Low cerebral pressure can cause headache, normal intracranial pressure is 80-180mmH2O, if it is lower than 60mmH2O, low intracranial pressure will occur, the patient will have headache, mainly due to the displacement of brain tissue for sinking, then it will pull and stimulate the intracranial venous sinus and the phenomenon of headache. When the patient is lying down, the headache will be relieved. When the patient is sitting or standing, the headache will be aggravated, and the main manifestation is a dull pain.