The region where disc herniations are seen most frequently is the lumbar region. They are most commonly seen at the L5–S1 and L4–5 levels. Lumbar disc herniation (LDH) is very rare in children and adolescents and is most often seen between the ages of 40 and 50. Heavy lifting, torsional (twisting) loads on the spine, strenuous physical work and excess body weight can be counted as risk factors. In addition, long-distance drivers, heavy manual workers, dentists and housewives are also considered at-risk groups.
Development of the Disease
Because the posterior longitudinal ligament is stronger in the midline and weaker laterally, disc herniations tend to occur posterolaterally and laterally. Less frequently, they may extend into the foramen or lateral to the foramen (extraforaminal or far lateral).
Disc Herniation (Lumbar Disc Herniation)
A posterolateral herniation compresses the nerve root that separates from the dura at that level and exits through the lower foramen, whereas a far lateral herniation compresses the nerve root exiting through the same-level foramen. For example, an L4–5 disc herniation compresses the L5 nerve root, while an L4–5 far lateral disc herniation compresses the L4 nerve root. As a result of the pressure exerted by the herniated disc on the nerve root, edema and ischemia develop in the nerve root, leading to radicular-type pain. However, there is no direct relationship between the severity of the compression and the intensity of the pain. Not every compression causes pain. It is accepted that in addition to mechanical factors, other mechanisms also play a role in the development of pain.
MR images in lumbar disc herniation
Clinical Findings
In most cases, the first symptom is low back pain; there is spasm in the paravertebral muscles, and a temporary scoliosis may occur due to this. Because of the spasm, lumbar movements are painful and restricted. Leg pain follows the low back pain. The pain increases with standing, walking, bending forward, coughing and straining. In this situation, the most useful examination is the straight leg raise (Lasegue) test. Sometimes, pain may occur when the straight leg raise test is performed on the opposite side; this is called the contralateral Lasegue sign. After the onset of pain, neurological signs and symptoms are added to the picture. Depending on the affected nerve root, numbness (hypoesthesia), loss of sensation (anesthesia), muscle weakness and loss of tendon reflexes occur in the corresponding dermatomes. Sensory dermatomes belonging to the nerve roots are shown in Figure 5. In midline (central) disc herniations, cauda equina syndrome develops. In this situation there are no radiculopathy findings. Instead, perineal numbness, loss of bladder and anal control, and weakness in the legs are present.
In the differential diagnosis, other space-occupying lesions compressing the nerve roots and dura, tumors, other degenerative changes, peripheral nerve lesions and diseases, diabetic neuropathies, intrapelvic masses or piriformis syndrome that may cause sciatic nerve entrapment, rheumatic diseases and trauma should be kept in mind. The diagnostic method used in disc herniations is MRI. Although diagnosis can be made with static MRI images, sometimes dynamic MRI provides better results. However, the fact that standing dynamic MRI is available in only a few centers and that its cost is high are disadvantages of this method. If there is neurological involvement, EMG provides valuable information about the location and severity of the lesion, but for reliable results at least a two-week interval must pass.
Treatment
Treatment options can be grouped under three headings.
Conservative treatment; treatment with NSAID drugs, muscle relaxants, low-dose controlled steroid applications and physical therapy are included in this group.
Algological (interventional pain) procedures
Surgical interventions. Indications for surgery are as follows:
Low back and leg pain that does not improve with other methods. Here, pain that persists despite approximately eight weeks of conservative treatment is considered.
The appearance of neurological findings
Surgical Treatment Methods
Hemilaminectomy: This is the most commonly used method in single-level disc herniations.
Total laminectomy: This method is preferred especially in central disc herniations, in the presence of cauda equina syndrome findings, and in spinal canal stenosis.
Microdiscectomy: These are procedures performed using a surgical microscope. Because the anatomical structures are largely preserved, outcomes are better. Magnification and illumination of the surgical field, a smaller skin incision, easier control of epidural bleeding, and shorter operation and hospital stay times are advantages of this method. On the other hand, the long learning curve is considered a disadvantage.
Minimally invasive and endoscopic procedures: With technological advances, especially in recent years, treatment of disc herniations through endoscopic or minimally invasive approaches has become a more commonly used method.