Headache

Many Causes of Headache

Acute or chronic headache have hundreds of causes. Among the more common headaches are migraine, cluster headaches, and tension headaches. Headaches such as these are often described as functional. Other headache causes, frequently described as structural, include hemorrhage secondary to the rupture of an aneurysm or vascular malformation, a hemorrhagic infarct, a benign or malignant tumor, an abscess or other bacterial or viral infection of the brain or its coverings, and changes to the cerebrospinal fluid pressure (including hydrocephalus).

Patients with headaches are usually first evaluated by a family practitioner or emergency medicine physician. Individuals with chronic or recurrent headaches are frequently referred to a neurologist, who is a physician trained to diagnose maladies of the nervous system, including the brain. A person with a sudden onset of severe headache (described as the "worst headache of my life") with or without a stiff neck and/or increased sensitivity to light should immediately go to the nearest emergency department because the symptoms may be caused by an acute intracranial hemorrhage.

Imaging for Headache Evaluation: CT and MRI

Currently, two primary imaging tests assist in the evaluation of a patient with a headache: computed tomography (CT) and magnetic resonance imaging (MRI). CT combines an x-ray machine and computer to provide detailed transverse images, or sections, of the brain. It has been available in the United States since the 1970s, and it is usually the preferred imaging option when the onset of headache is acute, as in a patient with a head injury, an abrupt onset of severe headache, or a sudden loss of consciousness. CT is very sensitive in diagnosing acute hemorrhage within or adjacent to the brain. Although CT uses x-rays, the x-ray dose is not harmful when a single or even several examinations are performed. A CT scan of the brain typically costs $300-$600. The cost includes the hospital or outpatient facility charge and the neuroradiologist's interpretation fee.

MRI is somewhat newer than CT, having entered clinical practice in the United States in the 1980s. Unlike CT, MRI does not use x-rays. MRI combines a large strong magnet with radio waves and a computer to provide superbly detailed images of the brain and other parts of the body in multiple planes. MRI is the procedure of choice for evaluating patients with subacute or chronic headaches, a suspected brain tumor, or other space-occupying mass and hydrocephalus. Although claustrophobia was a problem for many patients with the early MRI machines, recent developments have made the units much more patient-friendly. An MRI examination of the brain typically costs $600-$1,200. As in the case of CT, patients undergoing MRI examination may receive an injection of a contrast agent to help the neuroradiologist more thoroughly evaluate the brain and its associated blood vessels.

The interpretation of brain CT and MRI results should ideally be performed by a board-certified neuroradiologist. Neuroradiologists are radiologists who have undergone a year or more of specialized training after a radiology residency. Their training has an emphasis on imaging of the brain, neck, and spine, and neuroradiologists pass a rigorous examination administered by the American Board of Radiology. Most neuroradiologists in the United States are members of the American Society of Neuroradiology (ASNR). The ASNR is actively involved in neuroradiology education and research to provide patients with the highest-quality, most-advanced clinical care possible.