Clinical History.—A 7-month-old boy weighing 7.9 kg was referred to the Medical University Hospital for neurosurgical evaluation of increasing head size. Prenatal development, birth weight, and birth history were normal. Postnatal development has been normal with the exception of an increase in head circumference from 37 cm at birth to 50 cm. There was no history of seizures, weakness, cyanosis, or heart failure.
Physical Examination.—He was a well-developed, well-nourished infant who appeared alert and happy. The head was large, with a circumference of 50 cm. There was a palpable bruit over the frontal fontanel, but no evidence of increased intracranial pressure. The neck was supple, without masses. Examination of the chest and abdomen was normal. The extremities were also normal, with good motion. Sensory examination and motor function were normal.
Laboratory Studies.—Hemogram, urinalysis, electrolyte count, and clotting studies were normal. A chest roentgenogram and electrocardiogram were