<P> Duret haemorrhages are areas of bleeding in the midbrain and upper pons due to a downward traumatic displacement of the brainstem . </P> <P> Cysts known as syrinxes can affect the brainstem, in a condition called syringobulbia . These fluid - filed cavities can be congenital, acquired or the result of a tumor . </P> <P> Criteria for claiming brainstem death in the UK have developed in order to make the decision of when to stop ventilation of somebody who could not otherwise sustain life . These determining factors are that the patient is irreversibly unconscious and incapable of breathing unaided . All other possible causes must be ruled out that might otherwise indicate a temporary condition . The state of irreversible brain damage has to be unequivocal . There are brainstem reflexes that are checked for by two senior doctors so that imaging technology is unnecessary . The absence of the cough and gag reflexes, of the corneal reflex and the vestibulo - ocular reflex need to be established; the pupils of the eyes must be fixed and dilated; there must be an absence of motor response to stimulation and an absence of breathing marked by concentrations of carbon dioxide in the arterial blood . All of these tests must be repeated after a certain time before death can be declared . </P> <Ul> <Li> <P> The midbrain, pons, and medulla oblongata are labelled on this coronal section of the human brain . </P> </Li> <Li> <P> Brainstem . Anterior face. Deep dissection </P> </Li> <Li> <P> Brainstem . Posterior face. Deep dissection </P> </Li> <Li> <P> Sagittal section of brainstem marking nuclei </P> </Li> </Ul>

Major pathways and nuclei found in the medulla pons and midbrain