Your Discs Are Bulging—Does it Matter?

Have you been told that you have bulging, degenerated discs in your spine? If so, you are not alone. Millions of Americans undergo X-rays, CT scans, and MRI scans of their backs and necks each year and receive the same news. As a result, multiple millions of dollars are spent on medications, physical therapies, surgical procedures, and spinal manipulations in an effort to treat back pain. The people undergoing all this diagnosis and treatment might imagine that other, luckier people have normal spinal discs, but they might be surprised to learn that bulging discs are so common that they may be considered a normal part of aging. Most often, they cause no symptoms or problems, and it pays to be cautious about embarking on courses of investigation and treatment based simply on these “degenerative changes.” But it also pays to know when and why discs do cause trouble.

What and where are spinal discs?

The spine is a column of thick, circular bones—also called vertebral bodies—that in terms of anatomy is divided into three major sections: the cervical (neck) spine, thoracic (mid-back) spine, and lumbar (lower back) spine. The vertebral bodies have flat tops and bottoms, and they sit atop one another, separated by discs that cushion the spine and allow for the compression, rotation, and bending of the entire spinal column. The arches of bone on the back sides of each of the vertebral bodies line up with each other to form a bony tunnel, which surrounds the spinal cord and the nerves that connect it to the body. Pairs of these nerves exit from the sides of this canal below each vertebral body.

Spinal discs are a lot like flattened cream-filled doughnuts, with a soft center called the nucleus pulposus and a tougher perimeter called the annulus. Each annulus is attached to the ligaments that run the length of the spine and hold it together. Every day, gravity squeezes so much water out of each disc that an average adult shrinks by more than one-half inch between morning and night. As a disc loses water and flattens, it may protrude beyond the edges of the vertebral bodies located above and below it. Under these conditions, the ligaments bounding the disc tend to bow outward to accommodate the flattening, and the result is the classic “bulging” discs often seen on back scans. Is such bulging a cause of pain?

When bulging becomes cracking and herniation

Judging by the number of people who have bulging discs and no pain, the answer to this question is, not very often. But discs can cause pain if they are damaged. Cracks can develop in the back part of the annulus, especially in the lower neck and lower back, and are sometimes caused by sudden movement or excessive loading of the neck or back or sometimes with no readily identifiable cause. Risk factors for the development of cracks include age, smoking, and heavy weight lifting. When cracks form in the annulus, nerve fibers send out distress signals which feel like deep back pain that sometimes radiates down the legs. Symptoms usually improve over a period of six to eight weeks, but if the tear is extensive enough, it may open a path for part of the soft nucleus pulposus of the disc to work its way through, becoming a so-called herniated or “slipped” disc.

Location determines  symptoms

Extruded far enough, a herniated disc bulges straight backward into the bony tunnel that houses the spinal cord or off to either side, where it squeezes into the narrow canal that should hold only a spinal nerve root passing out to the body. Depending on the location and the extent of the disc herniation, pain in the back or neck might be accompanied by a set of neurological symptoms including numbness, tingling, and a sense of weakness in an arm or a leg. Symptoms may improve over time with no treatment or with relatively modest treatments, like physical therapy or cortisone injections, as the disc shrinks. But there is potential for the worsening of symptoms, so careful physical evaluation and follow-up are important.

More than 95 percent of disc problems occur in the lumbar spine. Here, as in the neck, discs tend to slip off to the side, compressing single nerves and causing pain to run down a leg or arm or weakness in corresponding muscles. Definite loss of strength in a muscle group controlled by the nerve under pressure most often calls for surgery to decompress the nerve. Sometimes scans indicate that a fragment of disc has broken off and lodged itself under a nerve. Unlike nonfragmented disc herniations, which may gradually shrink and relieve symptoms, symptoms caused by fragmented discs tend to be persistent unless the fragment is removed.

Disc herniation in the upper spine

When discs slip straight back into the central spinal canal, symptoms can range from none to neurological deficits that require immediate decompression surgery. Serious central disc herniations are uncommon in the neck and quite rare in the thoracic spine but in both locations may cause symptoms from the spinal cord itself that include pain, balance problems, weakness in the legs, and an inability to control the bladder.

Disc herniation in the lumbar spine

In the lumbar spine, because the spinal cord does not reach down this far, central disc herniations put pressure on the so-called cauda equine, or “horse’s tail” of nerves that travel down the spinal canal from the spinal cord to their exit points at different lumbar levels. Symptoms here often consist of a confusing array of pain, numbness around the groin and legs in a pattern that traces an area where a saddle would make contact with the body, leg weakness, fecal incontinence, and trouble initiating urination. This combination of symptoms requires immediate surgical decompression.

Surgery or not?

While surgery for severe symptoms is an easy decision and while many disc removals are done with microsurgical techniques and small incisions and are less invasive than in the past, the decision to try to improve back pain alone by operating on a bulging disc is not as easy. To improve the likelihood of good results, studies like disc injections are sometimes done. The dye used helps visualize the disc, and, if the injection reproduces the patient’s pain, confidence that the disc is the source of the back pain increases. Injections can be helpful in determining which of several bulging discs might be the source of pain.

Caution in the decision

Disc removal for pain alone or for pain combined with sensory symptoms that come and go should be approached with caution. First, every attempt should be made to improve the strength of the muscles that support and move the spine, to improve overall posture, and to lose excess weight that the spine is asked to support. Back and neck pain arise from many different structures—muscles, ligaments, tendons, bones, and nerves—and can improve dramatically with improved strength, flexibility, and posture—bulging discs or not.

 

Pain in the Neck: More than a Metaphor

The cervical spine is a slender stack of fragile bones that balances the 15-17 lb. skull atop the body. Each bone has a round thick body and an arch of thinner bone projecting from its backside. The knobs of bone you feel in your own spine are just the tips of each bony arch, called the spinous processes. A wide array of ligaments, tendons and muscles hold the vertebrae together, and thirty-seven separate joints allow the head to move through a wide range of finely calibrated movements.  Arthritic changes accumulate in most necks over the years, particularly in the lower regions where most movement takes place.   In scans of people over 50, almost all will show some degree of wear and tear change in the lower vertebrae.

Aging changes in bones neck bones and ligaments

Wear and tear takes form of thickening of bony edges of the vertebrae and degeneration of the discs between them.  These changes may put pressure on the nerves that exit from the spinal cord through bony canals between the stacked vertebrae, and occasionally on the spinal cord itself, which travels through a canal formed by the centers of the stacked arches.  The ligaments that line this canal also thicken with age and create ridges inside the canal that press on the spinal cord. Degenerative changes contribute to episodic neck pain, and sometimes to more severe symptoms that require medical attention.

Why the neck hurts

The neck is second only to the low back pain as a common source of pain. Most neck pain is benign and episodic, coming from muscles, tendons, ligaments and joints. Painful episodes usually occur after some unaccustomed activity, such as painting a ceiling or suddenly twisting or bending the neck, or after sustaining a neck position for an unusual amount of time – for example, over a long drive.  Even an unaccustomed head position occasioned by wearing new bifocals can trigger a bout of stiff neck.

Other symptoms

Neck pain requires medical attention when it persists or is associated with neurological symptoms in the arms or legs.  Sensory symptoms like numbness or tingling in fingers and arms are quite common when underlying degenerative changes are present in the neck. While they may indicate pressure on nerve roots, sensory symptoms also occur when neck pain is simply a reflection of tight muscles and ligaments. The same nerve fibers that carry pain sensations also carry sensory messages and pain seems to have a kind of spillover effect into other sensory pathways.  That same spillover effect also can also cause a wide variety of sensory and pain symptoms in the head.  Headaches, pain in the back of the head, and even eye pain can be attributed to some neck problems.

Red flag symtoms: weakness and bladder control problems

Neurological symptoms indicating trouble in the motor nerves or in the spinal cord, in the setting of neck pain and degenerative changes, often indicate a more serious degree of trouble. Weakness in arm or hand muscles may mean that motor nerve roots are being squeezed as they exit the spinal column.  Weakness, fatigue and stiffness in the legs, and new trouble with bladder control are symptoms of pressure on the spinal cord. Sensory problems usually recover when the painful cause is successfully treated, but motor nerves and the spinal cord are more fragile and less reliably improve even after surgical decompression.  When motor problems are part of the picture, medical attention should be sought sooner rather than later.

Diagnosis

Careful history and physical examination are crucial to the proper diagnosis.  Diagnosis of a painful, stiff neck begins with taking a history. Most people do this before they ever see a doctor. What did I do yesterday? Did I sleep sitting up on a plane? In a strange bed? What movement makes this worse? What makes it better? Do I have any other funny symptoms? Most people also do the right thing by avoiding maneuvers that cause pain, applying either heat or ice, and even trying a soft cervical collar, which does not really immobilize the neck, but gives the head a temporary place to rest. Most often the neck improves and no medical attention is required.

Medical attention, when sought, should begin with a very detailed history, not only of the current episode, but of past problems, and other medical problems which might cause or complicate neck problems.  Important facts include history of trauma, rheumatoid arthritis, cancer, vascular disease, infections and past radiation treatment. Evaluation then moves to a physical examination, not only of the neck, but a general physical exam and a neurological exam. Imaging studies, electrical evaluation of nerves and muscles, and blood work follow under some circumstances. These include symptoms persisting more than 6 weeks, severe symptoms involving a single joint, presence of fever and weight loss, suspected fracture or dislocation, associated neurological symptoms or findings, and failure of simple treatments over a course of 4-6 weeks.

Treatment

Conservative measures are effective for treating common types of neck pain, especially if carried out conscientiously. Massage, hot or cold applications, topical pain relieving and muscle relaxing creams and intermittent use of aspirin or non-steroidal anti-inflammatory agents are all helpful but they are play a  only a supporting role. The major goal is to correct posture, not only of the neck, but of the whole spine, by strengthening and stretching of the muscles that support the spine and those that suspend and move the shoulders.   An effective exercise program, under supervision of a qualified physical therapist, involves the entire spine, as well as legs and arms.  In addition, supporting the neck’s normal curve in sleep with a good cervical pillow is crucial.

When conservative measures fail, more invasive means of treatment such as injections of anti-inflammatory and analgesic drugs are often added. Surgical treatment of neck pain problems is reserved for situations in which a nerve root or the spinal cord must be decompressed, or ones in which pain is so severe and unremitting that fusing the bones to decrease movement of the neck is considered the only option. In comparison to the number of people with neck pain at some point in their lives, surgically treated neck complaints are actually few and far between.  Considering how much the neck moves, how much wear and tear it sustains and how little protection it has, this is a remarkable measure of its resilience.

No more posts.