Definition and Overview
Cervical disc herniation is a condition in which the nucleus pulposus of a cervical intervertebral disc protrudes through the annulus fibrosus, which has been weakened by degenerative changes or external forces, mechanically compressing adjacent nerve roots or the spinal cord and causing chemical inflammation.
The C5-6 (between cervical vertebrae 5 and 6) and C6-7 levels account for approximately 70-75% of all cervical disc herniations, due to the large range of motion of these segments. It occurs most often in people in their 30s to 50s, and is about 1.5 times more common in men.
pathophysiology
intervertebral disc degeneration
Cervical intervertebral discs begin to degenerate in the late 20s. When the water content of the nucleus pulposus decreases and proteoglycans degenerate, the shock absorption ability of the intervertebral disc decreases. When annular tears accumulate in the annulus fibrosus, a path for the nucleus pulposus to protrude is formed.
Types of Disc Herniation
- Bulging: The entire annulus fibrosus is bulged, but the nucleus pulposus is within the annulus fibrosus.
- Protrusion: The nucleus pulposus pushes out part of the annulus fibrosus, but does not go beyond the posterior longitudinal ligament.
- Extrusion: The nucleus pulposus completely breaks through the annulus fibrosus.
- Sequestration: A fragment of the herniated nucleus pulposus is separated from the parent disc.
Nerve Damage Mechanism
Ischemic damage caused by mechanical pressure and chemical radiculitis caused by inflammatory mediators such as phospholipase A2 and TNF-α secreted from the nucleus pulposus act simultaneously. For this reason, the degree of disc protrusion on the image and the severity of symptoms are not necessarily proportional.
symptoms
Neck pain
In most patients, pain occurs in the center of the neck or on one side, and may radiate between the shoulder blades. It is worsened by neck movements (especially extension and rotation of the affected side).
Radicular pain in upper extremities
When a disc compresses a nerve root, sharp pain radiates along the dermatome to the shoulder, arm, and hand.
- C5-6 herniation (C6 nerve root): Numbness in thumb and index finger, weakness in wrist dorsiflexion
- C6-7 herniation (C7 nerve root): numbness in middle fingers, triceps weakness.
- C7-T1 herniation (C8 nerve root): Numbness in the ring and little fingers, weakness in grip strength
Myelopathy
If the central herniation is large, it can put pressure on the spinal cord and cause myelopathy. It is characterized by fine motor impairment in both hands, gait instability, leg stiffness, and abnormal bladder function, and surgical decompression is necessary due to the risk of irreversible damage.
diagnosis
imaging test
- Cervical spine MRI: This is the standard test for evaluating soft tissue (discs, nerve roots, spinal cord). Herniated disc and nerve root compression can be directly confirmed on T2-weighted images.
- Cervical spine X-ray: Confirm indirect findings such as decreased disc height, osteophytes, and misalignment
- CT myelography: used as an alternative when MRI is not possible (pacemaker, etc.)
Frequency of asymptomatic disc abnormalities
In a study by Boden et al., cervical disc abnormalities were found on MRI in approximately 19% (under 40 years of age) to 57% (over 60 years of age) of asymptomatic adults. Therefore, surgery should not be decided solely on imaging findings, and must be checked to see if it matches clinical symptoms.
electrophysiological test
Nerve conduction testing and electromyography are useful for objectively confirming radiculopathy, determining the level of involvement, and differentiating it from peripheral nerve entrapment (carpal tunnel syndrome, etc.).
treatment
conservative treatment
It is the first-line treatment for cervical disc herniation. In 80-90% of patients, symptoms improve with conservative treatment alone.
- Medications: NSAIDs (for initial pain control), muscle relaxants (for cervical spasms), gabapentin or pregabalin (for neuropathic pain)
- Physical therapy: Cervical traction, manual therapy, neck strength strengthening exercises after the acute phase
- Cervical braces: short-term use for 1-2 weeks in the acute phase; long-term use may cause muscle atrophy
- Epidural steroid injection: Consider when there is no improvement even after 4 to 6 weeks of conservative treatment.
surgical treatment
Surgery is considered in the following cases:
- When there is no significant improvement even after 6 to 12 weeks of conservative treatment
- Progressive muscle weakness (strength grade 3 or lower)
- Findings of myelopathy (gait disturbance, hand fine motor impairment, bladder dysfunction)
- When daily functions are significantly limited due to severe pain
Representative surgical methods are as follows.
- Anterior cervical discectomy and fusion (ACDF): the most common surgical method. Using an anterior approach, the herniated disc is removed and the adjacent vertebral bodies are fused.
- Artificial disc replacement: It has the advantage of preserving motion segments and reducing the risk of adjacent segment degeneration.
- Posterior foraminotomy: Nerve root decompression is possible without fusion, but the scope of application is limited.
Progress and prognosis
Most have a good prognosis. In the conservative treatment group, more than 90% of patients achieve functional recovery within 4 to 6 months. Even when surgery is performed, long-term satisfaction is high, and the success rate of ACDF is reported to be approximately 90-95%.
Adjacent segment disease occurs with an annual frequency of approximately 2.9% after ACDF, and the 10-year cumulative incidence is approximately 25%. Long-term data are accumulating on whether artificial disc replacement surgery reduces this risk.
life guide
- Make it a habit to maintain a posture that maintains natural lordosis of the cervical spine.
- Place the computer monitor at eye level, and the keyboard and mouse at elbow height.
- Avoid being in a fixed position for long periods of time, and gently stretch your neck every 30 to 60 minutes.
- Perform deep neck flexor strengthening exercises every day.
- When sleeping, use a pillow that is neither too high nor too low to keep your cervical spine in a neutral position.
- Quit smoking: Smoking impedes the supply of nutrients to the intervertebral disc and promotes degeneration.