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Difficulty: HardPediatric Neurologic Disorders

A 6-month-old boy is brought to the pediatric clinic by his parents due to strange jerking movements that began two weeks ago. The parents report that he suddenly flexes his neck, trunk, and arms for 1 to 2 seconds. These movements occur in clusters of up to 20 episodes, typically just after he wakes from a nap. Previously, the infant had begun to roll over and smile, but he has not done either since these episodes started. He was born at 39 weeks' gestation without complications. Temperature is 37.0°C (98.6°F), heart rate is 120/min, and blood pressure is 85/50 mm Hg. Physical examination reveals three 1.5-cm elliptical, hypopigmented macules on his trunk that become more prominent under a Wood's lamp. The remainder of the examination shows decreased muscle tone. An electroencephalogram (EEG) demonstrates a high-amplitude, chaotic background with asynchronous, multifocal spikes and slow waves. Which of the following is the most appropriate next step in the management of this patient?

  1. A
    Administer adrenocorticotropic hormone therapy
  2. Initiate vigabatrin therapyAnswer
  3. C
    Reassure the parents that these are normal infant startle reflexes
  4. D
    Perform a lumbar puncture and administer intravenous antibiotics
  5. E
    Prescribe topical ketoconazole for the skin lesions

Answer

The most appropriate next step is to initiate vigabatrin therapy.
The correct answer is to initiate vigabatrin therapy. This patient presents with the classic triad of infantile spasms (West syndrome): clusters of flexor spasms, developmental regression, and an EEG showing hypsarrhythmia (a chaotic, high-amplitude background with multifocal spikes). Furthermore, the presence of hypopigmented, elliptical macules (ash-leaf spots) strongly suggests an underlying diagnosis of Tuberous Sclerosis Complex (TSC). While adrenocorticotropic hormone (ACTH) and corticosteroids are typically used for idiopathic infantile spasms, vigabatrin is the drug of choice specifically for infantile spasms associated with TSC due to its superior targeted efficacy in this subpopulation.

Step-by-Step Solution

1
Analyze the clinical presentation and EEG findings to identify the primary neurologic syndrome.
The patient exhibits clusters of flexor spasms upon awakening, developmental regression, and hypsarrhythmia on EEG, which together form the classic triad of infantile spasms (West syndrome).
Identifying the specific seizure type is necessary to determine the appropriate diagnostic and therapeutic algorithm.
2
Evaluate the physical examination findings to uncover the underlying etiology of the seizures.
The presence of hypopigmented, elliptical macules that enhance with a Wood's lamp (ash-leaf spots) establishes Tuberous Sclerosis Complex (TSC) as the underlying cause.
Infantile spasms can be idiopathic or secondary to structural/genetic abnormalities, and pharmacological management differs drastically based on this etiology.
3
Select the optimal targeted pharmacotherapy based on the identified etiology.
Vigabatrin is chosen as the drug of choice.
While ACTH or corticosteroids are first-line for idiopathic infantile spasms, vigabatrin has proven superior efficacy for spasms specifically associated with Tuberous Sclerosis Complex.

Key Concept

Vigabatrin is the specific first-line pharmacotherapy for infantile spasms when they are associated with Tuberous Sclerosis Complex (indicated by clinical findings such as ash-leaf spots).
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Topics

Pediatric Neurologic Disorders

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