A headache or cephalalgia is pain anywhere in the region of the head or neck. It can be a symptom of a number of different conditions of the head and neck.
Headaches can result from a wide range of causes both benign and more serious. Brain tissue itself is not sensitive to pain as it lacks pain receptors. Rather, the pain is caused by disturbance of the pain-sensitive structures around the brain. Nine areas of the head and neck have these pain-sensitive structures, which are the cranium (the periosteum of the skull), muscles, nerves, arteriesand veins, subcutaneous tissues, eyes, ears, sinuses and mucous membranes.
There are more than 200 types of headaches. Some are harmless and some are life-threatening. The description of the headache and findings on neurological examination, determine whether additional tests are needed and what treatment is best.
Primary vs. Secondary Headaches
Headaches are broadly classified as "primary" or "secondary".Primary headaches are benign, recurrent headaches not caused by underlying disease or structural problems. For example, migraine is a type of primary headache. While primary headaches may cause significant daily pain and disability, they are not dangerous. Secondary headaches are caused by an underlying disease, like an infection, head injury, vascular disorders, brain bleed or tumors. Secondary headaches can be harmless or dangerous. Certain "red flags" or warning signs indicate a secondary headache may be dangerous.
- Primary Headaches
90% of all headaches are primary headaches. Primary headaches usually first start when people are between 20 and 40 years old . The most common types of primary headaches are migraines and tension-type headaches. They have different characteristics. Migraines typically present with pulsing head pain, nausea, photophobia (sensitivity to light) and phonophobia (sensitivity to sound). Tension-type headaches usually present with non-pulsing "bandlike" pressure on both sides of the head, not accompanied by other symptoms. Other very rare types of primary headaches include:
- • Cluster headaches: short episodes (15–180 minutes) of severe pain, usually around one eye, with autonomic symptoms (tearing, red eye, nasal congestion) which occur at the same time every day. Cluster headaches can be treated with triptans and prevented with prednisone, ergotamine or lithium.
- • Trigeminal neuralgia: shooting face pain
- • Hemicrania continua: continuous unilateral pain with episodes of severe pain. Hemicrania continua can be relieved by the medication indomethacin.
- • Primary cough headache: starts suddenly and lasts for several minutes after coughing, sneezing or straining .
- • Primary exertional headache: throbbing, pulsatile pain which starts during or after exercising, lasting for 5 minutes to 24 hours. The mechanism behind these headaches is unclear, possibly due to straining causing veins in the head to dilate, causing pain.
- • Primary sex headache: dull, bilateral headache that starts during sexual activity. These headaches are thought to be due to lower pressure in the head during sex.
- • Hypnic headache: moderate-severe headache that starts a few hours after falling asleep and lasts 15–30 minutes. The headache may recur several times during night. Hypnic headaches are usually in older women. They may be treated with lithium.
- Secondary Headaches
Headaches may be caused by problems elsewhere in the head or neck. More serious causes of secondary headaches include:
- • meningitis: inflammation of the meninges which presents with fever and meningismus, or stiff neck
- • bleeding inside the brain (intracranial hemorrhage)
- • subarachnoid hemorrhage (acute, severe headache, stiff neck WITHOUT fever)
- • ruptured aneurysm, arteriovenous malformation, intraparenchymal hemorrhage (headache only)
- • brain tumor: dull headache, worse with exertion and change in position, accompanied by nausea and vomiting. Often, the person will have nausea and vomiting for weeks before the headache starts.
- • temporal arteritis: inflammatory disease of arteries common in the elderly (average age 70) with fever, headache, weight loss, jaw claudication, tender vessels by the temples, polymyalgia rheumatica
- • acute closed angle glaucoma (increased pressure in the eyeball): headache that starts with eye pain, blurry vision, associated with nausea and vomiting. On physical exam, the person will have a red eye and a fixed, mid dilated pupil.
The brain itself is not sensitive to pain, because it lacks pain receptors, also called nociceptors. However, several areas of the head and neck do have nociceptors, and can thus sense pain. These include the extracranial arteries, middle meningeal artery, large veins, venous sinuses, cranial and spinal nerves, head and neck muscles, the meninges, falx cerebri, parts of the brainstem, eyes, ears, teeth and lining of the mouth. Pial arteries, rather than pial veins are responsible for pain production.