Herniated Disc
Introduction
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A herniated disc is caused by the rupture of the fibrous annulus which constitutes the external portion of the intervertebral disc, with the consequent escape of the pulpy nucleus towards the spinal canal or neural foramina.
This results in back pain, pain, physical disability, or changes in sensitivity in different parts of the body. If the herniated disc is located in the lumbar region, the patient may also experience sciatica due to irritation of one of the nerve roots of the sciatic nerve.
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The most conclusive diagnostic tool for herniated disc is magnetic resonance imaging; while the treatment can vary from painkillers, to minimally invasive infiltrative therapies, up to surgery.
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Herniated Disc​
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Most herniated discs 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 represents only 1-2% of cases. Hernias usually occur posterolateral, in places where the annulus fibrosus is relatively thin and is not reinforced by the posterior or anterior longitudinal ligament. In the cervical spine, a symptomatic posterolateral hernia between two vertebrae affects the nerve exiting the spinal canal between those two vertebrae on that side. Thus, for example, a right posterolateral disc herniation between the C5 and C6 vertebrae will affect the right C6 spinal nerve. The rest of the spinal cord, however, is oriented differently, so a symptomatic posterolateral hernia between two vertebrae will affect the outgoing nerve at the next intervertebral level downward.
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Symptoms of the cervical hernia can be felt in the back of the skull, in the neck, in the scapular belt, in the scapula, in the arm and in the hand. The nerves of the cervical plexus and the brachial plexus can be affected.
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Lumbar Disc Herniation
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Hernias of the lumbar disc occur in the posterior part, most often between the fourth and fifth lumbar vertebral bodies or between the fifth and sacrum. Here, symptoms can be felt in the lower back, buttocks, thigh, anal / genital region and can radiate into the foot and / or fingertips.
The sciatic nerve is the most affected nerve, causing sciatica symptoms. The femoral nerve may also be affected and cause the patient a numbness and tingling sensation in one or both legs and even feet or a burning sensation in the hips and legs. A hernia in the lumbar region often compresses the nerve root that exits at the level below the disc. Therefore, an L4–5 disc herniation compresses the L5 nerve root, only if the hernia is posterolateral.
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Pathophysiology
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Disc herniation is frequently associated with age-related external ring degeneration, known as anulus fibrosus, but is normally triggered by trauma or lifting or twisting effort. A tear in the disc ring can cause the release of chemicals that cause inflammation, which can cause severe pain even in the absence of compression of the nerve root.
It is increasingly recognized that back pain resulting from herniated discs is not always solely due to compression of the spinal cord or nerve roots, but can also be caused by chemical inflammation. There is evidence that indicates a specific inflammatory mediator in back pain: an inflammatory molecule, called alpha tumor necrosis factor (TNF), is released not only from a herniated disc, but also in case of rupture of the disc, for facet joints and in spinal stenosis. In addition to causing pain and inflammation, TNF can contribute to disc degeneration.
Terms commonly used to describe the condition include herniated disc, prolapsed disc, and broken disc. Other conditions that are closely related include disc protrusion, radiculopathy (nerve compression), sciatica, disc degeneration, degenerative disc disease and black disc (a totally degenerated spinal disc).
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Diagnosis
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Spinal disc herniation is diagnosed by a doctor based on a patient's history and symptoms and by physical examination. During an evaluation, tests can be performed to confirm or rule out other possible causes with similar symptoms - spondylolisthesis, degeneration, tumors, metastases and space-occupying lesions, for example - as well as to evaluate the effectiveness of potential treatment options.
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X-Ray: X-rays do not allow to visualize soft tissues such as discs, muscles and nerves, but are still used to confirm or rule out other possibilities such as tumors, infections, fractures, etc. Despite their limitations, X-rays play a relatively inexpensive role in confirming suspicion of a herniated disc. If a suspect is thus reinforced, other methods may be used to provide final confirmation.
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Computed Tomography is a diagnostic image created after a computer reads X-rays. It can show the shape and size of the spinal canal, its contents and surrounding structures, including soft tissues. However, visual confirmation of a herniated disc can be difficult with a CT scan.
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Magnetic Resonance Imaging (MRI) without contrast is a diagnostic test that produces three-dimensional images of body structures using powerful magnets, radio frequencies and computer technology. It can show the spinal cord, nerve roots and surrounding areas, as well as intervertebral discs, disc degeneration, and tumors. Show soft tissue better than CT scans. An MRI performed with a high magnetic field intensity usually provides the most conclusive evidence for diagnosing a herniated disc. T2-weighted images allow clear visualization of disc material protruding into the spinal canal.
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Electromyography and nerve conduction (EMG) studies measure electrical impulses along nerve roots, peripheral nerves and muscle tissue. Tests can indicate if nerve damage is in progress, if the nerves are in a state of healing from a past injury, or if another nerve compression site exists. EMG studies are typically used to locate sources of nerve dysfunction distal to the spine.
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Differential diagnosis
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Various pathologies can simulate a herniated disc, or at least present similar symptoms, among these we must remember:
Discogenic pain
Mechanical pain
Myofascial pain
Abscess
Aortic dissection
Discitis or osteomyelitis
Hematoma
Tumor injury
Heart attack
Sacroiliac joint dysfunction / knee arthrosis
Spinal stenosis
Spondylosis or spondylolisthesis
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Treatment
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In most cases, the herniated disc can be successfully treated conservatively, without surgical removal of the herniated material. Sciatica is a collection of symptoms associated with a herniated disc. Several studies in this regard have shown that about a third of sciatica patients recover within two weeks of presentation using only conservative measures and about three quarters of patients recovered after three months of conservative treatment.
Initial treatment usually consists of nonsteroidal anti-inflammatory drugs (NSAIDs), but long-term use of NSAIDs for people with persistent back pain is complicated by their possible kidney and gastrointestinal toxicity.
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Epidural corticosteroid injections provide a slight and questionable short-term improvement for those with sciatica, but may have little long-term benefit.
Other infiltrative therapies include facial injection or deep paravertebral infiltrative therapies (e.g. ozone therapy).
Further therapies, which have the intervertebral disc as their direct target, can be performed on a day-hospital basis, or with a one / two day hospitalization, and include discolysis or coblation (nucleoplasty).
Surgery is reserved for cases that do not benefit from all these minimally invasive therapies, and in consideration of the non reversibility of the procedure, and the high risk of long-term recurrence (known as Failed Back Surgery Syndrome) which can go up to 20 % of cases, is reserved for cases of intractable pain or nervous paralysis.
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Physical therapy
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Exercises that increase back strength can also be used to prevent back injuries. The back exercises include inclined push-ups, upper back extension, transverse abdominal reinforcement and floor bridges. If pain is present, it can mean that the stabilizing muscles of the back are weak and a person needs to train the trunk muscles. Other preventive measures consist of losing weight and avoiding physical exertion. Heavy lifting should be done with the legs doing the job and not with the back.
Swimming, as well as all atraumatic physical activity, is a common tool used in training the strength of the aforementioned muscles. The use of lumbar-sacral support belts can limit the movements of the spine and support the back during lifting.
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