Common head discomfort, easily described as dizziness in several cases: 1, vertigo: often manifested by sudden and intermittent rotation of external objects or their own rotation in a certain direction, rolling, floating or drifting sensation (can not be relieved by closing the eyes) as the main symptom. It is a kind of motion hallucination, which is often referred to as “spinning”; the cause is mostly due to the lesion of the vestibular semicircular canal nervous system. Depending on the location of the lesion, there are sometimes symptoms such as nausea, vomiting, panic and sweating, as well as signs such as nystagmus and orientation dumping. 2, dizziness: often manifested as a persistent dullness and lack of clarity, accompanied by heavy head, dullness, headache, forgetfulness, weakness and other symptoms of neurological disorders or chronic somatic diseases, aggravated by exertion. It is caused by neurasthenia or chronic somatic diseases. 3, dizziness: often manifested as intermittent or persistent light-headedness and shaking unsteadiness, mostly aggravated by walking, standing, sitting or using the eyes. Such as ocular dizziness, deep sensory dizziness, etc. 4, syncope: The emphasis is on sudden onset of transient disorders of consciousness as the main symptom, although there may be vertigo or dizziness, blurred vision, unsteadiness and nausea at the beginning of the attack. It is caused by multiple causes of transient low blood pressure, slow heartbeat, and transient cerebral ischemia. For example, vascular reflex syncope and cardiogenic syncope. These four symptoms are not properly distinguished for the vast majority of people, and even some doctors, which is one of the reasons for misdiagnosis and confusion.