Cervical Disc Herniation Explained: Causes, Risks, and Treatment Options

In recent years, lifestyles among younger people have become increasingly sedentary. Students and office workers who sit in front of a computer for long hours have driven up the rate of abnormal cervical curvature.

The cervical lordosis is the first physiological curve of the human spine, and because of its load-bearing function it is a main site of disc herniation. It maintains the stability of the spine and is an important part of normal spinal biomechanics. A herniated disc is a condition in which the nucleus pulposus displaces from the disc space, and the most common cause of nerve root compression and irritation is cervical disc herniation and spondylosis. Mechanical compression may arise from hypertrophy of the facet joints and uncovertebral joints, vertebral body osteophytes, disc herniation, or a combination of all of the above.

Epidemiology

• The incidence of cervical disc disease rises with age, is common in adults over 40, and peaks between 50 and 60.
• Male patients outnumber female patients, at a ratio of 1.7:1.
• Annual incidence of cervical radiculopathy:
  • 107.3 per 100,000 in men
  • 63.5 per 100,000 in women
• The most common level of disc herniation is C6–C7 (70%), affecting the seventh nerve; C5–C6 is the second most common level (20%), affecting the sixth cervical nerve.
• Studies show that disc degeneration may be common on imaging, but only some patients develop clinical symptoms.

Pathophysiology

The intervertebral discs begin at the C2–C3 level and run downward, contributing to the mobility and stability of the cervical spine. Compared with the thoracic and lumbar spine, the cervical spine has a unique bony projection called the uncinate process, which forms the joint of Luschka with the adjacent vertebral body. This joint helps reinforce the disc and provides additional stability and motion. The disc is a complex structure made up mainly of two parts: the annulus fibrosus (AF) at the periphery and the nucleus pulposus (NP) in the center, which are responsible for its load-distribution function. The anterior and posterior longitudinal ligaments also reinforce the disc. The nucleus pulposus has a gel-like consistency, is mostly water, and this decreases with age (about 90% at birth, and about 70% by age 60).

• Pathophysiology of degenerative spondylosis

• With age, the disc loses water, becomes less compressible, and bulges, causing the disc space to narrow.

• Vertebral degeneration forms osteophytes at the uncovertebral and facet joints, and the ligaments also hypertrophy; these changes narrow the neural foramen and compress the nerve.

• Pathophysiology of disc herniation

• Disc herniation is more common in older patients. It can also occur in adults under 45, but at that age the disc is more elastic and greater force is needed to cause herniation.

• With age, the annular fibers gradually degenerate, and when exposed to mechanical force, the nucleus pulposus can herniate through the degenerated annular fibers, compressing the nerve root and triggering an inflammatory reaction.

• There are different types of disc herniation. If the nucleus pulposus protrudes but is still contained by the annulus fibrosus, it is called a disc bulge. The nucleus pulposus can also penetrate a damaged annulus fibrosus, and the disc contents can protrude through the annular defect, called disc extrusion. A disc fragment can separate from the extruded disc material, forming a disc sequestration.

• Disc herniation can also be asymptomatic. Most symptomatic herniations occur posterolaterally, because in this region the annulus fibrosus is thinner and weaker in structure, and the posterior longitudinal ligament also provides less coverage here.

• Because the nerve root lies posterolaterally, disc herniation can cause pain in two ways. One is that if the dorsal root ganglion (DRG) is compressed, the resulting symptoms usually follow a dermatomal pattern. The second is that if the herniation is directly posterior, spinal cord compression may occur, with symptoms distal to the injured level.

• Cervical lordosis

• The mechanism is still unclear.

• Some studies suggest an association between the neck muscles and disc compression.

• Loss of cervical lordosis affects the neck extensors more severely than the neck flexors in patients with neck pain, although it is not possible to determine the timing of the abnormal curvature and the disc herniation.

• A degenerative cascade may lead to disc dehydration and loss of height if load balance and lordosis are not restored.

Risk Factors

• Age is the main risk factor; with age, cervical degeneration becomes more pronounced.
• Other risk factors include smoking, repetitive manual labor, poor posture, and a family history.
• With the growing use of electronic products (such as smartphones and other handheld devices), prolonged neck flexion places greater pressure on the disc.

History

• Patients may have repeated episodes of posterior neck symptoms of varying severity and duration that gradually accumulate and lead to disc herniation.
• Symptoms may appear after an acute lifting or twisting injury and worsen with coughing, sneezing, or bearing down (the Valsalva maneuver).

Physical Examination

• Perform a physical examination of the spine and upper limbs, including a detailed neurological exam.
• Assess range of motion, strength, sensation, and reflexes.
• Specific tests such as Spurling’s test can provoke pain by extending the patient’s neck and rotating it toward the affected side, a commonly used exam for diagnosing cervical disc disease.

Diagnostic Tools

• X-ray imaging

• NCV/EMG: testing too early after symptoms begin (wait at least 2–3 weeks) may give false-negative results.

• MRI is the best imaging method for detecting disc and nerve compression.

• It can be considered if symptoms remain strong and do not improve after 6 to 8 weeks of conservative treatment.

• MRI should be interpreted with caution; the findings must correspond to clinically significant symptoms.

Initial Treatment

There is an ideal treatment strategy for managing spinal disc disease, but some repair and regenerative therapies are still in the less-studied or trial phase and cannot yet be widely applied in the general population until more evidence is gathered.

• Short-term anti-inflammatory pain medication (NSAIDs): for example, ibuprofen 600 mg four times a day, to suppress the inflammatory pain of disc herniation.

  • Use with caution, especially in patients at risk of gastrointestinal bleeding or kidney disease, and in older adults (over 65).

• Short-term oral corticosteroids: a stronger anti-inflammatory agent, used only when NSAIDs are ineffective or when there is severe pain.

• Rest and avoiding activities that provoke symptoms: relative rest means encouraging patients to stay active within the limits of their pain.

• Cervical collar: can be used to limit neck movement, but should not be used for more than 1–2 weeks to prevent muscle weakness and stiffness.

• Physical therapy or an exercise program: range-of-motion (ROM) exercises for the spine should begin as early as tolerated within the pain range.

• Manual therapy, traction, heat, shortwave, transcutaneous electrical stimulation, stretching, and muscle strengthening

• Posture correction and ergonomic adjustments to daily life

• Adding resistance training as tolerated

• Adding non-impact aerobic exercise; shifting to activities that keep the neck in a neutral position (for example, walking or a stationary bike)

Other Treatments

• Cervical injection treatments, performed after assessment of clinical imaging and condition
• Narcotic pain medication: such as hydrocodone/acetaminophen, for short-term control of severe pain, especially when NSAIDs and corticosteroids are ineffective
• Neuromodulators such as pregabalin or gabapentin, effective for controlling neuropathic pain

Surgery

• Surgical indications include severe or progressive neurological deficit, and no improvement in symptoms after 6 to 12 weeks of non-surgical treatment.

• The most common surgical procedure is anterior cervical discectomy and fusion (ACDF), which removes the disc and relieves the nerve compression.

• Newer total disc arthroplasty (artificial disc replacement)

• A motion-preserving procedure whose results are equivalent to and possibly better than cervical fusion, suitable for single- and two-level cervical radiculopathy or myelopathy

• No fusion, so the rate of subsequent reoperation is lower

• The main contraindication is progressive degenerative joint disease accompanied by neck pain

Follow-up

• If symptoms persist after rehabilitation, repeat imaging can be considered to rule out structural lesions.
• Patients should be followed regularly, especially those with persistent symptoms or a change in neurological symptoms.
• Most patients improve within 6 to 12 weeks with appropriate management, or recover on their own; but if there are clear signs of nerve compression, earlier evaluation is advised.

References

• Cervical Disc Arthroplasty - Spine - Orthobullets
• Disc Herniation - Physiopedia (physio-pedia.com)
• https://radiopaedia.org/articles/intervertebral-disc-disease-nomenclature
• Medicine (Baltimore). 2019 Aug; 98(31): e16545.
• Int J Mol Sci. 2020 Mar; 21(6): 2135.

Further reading

• Spine
• Rehabilitation Exercise Prescription
• Pain Management