Description:
- Seen in all age groups, most common ages 35-45
- Risk factors include: smoking, sedentary work and full-time motor vehicle driving
- Sciatica is found in 40% of patients
- 50% recover in 1 month, 96% function normally in 6 months
Pathophysiology:
- Disc herniation is preceded by degenerative changes inside disc
- Circumferential tears in annulus progress to radial tears and lead to herniation
- Annulus fibers intact in a contained disc protrusion
- Annulus fibers disrupted in noncontained herniation or extrusions, posterior longitudinal ligament intact
- Free disc fragments in canal are sequestered herniations, posterior longitudinal ligament disrupted
Signs/Symptoms:
- Low back pain
- Sciatica = pain radiating down leg in a dermatomal distribution
- Coughing, sneezing or Valsalva maneuver exacerbates radiating pain
- Prolonged sitting aggravates
- Straight leg-raising test is positive in 98% on affected side, 20% on contralateral leg (known as Lasegue and cross-Lasegue signs)
- > 90% disc herniations are L4-L5 or L5-S1, L4-5 most common
Description:
- Seen in all age groups, most common ages 35-45
- Risk factors include: smoking, sedentary work and full-time motor vehicle driving
- Sciatica is found in 40% of patients
- 50% recover in 1 month, 96% function normally in 6 months
Pathophysiology:
- Disc herniation is preceded by degenerative changes inside disc
- Circumferential tears in annulus progress to radial tears and lead to herniation
- Annulus fibers intact in a contained disc protrusion
- Annulus fibers disrupted in noncontained herniation or extrusions, posterior longitudinal ligament intact
- Free disc fragments in canal are sequestered herniations, posterior longitudinal ligament disrupted
Signs/Symptoms:
- Low back pain
- Sciatica = pain radiating down leg in a dermatomal distribution
- Coughing, sneezing or Valsalva maneuver exacerbates radiating pain
- Prolonged sitting aggravates
- Straight leg-raising test is positive in 98% on affected side, 20% on contralateral leg (known as Lasegue and cross-Lasegue signs)
- > 90% disc herniations are L4-L5 or L5-S1, L4-5 most common
| Level | Nerve Root | Sensory Loss | Motor Loss | Reflex Loss |
| L1-L3 | L2, L3 | Anterior Thigh | Hip Flexors | None |
| L3-L4 | L4 | Medial Calf | Quadriceps, Tibialis Anterior | Knee Jerk |
| L4-L5 | L5 | Lateral calf, dorsal foot | Extensor digitorum longus, Extensor hallicus longus | None |
| L5-S1 | S1 | Posterior calf, plantar foot | Gastrocnemius/soleus | Ankle Jerk |
| S2-S4 | S2,3,4 | Perianal | Bowel/Bladder | Cremasteric |
Anatomic Considerations:
- Central herniation: involves central portion of posterior annulus
- Paracentral herniation: adjacent to central portion of posterior annulus
- Far Lateral herniation: within or just lateral to the neural foramen
- Central or paracentral herniations tend to compress the traversing nerve root at a given disc level: a central or paracentral hernation at L4-L5 will compress the traversing nerve root L5, not the exiting nerve root at that level, L4
- A far lateral herniation is more apt to involve the foramen, thereby compressing the exiting nerve root at that spinal level. A far lateral L4-L5 herniation would compress exiting L4 nerve root, likely sparing the traversing L5 nerve root.
Imaging:
- MRI is the study of choice for diagnosis of a herniated disc
- Correlation of clinical symptoms and findings is crucial as 28% of asymptomatic people have evidence of a herniated disc on MRI
MRI of L4-5 disc herniation. A) T1 B) T2 C) T1 post-gadolinium
Treatment:
- Goal is to return patient to normal activities as quickly as possible
- Recent prospective studies have shown patients treated with surgical discectomy had better results at 1-year follow-up versus patients treated conservatively. Four and ten year follow-up yielded nearly equal function in both groups
- Conservative treatment:
- Minimal bedrest
- Physical therapy program
- Non-steroidal anti-inflammatory medications
- Possible role of epidural corticosteroids for acute sciatica
- Chiropractic adjustments should be avoided
- Surgical treatment:
- Approximately 10% of patients with disc herniation will require surgery
- Surgery recommended if
- sciatica pain severe and disabling,
- exam and diagnostic tests indicate nerve root compression,
- symptoms persist without improvement longer than one month
- Standard or microdiscectomy possible
- Equal success rate of 85-95%
- Risks of surgery include: dural tear, wrong level exploration, hemorrhage, infection, nerve deficit
- Contained disc protrusions may be treated with precutaneous automated discectomy or chemonucleolysis with success rate of up to 75%
- Chemonucleolysis is popular technique in Europe, but deaths due to anaphylaxis and other complications dissuade US patients and surgeons
Cauda Equina Syndrome
Descripton:
- Injury to the cauda equina between the conus and the lumbosacral nerve roots within the spinal canal, often due to massive disc herniation
- Complete cauda equina injury results in loss of nerves to bowel, bladder, perinanal and lower extremities
- Often presents as incomplete injury
- A surgical emergency
Signs/Symptoms:
- Bilateral buttock and lower extremity pain
- Bowel and bladder dysfunction (often urinary retention)
- Saddle anesthesia (distribution of sensory loss in perianal area, buttocks and posterior lower extremities)
- Varying degrees of lower extremity motor deficits
Examination:
- Digital Rectal Examination for determination of perianal sensation and sphincter tone essential
Treatment:
- Emergent surgical decompression
Anatomic Considerations:
- Central herniation: involves central portion of posterior annulus
- Paracentral herniation: adjacent to central portion of posterior annulus
- Far Lateral herniation: within or just lateral to the neural foramen
- Central or paracentral herniations tend to compress the traversing nerve root at a given disc level: a central or paracentral hernation at L4-L5 will compress the traversing nerve root L5, not the exiting nerve root at that level, L4
- A far lateral herniation is more apt to involve the foramen, thereby compressing the exiting nerve root at that spinal level. A far lateral L4-L5 herniation would compress exiting L4 nerve root, likely sparing the traversing L5 nerve root.
Imaging:
- MRI is the study of choice for diagnosis of a herniated disc
- Correlation of clinical symptoms and findings is crucial as 28% of asymptomatic people have evidence of a herniated disc on MRI
MRI of L4-5 disc herniation. A) T1 B) T2 C) T1 post-gadolinium
Treatment:
- Goal is to return patient to normal activities as quickly as possible
- Recent prospective studies have shown patients treated with surgical discectomy had better results at 1-year follow-up versus patients treated conservatively. Four and ten year follow-up yielded nearly equal function in both groups
- Conservative treatment:
- Minimal bedrest
- Physical therapy program
- Non-steroidal anti-inflammatory medications
- Possible role of epidural corticosteroids for acute sciatica
- Chiropractic adjustments should be avoided
Surgical treatment:
- Approximately 10% of patients with disc herniation will require surgery
- Surgery recommended if
- sciatica pain severe and disabling,
- exam and diagnostic tests indicate nerve root compression,
- symptoms persist without improvement longer than one month
- Standard or microdiscectomy possible
- Equal success rate of 85-95%
- Risks of surgery include: dural tear, wrong level exploration, hemorrhage, infection, nerve deficit
- Contained disc protrusions may be treated with precutaneous automated discectomy or chemonucleolysis with success rate of up to 75%
- Chemonucleolysis is popular technique in Europe, but deaths due to anaphylaxis and other complications dissuade US patients and surgeons
Cauda Equina Syndrome
Descripton:
- Injury to the cauda equina between the conus and the lumbosacral nerve roots within the spinal canal, often due to massive disc herniation
- Complete cauda equina injury results in loss of nerves to bowel, bladder, perinanal and lower extremities
- Often presents as incomplete injury
- A surgical emergency
Signs/Symptoms:
- Bilateral buttock and lower extremity pain
- Bowel and bladder dysfunction (often urinary retention)
- Saddle anesthesia (distribution of sensory loss in perianal area, buttocks and posterior lower extremities)
- Varying degrees of lower extremity motor deficits
Examination:
- Digital Rectal Examination for determination of perianal sensation and sphincter tone essential
- Treatment:
- Emergent surgical decompression