off into space" during class for 10 to 15 seconds at a time. During these episodes, the boy does not respond to his name and exhibits subtle lip smacking. Immediately after the episode ends, he resumes his schoolwork without any confusion or lethargy. His physical and neurological examinations are completely normal. Having the patient hyperventilate in the office for two minutes reproduces one of these episodes. Which of the following is the most likely diagnosis?

  1. Typical absence seizureAnswer
  2. B
    Focal seizure with impaired awareness
  3. C
    Normal developmental behavior
  4. D
    Attention-deficit/hyperactivity disorder
  5. E
    Infantile spasms

Answer

Typical absence seizure
The correct diagnosis is typical absence seizure. This condition classically affects school-aged children (ages 4-10) and presents with sudden, brief (usually 10-20 seconds) episodes of impaired consciousness. Patients appear to be staring blankly, may have subtle motor automatisms (such as lip smacking or rapid eyelid fluttering), and uniquely have no postictal state, returning immediately to their baseline activities. A classic trigger that is highly sensitive and specific for absence seizures in a clinical setting is hyperventilation. An EEG would characteristically show a generalized 3-Hz spike-and-wave pattern.

Step-by-Step Solution

1
Analyze the patient's age and primary symptom.
A 7-year-old boy presents with brief (10-15 seconds) episodes of staring and unresponsiveness.
Identifying the demographics and core paroxysmal event narrows the differential diagnosis to childhood seizure disorders versus behavioral issues.
2
Evaluate the associated features of the episodes.
The episodes feature subtle automatisms (lip smacking), lack a postictal state (immediate return to baseline), and are provoked by hyperventilation.
These specific features distinguish the condition from other seizure types (like focal seizures) and non-neurologic causes.
3
Synthesize the findings to make a diagnosis.
The combination of age, brief staring spells, lack of postictal confusion, and provocation by hyperventilation is the hallmark of typical absence seizures.
Direct application of classic clinical criteria leads to the correct diagnosis.

Key Concept

Typical absence seizures classically present in school-aged children as brief staring spells without a postictal state, and can often be provoked by hyperventilation.
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Pediatric Neurologic Disorders

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