Back Pain – Diagnosing the Cause of Your Low Back Pain

A thorough medical history and physical exam can generally identify any dangerous conditions or family history that may be associated with back pain.

During the exam, your physician will ask you to describe the onset, site, and severity of the pain; duration of symptoms and any limitations in movement; and your history of previous episodes or any health conditions that might be related to your pain. The physician will examine your back and conduct neurologic tests to determine the cause of the pain and appropriate treatment. Blood tests may be ordered and/or imaging tests to help diagnose tumors or other possible sources of the pain.

Following are diagnostic methods used to confirm the cause of low back pain:

• X-ray imaging. X-ray imaging includes conventional and enhanced methods to help diagnose the cause and site of back pain. A conventional x-ray looks for broken bones or an injured vertebra, but tissue masses such as injured muscles and ligaments or painful conditions such as a bulging disc are not visible on conventional x-rays. X-ray imaging is a fast, noninvasive, painless procedure performed in a doctor’s office or at a clinic.
• Discography. Discography involves the injection of a special contrast dye into a spinal disc thought to be causing low back pain. The dye outlines damaged areas on x-rays taken following the injection. Discography is often suggested for patients who are considering lumbar surgery or whose pain has not responded to conventional treatments.
• Computerized tomography (CT). This is a quick and painless process used when disc rupture, spinal stenosis, or damage to vertebrae is suspected as the cause of low back pain. X-rays are passed through the body at various angles and are detected by a computerized scanner to produce two-dimensional slices of the internal structures of the back. Computerized tomography is a diagnostic exam generally conducted at an imaging center or in a hospital.
• Magnetic resonance imaging (MRI). An MRI is used to evaluate the lumbar region for bone degeneration or injury or disease in tissues and nerves, muscles, ligaments, and blood vessels. The scanning equipment creates a magnetic field around the body strong enough to temporarily realign water molecules in the tissues. Then, radio waves are passed through the body to detect the “relaxation” of the molecules back to a random alignment and trigger a resonance signal at different angles within the body. A computer processes this resonance into a three-dimensional picture or a two-dimensional “slice” of the tissue being scanned. It differentiates between bone, soft tissues and fluid-filled spaces by their water content and structural properties. An MRI is a noninvasive procedure often used to identify a condition requiring prompt surgical treatment.
• Electrodiagnostic procedures. Electrodiagnostic procedures include electromyography (EMG), nerve conduction studies, and evoked potential (EP) studies. EMG assesses the electrical activity in a nerve to detect if muscle weakness results from an injury or a problem with the nerves that control the muscles. With EMG, very fine needles are inserted in muscles to measure electrical activity transmitted from the brain or spinal cord to a particular area of the body. Nerve conduction studies involve the use of two sets of electrodes placed on the skin over the muscles. The first set of electrodes give the patient a mild shock to stimulate the nerve that runs to a particular muscle. The second set of electrodes make a recording of the nerve’s electrical signals. From this information the doctor can determine if there is nerve damage. EP tests involve two sets of electrodes as well – one set to stimulate a sensory nerve and the other set on the scalp to record the speed of nerve signal transmissions to the brain.
• Bone scans. Bone scans are used to diagnose and monitor infection, fractures, or disorders in the bone. A small amount of radioactive material is injected into the bloodstream to collect in the bones, particularly in areas with some abnormality. Scanner-generated images are sent to a computer to identify areas of irregular bone metabolism or abnormal blood flow, and to measure levels of joint disease.
• Thermography. Thermography uses infrared sensing devices to measure small temperature changes between the two sides of the body or the temperature of a specific organ. It may be used to detect the presence or absence of nerve root compression.
• Ultrasound imaging. Also called ultrasound scanning or sonography, ultrasound imaging uses high-frequency sound waves to obtain images inside the body. Sound wave echoes are recorded and displayed as a real-time visual image. Ultrasound imaging can show tears in ligaments, muscles, tendons, and other soft tissue masses in the back.