Traumatic Disc Herniation¶

Definition¶

Traumatic disc herniation is the acute displacement of intervertebral disc material (nucleus pulposus and/or annulus fibrosus) into the spinal canal or neural foramina as a result of spinal trauma. Unlike degenerative disc herniations, which develop gradually, traumatic herniations occur acutely and may cause spinal cord compression or radiculopathy in the setting of fractures and ligamentous injuries.

Mechanism¶

Traumatic disc herniation results from:

Hyperflexion, hyperextension, or rotational forces that disrupt the annulus fibrosus
Axial loading combined with flexion or extension
Distraction injuries that tear the disc and allow extrusion

Traumatic herniations frequently accompany facet dislocations (present in up to 50% of cervical facet dislocations), burst fractures, and flexion-distraction injuries.

Clinical Significance¶

The primary clinical significance of traumatic disc herniation is its potential to cause or worsen spinal cord compression, particularly during reduction of cervical facet dislocations. A large herniated disc fragment anterior to the cord may be compressed against the cord during closed reduction, potentially worsening neurological injury.

This is the rationale for obtaining MRI before attempting closed reduction of cervical facet dislocations at many institutions — if a large disc herniation is identified, anterior discectomy is performed first, followed by reduction.

Imaging Findings¶

MRI¶

MRI is the primary modality for detecting traumatic disc herniation:

T2-weighted sagittal — Disc material extending beyond the posterior vertebral body margin into the spinal canal, compressing or displacing the thecal sac and spinal cord
T2-weighted axial — Laterality of the herniation (central, paracentral, foraminal), degree of canal compromise, and cord compression
High T2 signal within the disc (disrupted annulus) and adjacent edema
Associated findings: ligamentous injury, cord edema, epidural hematoma

CT¶

Disc material may be visible as intermediate-density material in the spinal canal, though it is less conspicuous than on MRI
CT myelography can demonstrate the herniation as a filling defect in the contrast column
Associated fractures are well demonstrated

Clinical Pearl

In the cervical spine, traumatic disc herniation accompanying a facet dislocation is a critical finding because it can influence the surgical approach. If a large herniation is present, many surgeons perform an anterior discectomy before or during facet reduction to prevent the disc from being pushed posteriorly against the cord during reduction. Always evaluate the disc space at the level of a facet dislocation on MRI.

Management¶

Traumatic disc herniations causing cord compression typically require surgical discectomy and decompression
In the cervical spine, anterior cervical discectomy and fusion (ACDF) is the standard approach
Small herniations without cord compression may not require specific intervention beyond management of the associated fracture or ligamentous injury
In the lumbar spine, cauda equina compression from traumatic herniation may require urgent decompression

Key Points¶

Traumatic disc herniation occurs acutely from spinal trauma and frequently accompanies facet dislocations and fractures
Present in up to 50% of cervical facet dislocations
MRI is essential for detection and evaluation of cord compression
Pre-reduction MRI is recommended for cervical facet dislocations to identify disc herniations that could worsen cord injury during reduction
Surgical discectomy is indicated when there is significant cord or cauda equina compression

References¶

Doran SE, Papadopoulos SM, Ducker TB, Lillehei KO. Magnetic resonance imaging documentation of coexistent traumatic locked facets of the cervical spine and disc herniation. J Neurosurg. 1993;79(3):341-345. https://pubmed.ncbi.nlm.nih.gov/8360729/
Botolin S, VanderHeiden TF, Moore EE, Fried H, Stahel PF. The role of pre-reduction MRI in the management of complex cervical spine fracture-dislocations: an ongoing controversy? Patient Saf Surg. 2017;11:23. https://pmc.ncbi.nlm.nih.gov/articles/PMC5591568/
Onishi FJ, Daniel JW, Joaquim AF, et al. The impact of traumatic herniated discs in cervical facets dislocations treatments: systematic review and meta-analysis. Eur Spine J. 2022;31(10):2664-2674. https://pubmed.ncbi.nlm.nih.gov/35763222/
Song J, Oh JYL. Traumatic intradural disc herniation following a cervical facet dislocation: a case report. J Spine Surg. 2022;8(1):76-83. https://pmc.ncbi.nlm.nih.gov/articles/PMC8990393/
Mubark I, Abouelela A, Hassan M, Genena A, Ashwood N. Sub-axial cervical facet dislocation: a review of current concepts. Cureus. 2021;13(1):e12581. https://pmc.ncbi.nlm.nih.gov/articles/PMC7870112/
Liu K, Zhang Z. Reduction of lower cervical facet dislocation: a review of all techniques. Neurospine. 2023;20(1):181-204. https://pmc.ncbi.nlm.nih.gov/articles/PMC10080426/
Discoligamentous injury. Radiopaedia.org. https://radiopaedia.org/articles/discoligamentous-injury-1