The majority of<unk> s occur in the lumbar spine (95% at L4–L5 or L5–S1). The second most common site is the cervical region (C5–C6, C6–C7). The thoracic region accounts for only 1–2% of cases.<unk> s usually occur postero-laterally, at the points where the annulus fibrosus is relatively thin and is not reinforced by the posterior or anterior longitudinal ligament. In the cervical spine, a symptomatic postero-lateral<unk>  between two vertebrae will impinge on the nerve which exits the spinal canal between those two vertebrae on that side. So, for example, a right postero-lateral<unk>  of the<unk>  between vertebrae C5 and C6 will impinge on the right C6 spinal nerve. The rest of the spinal cord, however, is oriented differently, so a symptomatic postero-lateral<unk>  between two vertebrae will impinge on the nerve exiting at the next intervertebral level down. Herniated lumbar<unk>  Lumbar<unk><unk> s occur in the back, most often between the fourth and fifth lumbar vertebral bodies or between the fifth and the sacrum. Here, symptoms can be felt in the lower back, buttocks, thigh, anal/genital region (via the perineal nerve), and may radiate into the foot and/or toe. The sciatic nerve is the most commonly affected nerve, causing symptoms of sciatica. The femoral nerve can also be affected and cause the patient to experience a numb, tingling feeling throughout one or both legs and even feet or a burning feeling in the hips and legs. A<unk>  in the lumbar region often compresses the nerve root exiting at the level below the<unk> . Thus, a<unk>  of the L4–5<unk>  compresses the L5 nerve root, only if the<unk>  is posterolateral. Cervical<unk><unk>  Herniated<unk>  at C6–C7 level Cervical<unk><unk> s occur in the neck, most often between the fifth and sixth (C5–6) and the sixth and seventh (C6–7) cervical vertebral bodies. There is an increased susceptibility amongst older (60+) patients to<unk> s higher in the neck, especially at C3–4. Symptoms of cervical<unk> s may be felt in the back of the skull, the neck, shoulder girdle, scapula, arm, and hand. The nerves of the cervical plexus and brachial plexus can be affected. Intradural<unk><unk>  Intradural<unk><unk>  is a rare form of<unk><unk>  with an incidence of 0.2–2.2%. Pre-operative imaging can be helpful for diagnosis, but intra-operative findings are required for confirmation. Inflammation It is increasingly recognized that back pain resulting from<unk><unk>  is not always due solely to compression of the spinal cord or nerve roots, but may also be caused by chemical inflammation. There is evidence that points to a specific inflammatory mediator in back pain: an inflammatory molecule, called tumor necrosis factor alpha (TNF), is released not only by a herniated<unk> , but also in cases of<unk>  tear (annulus tear) by facet joints, and in spinal stenosis. In addition to causing pain and inflammation, TNF may contribute to<unk>  degeneration.
Spinal disc herniation
Piriformis syndrome
Spinal tumor
Lumbar disc disease
Spinal stenosis
Degenerative disc disease
Lumbar spinal stenosis
Cervical spinal stenosis