CAUSES OF SECONDARY HEADACHES

About 90% of people seeking help for headaches have a primary headache. The remainder of cases are secondary headaches, caused by an underlying disorder that produces headache as a symptom. More than 300 conditions can cause headaches. Some of the most common are listed below.

Sinus Headaches. Many primary headaches, including migraines, are misdiagnosed as sinus headaches. Sinus headaches can occur in the front of the face, usually around the eyes, across the cheeks, or over the forehead. They are usually mild in the morning and increase during the day and are usually accompanied by fever, runny nose, congestion, and general debilitation. Sinus headaches spread over a larger area of the head than migraines, but it is often difficult to tell them apart, particularly if headache is the only symptom of sinusitis. Both types of headache even coexist in many cases. Often, the visual changes associated with migraine can rule out sinusitis, but such visual changes do not occur with all migraines. (In rare cases, sinusitis can cause double vision and even vision loss, a sign of very serious infection.)

Headaches that Originate in the Neck. Some headaches may be caused by abnormalities of the neck muscles (called cervicogenic headaches). Nerves in the neck converge in the trigeminal nerve, which is the largest nerve in the skull. It originates in the brain stem and supplies sensation to the face. This nerve can generate pain signals to the facial area that the brain may interpret as headache. Pain is usually on one side. Even if pain affects both sides of the head, it is usually more severe on one side. The quality of the headache may be difficult to distinguish from an aching tension headache or a mild migraine without aura. Cervicogenic headaches can result from prolonged poor posture (such as that caused by sitting in front of a computer keyboard or driving daily for long periods), arthritis, injuries of the upper spine, or abnormalities in the cervical spine (the spinal bones in the neck). Whiplash injuries involve the neck and can cause headaches, which, according to a 2001 British study, resolve within 3 weeks in 85% of patients.

Temporomandibular Joint Disorder (TMJ, also called TMD). Muscle contractions that cause headaches may be a result of temporomandibular joint dysfunction, which is caused by clenching the jaws or grinding the teeth (usually during sleep), or by abnormalities in the jaw joints themselves. The diagnosis is easy if chewing produces pain or if jaw motion is restricted or noisy. TMJ pain can occur in the ear, cheek, temples, neck, or shoulders. This condition often coexists with chronic tension headache.

Glaucoma. Acute glaucoma is caused by increased pressure in the eye and requires immediate medical attention. Throbbing pain may be felt around or behind the eyes or in the forehead. Patients have redness in the eye and may see halos or rings around lights.

Brain Tumor. Fear of brain tumor is common among people with headaches, but headache is almost never the first or only sign of a tumor. Changes in personality and mental functioning, vomiting, seizures, and other symptoms are more likely to appear first. When the headache does develop, it is often worse early in the morning or may awaken sufferers during the night.

Neuralgia. Neuralgia is pain due to nerve abnormalities, which can occur in the facial area and resemble migraines or sinus headaches.

Hypertension. Although many people attribute headaches to high blood pressure, the weight of evidence suggests that hypertension does not cause head aches. An exception is malignant hypertension, an uncommon medical emergency in which the blood pressure abruptly rises to extreme levels, causing damage to blood vessels in the brain, heart, and kidneys.

Strokes Caused by Blood Clots or Hemorrhages. A blood clot or hemorrhage in the brain leading to a stroke can cause a severe headache, sometimes referred to as a thunderclap headache when it is very sudden and severe. The onset of such a headache, particularly if it is associated with confusion, stupor, or other neurologic symptoms, mandates prompt medical attention.

Epilepsy. Severe headaches that can last 12 hours or longer are very common in epilepsy. Migraine is particularly associated with epilepsy.

Head Injuries. It is obvious that a significant blow to the head will cause pain. In most cases, the pain is similar to tension-type headache and is treated in the same way as the primary headache. Post-injury headaches, however, can reflect serious damage, ranging from skull fractures to internal bleeding, and monitoring is important.

Disorders of the Meninges. The meninges are the membranes covering the brain and the spinal cord. Meningitis, which is an infection or irritation of these membranes, is an uncommon but potentially serious cause of severe headache. Other symptoms include nausea and stiffness or pain in the neck.

Gynecologic Problems. Many clinicians have anecdotally linked gynecologic problems, such as ovarian cysts and menstrual disorders, to chronic headaches, and new data are emerging to support this association.

Temporal (Giant Cell) Arteritis. Certain causes of headaches are unique to the elderly, such as temporal arteritis, also called giant cell arteritis. Inflammation in arteries that carry blood to the head, neck, and sometimes the upper part of the body can cause very severe headaches. The risk for this headache is highest in people over age 70, especially among women, people of European heritage, and patients with polymyalgia rheumatica.

Miscellaneous Causes of Benign Headaches. Rapid consumption of ice cream or other very cold foods or beverages is the most common trigger of sudden headache pain, which may be prevented by warming the food or drink for a few seconds in the front of the mouth before swallowing. Other common benign causes of headache include eyestrain, dental problems, allergies, systemic infections, and caffeine withdrawal. Headaches may be induced by sexual activity or intense physical exertion. Leakage from spinal cord fluid is rare but can cause headaches that may be mistaken for brain tumors.