• Cervical vertebrae: the seven vertebrae forming the upper part of the spine
• Thoracic vertebrae: the 12 bones between the neck and the lower back
• Lumbar vertebrae: the five largest and strongest vertebrae located in the lower back between the chest and hips
• The sacrum and coccyx are the bones at the base of the spine. The sacrum is made up of five vertebrae fused together, while the coccyx (tailbone) is formed from four fused vertebrae.

What Causes Back Pain?

The causes of back pain can be complex. Some causes of back pain include accidents, muscle strains, and sports injuries.

How Is Back Pain Diagnosed?

In addition to performing a complete history and physical exam, your doctor may suggest one of the following diagnostic studies:

• X-rays, which can be used to provide detail of the bone structures in the spine and to check for instability (such as spondylolisthesis, see below), tumors and fractures.
• CT scans, which can identify specific conditions, such as a herniated disc or spinal stenosis.
• MRI scans, which can provide details about the backs discs and nerve roots. MRI scans are most commonly used for pre-surgical planning.
• CT scans, which can identify specific conditions, such as a herniated disc or spinal stenosis.

A number of other imaging and electrical studies may also be used to identify back problems, and some injections are used for diagnostic purposes as well as for pain relief.
Types of Back Injury

• Spondylolisthesis: This is a slipping of vertebra that occurs, in most cases, at the base of the spine. Spondylolysis, which is a defect or facture of one or both wing-shaped parts of a vertebra, can result in vertebrae slipping backward, forward, or over a bone below.

•  Cervical Radiculopathy: Cervical radiculopathy is the damage or disturbance of nerve function that results if one of the nerve roots near the cervical vertebrae is compressed. Damage to nerve roots in the cervical area can cause pain and the loss of sensation in various upper extremities, depending on where the damaged roots are located.

Causes of Spondylolithesis

There are many causes for spondylolithesis. A vertebra might be defective from the time a person is born, or a vertebra may be broken by trauma or a stress fracture. In addition, vertebrae can be broken down by infection or disease. Most commonly, this disorder occurs in children and adolescents who are active in athletics.

Symptoms of Spondylolithesis

Symptoms include:

• Lower back pain
• Muscle tightness and stiffness
• Pain in the buttocks
• Pain radiating down the legs (due to pressure on nerve roots)

Spondylolithesis Treatments

Spondylolisthesis is treated with the strengthening of supportive abdominal and back muscles through physical therapy. For patients who continue to have severe pain and disability after physical therapy, there is the option of surgical fusion (arthrodesis) of the vertebra to the bone below.
Causes of Cervical Radiculopathy

Damage can occur as a result of pressure from material from a ruptured disc, degenerative changes in bones, arthritis, or other injuries that put pressure on the nerve roots. In older people, normal degenerative changes in the discs can cause pressure on nerve roots. In younger people, cervical radiculopathy tends to be the result of a ruptured disc. This disc material then compresses the nerve root, causing pain.
Symptoms of Cervical Radiculopathy

The main symptom of cervical radiculopathy is pain that spreads into the arm, neck, chest, and/or shoulders. A person with radiculopathy may experience muscle weakness and/or numbness or tingling in fingers or hands. Other symptoms may include lack of coordination, especially in the hands.
Treatments of Cervical Radiculopathy

Cervical radiculopathy may be treated with a combination of pain medications such as corticosteroids (powerful anti-inflammatory drugs) or non-steroidal pain medication (Motrin or Aleve) and physical therapy. Steroids may be prescribed either orally or injected epidurally (into the dura, which is the membrane that surrounds the spinal cord).

Physical therapy might include gentle cervical traction and mobilization, exercises, and other modalities to reduce pain.

If significant compression on the nerve exists to the extent that motor weakness results, surgery may be necessary to relieve the pressure.

What Are the Causes of Back Pain?

It is important to understand that back pain is a symptom of a medical condition, not a diagnosis itself. Medical problems that can cause back pain include the following:

Mechanical problems: A mechanical problem is a problem with the way your spine moves or the way you feel when you move your spine in certain ways. Perhaps the most common mechanical cause of back pain is a condition called intervertebral disc degeneration, which simply means that the discs located between the vertebrae of the spine are breaking down with age. As they deteriorate, they lose their cushioning ability. This problem can lead to pain if the back is stressed. Other mechanical causes of back pain include spasms, muscle tension, and ruptured discs, which are also called herniated discs.

Injuries: Spine injuries such as sprains and fractures can cause either short-lived or chronic pain. Sprains are tears in the ligaments that support the spine, and they can occur from twisting or lifting improperly. Fractured vertebrae are often the result of osteoporosis, a condition that causes weak, porous bones. Less commonly, back pain may be caused by more severe injuries that result from accidents and falls.

Acquired conditions and diseases: Many medical problems can cause or contribute to back pain. They include scoliosis, which causes curvature of the spine and does not usually cause pain until mid-life; spondylolisthesis; various forms of arthritis, including osteoarthritis, rheumatoid arthritis, and ankylosing spondylitis; and spinal stenosis, a narrowing of the spinal column that puts pressure on the spinal cord and nerves. While osteoporosis itself is not painful, it can lead to painful fractures of the vertebrae. Other causes of back pain include pregnancy; kidney stones or infections; endometriosis, which is the buildup of uterine tissue in places outside the uterus; and fibromyalgia, which causes fatigue and widespread muscle pain.

Infections and tumors: Although they are not common causes of back pain, infections can cause pain when they involve the vertebrae, a condition called osteomyelitis, or when they involve the discs that cushion the vertebrae, which is called discitis. Tumors, too, are relatively rare causes of back pain. Occasionally, tumors begin in the back, but more often they appear in the back as a result of cancer that has spread from elsewhere in the body.

Although the causes of back pain are usually physical, it is important to know that emotional stress can play a role in how severe pain is and how long it lasts. Stress can affect the body in many ways, including causing back muscles to become tense and painful.


Causes of Lower Back Pain

Back Pain Causes

Back pain is a symptom. Pain arising from other organs may be felt in the back. This is called referred pain. Many intra-abdominal disorders -- such as appendicitis, aneurysms, kidney diseases, bladder infections, pelvic infections, and ovarian disorders, among others -- can cause pain referred to the back. Your doctor will have this in mind when evaluating your pain.

• Nerve root syndromes are those that produce symptoms of nerve impingement (a nerve is touched), often due to a herniation (or bulging) of the disc between the lower back bones. Sciatica is an example of nerve root impingement. Impingement pain tends to be sharp, in one spot, and associated with numbness in the area of the leg that the affected nerve supplies.

• Herniated discs are produced as the spinal discs degenerate or grow thinner. The jellylike central portion of the disc bulges out of the central cavity and pushes against a nerve root. Intervertebral discs begin to degenerate by the third decade of life. Herniated discs are found in a third of adults older than 20. Only 3% of these, however, produce symptoms of nerve impingement.

• Spinal stenosis occurs as intervertebral discs lose moisture and volume with age, which decreases the disc spaces. Even minor trauma under these circumstances can cause inflammation and nerve root impingement, which can produce classic sciatica without disc rupture.

• Spinal degeneration is caused by alterations in the disc that progress to degeneration. This, coupled with disease in joints of the low back, causes spinal canal narrowing. These changes in the disc and the joints produce symptoms and can be seen on an x-ray. A person with spinal degeneration may have morning stiffness or pain while standing for a long time or walking even short distances.

• Cauda equina syndrome is a medical emergency. Disc material expands into the spinal canal, which compresses the nerves. A person would experience pain, possible loss of sensation, and bowel or bladder dysfunction. This could include inability to control urination causing incontinence, or the inability to begin urination.

• Musculoskeletal pain syndromes that produce low back pain include myofascial pain syndromes and fibromyalgia.

• Myofascial pain is characterized by pain and tenderness over localized areas (trigger points), loss of range of motion in the involved muscle groups, and pain radiating in a characteristic distribution but restricted to a peripheral nerve. Relief of pain is often reported when the involved muscle group is stretched.

• Fibromyalgia results in pain and tenderness on 11 of 18 trigger points when touched, one of which is the low back area, as classified by the American College of Rheumatology. Generalized stiffness, fatigue, and muscle ache are reported.

• Other skeletal causes of low back pain include osteomyelitis or sacroiliitis (infections of the bones of the spine). This pain is usually worse at night and is worse when sitting or standing for a long time.

• Tumors, possibly cancerous, can be a source of skeletal pain.

Understanding Spinal Disk Problems - Basic Information

What Are Spinal Disk Problems?

Only a person who has experienced a damaged spinal disk understands the agony and helplessness it brings. The pain can be excruciating. Every movement seems to make it worse.

This pain is a warning signal. If you heed the warning and take proper action, the discomfort usually stops, and the problem can be corrected. If you ignore the warning, you could suffer permanent damage.

Spinal disks are supple pads tightly fixed between the vertebrae, the specialized bones that make up the spinal column. Doctors call them intervertebral disks. Each disk is a flat, circular capsule about an inch in diameter and one-quarter inch thick. They have a tough, fibrous, outer membrane called the annulus fibrosus. Inside is an elastic core called the nucleus pulposus.

The disks are firmly embedded between the vertebrae and are held in place by the ligaments connecting the spinal bones and the surrounding sheaths of muscle. There is really little, if any, room for disks to slip or move. The points on which the vertebrae actually turn are called facet joints, which stick out like arched wings on either side of the rear part of the vertebrae. These facet joints keep the vertebrae from bending and twisting too far -- far enough to damage the spinal cord, the vital network of nerves that runs through the center of each vertebra.

The disk is sometimes described as a shock absorber for the spine, which makes it sound more flexible or pliable than it really is. While the disks do separate the vertebrae and keep them from rubbing together, they are far from pneumatic or spring-like. In children, they are gel- or fluid-filled sacs, but they begin to solidify as part of the normal aging process. By early adulthood, the blood supply to the disk has stopped, the soft inner material has begun to harden, and the disk is less elastic. In middle-aged adults, the disks are tough and quite unyielding, with the consistency of a piece of hard rubber. These changes related to aging make the outer protective lining more weak and the disks more prone to injury.
Understanding Spinal Disk Problems - Herniated Disk

The pain of a herniated disk is debilitating, and further spinal disk damage may be irreversible.

Under stress, a disk's inner material may swell, pushing through its tough outer membrane. The entire disk becomes distorted. All or part of the core material protrudes through the outer casing at a weak spot, pressing against surrounding nerves. If further activity or injury causes the membrane to rupture or tear, the disk material can injure the spinal cord or the nerves that radiate from it. This causes extreme, debilitating pain. It's an unmistakable signal to stop all movement immediately. Further disk damage may be irreversible. In some instances, the injured disk itself is the source of pain.

The vast majority of disk injuries occur in the lumbar region of the lower back. Only 10% of these injuries affect the upper spine. Not all herniated disks press on nerves, however, and it is entirely possible to have deformed disks without any pain or discomfort.

Herniated disks are most common in men and women aged 30 to 50, although they also occur in active children and young adults. Older people, whose disks no longer have fluid cores, are much less likely to encounter the problem. People who do regular, moderate exercise are much less likely to suffer from disk problems than sedentary adults. People who exercise tend to stay flexible considerably longer.
What Causes a Herniated Disk?

Although a violent injury can damage a disk, problems with disks are often brought on by the normal aging process or by everyday activities, such as lifting heavy objects the wrong way, stretching too hard during a tennis volley, or slipping and falling on an icy sidewalk. Any such event can cause the fibrous outer covering of the disk to break or distort to the point that it presses on a spinal nerve. Sometimes a disk swells, tears, or degenerates without any apparent cause.
Understanding Spinal Disk Problems - Degenerative Disk Disease

Disk problems are sometimes lumped together under the term degenerative disk disease. Change in the condition of the disk is a natural result of aging. This is part of our gradual loss of flexibility as we grow older.

But disk degeneration is far more serious in some people than in others. Severe cases may be the result of a deficiency in collagen, the material that makes up cartilage. Poor muscle tone, poor posture, and obesity also put excessive strain on the spine and the ligaments that hold the disks in place.

Pain Management: Spinal Stenosis

Spinal stenosis is the narrowing of spaces in the spine (backbone) which causes pressure on the spinal cord and/or nerves. About 75% of cases of spinal stenosis occur in the low back (lumbar spine). In most cases, the narrowing of the spine associated with stenosis compresses the nerve root, which can cause pain along the back of the leg.

What Causes Spinal Stenosis?

There are many potential causes for spinal stenosis, including:

• Aging: With age, the body's ligaments (tough connective tissues between the bones in the spine) can thicken. Spurs (small growths) may develop on the bones and into the spinal canal. The cushioning disks between the vertebrae may begin to deteriorate. The facet joints (flat surfaces on each vertebra that form the spinal column) also may begin to break down. All of these factors can cause the spaces in the spine to narrow.

• Arthritis: Two forms of arthritis that may affect the spine are osteoarthritis and rheumatoid arthritis.

• Heredity: If the spinal canal is too small at birth, symptoms of spinal stenosis may show up in a relatively young person. Structural deformities of the involved vertebrae can cause narrowing of the spinal canal.

• Instability of the Spine, or Spondylolisthesis: When one vertebra slips forward on another, that can narrow the spinal canal.

• Tumors of the spine: Abnormal growths of soft tissue may affect the spinal canal directly by causing inflammation or by growth of tissue into the canal. Tissue growth may lead to bone resorption (bone loss due to overactivity of certain bone cells) or displacement of bone and the eventual collapse of the supporting framework of the spinal column.

• Trauma: Accidents and injuries may either dislocate the spine and the spinal canal or cause burst fractures that produce fragments of bone that penetrate the canal.

What Are the Symptoms of Stenosis?

Stenosis may result in low back pain as well as pain in the legs. Stenosis may pinch the nerves that control muscle power and sensation in the legs. Additional symptoms may include:

• Frequent falling, clumsiness
• Pain and difficulty when walking
• Numbness, tingling, hot or cold feelings in the legs

How Is Spinal Stenosis Diagnosed?

Spinal stenosis can be difficult to diagnose because its symptoms can be caused by other conditions. Usually, people who develop stenosis have no history of back problems or any recent injury. Often, unusual leg symptoms are a clue to the presence of spinal stenosis.

If simple treatments, such as postural changes or nonsteroidal anti-inflammatory drugs, do not relieve the problem, special imaging studies may be needed to determine the cause of the problem. An MRI (magnetic resonance image) or CAT (computed tomography) scan may be requested. A myelogram (an X-ray taken after a dye is injected into the spine) may be performed. These and other imaging studies can offer details about the bones and tissues and help with diagnosis.

How Is Spinal Stenosis Treated?

• Changes in posture: People with spinal stenosis may find that flexing the spine by leaning forward while walking relieves their symptoms. Lying with the knees drawn up to the chest also can offer some relief. These positions enlarge the space available to the nerves and may make it easier for people with stenosis to walk longer distances.

• Medications: In some cases, the pressure on the nerves is caused by inflammatory swelling. Nonsteroidal anti-inflammatory medications such as aspirin or ibuprofen may help relieve symptoms.

• Rest: Rest, followed by a gradual resumption of activity, can help. Aerobic activity such as bicycling is often recommended.

• Surgery: If other treatments do not ease the pain, surgery may be recommended to relieve the pressure on affected nerves.

Low Back Pain Risk Factors

What Are the Risk Factors for Back Pain?

Although anyone can have back pain, a number of factors increase your risk. They include:

Age: The first attack of low back pain typically occurs between the ages of 30 and 40. Back pain becomes more common with age.

Fitness level: Back pain is more common among people who are not physically fit. Weak back and abdominal muscles may not properly support the spine. “Weekend warriors” – people who go out and exercise a lot after being inactive all week – are more likely to suffer painful back injuries than people who make moderate physical activity a daily habit. Studies show that low-impact aerobic exercise is good for the discs that cushion the vertebrae, the individual bones that make up the spine.

Diet: A diet high in calories and fat, combined with an inactive lifestyle, can lead to obesity, which can put stress on the back.

Heredity: Some causes of back pain, including disc disease, may have a genetic component.

Race: Race can be a factor in back problems. African American women, for example, are two to three times more likely than white women to develop spondylolisthesis, a condition in which a vertebra of the lower spine – also called the lumbar spine – slips out of place.

The presence of other diseases:   Many diseases can cause or contribute to back pain. These include various forms of arthritis, such as osteoarthritis, rheumatoid arthritis, and ankylosing spondylitis, and cancers elsewhere in the body that may spread to the spine.

Occupational risk factors: Having a job that requires heavy lifting, pushing, or pulling, particularly when this involves twisting or vibrating the spine, can lead to injury and back pain. An inactive job or a desk job may also lead to or contribute to pain, especially if you have poor posture or sit all day in an uncomfortable chair.

Cigarette smoking: Although smoking may not directly cause back pain, it increases your risk of developing low back pain and low back pain with sciatica. (Sciatica is back pain that radiates to the hip and/or leg due to pressure on a nerve.) For example, smoking may lead to pain by blocking your body’s ability to deliver nutrients to the discs of the lower back. Or, repeated coughing due to heavy smoking may cause back pain. It is also possible that smokers are just less physically fit or less healthy than nonsmokers, which increases the likelihood that they will develop back pain. Furthermore, smoking can slow healing, prolonging pain for people who have had back injuries, back surgery, or broken bones.


Can You Prevent Back Pain?

Prevention

The prevention of back pain is, itself, somewhat controversial. It has long been thought that exercise and an all-around healthy lifestyle would prevent back pain. This is not necessarily true. In fact, several studies have found that the wrong type of exercise such as high-impact activities may increase the chance of suffering back pain. Nonetheless, exercise is important for overall health and should not be avoided. Low-impact activities such as swimming, walking, and bicycling can increase overall fitness without straining the low back.

Specific exercises: Talk to your doctor about how to perform these exercises.

• Abdominal crunches, when performed properly, strengthen abdominal muscles and may decrease tendency to suffer back pain.

• Although not useful to treat back pain, stretching exercises are helpful in alleviating tight back muscles.

• The pelvic tilt also helps alleviate tight back muscles.

• Lumbar support belts: Workers who frequently perform heavy lifting are often required to wear these belts. There is no proof that these belts prevent back injury. One study even indicated that these belts increased the likelihood of injury.

• Standing: While standing, keep your head up and stomach pulled in. If you are required to stand for long periods of time, you should have a small stool on which to rest one foot at a time. Do not wear high heels.

• Sitting: Chairs of appropriate height for the task at hand with good lumbar support are preferable. To avoid putting stress on the back, chairs should swivel. Automobile seats should also have adequate low-back support. If not, a small pillow or rolled towel behind the lumbar area will provide adequate support.

• Sleeping: Individual tastes vary. If the mattress is too soft, many people will experience backaches. The same is true for sleeping on a hard mattress. Trial and error may be required. A piece of plywood between the box spring and mattress will stiffen a soft bed. A thick mattress pad will help soften a mattress that is too hard.

• Lifting: Don't lift objects that are too heavy for you. If you attempt to lift something, keep your back straight up and down, head up, and lift with your knees. Keep the object close to you, don't stoop over to lift. Tighten your stomach muscles to keep your back in balance.

Understanding Back Pain - Symptoms

What Are the Symptoms of Back Pain?

Most people have experienced back pain sometime in their life. The causes of back pain are numerous; some are self-inflicted due to a lifetime of bad habits. Other back pain causes include accidents, muscle strains, and sports injuries. Although the causes may be different, most often they share the same symptoms.

The symptoms for back pain are:

• Persistent aching or stiffness anywhere along your spine, from the base of the neck to the hips.

• Sharp, localized pain in the neck, upper back, or lower back -- especially after lifting heavy objects or engaging in other strenuous activity.

• Chronic ache in the middle or lower back, especially after sitting or standing for extended periods.

• Back pain that radiates from the low back to the buttock, down the back of the thigh, and into the calf and toes.

• Inability to stand straight without having severe muscle spasms in the low back.

Call Your Doctor About Back Pain If:

• You feel numbness, tingling, or loss of control in your arms or legs. This may signal damage to the spinal cord.

• The pain in your back extends downward along the back of the leg. You may be suffering from sciatica.

• The pain increases when you cough or bend forward at the waist. This can be the sign of a herniated disc.

• The pain is accompanied by fever, burning during urination, or strong-smelling urine. You may have a bacterial urinary tract infection.

• You have urine or fecal incontinence.

• You have dull pain in one area of your spine when lying in or getting out of bed. If you are over 50 you may be suffering from osteoarthritis.

When Should I See a Doctor for Pain?

In most cases, it is not necessary to see a doctor for back pain because pain usually goes away with or without treatment. However, a trip to the doctor is probably a good idea if you have numbness or tingling, if your pain is severe and doesn’t improve with medications and rest, or if you have pain after a fall or an injury. It is also important to see your doctor if you have pain along with any of the following problems: trouble urinating; weakness, pain, or numbness in your legs; fever; or unintentional weight loss. Such symptoms could signal a serious problem that requires treatment soon.

Which Type of Doctor Should I See?

Many different types of doctors treat back pain, from family physicians to doctors who specialize in disorders of the nerves and musculoskeletal system. In most cases, it is best to see your primary care physician first. In many cases, he or she can treat the problem. In other cases, your doctor may refer you to an appropriate specialist.


Acute Back Pain, Chronic Back Pain

What Is the Difference Between Acute and Chronic Pain?

Pain that hits you suddenly – after falling from a ladder, being tackled on the football field, or lifting a load that is just too heavy, for example – is acute pain. Acute pain comes on quickly and often leaves just as quickly. To be classified as acute, pain should last no longer than 6 weeks. Acute pain is the most common type of back pain.

Chronic pain, on the other hand, may come on either quickly or slowly, and it lingers a long time. In general, pain that lasts more than 3 months is considered chronic. Chronic pain is much less common than acute pain.

Cauda Equina Syndrome

The spinal cord extends from the brain down through the spinal canal inside the vertebral column. The spinal cord is surrounded by dural sacs, which are extensions of the brain-covering membranes. The brain-covering membranes are dura matter; arachnoid, which contains cerebrospinal fluid; and pia matter. Nerves that branch off of the spinal cord (also called nerve roots) are an extension of the spinal cord and are responsible for sending signals to and from the muscles and other structures throughout the body. These signals allow the brain to interpret information from the body including pain, touch, and sense of position. Outgoing signals allow the brain to control actions of the organs and muscle movements.

The spinal cord ends near the first lumbar vertebra in the lower back, forming the conus medullaris. The fibrous extension of the spinal cord is the filum terminale. The bundle of nerve roots below the conus medullaris is named the cauda equina (see Multimedia File 1).

Compression or inflammation of the nerves roots can cause symptoms of pain, altered reflexes, decreased strength, and decreased sensation. Although these symptoms can become severe, and in some cases disabling, most are self-limiting and respond to conservative care.


How Do I Know What Kind of Back Problem I Have?

Unless you are totally immobilized from a back injury, your doctor probably will test your range of motion and nerve function and touch your body to locate the area of discomfort.

Blood and urine tests will make sure the pain is not due to an infection or other systemic problem.

X-rays are useful in pinpointing broken bones or other skeletal defects. They can sometimes help locate problems in connective tissue. To analyze soft-tissue damage, computed tomography (CT) or magnetic resonance imaging (MRI) scans may be needed. X-rays and imaging studies are generally used only for checking out direct trauma to the back, back pain with fever, or nerve problems such as extremity weakness or numbness. To determine possible nerve or muscle damage, an electromyogram (EMG) can be useful.


Back Pain Tests

Exams and Tests

Medical history

• Because many different conditions may cause back pain, a thorough medical history will be performed as part of the examination. Some of the questions you are asked may not seem pertinent to you but are very important to your doctor in determining the source of your pain.

• Your doctor will first ask you many questions regarding the onset of the pain. (Were you lifting a heavy object and felt an immediate pain? Did the pain come on gradually?) He or she will want to know what makes the pain better or worse. The doctor will ask you many questions referring to the “red flag” symptoms. He or she will ask if you have had the pain before. Your doctor will ask about recent illnesses and associated symptoms such as coughs, fevers, urinary difficulties, or stomach illnesses. In females, the doctor will want to know about vaginal bleeding, cramping, or discharge. Pain from the pelvis, in these cases, is frequently felt in the back.

Physical examination

• To ensure a thorough examination, you will be asked to put on a gown. The doctor will watch for signs of nerve damage while you walk on your heels, toes, and soles of the feet. Reflexes are usually tested using a reflex hammer. This is usually done at the knee and behind the ankle. As you lie flat on your back, one leg at a time is elevated, both with and without the assistance of the doctor. This is done to test the nerves, muscle strength, and assess the presence of tension on the sciatic nerve. Sensation is usually tested using a pin, paper clip, broken tongue depressor, or other sharp object to assess any loss of sensation in your legs.

• Depending on what the doctor suspects is wrong with you, the doctor may perform an abdominal examination, a pelvic examination, or a rectal examination. These exams look for diseases that can cause pain referred to your back. The lowest nerves in your spinal cord serve the sensory area and muscles of the rectum, and damage to these nerves can result in inability to control urination and defecation. Thus, a rectal examination is essential to make sure that you do not have nerve damage in this area of your body.

Imaging

• Doctors can use several tests to "look inside you" to get an idea of what might be causing the back pain. No single test is perfect in that it identifies the absence or presence of disease 100% of the time.

• The medical literature is very clear: If there are no red flags, there is little to be gained in imaging acute back pain. Because about 90% of people have improved within 30 days of the onset of their back pain, most doctors will not order tests in the routine evaluation of acute, uncomplicated back pain.

• Plain x-rays are generally not considered useful in the evaluation of back pain, particularly in the first 30 days. In the absence of red flags, their use is discouraged. Their use is indicated if there is significant trauma, mild trauma in those older than 50, people with osteoporosis, and those with prolonged steroid use. Do not expect an x-ray to be taken.

• Myelogram is an x-ray study in which a radio-opaque dye is injected directly into the spinal canal. Its use has decreased dramatically since MRI scanning. This test is now usually done in conjunction with a CT scan and, even then, only in special situations when surgery is being planned.

• Magnetic resonance imaging (MRI) scans are a highly sophisticated test and, as such, are very expensive. The test does not use x-rays but very strong magnets to produce images. Their routine use is discouraged in acute back pain unless a condition is present that may require immediate surgery, such as with cauda equina syndrome or when red flags are present and suggest infection of the spinal canal, bone infection, tumor, or fracture.

• MRI may also be considered after 1 month of symptoms to rule out more serious underlying problems.

• MRIs are not without problems. Bulging of the discs is noted on up to 40% of MRIs performed on people without back pain. Other studies have shown that MRIs fail to diagnose up to 20% of ruptured discs that are found during surgery.

Nerve tests

• Electromyogram or EMG is a test that involves the placement of very small needles into the muscles. Electrical activity is monitored. Its use is usually reserved for more chronic pain and to predict the level of nerve root damage. The test is also able to help the doctor distinguish between nerve root disease and muscle disease.