The main causes of inadequate blood supply to the brain include the following categories.
Compression of blood vessels: Various causes lead to compression of blood supply vessels in the brain, which can cause cerebral blood supply deficiency, such as patients with vertebral artery type cervical spondylosis, which can cause symptoms of cerebral blood supply deficiency due to compression of vertebral artery.
Thrombosis: localised in situ obstruction of an artery. Obstruction may be caused by lesions in the arterial wall, such as atherosclerosis, arterial entrapment or fibromuscular dysplasia, and smouldering disease.
Embolism: is the blockage of a specific cerebral artery by debris or particles originating from another part of the body. For example, atrial fibrillation causes a thrombus to dislodge and follow the blood flow to block an artery in the brain, leading to a lack of blood supply to the brain or even a stroke.
Systemic insufficiency of perfusion: cardiac pump failure due to cardiac arrest or arrhythmia, or reduced cardiac output associated with acute myocardial ischaemia, pulmonary embolism, pericardial effusion or haemorrhage. Hypoxaemia may further reduce the amount of oxygen delivered to the brain.
Blood disorders : Blood and coagulation disorders are uncommon primary causes of stroke and inadequate blood supply to the brain, but they should be considered in patients younger than 45 years of age, those with a history of coagulation disorders, and those with a history of cryptogenic stroke.