Differential Diagnosis for 8-Month-Old Girl with Recurring Bouts of Leg Extension and Posturing

• Single Most Likely Diagnosis
  • Infantile Spasms: This condition is characterized by sudden, brief contractions of one or more muscle groups, often involving the neck, trunk, or legs, and can present with leg extension and posturing. The distractibility of the episodes could be related to the spasms being triggered or interrupted by external stimuli.
• Other Likely Diagnoses
  • Benign Infantile Epilepsy: This condition involves seizures that can manifest as brief episodes of limb extension or posturing and is often seen in infants with normal development.
  • Sandifer Syndrome: Although more commonly associated with gastroesophageal reflux, it can cause arching of the back and extension of the legs in response to discomfort, which might be distractible if the infant is positioned or soothed.
• Do Not Miss Diagnoses
  • Meningitis or Encephalitis: Infections of the central nervous system can cause seizures, including those with focal signs like leg extension, and are medical emergencies.
  • Metabolic Disorders: Certain metabolic disorders can cause seizures or episodic neurological symptoms, including those that might resemble leg extension and posturing.
  • Intracranial Hemorrhage or Mass: Although less common, any intracranial pathology could potentially cause seizures or episodic neurological symptoms, including those described.
• Rare Diagnoses
  • Alternating Hemiplegia of Childhood: A rare disorder that can cause episodes of hemiplegia (weakness on one side of the body) and other neurological symptoms, including dystonic posturing.
  • Pyridoxine-Dependent Epilepsy: A rare condition where seizures are resistant to conventional antiepileptic drugs but respond to pyridoxine (vitamin B6) supplementation, which could potentially cause episodic symptoms like those described if not adequately managed.