Cervical Disc Herniation¶
Definition¶
Cervical disc herniation is the displacement of disc material beyond the normal margin of the intervertebral disc space in the cervical spine. It most commonly occurs at C5–C6 and C6–C7 and can cause radiculopathy (nerve root compression) or myelopathy (spinal cord compression).
Epidemiology¶
- Peak incidence: 40–60 years of age
- Most common levels: C5–C6 (most common) and C6–C7 (second most common)
- Cervical nerve roots exit above their numbered vertebra: the C6 root exits at C5–C6
Nerve Root Compression Patterns¶
| Level | Root Compressed | Motor Deficit | Reflex Affected | Sensory Distribution |
|---|---|---|---|---|
| C4–C5 | C5 | Deltoid, biceps weakness | Biceps | Lateral arm |
| C5–C6 | C6 | Biceps, wrist extensors | Brachioradialis | Lateral forearm, thumb, index finger |
| C6–C7 | C7 | Triceps, wrist flexors, finger extensors | Triceps | Middle finger |
| C7–T1 | C8 | Hand intrinsics, finger flexors | — | Medial forearm, ring/small finger |
Imaging Findings¶
MRI¶
- Sagittal T2: disc extension indenting the thecal sac or cord; assess cord signal (myelopathy = T2 hyperintensity in the cord)
- Axial T2: characterize location and relationship to cord and nerve roots; evaluate uncovertebral and facet hypertrophy
- Sagittal T1: evaluate foraminal narrowing
- Axial GRE (gradient echo): can overestimate the degree of stenosis due to susceptibility artifact from osteophytes — use with caution
Cord Compression Signs¶
- T2 hyperintensity within the cord at the level of compression → suggests myelopathy
- T1 hypointensity within the cord → suggests more chronic/severe injury (gliosis or myelomalacia)
- Cord deformation or flattening on axial images
Clinical Pearl
In the cervical spine, disc herniations often coexist with uncovertebral joint hypertrophy (bony spurs from the joints of Luschka) and facet hypertrophy, creating a combined "hard" (osteophyte) and "soft" (disc) stenosis. Pure soft disc herniations are more common in younger patients; combined disc-osteophyte complexes are typical in older patients. The distinction matters because soft discs may respond to conservative management, while hard stenosis from osteophytes typically does not.
Key Points¶
- Most common at C5–C6 and C6–C7
- Cervical nerve roots exit above their numbered vertebra — C6 root exits at C5–C6
- MRI is essential — always assess for cord signal change indicating myelopathy
- Combined disc-osteophyte complexes are common in older patients
- Myelopathy (cord T2 signal change) may indicate need for surgical decompression
References¶
- Fardon DF, Williams AL, Dohring EJ, Murtagh FR, Gabriel Rothman SL, Sze GK. Lumbar disc nomenclature: version 2.0: Recommendations of the combined task forces of the North American Spine Society, the American Society of Spine Radiology and the American Society of Neuroradiology. Spine J. 2014;14(11):2525-2545. doi:10.1016/j.spinee.2014.04.022. PMID: 24768732. https://pubmed.ncbi.nlm.nih.gov/24768732/
- Iyer S, Kim HJ. Cervical radiculopathy. Curr Rev Musculoskelet Med. 2016;9(3):272-280. https://pmc.ncbi.nlm.nih.gov/articles/PMC4958381/
- Wang S, Zhao T, Han D, et al. Classification of cervical disc herniation myelopathy or radiculopathy: a magnetic resonance imaging-based analysis. Quant Imaging Med Surg. 2023;13(8):4984-4994. https://pmc.ncbi.nlm.nih.gov/articles/PMC10423346/
- Yi JS, Cha JG, Han JK, Kim HJ. Imaging of Herniated Discs of the Cervical Spine: Inter-Modality Differences between 64-Slice Multidetector CT and 1.5-T MRI. Korean J Radiol. 2015;16(4):881-888. doi:10.3348/kjr.2015.16.4.881. https://pmc.ncbi.nlm.nih.gov/articles/PMC4499554/
- Kushchayev SV, Glushko T, Jarraya M, et al. ABCs of the degenerative spine. Insights Imaging. 2018;9(2):253-274. doi:10.1007/s13244-017-0584-z. PMID: 29569215. https://pubmed.ncbi.nlm.nih.gov/29569215/
- Disc extrusion. Radiopaedia.org. https://radiopaedia.org/articles/disc-extrusion