Low Back Problems

Most low back problems that might be considered surgically treatable involve pinched spinal nerve roots that produce radiating leg pain (sciatica). Sciatica is a nerve pain that follows the course of the major nerve to the leg, the sciatic nerve, and is variably described as an electricity or burning pain. In general, sciatica is produced by one of two common conditions:



Lumbar Disc Herniation ^

The disc, or more properly intervertebral disc, is a shock absorbing structure located between the spinal bones called vertebrae. The consistency of the disc is often referred to as jelly like, although in reality it is much more substantial. The disc tissue is held between the bones by ligaments that form a capsule or annulus. If the ligaments (annulus) weaken or tear, either through normal degenerative processes or injury, the upright posture of the human body produces sufficient compressive force to cause some of the softer centrally located disc tissue (the nucleus) to extrude through the capsule (the annulus). This is variably called a slipped disc, ruptured disc, herniated disc, or extruded disc. The extruded fragment can compress a lumbar spinal nerve root and cause the hallmark symptom of sciatica. If the pressure on the nerve root is significant enough, pain can be followed by loss of function which can include weakness in the leg, loss of sensation, changes in reflexes, or in extreme cases, impairment of bowel or bladder function.

Unless there is a significant loss of neurological function, treatment initially usually revolves around a short course of bed rest, nonsteroidal anti-inflammatory medications, physical therapy and the passage of time.

With persistent pain and/or loss of function refractory to the above conservative treatment, surgical intervention becomes a consideration. The goal of surgery is to relieve the pressure on the spinal nerve root by removing the extruded fragment of disc tissue and reduce if not eliminate the sciatic pain and restore neurological function if such function has been lost.

Surgery is always preceded by imaging studies which provide the surgical roadmap and confirm the clinical diagnosis. The most common study performed is an MRI scan (magnetic resonance imaging), which is painless and non-invasive. Sometimes CT scans (computed tomography) are used, either alone or in combination with a procedure known as a myelogram, which involves an injection of X-ray dye into the spinal fluid space.

The usual surgical procedure is a microsurgical discectomy or microendoscopic discectomy. The hospital stay is normally overnight or less and at the time of discharge, patients are able to walk and are capable of basic self-care. Restrictions on lifting and more strenuous physical activity are important postoperatively to reduce the risk of a recurrent disc herniation and the need for reoperation. Equally important is a structured back exercise and therapy program, usually started about one month postoperatively, to strengthen the back and abdominal muscles and to increase flexibility.

For a patient in good health without serious medical problems, the overall complication risk rate of the procedure is less than 1%. The risk of a recurrent herniation necessitating a second operation is about 4%.

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Lumbar Spinal Stenosis ^

Lumbar stenosis is a condition of aging and degenerative change and therefore occurs in a more elderly population than lumbar disc herniations. Stenosis means narrowing of the spinal canal and occurs when arthritic bone arising from the facet joints of the low back grows centrally into the spinal canal. Degenerative narrowing of the disc spaces further compounds the problem, sometimes producing a spinal canal that is 10% or less of it's normal diameter. The stenosis causes pinching of the nerve roots and symptoms secondary to their irritation.

The most common complaint is leg pain, usually involving both legs, aggravated by standing or walking and usually alleviated by sitting or lying down. Sometimes, the capacity to walk is limited to a block or less, or standing to no more than a few minutes. The symptoms are often reduced by bending forward at the waist or walking in a flexed posture.

With lumbar stenosis, symptoms predominate whereas actual loss of neurological function occurs very late in the process, if at all. A high index of suspicion is therefore needed to make the diagnosis, as the clinical or neurological examination might be quite unremarkable. An MRI or CT scan confirms the diagnosis.

Initial treatment is usually conservative and focuses on flexion exercises and a non-steroidal anti-inflammatory drug. Flexion exercises tend to "open" the spinal canal and the NSAID's reduce arthritic inflammation. When these measures fail, an injection into the spine of a long acting cortisone derivative anti-inflammatory drug, called an epidural steroid injection, is often undertaken. The injection is attractive because it is a minimally invasive outpatient procedure. However, there is tremendous variability in response, with some patients having no improvement whatsoever and others achieving good pain relief for a protracted interval of time.

When more conservative measures fail, consideration is given to surgery which is the most definitive solution but also the most invasive. The operation performed is called a decompressive laminectomy and involves removing the lamina, which form the "roof" of the spinal canal. The surgery typically involves operating at two or more segments, involves a 3 to 4 day stay in the hospital and a recovery that spans a number of months. In certain very specific cases, a fusion of the spine is performed as well, increasing the magnitude of the procedure and recovery time significantly. At the time of hospital discharge, patients are ambulatory and capable of basic self-care. In an otherwise healthy individual, the surgical risks are no more than 1%.

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Lumbar Fusion ^

A fusion is a surgical process to make adjacent bones grow or knit together as one unit. The intent is to create "stability", which in surgical terminology means to stop movement between adjacent bones.

Fusions are a major surgical procedure with a relatively long recovery and are performed for very specific reasons. Common examples might include the treatment of a fracture of the back or to deal with a condition known as spondylolisthesis. This means a slippage of one vertebra forward on another and can either be developmental or degenerative, meaning due to arthritic changes. Spondylolisthesis can be either fixed (stable) or dynamic (unstable) and can provoke back or leg pain or both. The leg pain is a form of sciatica and is usually the primary indication for the surgery being performed.

Fusions often involve "hardware" which means surgically implanted screws or devices to minimize movement of the adjacent bones to improve the chances of the fusion "taking" or healing. Some of the devices are pedicle screws, which track down through the bone of the spine into the main body of the vertebrae, whereas others are used to replace the disc and create a fusion across the disc space. These are often referred to as "cages" or more properly interbody fusion devices. Bone is often harvested from the nearby hip or iliac crest and may be used in conjunction with other bone products to augment the fusion.

Stopping motion after fusions helps the healing process, so many if not most patients are also put in a specially fabricated back brace to be worn when out of bed for the first several months.

Full recovery takes many months of time, so having a fusion means a big commitment of time and energy on the part of the patient.

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