[Traumatic internal carotid artery dissection due to compression by a helmet strap].

It is well known that wearing a helmet can reduce the risk of head injury in a traffic accident. We report a case of traumatic cervical internal carotid artery dissection due to compression by the strap of a helmet after a motorcycle accident. A 21 year-old man fell off his motorcycle and his head was struck at the right parietal region. His helmet prevented head injury, but the helmet strap which was fixed around his neck compressed his cervical internal carotid artery. He lost consciousness and developed left hemiparesis two hours after being admitted to an emergency department. Cerebral angiography revealed dissection of he right cervical internal carotid artery. This lesion was treated successfully by stent placement two months after the accident. The cause of carotid dissection was thought to be compression of his neck by the helmet strap. If the strap of a helmet is fixed around the neck, it can cause carotid artery injury during an accident, so it can be concluded that the strap of a helmet should be fixed firmly at the chin.