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Difficulty: Very hardPediatric Neurologic Disorders

A 7-month-old boy is brought to the outpatient clinic by his mother due to a two-week history of unusual movements. The mother states that shortly after waking from naps, the infant suddenly flexes his head and pulls his arms forward synchronously. These episodes last for a few seconds and occur in clusters of 10 to 15. Prior to this, he had been babbling and rolling over, but he has stopped performing these skills over the past week. Vitals are: temperature 37.0°C (98.6°F), heart rate 110/min, respiratory rate 28/min, and blood pressure 90/55 mm Hg. Neurological examination reveals axial hypotonia and poor head control. Skin examination is notable for three 1.5-cm elliptical, hypopigmented macules on the trunk and right thigh. An electroencephalogram demonstrates a disorganized pattern of chaotic, high-amplitude slow waves and multifocal spikes. Which of the following is the most appropriate initial pharmacotherapy for this patient's condition?

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

Answer

Vigabatrin is the most appropriate initial pharmacotherapy for infantile spasms associated with Tuberous Sclerosis Complex.
The correct answer is Vigabatrin because this patient presents with infantile spasms (West syndrome) secondary to Tuberous Sclerosis Complex (TSC). The diagnosis of infantile spasms is supported by the triad of clustered symmetric spasms, developmental regression, and hypsarrhythmia on EEG. The underlying diagnosis of TSC is indicated by the presence of multiple ash-leaf spots (hypopigmented macules). While adrenocorticotropic hormone (ACTH) and corticosteroids are first-line for idiopathic infantile spasms, Vigabatrin is the first-line, preferred medication for TSC-associated infantile spasms. It acts by irreversibly inhibiting GABA transaminase, leading to increased GABAergic inhibition in the brain.

Step-by-Step Solution

1
Analyze the clinical presentation and EEG findings.
The infant has clustered symmetric flexor movements upon awakening, developmental regression, and an EEG showing chaotic, high-amplitude slow waves with multifocal spikes (hypsarrhythmia).
This classic triad definitively diagnoses infantile spasms (West syndrome).
2
Evaluate the physical examination findings to determine the etiology.
The presence of three elliptical, hypopigmented macules (ash-leaf spots) strongly suggests Tuberous Sclerosis Complex (TSC).
Identifying the underlying cause of infantile spasms is critical, as it dictates the choice of specific pharmacotherapy.
3
Select the appropriate targeted pharmacotherapy based on the etiology.
While ACTH or oral corticosteroids are first-line for idiopathic infantile spasms, Vigabatrin is the drug of choice for TSC-associated infantile spasms.
Vigabatrin has superior efficacy specifically for patients with TSC and infantile spasms.

Key Concept

Vigabatrin is the preferred initial treatment for infantile spasms in patients with Tuberous Sclerosis Complex (TSC), presenting with the triad of clustered spasms, developmental regression, and hypsarrhythmia on EEG.
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Topics

Pediatric Neurologic Disorders

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