sensation, muscle weakness, hearing problems, vertigo, swallowing and speech difficulty, voice change, and co-ordination problems. localizing neurological lesions in the brainstem may be very precise, although it relies on a clear understanding on the functions of brainstem anatomical structures and how to test them. brainstem stroke syndrome can cause a range of impairments including locked-in syndrome. duret haemorrhages are areas of bleeding in the midbrain and upper pons due to a downward traumatic displacement of the brainstem.: 842 cysts known as syrinxes can affect the brainstem, in a condition, called syringobulbia. these fluid-filled cavities can be congenital, acquired or the result of a tumor. 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. additional images the midbrain, pons, and medulla oblongata are labelled on this coronal section of the human brain. 3d visualization of the brainstem in an average human brain