Approximately 80% of the population is plagued at one time or another by back pain, especially lower back pain. Associated leg pain (called lumbar radiculopathy or sciatica) occurs less frequently. Pain can be bothersome and debilitating, limiting daily activities. Leg and back pain can be caused by a variety of reasons, not all of which originate in your spine.

For the purpose of this article, we will focus on lumbar radiculopathy, which refers to pain in the lower extremities in a dermatomal pattern (see image below). A dermatome is a specific area in the lower extremity that has nerves going to it from a specific lumbar nerve. This pain is caused by compression of the roots of the spinal nerves in the lumbar region of the spine. Diagnosing leg and lower back pain begins with a detailed patient history and examination.

Dermatomes (above): Where you feel back and/or leg pain
may help your doctor diagnose nerve compression.

Medical History: Important when Diagnosing Lower Back Pain and Sciatica

Your medical history helps the physician understand the problem. It is important to be specific when answering medical questions related to pain onset but remembering every detail is often not critical. Keeping records of your medical history, including medical problems, medications you are taking and surgeries you have had in the past is helpful.

Journal Your Back and Leg Pain
Regarding your leg and back pain, it may be helpful to keep a journal of your activities, documenting when the pain began, the activities that aggravate your pain and those that relieve your symptoms. It is also important to determine whether your back pain is more bothersome than your leg pain or visa versa. You may be asked if you are experiencing any numbness or weakness in your legs or any difficulty walking. Remember, understanding the cause of your problem is based on the information you provide.

Most people describe radicular pain as a sharp or burning pain that shoots down the leg. This is what some people call sciatica. This pain may or may not begin in the low back. Leg pain caused by compressed nerve roots generally has specific patterns. These patterns of pain depend on the level of the nerve being compressed. After reviewing your history, your physician will perform a physical examination. This will help the physician determine if your symptoms are due to a problem that is caused by spinal nerve root compression. To help you understand the exam performed by your physician lets pause for a quick anatomy lesson.

Spinal Anatomy: Helpful for Understanding Your Lower Back Pain

The spine is comprised of 33 vertebrae (bones stacked on top of each other in a "building-block" fashion) that have 4 distinct regions: cervical (neck), thoracic (upper/mid back), lumbar (low back), and sacrum (pelvis).

Discs are cushion-like tissues that separate most vertebrae and act as the spine's shock absorbing system. Eaach disc is comprised of a tough outer ring of fibers called the annulus fibrosus, and a soft gel-like center called the nucleus pulposus.

There are 7 flexible cervical (neck) vertebrae that help to support the head. Twelve thoracic vertebrae attach to ribs. Next, are 5 lumbar vertebrae; they are large and carry the majority of the body weight. The sacral region helps distribute the body weight to the pelvis and hips.

The spinal cord is housed within the protective elements of spinal canal. Spinal nerves branch from the spinal cord and exit the spinal canal through passageways between the vertebral bodies. The passageways are called neuroforamen. Nerves provide sensory (allowing you to touch and feel) and motor information (allowing the muscles to function) to the entire body.

In the next article (click the Continue Reading link below), we discuss how your doctor determines what is causing your lower back pain and sciatica, which is essential to the proper treatment plan and symptom relief.

Commentary by a Spine Expert

Lumbar radiculopathy is a common problem that results when nerve roots are compressed or irritated. This excellent article discusses the basic anatomy and clinical manifestations of lumbar radiculopathy, which is often referred to generically as sciatica. These symptoms can be due to a variety of causes such as disc bulges, degenerative narrowing of the space for the nerves (spinal stenosis or foraminal stenosis), spinal instability, deformity of the vertebrae, or herniated disc fragments outside of the disc space.

In 70-80% of patients, sciatica is transient, and resolves with nonsurgical treatments such as anti-inflammatory medications, physical therapy, exercise, spinal manipulation, or other nonsurgical modalities. A proportion of patients with sciatica require surgical intervention in instances where nonsurgical therapies have failed to provide adequate pain relief, and there is pathology [cause] that is present compressing the nerves. A very small proportion of patients require urgent surgery. If a very large lumbar disc herniation causes severe nerve damage, with paralysis or acute bowel or bladder incontinence, then emergency surgery may be required.—Curtis A. Dickman, MD