Lumbar disc herniation is a condition when degenerated intervertebral disc material slips into the spinal canal, causing compression of the lumbar nerve roots.
The human spine is the major supporting structure in the body. It is composed of vertebral bones and joints connecting them. The spine is arbitrarily divided into four parts: cervical, thoracic, lumbar, and sacral. The coccyx is a small bone attached to the sacrum at its lowest part. The lumbar spine is composed of five lumbar vertebrae and joints between them.
These joints provide mobility to the spine. Each vertebral bone is connected to its neighbor with three joints. The disc joint is the major load-bearing structure of the spine. It is composed of a core gelatinous component called a nucleus and a stronger external ring. The nucleus is very rich in water and is very elastic. It provides cushion for the bones as well as allows bones to move. With time, the nucleus undergoes "wear and tear," loses its elastic properties, and breaks to pieces. This process is called degenerative disc disease.
With loss of properties, the degenerated nucleus cannot hold the body load, and usually, at this stage, patients have low back pain. Most of the patients usually do not advance to further stages. However, in some instances, one of these fragments can make a tear in the outer ring and slip out. This condition is called lumbar disc herniation. Ruptured disc fragment usually compresses the nerve passing in the spinal canal, causing pain, numbness, and weakness in the leg. This condition is called lumbar radiculopathy. There are various stages of lumbar disc herniation. Initially, the degenerated nucleus makes a small bulge, which later may advance a make disc protrusion. At this stage, the pain is usually the main symptom. With further advancement, disc herniation progresses to extrusion and even to complete sequestration of the ruptured disc fragment.
The fragmented parts may remain inside the disc joint. With time, they completely tear off, and since there is nothing to hold, the entire joint collapses under body weight. Vertebral bones experience greater pressure under this condition and start developing bone spurs or lumbar osteophytes. The whole process is slow and takes years to develop, but eventually, spinal nerves get pinched. This condition is called spinal stenosis. Spinal stenosis is slightly different from lumbar disc herniation because it takes a long period to develop, and usually, the patient's neurological status is good. Usually, the patients cannot walk long distances. In some cases, disc joint laxity causes backbones to slip. This condition is called lumbar spondylolisthesis or simply slippage.
There are several stages of lumbar disc herniation. The healthy nucleus is very elastic and keeps two adjacent vertebrae at a normal distance. With degeneration, the disc desiccates, shrinks, and loses its elastic property, which results in an overall joint height decrease. Such a collapse leads the annulus fibrosus to bulge outwards, narrowing the canal. At this stage, back pain is usually the main symptom. Later, fragmented nucleus parts may cause a rupture in the annulus fibrosus and advance outward. This condition is called disc protrusion. Radiculopathy may be present at this stage. With further advancement, disc herniation progresses to extrusion and then to complete sequestration of the ruptured disc fragment.
Symptoms of the disease depend on the duration and extent of the process. Degeneration alone causes low back pain. The mechanical nature of the pain is very specific to this condition. Pain is aggravated by increased load and relieved by resting. Bending forward combined with heavy object lifting may produce significant pain and trigger an acute low back pain attack. Usually, these attacks last from several days to several weeks and respond very well to resting and pain remedies. Pain might also be aggravated by cold, and that is why it is usually worse during the winter season.
The presence of leg pain indicates nerve root compromise and is an early sign of radiculopathy. Usually, this type of pain originates in the lower back region and radiates to the leg. The presence of pain in one extremity is a typical finding, yet both legs may be affected, too. The extent of leg pain depends on nerve root involvement. Physicians may diagnose the affected nerve root by asking the patient to localize leg pain. Advanced compression causes nerve function compromise and results in loss of sensation (hypoesthesia) and weakness of the leg muscles (paresis). These symptoms are referred to as neurological deficits and should alarm patients and physicians and should be treated promptly. Delays in diagnosis and treatment of neurological deficits may cause permanent loss of neurological function.
Lumbar stenosis causes a specific set of symptoms that are different from lumbar disc herniation. Since the process is very slow, classical radiculopathy is not usually present. Patients often experience "neurogenic claudication," – which is characterized by the inability to walk long distances without rest. As the disease progresses, walking distances become shorter, significantly compromising the patient's quality of life. Usually, both legs are involved, though one side is affected more than the other.
The diagnosis of lumbar disc herniation is done by meticulous clinical examination and radiological assessment. History of the disease and physical examination are the most crucial parts of the patient's management. Not only is clinical examination important for the evaluation of neurological status, but it also provides crucial information for a correct treatment plan.
Radiological evaluation is a very important part of assessment. MRI of the lumbar spine is the diagnostic test of choice. It shows the number of affected discs, the extent of disc degeneration, the presence of herniation, and nerve root compression. Disc degeneration is best appreciated on T2-weighted MRI scans. Since water loss is an essential part of degeneration, the damaged disc will appear dark, while normal discs are white.
X-ray and CT scans can also performed for evaluation, especially if bone structures need to be visualized. X-rays provide overall information about lumbar spine alignment, presence of deformity, bone spurs, narrowing of the disc spaces, vertebral slippage, etc. CT scans provide more detailed information about bone structures than X-rays but require more radiation exposure.
EMG, nerve conduction, and evoked potential studies can be performed in some cases to confirm the presence of radiculopathy if the diagnosis is doubtful. These studies are especially helpful in distinguishing radiculopathy from peripheral nerve compression syndromes.
Initially, disc degeneration and lumbar herniation are treated conservatively. Painkillers, resting, physical therapy, chiropractic manipulation, acupuncture, and other means are usually effective in most cases. Patients should be noted that degeneration is an irreversible process, and these treatment options provide symptomatic relief. Therefore, they do not provide long-term benefits. In order to decrease the speed of degeneration and avoid surgery, patients should lose weight and avoid smoking and strenuous activity, especially associated with significant mechanical load to the lower back.
In some patients, spinal injections and radio-frequency ablations may alleviate symptoms. Epidural steroid injections might be very helpful in cases of acute pain. However, it should be reserved for cases when other treatment options fail to alleviate pain. It was shown that injected steroids cause fibrosis in epidural space in the long term. The nerves get attached to the spine and lose their mobility, causing pain. Another disadvantage of epidural fibrosis is lowering the success of the surgery. It was clearly demonstrated by the SPORT trial (spine patient outcome research trial) that patients who received steroid injections showed lesser improvement with surgery.
Advanced disease is treated surgically. Indications for surgery are as follows: the presence of neurological deficit (paresis with or without hypoesthesia), inability to control pain with non-surgical treatments, and significant compromise in quality of life due to degenerative disc disease. There are various surgical solutions for these patients, and the optimal treatment is based on individual conditions. However, the main goal of the surgery is to relieve the pressure on the nerves. Discectomy or removal of the disc is the cornerstone of lumbar disc herniation treatment. There are various forms of discectomy: open discectomy, micro-discectomy, endoscopic discectomy, percutaneous discectomy, etc.
All these procedures relieve the pressure from the nerves by removing the herniation that causes nerve compression. Additional discectomy is performed in order to decrease the likelihood of future herniation. Lumbar discectomy is a very effective method of treating disc herniation. Yet, there are two major drawbacks of this technique. First, intervertebral joint degeneration is not addressed by this surgery. The affected disc joint may continue to cause low back pain. The second disadvantage is the possibility of recurrent disc herniation. The risk of future re-herniation is especially high in patients with large herniations. The surgeon may need to perform spinal fusion, i.e., to place hardware following discectomy.
Usual indications for stabilization are spinal instability, recurrent herniations, and intent to avoid future herniations. Stabilization is usually performed by using the interbody technique. In time, a stabilized segment of the spine fuses into one solid piece of bone, thus effectively eliminating the risk of future disc problems. It should be noted that fusion eliminates motion at the portion of the spine. Therefore, neighbor levels experience increased load and may degenerate faster. Thus, the risks and benefits of fusion surgery should be weighed carefully prior to the surgical procedure.
Tags: lumbar disc degeneration, lumbar radiculopathy, lumbar disc herniation symptoms, lumbar disc herniation diagnosis, lumbar disc herniation treatment, lumbar discectomy, lumbar fusion