Low Back Pain - Four Common Problems

Most people suffer incapacitating back pain at some point in their lives.  In fact, low back pain is second only to headache among the leading causes of pain.  On any given day, an estimated 6.5 million people in the U.S. are bedridden because of back pain, and approximately 1.5 million new cases of back pain are seen by physicians each month.

Most cases of persistent back pain arise from routine daily events rather than from significant trauma.  Even among athletes, the sudden onset of pack pain is seldom related to athletic activity, but is instead associated with normal physical activity.  Persons in good physical condition are less likely to have back pain.

There are many conditions which can present as low back pain, the four most common being:

1. Low back strain
2. Herniated disc
3. Spinal stenosis
4. Spondylolisthesis (slipped vertebrae)

1.  Low Back Strain

The vast majority of people who have low back discomfort are suffering from a non-radiating type of low back pain called "back strain".  The etiology is not always clear, but it probable is a ligamentous or muscular strain secondary to either a specific traumatic episode or the continuous mechanical stress of a postural inadequacy.

These patients main complaint is back pain and it can be limited to one spot or cover a diffuse area of the lumbosacral spine.  At times there may be a referral of pain to the buttocks or posterior thigh since the lower back, buttocks or posterior thigh all originate from the same embryonic tissue.  Such referral of pain does not necessarily connote any mechanical compression of the nerves the originate from the spinal cord or are more peripherally located away from the spine, nor should this condition be called "sciatica".  Sciatica will be discussed later.

The usual physical findings are limited to local tenderness over the involved area and muscle spasm;  however, the attacks will vary in intensity and can conveniently be divided into three categories:  Mild, moderate and severe.  These placed in the mild group have subjective pain without objective findings and usually are able to return to regular activity in less than a week.

The moderate group is characterized by a limited range of spinal motion and paravertebral muscle spasm as well as pain and usually are able to resume full activity in under two weeks.  The severe group includes those patients who are tilted forward or to the side.  These patients usually have trouble ambulating and can take up to three weeks to become functional again.

Plain X-Rays and MRT's are diagnostic investigations used by physicians  and are found to be normal.

The accepted treatment for low back pain is the functional restorative approach.  The mainstay of treatment is rest (1 to 3 days), with the judicious use of back flexibility and strengthening exercises as the acute phase subsides.  Although non-steroidal anti-inflammatory medication may be of some help, drugs for the relief of pain and muscle spasm do not seem to alter the course of the attack.

The prognosis of patients with low back strain is excellent and they will usually recover with no lasting impairment.

2. Acute Herniated Disc

A herniated disc can be defined as the herniation of the nucleus pulposus through the fibers for the annulus fibrosis of the disc.  An analogy is that of the soft core of a golf ball comes through the tightly wound twine of rubber.  Most disc ruptures occur during the third and fourth decade of life while the nucleus pulposus is still gelatinous.  The two most common levels for disc herniation are the lowest two levels L4-5 and L5-S1.  These two discs account for 95% of all lumbar disc herniations.

Disc herniations at L5-S1 may compromise the first sacral nerve root;  the L4-L5 level disc herniation may compress the L5 nerve root.

Clinically, the patient's major complaint is pain, although a small minority of patients with a disc herniation have minimal discomfort.  The pain may also radiate down the leg in the distribution of the affected nerve root (dermatomal pattern).  The pain is usually described as sharp or lancinating, progressing from above downward in the involved leg.  Its onset may be insidious or sudden and associated with a tearing or snapping sensation in the spine.

On physical examination, there is decreased range of motion in flexion (bending forward) and the patient will tend to drift away from the involved side as he bends.  On ambulation (walking) the patient walks with a painful limp, holding the involved leg flexed so as to put as little weight as possible on it.

Thy physical exam assesses for evidence of nerve compression looking for significant changes in reflexes, weakness, loss of muscle bulk or loss of sensation in the appropriate nerve root distribution.

The initial diagnosis of a herniated disc is ordinarily made on the bases of the history and physical examination and confirmed MRI.  Plain X-Rays of the lower spine will rarely add to the diagnosis but should be obtained anyway to help rule out other causes of pain such as infection or tumor. 

Treatment options differ for each type of herniation.  Any herniation that causes spinal cord compression symptoms requires immediate surgical decompression;  whereas, other non-spinal compressive herniation may or may not require surgical decompression.  Microscopic disectomy is preferred over more invasive surgeries.  Epidural corticosteroid injections can be used for focal disc protrusions and centrally located disc protrusions respond to traditional therapy and conservative care.

3.  Spinal Stenosis

Spinal stenosis is defined as narrowing of the spinal canal mechanical pressure within the spinal cord on the nerve structures will depend upon the degree of narrowing.  Every person's spine becomes narrower with age.  The symptoms a person will have depend on the original size of the canal;  if the spinal canal is small, the changes caused by aging of the disc and other structures of the spine can lead to an absolute compression of these nerve structures.  If, however, the spinal canal is large to begin with, the aging process will only lead to an asymptomatic relative spinal stenosis without nerve compression.

The symptoms of those patients who have spinal stenosis that compress the nerve structures, these individuals may present with the following complaints which may vary from mild pain to an inability to walk.  Patients of either sex, usually not before their fifth decade, will first complain of vague pains, abnormal sometimes painful sensations in their lower extremities with ambulation but the will have excellent relief of their symptoms when they are sitting or lying down.  The increased curvature of the spine (lordotic stance) assumed with walking and particularly walking downgrades or inclines, is the most likely inciting cause.  As the compression increases, symptoms may start to occur at rest.  This is followed by muscle weakness and loss of muscle bulk.

MRI's are ex excellent to diagnose spinal stenosis.  An EMG (electromyography) can be done to assess the degree of nerve damage and an approximation of how long the nerve has been compressed.

The majority of patients with spinal stenosis, especially the degenerative (secondary to the aging process) can be treated non-surgically.  Usually the symptoms are intermittent and the patient will often require encouragement in getting through these episodes without getting depressed.  non-operative management is preferable as long as the pain is tolerable without neurological damage which affect function.

4.  Spondylolisthesis

Spondylolisthesis is a spinal condition where all or a part of a vertebrae has slipped on another.  The cause of this occurrence may be inherited, due to a small fracture, related to natural aging process, related to injury, or pathologic (relating to a disease process such as cancer).

Spondylolisthesis has several characteristic features, but the forward displacement is easily recognized on plain X-Rays notably the lateral views.

The degree of slip varies from patient to patient and can range from minimal displacement to complete dislocation of the vertebra.  Increased slipping rarely occurs after the age of 20 unless there has been a severe superimposed injury or surgical intervention.  The period of most rapid progression coincides with the rapid growth spurt between the ages of nine and fifteen.

The most common clinical manifestation of Spondylolisthesis is low back pain.  Once the symptoms begin, the patient usually has constant low grade back discomfort that is aggravated by activity and relieved by rest.  There are some periods during which the pain is more intense than others, but unless the picture is complicated by severe leg pain, total incapacitation is rare.  The patient seldom identifies any weakness or abnormal changes in sensation.

Plain X-Rays, particularly the lateral view, confirm the diagnosis.  Even the slightest amount of forward slipping of the body of the involved vertebra is readily discernable.

Non-operative treatment of the adult with Spondylolisthesis is much the same as that used for backache from other causes.  When the symptoms are acute (recent onset), rest is indicated.  If leg pain is a significant problem, then anti-inflammatory medication can be quite beneficial.  Exercises should be started once the patient is in a remission and they are usually advised to own a corset for use during occasional strenuous activity.  Exercise should be flexion not extension.

Sciatica

Sciatica, which is sciatic nerve pain, is considered to result from irritation or inflammation of the nerve roots.  Two nerve roots principally make up the sciatic nerve.  These are the fifth lumbar (L5) and the first sacral (S1) nerve roots, and they are the nerve roots that radiate down the back portion of the thigh, calf, ankle and toes.  The etiology of the mechanical pressure on the nerve root can be a herniated disc, piriformis muscle or iliopsoas muscle.

The diagnosis of sciatica is made by physical exam and confirmed by MRI and or EMG.  The most likely treatment plan includes initially bed rest with appropriate medication, along with increasing functional capabilities as the pain subsides.  If the pain persists for over six weeks, one should consider an epidural steroid injection if the disc is involved.  An epidural injection implies injecting cortisone like substance directly into the spinal canal.

Should the conservative techniques fail, the physician must re-evaluate the patient in order to consider the possibility of surgical intervention.  If objective findings are present, the surgeon would go over the surgical procedure, the risks, the unpredictable result, and the potential side-effects, especially if the patient has other complicating serious medical problems.  If there are no objective findings, the physician should avoid surgery and proceed to the pain management evaluation to help the patient learn how to better manage the pain.

Statistics show that no more than 5-10% of patients with sciatica require an operation.  The lifetime prevalence of sciatica is 40%, but only 1% of patients with acute back pain have nerve root symptoms.  Sciatica occurs in patients during the fourth and fifth decades of life.  The average age of patients undergoing lumbar disc removal is 42 years of age.  men and woman are equally affected in regards to low back pain, but women more often report low back symptoms after the age of 60.

Summary

This brief introduction of the four most common causes of back pain is by no means comprehensive nor complete.  There are a great many conditions which may cause back pain including cancer, infection, post pregnancy, osteoporosis, hormonal imbalances, inflammatory arthritic conditions, postural deviations, etc. 

Should you have any further questions regarding this article, please direct your questions or comments to "Ask the Doctor" section.

Copyright © 2004 - 2008 Taras V. Kochno, M.D.  All Rights Reserved
Board Certified in Physical Medicine and Rehabilitation

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