Hernias may also occur as a result of congenital malformation, a congenital diaphragmatic hernia. Major causes of infant mortality include dehydration, infection, congenital malformation and SIDS. Less common causes include a tumor or arteriovenous malformation. Cases of congenital Chiari malformation may be explained by evolutionary and genetic factors. It is usually considered a congenital malformation of unknown cause. Women can also have this type of congenital malformation. Occasionally, Chiari malformation (type 1),may occur, which can lead to hydrocephalus. Kernohan's notch phenomenon associated with a ruptured arteriovenous malformation (AVM) is rare, but not unknown. Incorrect diagnoses include migraines, meningitis, Chiari malformation, and psychiatric disorders. Women are three times more likely than men to have a congenital Chiari malformation. Chiari malformation, necessitating a VP shunt placement. Nystagmus is often very commonly present with Chiari malformation. Powers underwent surgery for a cerebral arteriovenous malformation (CAVM) in the late 1980s. He thought the condition to be the result of "a congenital malformation of the brain". Chiari malformation is a malformation of the brain.