Common but Confusing
Herniated disc is a common spinal pathology, but its occurrence as a direct result of motor vehicle accidents (MVAs) is infrequent. Most herniated discs arise from chronic degenerative changes and repetitive loading rather than acute trauma.
A key misunderstanding is the difference between "bulging" and "herniated."
The Difference: Bulge vs. Herniation
Definitions Matter
A herniated disc is defined as a focal displacement of disc material (nucleus pulposus or annulus fibrosus) beyond the normal confines of the disc space. Only protrusion, extrusion, and sequestration are considered true herniations.
A disc bulge is a more diffuse, symmetric extension of the annulus (like a tire going flat). Bulging does not meet the definition of herniation and is frequently seen in asymptomatic individuals as a normal part of aging [9][10].
Extrusion: The herniated material extends beyond the disc space, narrower at the neck.
Sequestration: A fragment of disc material breaks off completely and is free-floating in the canal.
🚗 Rare in Collisions
Biomechanical and epidemiological studies show that spinal disc injuries are extremely rare in MVAs—estimated at 0.01 occupants per 10,000 exposed—typically occurring only with significant concomitant trauma or unusual loading conditions (e.g., high flexion and compression) [1].
Retrospective reviews confirm that while cervical and lumbar spine injuries are common after MVAs, disc derangements are much less frequent than sprain/strain injuries [2]. National data also suggest that disc herniation is a rare outcome compared to other spinal injuries [3].
Treatment: Do Injections Fix It?
Epidural steroid injections (ESIs) are effective primarily for radicular pain due to nerve root irritation, and their benefit is most pronounced in patients with true radiculopathy.
However, guidelines from the American Academy of Neurology confirm that ESIs provide only modest, short-term pain relief, with little to no benefit for axial back pain or radicular pain without objective neurological findings [1][2][3][4][5].
Modest & Short-Term
Meta-analyses show a small reduction in pain scores at three months, but the number needed to treat (NNT) for relief is high (7) [1].
No Long-Term Fix
The SPORT trial found no difference in outcomes at four years between patients who received ESIs and those who did not [8].
Chemical vs. Mechanical
Radiculopathy is often driven by chemical irritation (inflammation) from the disc material, not just compression. This is why steroids can help calm the nerve even if the disc doesn't move [2][11][12].
🚨 Radiculopathy vs. Radicular Pain
Radiculopathy refers to objective neurologic deficits, such as muscle weakness, loss of reflexes, or sensory loss in a specific dermatome.
Radicular pain (sciatica) is simply the sensation of pain traveling down the nerve path.
Clinical Insight: ESIs are indicated for inflammation-driven radicular pain with objective signs of radiculopathy. They rarely help "pain only" cases without neurological deficits.
Finding the Source: Sensory Mapping
This is why I use sensory mapping in my clinic. By carefully mapping skin sensation, we can often detect nerve root irritation that an MRI might miss, or confirm that a "bulge" seen on MRI is actually the source of your symptoms.
Sensory changes in radiculopathy can be subtle. Studies using pinprick and light touch demonstrate that sensory dysfunction is common in patients with radicular pain and can be reliably identified with bedside examination, even when imaging does not show a clear herniation [6][7][8].
Mapping the Dermatome
A true radiculopathy will follow a specific "stripe" of skin (dermatome) supplied by that nerve. If the sensory change doesn't follow this map, the pain is likely not from the disc.
Conservative Management vs. Surgery
Physical Therapy & Time
Other treatment strategies, such as physical therapy and supervised exercise, may be more effective for selected patients. Conservative management is favored initially, as most patients improve over time without intervention [9][10].
When Surgery Fits
Surgery (microdiscectomy) is reserved for those with severe or progressive neurologic deficits or persistent symptoms unresponsive to non-surgical care. It offers faster relief of sciatica but similar long-term outcomes compared to conservative treatment [10].
Summary: Herniated disc is rarely caused by MVAs, and ESIs offer only limited, short-term benefit compared to other treatments. Conservative management remains the mainstay, with surgery considered for refractory cases.
References
- Epidural Steroids for Cervical and Lumbar Radicular Pain... AAN Guidelines. Armon C, et al. Neurology. 2025.
- Low Back Pain. Knezevic NN, et al. Lancet. 2021.
- Epidural Corticosteroid Injections for Lumbosacral Radicular Pain. Oliveira CB, et al. Cochrane Database. 2020.
- Epidural Corticosteroid Injections... Systematic Review. Chou R, et al. Annals of Internal Medicine. 2015.
- Epidural Corticosteroid Injections. AAFP (2021).
- Pinprick and Light Touch Are Adequate... Hasvik E, et al. Clinical Orthopaedics. 2021.
- Lumbar Disc Herniation... Sensory Test. Erbüyün SC, et al. Pain Medicine. 2018.
- Thermal Quantitative Sensory Testing... Samuelsson L, et al. European Spine Journal. 2002.
- Herniated Lumbar Intervertebral Disk. Deyo RA, Mirza SK. NEJM. 2016.
- Lumbar Disc Herniation: Diagnosis and Management. Zhang AS, et al. American Journal of Medicine. 2023.
- Value of 3D MR Lumbosacral Radiculography... Byun WM, et al. AJNR. 2012.
- Pathomechanisms of Nerve Root Injury... Takahashi N, et al. Spine. 2003.