Musculoskeletal System

Herniated intervertebral disk

Herniation of ucleus pulposus due to damaged annulus fibrosus compressing the nerves or spinal cord causing pain and spinal cord dysfunction.

Herniation of ucleus pulposus due to damaged annulus fibrosus compressing the nerves or spinal cord causing pain and spinal cord dysfunction.


Intervertebral disc:

Intervertebral disc is composed of annulus fibrous—the annulus fibrous, dense collagenous ring encircling the nucleus pulposus. Disc herniation occurs when part or all the nucleus pulposus protrudes through the annulus fibrous.
Intervertebral disc
Intervertebral disc, anulus fibrosus, annulus fibrosus, nucleus pulposus. | Illustration from Anatomy & Physiology, Connexions Web site., Jun 19, 2013. This file is licensed under the Creative Commons Attribution 3.0 Unported license.

Risk factors:

The pathophysiology of herniated discs is believed to be a combination of the mechanical compression of the nerve by the bulging nucleus pulposus and the local increase in inflammatory chemokines.
  • Age-related degenerative changes (M/C cause): Nucleus pulposus becomes less hydrated and weakens leading to a progressive disc herniation
  • Trauma (#2 M/C cause)
  • Other causes: Connective tissue disorders, congenital disorders

Lumbar sites:

Higher rate of disc herniation is seen in lumbar & cervical spine due to biomechanical forces in the flexible part of the spine
Schematic representation of typical L4–L5 hernia, with compression and possible rupture of posterior longitudinal ligament (PLL)
a Schematic representation of typical L4–L5 hernia, with compression and possible rupture of posterior longitudinal ligament (PLL). b Human LDH fragment, obtained from patient who underwent microdiscectomy after informed consent and ethics committee approval from Centro Hospitalar São João. c Histological staining of tissue collected in (b), showing cell clusters producing proteoglycans (Alcian blue) embedded in a collagen matrix (Picrosirius red). d LDH is currently divided into four subtypes, according to MRI, as bulging disc (mildest form), protrusion, extrusion, and sequestration, the severest form of LDH. Proteoglycan-rich nucleus pulposus in center is surrounded by collagen-rich concentric rings of annulus fibrosus. Scale bars: (b) 3 cm, (c) 100 μm. | Cunha, C., Silva, A.J., Pereira, P. et al. The inflammatory response in the regression of lumbar disc herniation. Arthritis Res Ther 20, 251 (2018).
  • Common sites: Lumbar > cervical spine
  • Uncommon site: Thoracic spine

Types of herniation:

Posterolateral herniation:

M/C type as annulus fibrosus is thinner and lacks structural support from anterior/posterior longitudinal ligaments. Due to its proximity, a posterolateral herniation is more likely to compress the nerve root.
  • Nerve root compression

Midline herniation:

  • Spinal cord compression
  • Clinical myelopathy


Chief complaint: Localized back pain

Localized back pain is a combination of the herniated disc pressure on the longitudinal ligament, and chemical irritation due to local inflammation.
  • Sharp or burning pain often radiating in the distribution of the compressed nerve root
  • Numbness and tingling, as well as decreased sensation along the path of the nerve root
  • Severe cases: Weakness or a feeling of instability while ambulating may be endorsed.

Cervical Spine

In the cervical spine, the C6-7 is the most common herniation disc that causes symptoms, mostly radiculopathy.
  • Cervical radiculopathy
Typical Dermatomal Pattern of the Upper Limb
Typical Dermatomal Pattern of the Upper Limb: Radicular pain corresponds to the following distribution | Cervical Radiculopathy. (2022, February 20). Physiopedia, . Retrieved 10:12, August 21, 2022 from

Thoracic Spine

Most thoracic disc herniations are asymptomatic and discovered incidentally with an MRI.Unlike the lumbar and cervical disc herniations, thoracic disc herniations have atypical symptoms and often a diagnosis of exclusion.
  • Thoracic discogenic pain syndrome (TDPS): Radicular pain secondary to posterolateral herniations that compress spinal nerves as they exit through the intervertebral foramen

Lumbar Spine

Herniated disc can present with symptoms including sensory and motor abnormalities limited to a specific myotome.
  • Lower backache + specific dermatomyotomal involvement
MRI: Lumbar disc herniation
Sagittal magnetic resonance image of an L5/S1 disc herniation in the setting of degenerative disc disease. The patient was a 41-year-old woman with a six-week history of right-sided radicular leg pain in an S1 nerve root distribution. The patient failed conservative treatment, including physical therapy and pain management. Her symptoms were successfully relieved with a right-sided L5/S1 microdiscectomy. | Schoenfeld, A. J., & Weiner, B. K. (2010). Treatment of lumbar disc herniation: Evidence-based practice. International journal of general medicine, 3, 209–214.
  • Straight leg raise test (SLRT): Examiner slowly elevates symptomatic leg at increasing angles on a supine patient, while keeping the leg straight at the knee joint. The test is positive if it reproduces the patient’s typical pain and paresthesia.
  • Contralateral (crossed) SLRT: Examiner slowly elevates asymptomatic leg at an increasing angle on a supine patient. The test is positive if the maneuver reproduces the patient’s typical pain and paresthesia.


Conservative management:

Acute cervical and lumbar radiculopathies due to a herniated disc are primarily managed with non-surgical treatments.

First-line modalities:

  • NSAIDs
  • Physical therapy: Started after 2 weeks as most cases resolve
  • Refractory pain: Opioid analgesics

Second-line modalities:

  • Translaminar epidural injections
  • Selective nerve root blocks

Surgical management:

Benefits are moderate and tend to decrease over time following surgery
  • Laminectomies with discectomies
  • Artificial disk replacement

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