Benign Extra-Axial Fluid Collection
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 9-12 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.
The theory beyond why BEFI develops is that in many infants the channels to absorb CSF do not develop early enough so that now more CSF is being made then can be absorbed. In this entity, the CSF accumulates in the subarachnoid space outside the brain rather than within the ventricles. Fortunately, BEFI almost always resolves on it's own without treatment by two years of age. All that is recommended is that these children be watched closely in terms of their development and head growth pattern.