Brain Stem Hemorrhage, Traumatic: Bleeding into structures of BRAIN STEM, including the MIDBRAIN; PONS; or MEDULLA OBLONGATA, as the result of CRANIOCEREBRAL TRAUMA. DIFFUSE AXONAL INJURY is commonly associated. Clinical manifestations may include OCULAR MOTILITY DISORDERS; ATAXIA; PARALYSIS; PERSISTENT VEGETATIVE STATE; and COMA.Brain Stem: The part of the brain that connects the CEREBRAL HEMISPHERES with the SPINAL CORD. It consists of the MESENCEPHALON; PONS; and MEDULLA OBLONGATA.Cerebral Hemorrhage: Bleeding into one or both CEREBRAL HEMISPHERES including the BASAL GANGLIA and the CEREBRAL CORTEX. It is often associated with HYPERTENSION and CRANIOCEREBRAL TRAUMA.Hemorrhage: Bleeding or escape of blood from a vessel.Subarachnoid Hemorrhage: Bleeding into the intracranial or spinal SUBARACHNOID SPACE, most resulting from INTRACRANIAL ANEURYSM rupture. It can occur after traumatic injuries (SUBARACHNOID HEMORRHAGE, TRAUMATIC). Clinical features include HEADACHE; NAUSEA; VOMITING, nuchal rigidity, variable neurological deficits and reduced mental status.Stem Cells: Relatively undifferentiated cells that retain the ability to divide and proliferate throughout postnatal life to provide progenitor cells that can differentiate into specialized cells.