Some patients suddenly experience dizziness, blackness before the eyes and weakness in the limbs. First of all, blood sugar should be monitored to see if there are symptoms of hypoglycemia. Secondly, if the symptoms of dizziness, blackness and weakness of limbs appear after standing up suddenly after a long period of time in the squatting position or lying position, the patient should be monitored for hypoglycemia. If the above symptoms appear after a sudden change of position, it is considered to be a sudden change of position, the intracranial blood supply is insufficient. Some people have low blood pressure, and when the position is changed, the pressure difference is large, and the blood entering the skull becomes less, resulting in the symptoms of blackness and weakness of limbs. You can monitor the blood pressure in prone and standing position, and at the same time improve the head magnetic resonance and head MRA and other related examinations, to clarify whether there is intracranial vascular stenosis, leading to the symptoms of insufficient blood supply to the skull and brain.