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