Lumbar Disc Herniation

Ages affected
1. Disc Herniation rarely occurs before age 20 years
2. Age 20-30 years: Up to one third have at least one degenerative lumbar disc
3. Most common ages 30 to 50 years
Most common spinal levels affected (95% of lumbar disc)
1. Vertebral level L4-5
2. Vertebral level L5-S1
Olympic athletes (worldwide, multiple sports)
1. L5-S1 disc displacement in 58%
2. Ong (2003) Br J Sports Med 37(3): 263-6 [PubMed]

Progressive degeneration of disc nucleus pulposus
1. Results from normal aging or repetitive Trauma
Protrusion of disc (most commonly posterior-lateral)
1. Herniation affects spinal root one level below
Other Changes: Spondylosis (Chronic disc deterioration)
1. Spur Formation
2. Disc space narrowing
3. Facet joint degeneration

See Low Back Pain
Always inquire about Low Back Pain Red Flags (e.g. Cauda Equina Syndrome symptoms, fever, IVDA, Cancer)
Usually insidious onset
1. Acute Trauma may have preceded symptoms
Low Back Pain (deep aching)
1. Aggravated by activity, coughing, sneezing or Valsalva Maneuver
2. Provoked by prolonged sitting and forward bending
3. Relieved by rest
4. Localized to affected disc
Intense Radicular Pain
1. See Sciatica
2. Referred pain to iliac crest or buttock
3. Radiation of pain down posterior thigh and calf
4. Pain may radiate into foot
Paresthesias
1. Numbness or tingling in distal extremity

Restricted low back range of motion
Pain exacerbated by bending to affected side
Local tenderness and Muscle guarding
Painful gait
Posturing to avoid pressure on disc
1. Bent away from affected side
2. Hip and knee flexed on affected side
Nerve Root Tension Tests
1. Straight Leg Raise
Neurologic Examination
1. Deep Tendon Reflexes
  1. L4 Nerve Root (L3-4 disc): Patellar Reflex
  2. S1 Nerve Root (L5-S1 disc): Achilles Reflex
2. Motor Exam
  1. L4 Nerve Root (L3-4 disc): Ankle dorsiflexion
  2. L5 Nerve Root (L4-5 disc): Great toe dorsiflexion (extensor hallucis longus)
  3. S1 Nerve Root (L5-S1 disc): Ankle plantar flexion (gastrocnemius-soleus complex)
3. Sensory Exam
  1. L4 Nerve Root (L3-4 disc): Medial malleolus
  2. L5 Nerve Root (L4-5 disc): Dorsal third metatarsophalangeal joint
  3. S1 Nerve Root (L5-S1 disc): Lateral heel
Radicular patterns by disc Herniation type
1. Central DIsk Herniation
  1. Nerve root affected is ABOVE the disc
  2. Example: Central L3 disc Herniation causes findings above the L2-3 Nerve root
2. Paracentral disk Herniation
  1. Nerve root affected is AT the disc
  2. Example: Paracentral L3 disc Herniation causes findings at the L2-3 Nerve root
3. Lateral disk Herniation
  1. Nerve root affected is BELOW the disc (foraminal effects)
  2. Example: Lateral L3 disc Herniation causes findings at the L3-4 Nerve root

Findings with strongest Positive Predictive Value for Lumbar Disc Disease
1. Symptoms: Sciatica pain associated with:
  1. Pain in leg worse than back
  2. Typical Dermatomal Distribution of pain
  3. Pain provoked by Valsalva Maneuver
2. Exam findings
  1. Crossed Straight Leg Raise positive
  2. Weak ankle dorsiflexion
  3. Absent ankle reflex
  4. Calf Muscle wasting (late finding)
Findings with strongest Negative Predictive Value for Lumbar Disc Disease
1. No Sciatica
2. Negative Straight Leg Raise

See Sciatica
See Low Back Pain Red Flags
See Musculoskeletal Low Back Pain
Lumbar spine Degenerative Joint Disease
1. Lumbar Radiculopathy due to spine degeneration (osteophytes or bone spurs) typically follows a fixed or progressive course
2. Contrast with Lumbar Disc Herniation which tends to improve as the disc Herniation resorbs
Spinal Cord Tumor
1. Consider especially in age under 20 or over 60 years
2. Relentless pain aggravated or not relieved with rest

See Low Back Imaging
Lumbar Spine MRI has a 50% False Positive Rate (asymptomatic findings)
1. Correlate pain and symptoms with MRI findings