Pathophysiology of Nonneoplastic Obstruction of the Foramen of Monro and Progressive Unilateral Hydrocephalus

Our experience with progressive unilateral hydrocephalus in children and the pathophysiology of nonneoplastic obstruction of the foramen of Monro has been analyzed. The status of the foramen of Monro in either congenital or acquired progressive unilateral hydrocephalus was classified into the following four categories: Category 1, atresia of the foramen; Category 2, morphological obstruction; Category 3, functional obstruction; and Category 4, patent foramen. Illustrative cases including hydrodynamic studies and intracranial pressure monitoring are discussed.