This diagnosis is one of the most common reasons for referrals of new patients to our practice. This entity occurs in infants and becomes apparent as head growth begins to accelerate abnormally, typically beyond the age of three months. This abnormally accelerated head growth continues until about nine to 12 months of age. At this point head growth usually returns to a normal rate. Development proceeds normally in a great majority of these patients. In these cases, a head CT scan or MRI will show abnormally prominent fluid spaces (filled with CSF) between the brain and it’s covering. Up to 45% may show a mild to moderate concomitant increase in ventricular size.