Question: what are the causes of headaches

Reference:
 Spinal headaches Overview Spinal headaches occur in up to 40 percent of those who undergo a spinal tap (lumbar puncture) or spinal anesthesia. Both procedures require a puncture of the tough membrane that surrounds the spinal cord and, in the lower spine, the lumbar and sacral nerve roots. During a spinal tap, a sample of cerebrospinal fluid is withdrawn from your spinal canal. During spinal anesthesia, medication is injected into your spinal canal to numb the nerves in the lower half of your body. If spinal fluid leaks through the tiny puncture site, you may develop a spinal headache. Most spinal headaches - also known as post-lumbar puncture headaches - resolve on their own with no treatment. However, severe spinal headaches lasting 24 hours or more may need treatment. Symptoms Spinal headache symptoms include: - Dull, throbbing pain that varies in intensity from mild to incapacitating - Pain that typically gets worse when you sit up or stand and decreases or goes away when you lie down Spinal headaches are often accompanied by: - Dizziness - Ringing in the ears (tinnitus) - Light sensitivity (photophobia) - Nausea - Neck stiffness When to see a doctor Tell your doctor if you develop a headache after a spinal tap or spinal anesthesia - especially if the headache gets worse when you sit up or stand. Causes Spinal headaches are caused by leakage of spinal fluid through a puncture hole in the tough membrane (dura mater) that surrounds the spinal cord. This leakage decreases the pressure exerted by the spinal fluid on the brain and spinal cord, which leads to a headache. Spinal headaches typically appear within 48 hours after a spinal tap or spinal anesthesia. Sometimes epidural anesthesia may lead to a spinal headache as well. Although epidural anesthetic is injected just outside the membrane that surrounds the spinal cord, a spinal headache is possible if the membrane is unintentionally punctured. Diagnosis The doctor will ask questions about your headache and do a physical exam. Be sure to mention any recent procedures - particularly a spinal tap or spinal anesthesia. Sometimes the doctor will recommend magnetic resonance imaging (MRI) to rule out other causes of your headache. During the exam, a magnetic field and radio waves create cross-sectional images of your brain. Treatment Treatment for spinal headaches begins conservatively. Your doctor may recommend bed rest, fluids, caffeine and oral pain relievers. If your headache hasn't improved within 24 hours, your doctor may suggest one or more of the following treatments: - Epidural blood patch. Injecting a small amount of your blood into the space over the puncture hole will often form a clot to seal the hole, restoring normal pressure in the spinal fluid and relieving your headache. This is the usual treatment for persistent spinal headaches that don't resolve on their own. - IV caffeine. Delivered directly into your bloodstream, caffeine helps relieve spinal headaches - usually within a few hours - by constricting blood vessels within your head. 

Answer: Spinal headaches are caused by leakage of spinal fluid through a puncture hole in the tough membrane (dura mater) that surrounds the spinal cord. This leakage decreases the pressure exerted by the spinal fluid on the brain and spinal cord, which leads to a headache.