If you have symptoms of a neurological disorder, your doctor will use one or more of the following diagnostic procedures to determine the cause of your symptoms. He or she may refer you to a neurologist (a physician who specializes in treating disorders of the brain and spinal cord) for further evaluation and treatment.
• Neurological examination. During a neurological examination, a physician performs a variety of physical tests to check the functioning of a person's nervous system. He or she will test vision (by examining eye movement, pupil reaction, and other eye reflexes); reflexes (by tapping the knee with a rubber hammer, for example); hearing; sensation (by gently sticking the foot with a pin); movement (by asking the person to perform simple tasks); and balance and coordination (by asking the person, for example, to balance on one foot, touch the nose with the eyes closed, or walk heel-to-toe).
• Lumbar puncture. For a lumbar puncture (also called a spinal tap), a hollow needle is inserted into the spinal column in your lower back to obtain a sample of cerebrospinal fluid, which circulates around the brain and spinal cord. The fluid is examined for signs of infection, cancer, bleeding, or inflammation. A lumbar puncture also is performed as part of myelography (see next page).
• Electroencephalography. This is a painless examination in which electrodes are placed on the scalp to record the electrical activity of the brain. Electroencephalography helps identify signs of a tumor, epilepsy, or other neurological disorders.
• Computed tomography (CT) scanning. CT scanning uses computer and low-dose X rays to produce detailed cross-sectional images of body tissues such as the brain and spinal cord. The images, which are clearer than conventional X-ray images, are displayed on a video monitor. During the procedure, you lie on a table inside a circular opening in the scanner. A contrast medium (a dye) may be injected before the scan to highlight blood vessels, organs, or any abnormalities. The procedure is painless.
Magnetic resonance imaging (MRI). MRI uses a computer, a powerful magnet, and radio waves to create detailed two- or three-dimensional images of body tissues. The images are displayed on a video monitor. MRI often produces better images than CT scanning, especially when the tissue being examined is located near bone. The procedure is painless and has no known side effects. During the procedure, you lie in a tunnel inside the magnet. Some people feel claustrophobic during an MRI. You are given a signal button to hold so that you can signal the technician to stop the procedure if you become anxious. If you think that you might feel claustrophobic during the MRI, ask the doctor for a tranquilizer before the procedure. Because the magnet makes loud knocking noises, you may be offered headphones to wear during the procedure, to help block the noise. Also, because of the powerful magnetic field that is created during the procedure, you cannot carry or wear any metal objects (such as jewelry or a watch) or electronic devices (such as a hearing aid or a pager). You cannot have an MRI if you have a pacemaker or any magnetic metal (including plates, screws, or artificial joints) implanted in your body.
Cerebral angiography. This diagnostic procedure is used to examine the arteries in the brain and the carotid arteries in the neck and to help diagnose problems such as narrowed or blocked arteries, aneurysms (see page 323), and arteriovenous malformations (see page 341). In cerebral angiography, a catheter (a thin, flexible tube) is inserted into the femoral artery, a large blood vessel in the groin area, and threaded up through the main blood vessels of the abdomen and chest and into the main arteries in the neck (carotid arteries). Contrast medium (a dye) is injected through the catheter into the arteries, and a series of rapid-sequence X rays (similar to a movie) is taken. The images are displayed on a video monitor. Cerebral angiography produces better images than carotid ultrasound (see below) and allows the doctor to look deeper inside the brain.
Myelography. Before CT scanning and MRI (see above) became available, doctors relied on myelography to look inside the spinal canal. In this procedure, contrast medium is injected into the spinal canal after a lumbar puncture, and a series of X rays is taken. Because the procedure is lengthy and may be painful, myelography is generally used only when CT scanning or MRI cannot be performed or do not provide enough information. Carotid ultrasound. If you are at risk for stroke (see page 323) or have experienced a transient ischemic attack (see page 323), you will likely undergo a carotid ultrasound. In this procedure, sound waves are used to produce images that help the doctor detect changes in the rate of blood flow through the carotid arteries (the major arteries in the neck that supply blood to the brain). The images, which are displayed on a video monitor, reveal blockages or potential blockages in the carotid arteries.
Brain and Nervous System
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