Intracranial low pressure cannot be considered a disease in itself, but a group of syndromes, called hypocranial pressure syndromes, whenever there is cerebrospinal fluid pressure below 60 mmH2O, characterized by postural headache. There are many causes of the syndrome, some serious and some not so serious, listed below. Excessive dehydration or cachexia state can cause the volume of the brain to shrink, resulting in lower cranial pressure, and cachexia state is mostly seen in the advanced stages of malignancy, which is a more serious disease. Dehydration depends on the patient’s condition. If the dehydration is caused by the use of dehydrating agents for certain diseases, rehydration can be restored to normal. There is also an increase in cerebrospinal fluid leakage, such as the leakage of cerebrospinal fluid from the puncture hole after lumbar puncture, resulting in low cranial pressure headache, which can generally improve within a short time as long as the rehydration is enhanced.