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Musculoskeletal System ORGAN SYSTEMS

Sciatica

Introduction

Pain and/or paresthesias in the distribution of the sciatic nerve or an associated lumbosacral nerve root.

  • Sciatica is a symptom of an underlying condition and not a disease itself
sciatica_herniated_disc_woman_illustration_123rf_110481216_ml
Sciatica is characterized by low back pain that radiates downward into one leg. | 123RF.com.

Aetiology

Spinal causes:

  • Herniated lumbar disc with nerve root compression (M/C cause overall, 90% cases)
    • Poor posture, trauma, strong rotational movement
  • Lumbar spinal stenosis (elderly)
    • Narrowing of spinal canal (intravertebral foramen)
    • Due to:
      • Degenerative bone disorders
      • Trauma
      • Autoinflammatory conditions (rheumatoid arthritis, etc)
  • Spondylolisthesis
    • Relative misalignment of one vertebra relative to another
  • Lumbar/pelvic muscular spasm and/or inflammation (may impinge a lumbar or sacral nerve)
  • Spinal/paraspinal mass (cause mass effect and sciatica symptoms):
    • Malignancy
    • Epidural hematoma
    • Epidural abscess
728_herniated_disk
Left: Illustration of herniated spinal disc, superior view. Right: MRI showing herniated L5-S1 disc (red arrow tip), sagittal view. | OpenStax College – Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun 19, 2013., CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=30131498

Non-spinal causes:

  • Piriformis syndrome (M/C non-spinal cause)
    • Muscle inflammation/spasms causing sciatic nerve compression
  • Wallet sciatica (Credit-carditis)
    • Wallets in pockets → Pressure on gluteus muscles → Pressure on sciatic nerve
  • Pregnancy (vertex presses on sciatic nerve)
  • Trauma to leg
  • Pelvic tumours

Risk factors:

  • Personal factors:
    • Age (peak 45-64 years)
    • Increasing risk with height
    • Smoking
    • Mental stress
  • Occupational factors:
    • Strenuous physical activity (frequent lifting, especially while bending and twisting)
    • Driving (including vibration of whole body)

Pathoanatomy


Clinical features

  • Aching and sharp leg pain following dermatomal pattern
    • Unilateral leg pain greater than low back pain

    • Pain radiating to foot/toes

    • Numbness and paraesthesia in the same distribution

    • Straight leg raising test induces more leg pain

    • Localised neurology (limited to one nerve root)

  • Low backache (less severe than leg pain)
straight-leg-test
Straight Leg test sometimes used to help diagnose a lumbar herniated disc | Davidjr74 – http://www.herniateddiscrecovery.info/diagnosing-a-herniated-disc/lumbar-disc-herniation/, CC0, https://commons.wikimedia.org/w/index.php?curid=15289227

Diagnosis

Imaging

MRI:

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T2-weighted (A) and proton density (B) sagittal MR images of the patient’s lower lumbar spine showing a contained intervertebral disc herniation at L5-S1. Mild-to-moderate disc dessication is also evident at both the L4–5 and L5-S1 levels. (C) T2-weighted coronal spot view of L5-S1 revealing a right paracentral disc protrusion, resulting in both displacement of the right S1 nerve root and intervertebral foraminal encroachment at L5-S1 on the right (arrows). |

Differential diagnosis

  • Herniated lumbosacral disc
  • Muscle spasm
  • Nerve root impingement
  • Epidural abscess
  • Epidural hematoma
  • Tumour
  • Potts Disease (spinal tuberculosis)
  • Piriformis syndrome

Management

Pain resolves on its own over time.

Lifestyle changes:

  • Hot/cold formentation
  • Avoidance of inciting activities or prolonged sitting/standing
  • Practicing good, erect posture
  • Use of proper lifting techniques
  • Regular light exercises such as walking, swimming, or aquatherapy

Physiotherapy:

  • Core strength exercises
  • Gentle stretching of the lumbar spine and hamstrings

Medical management:

  • Oral NSAIDs
  • Opioid and nonopioid analgesics (if NSAIDs do not work)
  • Muscle relaxants

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