SCIATICA
SCIATICA – UNDERSTANDING YOUR CONDITION
True story: In primitive times, before the ancient Greeks and Romans came to prominence, the early Germans and Celts believed that sciatica was caused by a shot in the back by the arrow of an “elf.” How else could they explain a sudden, shocking bolt of pain in the lower back and down the leg? The Classical Greek physician Hippocrates, eschewing these unenlightened superstitions, observed that people tended to suffer from sciatica more often during the summer and fall. Even he, the Father of Western Medicine, attributed the warm-weather prevalence of sciatica to the heat of the sun causing the fluid of the spinal joints to dry up. We know now, of course, that none of this is true. But what is sciatica, exactly? How is it caused? Who gets it, and why? And most important – especially if you suffer from it – how can it be managed or eliminated?
Today, thousands of years after the Greeks first began to identify sciatica as a medical condition or disease (rather than a supernatural curse), there remains some confusion about it among a large segment of the population. To begin with, sciatica is not technically a “medical condition.” Rather, it is a set of symptoms in the lower back, buttocks, legs, and/or feet that can arise when the largest and longest nerve in the body, the sciatic nerve, becomes compressed. And how does that happen? One way to develop sciatic nerve compression is repetitive motion in the lower back. So, Hippocrates and his ilk were not far off when they associated an increase in sciatica with warmer weather and autumn, when the upper classes were more active and when agricultural practitioners (i.e., farmers) were busy bringing in the harvest.
If you suffer from sciatica, perhaps this little history lesson might be interesting. Chances are, though, all you care about is finding a way to not suffer from sciatica anymore. After all, the active lifestyle you once enjoyed may be in jeopardy, and you want answers. In light of the potentially debilitating nature of sciatica, that’s completely understandable. Still, one of the most difficult aspects of dealing with sciatica is the uncertainty. With knowledge comes understanding, and in developing an understanding of sciatica, you may find that you are better equipped mentally and emotionally to manage your symptoms. It begins with a brief study of the anatomy involved with the development of sciatica.
Anatomy of Sciatica
The sciatic nerve is formed in the lower back by five sets of paired nerve roots that branch off the spinal cord within the lumbar region of the spine. The lumbar region is composed of five (sometimes six) vertebrae, which are denoted L1-L5 (or L6). The nerve roots that join to form the sciatic nerve typically begin between the L4 and L5 vertebrae. The sciatic nerve runs down the lower spine, beneath the piriformis muscle, through the buttocks, and down the back of the legs. Around the knees, smaller nerves branch off the sciatic nerve and run down into the lower legs, the feet, and the toes. The sciatic nerve is responsible for the innervation of the skin, muscles, and other parts of the lower body.
The sciatic nerve does not exist in an anatomical vacuum, of course. It is tucked in snugly among a wide array of other anatomical components, any of which can be suspected if sciatic nerve compression begins to occur. These components include:
Vertebrae – These are the bony building blocks of the spine. In the case of the lumbar spine, the five (or six) vertebrae are subjected to a great deal of upper body weight and stress-inducing movement, such as bending, twisting, and turning at the waist.
Facet joints – Vertebrae from the cervical (upper) spine to the lumbar spine meet and articulate at paired joints called facet joints, which extend off the vertebral bodies laterally (to the side). These joints are lined with cartilage to allow for smooth movement, and in the lower back, they carry much of the burden of upper body weight.
Intervertebral discs – These spongy wedges of gel-like liquid enclosed in elastic layers of cartilage are situated between the vertebrae and serve as cushions. They are composed of two main parts: the gel-like center, or nucleus pulposus; and the layered outer wall, or annulus fibrosus.
Ligamenta flava – These ligaments connect and help stabilize adjacent vertebrae. A ligamentum flavum typically is located in a posterior (rearward) position related to the intervertebral disc.
In general, sciatic nerve compression can be traced to some sort of abnormality within one of these anatomical components. All of these components are vulnerable to instability should you suffer a traumatic injury to the lower spine, as in a car accident, a sports injury, or calamitous fall. Even in the absence of an injury, these anatomical components will begin to wear down over time. Anatomical deterioration may be accelerated if you suffered even a minor lower back injury during childhood or adolescence. Read on for a more detailed explanation of how specific anatomical abnormalities – especially those related to the process of aging – may lead to the development of sciatica.
Causes and Risk Factors
As the body ages, the near-constant pressures of bearing weight and supporting a wide range of motion can begin to take a toll on the anatomical components of the lower back. The aging process can give rise to a wide variety of degenerative spine conditions, including the following:
Bulging disc – the protrusion of a portion of the outer wall of an intervertebral disc.
Herniated disc – the extrusion into the spinal column of the gel-like inner material of an intervertebral disc through a tear in the outer wall.
Spinal osteoarthritis – the degeneration of cartilage that lines the vertebral joints.
Vertebral body displacement – also known as spondylolisthesis, which is the slippage of one vertebra over another.
Spinal stenosis – the narrowing of the spinal canal, or of the nerve pathways within the spinal column.
Ligament calcification – the loss of flexibility and tensile strength of spinal ligaments.
Piriformis syndrome – spasms in the piriformis muscle, which attaches to the thigh and allows for hip rotation.
Pregnancy is also a leading cause of sciatica. As the weight and size of a fetus increases, other anatomical components are displaced by the growing uterus, leading to potential sciatic nerve compression. However, this should not be confused with the lower back pain often experienced by women in late pregnancy, which normally is associated with muscle strain or ligament stretching related to carrying extra body weight.
Spinal tumors, benign or malignant, may also produce sciatic nerve compression. Most non-cancerous tumors are not considered a major problem in other parts of the body, but those that occur within the spine can lead to debilitating symptoms, including sciatica. Tumors can originate in other parts of the body and spread to the spine, or they can develop within the membranes of the spinal cord and surrounding cells.
While the causes of sciatica generally are not considered preventable, spinal deterioration can be exacerbated by certain activities. In addition, some groups of people are considered at greater risk for developing the degenerative spine conditions most often responsible for sciatica. Risk factors and at-risk groups include:
Age – People 50 or older are more likely to develop degenerative spine conditions.
Genetics – Inherited traits can make certain people more vulnerable, especially in cases of spinal osteoarthritis.
Smoking – Ingredients in cigarettes can constrict blood vessels and other passages, reducing the body’s ability to deliver vital nutrients.
Injury history – A spinal injury suffered early in life can affect spinal stability later on and accelerate the degeneration process.
Obesity – Excess body weight places more stress on the spine, which can lead to accelerated instability.
Repetitive motion – Occupations or pastimes that require repeated movement within the lower back over a long period of time can accelerate anatomical deterioration.
How, then, do these anatomical abnormalities actually cause sciatica? It depends upon the condition you’re talking about. For example, spinal osteoarthritis may lead to sciatic nerve compression in a number of different ways. As the cartilage at the end of facet joints deteriorates, the body often responds to the resulting reduction in spinal stability by producing excess growths of bone known as osteophytes. Also known as bone spurs, these smooth protrusions usually grow along the edges of affected vertebrae, near the joint itself, as the body attempts to improve stability within the adjacent vertebral segment. If a bone spur grows large enough, or if it grows in the vicinity of one of the nerve roots that helps form the sciatic nerve, compression may occur. Osteoarthritis might also cause nerve compression if the joint instability leads to spondylolisthesis. Should a vertebra slip far enough over the one below it, adjacent nerve structures like the sciatic nerve might be in jeopardy.
Another example is that of the bulging or herniated disc. These are the most common causes of sciatica, especially among men in their 30s and 40s. In the case of a bulging disc, the protruding outer wall may make contact with the sciatic nerve, often only when you bend, twist, or turn the body in a certain direction. With a herniated disc, the extruded portion of the nucleus could seep through a tear in the outer wall and migrate toward the sciatic nerve. In general, compared to a bulging disc, symptoms are more constant (as opposed to intermittent) when herniated disc material begins to press against the sciatic nerve. However, the extruded disc material may dissipate in a process known as resorption, reducing the duration of symptoms.
Symptoms of Sciatica
As we’ve learned, sciatica actually is not a medical condition, per se. It is a set of symptoms, not all of which occur for every patient suffering from sciatic nerve compression. In general, though, signs of sciatic nerve compression include:
Sharp pain or a dull ache experienced at the site of the nerve compression
Intermittent or constant pain in the hamstring, front of the thigh, or buttocks
Shooting or burning pain that radiates down the lower back, the buttocks, thighs, and calves
Diminished sensation (tingling or numbness) in the lower back, buttocks, legs, feet, or toes
Unexplained muscle weakness in an area of the lower body innervated by the sciatic nerve
You may also experience a change in gait associated with a symptom known as foot drop, which is an inability to raise the ankles and toes in a normal upward position. It is characterized by dragging your toes, or by lifting the knee higher than usual to allow the foot to move forward. Foot drop is also a symptom of several less-common (if more serious) conditions, such as Parkinson’s disease and multiple sclerosis.
In most cases of sciatic nerve compression, symptoms are experienced only on one side of the body. This is known as unilateral sciatica, and it is an indication of which side of the spine the compression is on. If symptoms are felt in both legs, it is known as bilateral sciatica. This can mean a couple of things. Either the underlying cause of sciatic nerve compression – a herniated disc, for example – is so large that the nerve roots on both sides are compressed, or two separate conditions have developed on either side. In bilateral sciatica, symptoms might be experienced simultaneously or alternately on one side and the other.
Once you begin to experience these symptoms, when should you see a doctor?
At first, because symptoms might be mild or intermittent, your initial inclination might be to treat it yourself. This is a natural response, especially if you’ve never had a serious back problem. In fact, many of the conditions that produce sciatic nerve compression remain asymptomatic, or only rarely cause pain and other discomfort. A sudden sharp twinge down your leg may be unpleasant, but it won’t necessarily raise an internal alarm, especially if that twinge only happens once. Repeated twinges, though, or an occasional, unexplained tingling in the toes of one foot, ought to make you consider seeking medical attention.
The initial onset of symptoms is often considered acute, which means it lasts only for a short period of time. Should the shooting pain, numbness, or other symptoms last longer than three months, they are classified as chronic. In all likelihood, you won’t want to wait that long if the symptoms are obviously becoming worse with time. The best rule of thumb is to see a doctor if there is any question at all about the health of your spine.
If you do decide to visit the doctor to have your symptoms diagnosed, come prepared. Once you realize that these symptoms are a recurring problem, start to keep a written journal. Record the time of day you felt the symptoms, as well as a description of your discomfort. Write down what you were doing when it happened. Log all of the pain medication you used in an effort to manage your symptoms. Make notes about your family’s medical history, especially as it pertains to the spine. And finally, think back to your childhood and adolescence and try to recall any spinal injuries you may have suffered. The more detail you can provide your doctor, the better the chances of arriving at a correct diagnosis.
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