Phrenitis is a rare disease that involves inflammation of the brain and causes confusion, fever, and seizures. There are several alternative names for phrenitis, including encephalitis, cerebral inflammation, brain fever, cerebritis, meningoencephalitis, meningoencephalomyelitis, and acute encephalopathy. While these different terms are often used interchangeably, they may refer to slightly different forms of the disease depending on the location or cause of the brain inflammation. Ultimately, any form of phrenitis requires prompt medical attention to alleviate symptoms and prevent further damage to the brain.