If a patient has sudden vertigo, the cause of vertigo attack, the duration of vertigo, or the relief of vertigo should be analyzed. 1. If a patient has transient vertigo during the process of squatting or lying down or getting up, consider that it may be caused by postural hypotension, suggest the patient to measure the blood pressure in lying and standing position to clarify, if the difference between the two blood pressure is more than 20mmHg, consider that it is caused by postural hypotension. 2. If the difference between the two blood pressures is more than 20 mmHg, it is considered to be caused by postural hypotension. 2. If the patient turns over in bed, or if the position of the head changes, the transient vertigo is considered to be caused by benign paroxysmal positional vertigo, also known as otolithiasis, which usually lasts no more than one minute and can be seen as rotational fluttering of the eyes. If it is caused by posterior circulation ischemia, if it is a transient cerebral blood supply deficiency, the patient will also show a sudden vertigo.