Two patients sustained an ischemic brain stem infarction during medical examination and treatment. The first patient lost consciousness and the spontaneous respiration ceased during X-ray examination of the cervical spine when the neck was hyperextended. After some minutes he regained conciousness but was found to be tetraplegic, and the patient deceased 4 months later. The angiogram revealed thrombosis of the basilar artery. The other patient had profuse nosebleed and was treated with posterior tamponation during which she sat for about 10 min with the neck hyperextended. Some hours after this procedure symptoms and signs of lateral caudal brain stem infarction emerged.