The vertebral artery supplies a number of vital structures in the posterior cranial fossa, such as the brainstem, the cerebellum and the occipital lobes. The brainstem harbors a number of vital functions (such as respiration) and controls the nerves of the face and neck. The cerebellum is part of the diffuse system that coordinates movement. Finally, the occipital lobes participate in the sense of vision.Dissection occurs when blood accumulates in the wall of the blood vessel. This is most likely due to a tear in the tunica intima (the inner layer), allowing blood to enter the tunica media, although other lines of evidence have suggested that the blood may instead arise from the vasa vasorum, the small blood vessels that supply the outer layer of larger blood vessels. Various theories exist as to whether people who sustain carotid and vertebral artery dissection, even if they do not have a connective tissue disorder, have an underlying vulnerability. Biopsy samples of skin and other arteries has indicated that this might be a possibility, but no genetic defect in collagen or elastin genes has been convincingly proven. Other studies have indicated inflammation of the blood vessels, as measured by highly sensitive C-reactive protein (hsCRP, a marker of inflammation) in the blood.Once dissection has occurred, two mechanisms contribute to the development of stroke symptoms. Firstly, the flow through the blood vessel may be disrupted due to the accumulation of blood under the vessel wall, leading to ischemia (insufficient blood supply).
In medicine, an external cause is a reason for the existence of a medical condition which can be associated with a specific object or acute process that was caused by something outside the body. Such causes are classified as "E codes" in ICD 9.External Cause of Injury Codes (E codes) are ICD-9-CM codes or ICD-10 codes that are used to define the mechanism of death or injury, along with the place of occurrence of the event. [1] E codes are assigned on death certificates based on the manner of death. ICD-10 codes in the range V01–X59 refer to unintentional injuries. Codes in the range X60–X84 refer to intentional self-harm. Codes in the range Y85–Y09 refer to assault, and codes in the range Y10–Y34 refer to events of undetermined intent.E codes are well-collected on death certificate data, but less so on hospital discharge data. Numerous initiatives have increased the percentage of records coded (CDC, MMWR March 28, 2008 / Vol. 57 / No. RR-1). == References ==