Article abstract-The authors analyzed whether the pituitary gland enlarges in intracranial hypotension syndrome by studying 11 consecutive patients. Initial MRI scans showed pituitary gland enlargement with a convex superior margin. Follow-up MRI studies revealed that the size of the gland invariably diminished in all patients. The authors hypothesize that pituitary gland enlargement in intracranial hypotension syndrome is due to hyperemia of dural and epidural venous sinuses.