Herniated Disc

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A spinal disc herniation, incorrectly called a "slipped disc", is a medical condition affecting the spine, in which a tear in the outer, fibrous ring (annulus fibrosus) of an intervertebral disc allows the soft, central portion (nucleus pulposus) to herniate.

It is normally a further development of a previously existing disc protrusion, a condition in which the outermost layers of the annulus fibrosus are still intact, but can bulge when the disc is under pressure.



Frequency

Disc herniation can occur in any disc in the spine, but the two most common forms are the cervical disc herniation and the lumbar disc herniation. The latter is the most common, causing lower back pain and often leg pain as well, in which case it is commonly referred to as sciatica.

Lumbar disc herniation occurs 15 times more often than cervical disc herniation, and it is one of the most common causes of lower back pain. The cervical discs are affected 8% of the time and the upper-to-mid-back (thoracic) discs only 1 - 2% of the time.1

The following locations have no discs and are therefore exempt from the risk of disc herniation: the upper two cervical intervertebral spaces, the sacrum, and the coccyx.

Most disc herniations occur when a person is in their thirties or forties when the nucleus pulposus is still a gelatin-like substance. With age the nucleus pulposus changes (dries out) and the risk of herniation is greatly reduced. After age 50 or 60, osteoarthritic degeneration or spinal stenosis are more likely causes of low back pain or leg pain.

Cervical disc herniation

Cervical disc herniations occur in the neck, most often between the sixth and seventh cervical vertebral bodies. Symptoms can affect the back of the skull, the neck, shoulder girdle, scapula, shoulder, arm, and hand. The nerves of the cervical plexus and brachial plexus can be affected.2


Thoracic disc herniation

Thoracic discs are very stable and herniations in this region are quite rare. Herniation of the uppermost thoracic discs can mimic cervical disc herniations, while herniation of the other discs can mimic lumbar herniations.3

Lumbar disc herniation

[umbar disc herniations occur in the lower back, most often between the fourth and fifth lumbar vertebral bodies or between the fifth and the sacrum. Symptoms can affect the lower back, buttocks, thigh, 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.4 Can cause the patient to experience a numb, tingling feeling throughout one or both legs and even feet.

Causes

Causes of a disc herniation can include general wear and tear on the disc over time, repetitive movements, stress on the disc that occurs while twisting and lifting, genomic susceptibility, or other injuries.

Symptoms

The chief complaint for spinal disc herniation is leg pain greater than lower back pain, symptoms of a herniated disc can vary depending on the location of the herniation and the types of soft tissue that become involved. They can range from little or no pain if the disc is the only tissue injured to severe and unrelenting neck or low back pain that will radiate into the regions served by an affected nerve root when it is irritated or impinged by the herniated material. Other symptoms may include sensory changes such as numbness, tingling, muscular weakness, paralysis, paresthesia, and affection of reflexes. If the herniated disk is of the Lumbar region the patient may also experince sciatica due to irritation of the sciatic nerve. Unlike a pulsating pain or pain that comes and goes, which can be caused by muscle spasm, pain from a herniated disc is usually continuous.

It is possible to have a herniated disc without any pain or noticeable symptoms, depending on its location. If the extruded nucleus pulposus material doesn't press on soft tissues or nerves, it may not cause any symptoms. It has been estimated that as many as 50% of the population have focal herniated discs in their cervical region that do not cause noticeable symptoms.5

Typically, symptoms are experienced only on one side of the body. If the prolapse is very large and presses on the spinal cord or the cauda equina in the lumbar region, affection of both sides of the body may occur, often with serious consequences.

Diagnosis

Diagnosis is made by a practitioner based on the history, symptoms, and physical examination. At some point in the evaluation, tests may be performed to confirm or rule out other causes of symptoms such as spondylolisthesis, degeneration, tumors, metastases and space-occupying lesions as well as evaluate the efficacy of potential treatment options. These tests may include the following:

  • X-ray: Although traditional plain X-rays are limited in their ability to image soft tissues such as discs, muscles, and nerves, they are still used to confirm or exclude other possibilities such as tumors, infections, fractures, etc.. In spite of these limitations, X-ray can still play a relatively inexpensive role in confirming the suspicion of the presence of a herniated disc. If a suspicion is thus strengthened, other methods may be used to provide final confirmation.
  • Computed tomography scan: A diagnostic image created after a computer reads x-rays. It can show the shape and size of the spinal canal, its contents, and the structures around it, including soft tissues.
  • Magnetic resonance imaging: A diagnostic test that produces three-dimensional images of body structures using powerful magnets and computer technology. It can show the spinal cord, nerve roots, and surrounding areas, as well as enlargement, degeneration, and tumors. It shows soft tissues even better than CAT scans.
  • Myelogram: An x-ray of the spinal canal following injection of a contrast material into the surrounding cerebrospinal fluid spaces. By revealing displacement of the contrast material, it can show the presence of structures that can cause pressure on the spinal cord or nerves, such as herniated discs, tumors, or [[bone spur]]s. Because it involves the injection of foreign substances, scans are now preferred when available, although myelograms still provide excellent outlines of space-occupying lesions.
  • Electromyogram and Nerve conduction studies (EMG/NCS): These tests measure the electrical impulse along nerve roots, peripheral nerves, and muscle tissue. This will indicate whether there is ongoing nerve damage, if the nerves are in a state of healing from a past injury, or whether there is another site of nerve compression.

Treatment

The majority of herniated discs will heal themselves in about six weeks and do not require surgery.One study found that "After 12 weeks, 73% of patients showed reasonable to major improvement without surgery.".6

Conservative treatment

Pain medications are often prescribed to alleviate the acute pain and allow the patient to begin exercising and stretching.

There are a variety of non-surgical care alternatives to treat the pain, including:


  1. Bed rest and lumbo-sacral support belt.
  2. Physical therapy
  3. Osteopathic/chiropractic manipulations. A systematic review by Clinical Evidence concluded that spinal manipulation for herniated lumbar disc was likely to be beneficial.7 The review was largely based on two randomized controlled trials..8,9 Patients with a herniated disc may be at increased risks of worsening disk herniation or cauda equina syndrome due to manipulation.10
  4. Massage therapy
  5. Non-steroidal anti-inflammatory drugs (NSAIDs)
  6. Oral steroids (e.g. prednisone or methyprednisolone)
  7. Epidural (cortisone) injection
  8. Intravenous sedation, analgesia-assisted traction therapy (IVSAAT)

Surgery

Surgery should be considered if a patient has a significant neurological deficit, or if they fail non-surgical therapy. The presence of cauda equina syndrome (in which there is incontinence, weakness and genital numbness) is considered a medical emergency requiring immediate attention and possibly surgical decompression.

Regarding the role of surgery for failed medical therapy in patients without a significant neurological deficit, a meta-analysis]of randomized controlled trials by the Cochrane Collaboration concluded that "limited evidence is now available to support some aspects of surgical practice". More recent studies refine indications for surgery

  • The Spine Patient Outcomes Research Trial (SPORT)
    • Patients studied. "intervertebral disk herniation and persistent symptoms despite some nonoperative treatment for at least 6 weeks; radicular pain (below the knee for lower lumbar herniations, into the anterior thigh for upper lumbar herniations) and evidence of nerve-root irritation with a positive nerve-root tension sign (straight leg raise–positive between 30° and 70° or positive femoral tension sign) or a corresponding neurologic deficit (asymmetrical depressed reflex, decreased sensation in a dermatomal distribution, or weakness in a myotomal distribution)
    • Conclusions. "Patients in both the surgery and the nonoperative treatment groups improved substantially over a 2-year period. Because of the large numbers of patients who crossed over in both directions, conclusions about the superiority or equivalence of the treatments are not warranted based on the intent-to-treat analysis".11,12
  • The Hague Spine Intervention Prognostic Study Group13
    • Patients studied. "Incapacitating lumbosacral radicular syndrome that had lasted for 6 to 12 weeks..Patients presenting with cauda equina syndrome, muscle paralysis, or insufficient strength to move against gravity were excluded."
    • Conclusions. "The 1-year outcomes were similar for patients assigned to early surgery and those assigned to conservative treatment with eventual surgery if needed, but the rates of pain relief and of perceived recovery were faster for those assigned to early surgery. "

Surgical options include:

  • Microdiscectomy.14
  • IDET (a minimally invasive surgery for disc pain)
  • Laminectomy - to relieve spinal stenosis or nerve compression
  • Hemilaminectomy - to relieve spinal stenosis or nerve compression
  • Lumbar fusion (lumbar fusion is only indicated for recurrent lumbar disc herniations, not primary herniations)
  • Anterior cervical discectomy and fusion (for cervical disc herniation)
  • Disc arthroplasty (experimental for cases of cervical disc herniation)
  • Dynamic stabilization (dynamic stabilization is an experimental procedure with no data supporting its use for primary disc herniations)
  • Artificial disc replacement, a relatively new form of surgery in the U.S. but has been in use in Europe for decades, primarily used to treat low back pain from a degenerated disc.

Surgical goals include relief of nerve compression, allowing the nerve to recover, as well as the relief of associated back pain and restoration of normal function.

Classical surgery for lumbar disc herniation is carried out by using a vertical median incision over the level which has an herniation. The dorsolumbar fascia is incised about 0.5 cm laterally on the affected side. The paravertebral muscles are dissected free from underlying bony structures, namely the spinous process and laminae, and retracted laterally. The level of disc herniation is identified using C-arm fluoroscopy or by palpating the sacrum. The lamina is then fenestrated with bone rongeurs after which the exposed ligamentum flavum is excised. The epidural soft tissue and venous plexus is gently explored to find the nerve root exiting from the associated neural foramina. The herniated disc is usually found beneath the nerve root. The nerve root is protected using root retractors. The posterior longitudinal ligament is incised with a fine blade and herniated disc material and degenerated nucleus pulposus are evacuated using different kinds of disc forcepses. Meticulous control of haemostasis is employed and irrigation with warm saline is essential. The muscle layers and the fascia is repaired, generally, without using a drain. The skin wound is closed.

Cervical disc herniations are operated using a horizontal paramedian anterior neck incision parallel to skin folds, a surgical procedure called ~~Anterior cervical discectomy and fusion[[. After dissecting the neck structures (which are vital organs, such as trachea, esophagus, carotid arteries etc.), the front of the vertebral column is reached and exposure is maintained by automatic retractors. The dissection is blunt and is carried out through natural anatomic planes, thus causing minimal trauma to tissues here. The level is again verified using the C-arm. The disc is evacuated using curettes and high speed drills. The surgeon may place an intervertebral support, such as autologous bone or allogrefts, or metallic elements for fusion. The incision is then closed layer by layer. Another approach for cervical herniations is the posterior approach, which is basically identical to surgical treatment for lumbar disc surgery. The decision of which route to employ is arrived after complete workup of a patient.

Investigational treatments

Future treatments may include stem cell therapy. Doctors Victor Y. L. Leung, Danny Chan and Kenneth M. C. Cheung have reported in the European Spine Journal that "substantial progress has been made in the field of stem cell regeneration of the intervertebral disc. Autogenic [[mesenchymal stem cells[[in animal models can arrest intervertebral disc degeneration or even partially regenerate it and the effect is suggested to be dependent on the severity of the degeneration."15


References

  1. Frequency
  2. Cervical herniation
  3. Thoracic herniation
  4. Lumbar herniation
  5. Symptoms
  6. Vroomen PC, de Krom MC, Knottnerus JA (2002). "Predicting the outcome of sciatica at short-term follow-up". The British journal of general practice : the journal of the Royal College of General Practitioners 52 (475): 119-23. PMID 11887877. |full text at PubMed Central
  7. Jordon J, Shawver Morgan T, Weinstein J, Konstantinou K (2006). "Herniated lumbar disc". Clinical evidence (15): 1570-86. PMID 16973060.
  8. Mathews JA, Mills SB, Jenkins VM, et al (1987). "Back pain and sciatica: controlled trials of manipulation, traction, sclerosant and epidural injections". Br. J. Rheumatol. 26 (6): 416-23. PMID 2961394.
  9. Liu J, Zhang S (2000). "Treatment of protrusion of lumbar intervertebral disc by pulling and turning manipulations". Journal of traditional Chinese medicine = Chung i tsa chih ying wen pan / sponsored by All-China Association of Traditional Chinese Medicine, Academy of Traditional Chinese Medicine 20 (3): 195-7. PMID 11038982.
  10. Stevinson C, Ernst E (2002). "Risks associated with spinal manipulation". Am J Med 112 (7): 566-71. PMID 12015249.
  11. Weinstein JN, Tosteson TD, Lurie JD, et al (2006). "Surgical vs nonoperative treatment for lumbar disk herniation: the Spine Patient Outcomes Research Trial (SPORT): a randomized trial". JAMA 296 (20): 2441-50. DOI:10.1001/jama.296.20.2441. PMID 17119140.
  12. Weinstein JN, Lurie JD, Tosteson TD, et al (2006). "Surgical vs nonoperative treatment for lumbar disk herniation: the Spine Patient Outcomes Research Trial (SPORT) observational cohort". JAMA 296 (20): 2451-9. DOI:10.1001/jama.296.20.2451. PMID 17119141.
  13. Peul WC, van Houwelingen HC, van den Hout WB, et al (2007). "Surgery versus prolonged conservative treatment for sciatica". N. Engl. J. Med. 356 (22): 2245-56. DOI:10.1056/NEJMoa064039. PMID 17538084.
  14. Microdiscectomy
  15. Leung, Chan, Cheung, Regeneration of intervertebral disc by mesenchymal stem cells: potentials, limitations, and future direction. European Spine Journal, Volume 15, Supplement 15 / August, 2006

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