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Difficulty: HardPediatric Neurologic Disorders

A 7-month-old female infant is evaluated in the pediatric neurology clinic due to abnormal body movements that began two weeks ago. Her parents report that she experiences sudden, brief episodes where her neck, trunk, and arms flex symmetrically while her legs pull upward. These movements occur in clusters of 10 to 15, almost exclusively when she is waking up from her daytime naps. Before these episodes began, she was able to roll over and sit with support, but she now appears less interactive and no longer attempts to sit. Her prenatal history is notable for a fetal ultrasound that demonstrated a suspected cardiac mass, which was observed but required no postnatal surgical intervention. Her vital signs are within normal limits. Neurological examination reveals a socially disengaged infant with mild axial hypotonia. Wood's lamp examination of the skin reveals three 1-cm elliptical, hypopigmented macules on her lower back and left thigh. An electroencephalogram (EEG) demonstrates a chaotic, high-voltage background with multifocal spikes and slow waves. Which of the following is the most appropriate initial pharmacotherapy for this patient's current neurological condition?

  1. VigabatrinAnswer
  2. B
    Adrenocorticotropic hormone
  3. C
    Ethosuximide
  4. D
    Phenobarbital
  5. E
    Reassurance and observation

Answer

Vigabatrin is the correct initial treatment due to the underlying Tuberous Sclerosis Complex.
The patient's presentation of clustered sudden flexion movements upon awakening, coupled with developmental regression and an EEG showing hypsarrhythmia, is the classic triad of infantile spasms (West syndrome). The additional historical and physical clues—a prenatal cardiac mass (rhabdomyoma) and hypopigmented macules (ash-leaf spots)—are pathognomonic for Tuberous Sclerosis Complex (TSC). While adrenocorticotropic hormone (ACTH) is generally the first-line treatment for idiopathic infantile spasms, vigabatrin is the specific and preferred first-line therapy for infantile spasms associated with TSC.

Step-by-Step Solution

1
Analyze the semiology of the patient's movements and the EEG findings.
The clusters of symmetric flexion upon awakening combined with developmental regression and a chaotic, high-voltage EEG (hypsarrhythmia) confirm the diagnosis of infantile spasms (West syndrome).
Identifying the specific pediatric seizure syndrome is required to guide further etiological workup and select the correct antiepileptic drug.
2
Evaluate the patient's systemic findings to determine the etiology of the infantile spasms.
The prenatal history of a cardiac mass (cardiac rhabdomyoma) and the Wood's lamp findings of hypopigmented macules (ash-leaf spots) strongly point to Tuberous Sclerosis Complex (TSC) as the underlying cause.
Infantile spasms can be idiopathic or secondary to structural/genetic disorders. Identifying TSC alters the specific pharmacological management.
3
Select the appropriate pharmacotherapy based on the established etiology.
For idiopathic infantile spasms, ACTH or systemic corticosteroids are preferred. However, for infantile spasms associated with TSC, vigabatrin is the superior first-line agent.
Vigabatrin specifically targets the pathophysiological pathways implicated in TSC-associated seizures, offering significantly better efficacy in this subpopulation.

Key Concept

Vigabatrin is the first-line treatment for infantile spasms (West syndrome) when the underlying etiology is Tuberous Sclerosis Complex.
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Topics

Pediatric Neurologic Disorders

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