Updated: 12/2/2019

Intervertebral Disk Herniation

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  • A 59-year-old woman presents to the emergency room with severe low back pain. She reports pain radiating down her left leg into her left foot. The pain started after lifting multiple heavy boxes at her work as a grocery store clerk. On exam, she is unable to bend over due to pain. A straight leg raise elicits severe radiating pain into her left lower extremity. The patient reports that the pain is worst along the posterior thigh and posterolateral leg into the fourth and fifth toes. 
  • Clinical definition
    • a condition in which the central portion of the intervertebral disc herniates beyond the firm outer ring
      • can lead to spinal inflammation +/- nerve root compression
      • also known as a slipped disc, herniated disc, or herniated nucleus pulposus (HNP)
  • Epidemiology
    • demographics
      • male:female ratio is approximately 2:1
      • peak incidence in 4th and 5th decades
    • location
      • lumbar >> cervical > thoracic
    • risk factors
      • manual labor
      • heavy lifting
      • competitive sports
  • Pathophysiology
    • normal anatomy
      • intervertebral disc
        • functions
          • permit spinal motion
          • link adjacent vertebral bodies
          • provide 25% of spinal column height
        • composition
          • annulus fibrosis
            • thick outer layer of disc
            • composed of type I collagen, water, and proteoglycans
          • nucleus pulposus
            • soft central layer of disc
            • composed of type II collagen, water, and proteoglycans
    • pathoanatomy
      • torsional strain leads to degeneration and tears in the annulus fibrosis
      • nucleus pulposus is able to protrude through the torn annulus fibrosis
      • leads to release of inflammatory markers and may compress a nearby nerve root
        • nucleus pulposus can herniate in different directions (e.g., posterolaterally, laterally, and centrally)
        • direction of herniation (e.g., posterolateral vs. far lateral) and the location of the herniation within the spine (e.g., lumbar vs. cervical) may change the nerve root that is compressed
      • common disc herniations
        • a posterolateral herniation of the 
          • C5-C6 disc results in compression of the C6 nerve root
          • L4-L5 disc results in compression of the L5 nerve root
          • L5-S1 disc results in compression of the S1 nerve root 
  • Associated conditions
    • cauda equina syndrome
      • rare
      • caused by a large disc herniation compressing the nerve roots at the end of the spinal cord
    • radicular pain
      • may occur if descending nerve roots into lower extremity are compressed
  • Prognosis
    • natural history of disease
      • 90% of patients will experience symptom improvement within 3 months with nonoperative management
  • Lumbar disc herniation
    • symptoms
      • low back pain
      • radicular leg pain
        • radiates from the buttock into the leg
        • worsens with sitting, coughing, valsalva, and sneezing
        • improves with standing
    • physical exam
      • motor exam
        • findings will depend on nerve roots compressed
          • L5 radiculopathy
            • weakness in extensor hallucis longus, ankle dorsiflexion, and hip abduction
            • normal patellar and Achilles reflexes
          • S1 radiculopathy 
            • weakness in ankle plantarflexion
            • diminished Achilles reflex
      • provocative tests
        • straight leg raise
          • elicit pain and paresthesias in the leg at 30-70 degrees of hip flexion
          • caused by tension in the L5 or S1 nerve roots
        • bowstring sign
          • straight leg raise that is aggravated by compression of the popliteal fossa
  • Cervical disc herniation
    • symptoms
      • occipital headache
      • neck pain
      • unilateral arm pain, numbness, weakness, and/or tingling 
    • physical exam
      • motor exam
        • findings will depend on nerve roots compressed
          • C5 radiculopathy
            • weakness in deltoid and biceps
            • diminished biceps reflex
          • C6 radiculopathy
            • weakness in brachioradialis and wrist extension
            • diminished brachioradialis reflex
          • C7 radiculopathy 
            • weakness in triceps and wrist flexion
            • diminished triceps reflex 
      • provocative tests
        • Spurling test
          • test by extending head, rotating and laterally bending to the affected side, and vertically compressing the head downward
          • positive if this maneuver reproduces pain in the ipsilateral arm
  • Radiographs
    • indications
      • radiographs not typically indicated
    • findings
      • often normal
      • may demonstrate loss of disc height or loss of lordosis
  • MRI
    • indications
      • not typically indicated unless operative management is being considered
      • best imaging modality to characterize site and extent of lesion 
  •  Paraspinal muscle strain
    • distinguishing factors
      • will not present with radicular pain
      • will typically resolve within 6 weeks
  • Spondylolisthesis
    • distinguishing factors
      • radiographs will demonstrate slippage of one vertebrae relative to the inferior vertebrae
  • Nonoperative
    • rest, physical therapy, and anti-inflammatory medications
      • indications
        • first-line treatment for the majority of patients with intervertebral disc herniations
    • nerve root corticosteroid injections
      • indications
        • alternative treatment if physical therapy and medications fail
  • Operative
    • microdiscectomy
      • indications
        • failure of nonoperative management
        • cauda equina syndrome
  • Cauda equina syndrome
    • incidence
      • occurs in 1-10% of lumbar disc herniations

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Questions (3)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2

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Topic COMMENTS (13)
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