Case 336

History A 10-month-old female infant, who was second-born, was referred for progressive macrocephaly, axial hypotonia, developmental delay, and limb stiffness. Birth had occurred at 41 weeks, after an uneventful pregnancy and delivery, to nonconsanguineous parents. Noticeably, the child could not hold her head up at 4 months or sit at 10 months of age. Her vocalizations were modulated to express contentment or anger, without developmentally appropriate babbling. Neurologic examination revealed poor visual contact, progressive macrocephaly, substantial axial hypotonia, and limb stiffness with brisk osteotendinous reflexes, suggestive of spastic diplegia. No swallowing difficulties or seizures were reported, and long-term electroencephalographic monitoring revealed no abnormalities. The patient underwent 3-T MRI (Siemens Healthineers) of the brain, including morphologic sequences and spectroscopy ( Figs 1 – 4 ), under general anesthesia with and without gadolinium-based contrast media administration (Dotarem; Guerbet).