Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

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Sciatica

Basics
Description
  • Sciatica is pain referred down the leg in a distribution of the sciatic nerve, which courses from the lumbosacral plexus L2, S3.
  • 5 different areas of pain may be noted:
    • Back: Midline lumbosacral, radicular radiation pattern
    • Buttocks: Deep-seated, crampy pain
    • Posterior or lateral thigh (L5, S1)
    • On occasion, both posterior and lateral thigh
    • Anterior thigh (high lumbar root L2, L3, L4)
Epidemiology
Incidence
2% of the general population, with lifetime incidence near 40%
Etiology
Most sciatica is from the intervertebral disc (most commonly, L4, L5) and mechanical compression of the lumbosacral nerve roots.
Diagnosis
Signs and Symptoms
  • Back:
    • Most patients have previous back pain, and 50% of those have a history of trauma.
    • Pain lateralizes to the hip or leg, gradually or suddenly.
    • A precipitating event may occur, such as bending over or straining.
  • Leg:
    • Pain can be more debilitating than back pain.
    • L5, S1 root compression: Cramp or a viselike feeling in the gastrocnemius or peroneal muscle belly
    • L4: Medial shin or lateral thigh
    • L5: Lateral calf
    • S1: Back of calf
    • L1: Groin
    • L2: Medial thigh
    • L3: Anterior thigh
    • Most adults have pain below the knee.
  • Foot:
    • The most common symptom is paresthesia.
    • L5: Foot dorsum
    • S1: Lateral foot
    • Actual foot pain is unusual.
  • Rarely, motor symptoms predominate; if they do, consider spinal tumor or peripheral neuropathy.
  • Aggravating or relieving factors:
    • Bending, stooping, lifting, coughing, sneezing, straining, and sitting worsen pain.
    • Standing, walking, and resting are more tolerable.
    • Lying with the knee or hip flexed and sleeping with a pillow under the knees give some relief.
Physical Exam
  • Spine:
    • Variable examination: Most physical findings are in the legs, not the back.
    • Lumbar spine flattened and flexed
    • Limited spine extension, forward flexion, and lateral flexion toward affected side
    • Sciatic scoliosis: Patient leans away from side of pain
  • Extremities:
    • Test all muscle groups and make a chart to document baseline:
      • Flexion/extension/adduction/abduction for the hip
      • Flexion/extension of the knee
      • Dorsiflexion/plantarflexion/eversion/inversion/ flexion of the ankle
      • Flexion/extension of the 1st toe
    • Test sensation with pinprick in all dermatomes and compare with those in the contralateral limb.
    • Test reflexes
    • Trendelenburg sign: A lurch or pelvic tilt is noted with ambulation, as is weakness of the hip adductors (gluteus medius and minimus).
    • Root tension sign: A limited straight-leg raise (with a small amount of hip internal rotation and adduction, slowly raise leg) reproduces leg pain at <60° of flexion.
    • Contralateral straight-leg raise: When the unaffected leg is lifted, the opposite symptomatic side has a painful axilla or midline disc.
    • Lasegue sign: Pain is increased on forced dorsiflexion of the ankle with straight-leg raising and is relieved with hip or knee flexion.
    • Bowstring sign:
      • Perform straight-leg raise to the point of sciatica.
      • Allow the knee to flex.
      • Apply pressure to the hamstring insertion at the knee, which stretches the nerve to reproduce leg pain.
    • Femoral nerve stretch test: Unilateral thigh pain is produced by knee flexion, tension on the 2nd to the 4th roots.
  • The diagnosis also is suggested by motor weakness or by sensory or reflex changes.
  • Muscle wasting:
    • Rare unless the lesion is present for >3 weeks
    • Marked wasting suggests a tumor.
Tests
Lab
In patients >50 years old, one should exclude the diagnosis of multiple myeloma with a complete blood count, ESR, and serum protein electrophoresis.
Imaging
  • Conventional radiography:
    • AP view of the lumbosacral spine
    • AP view of the pelvis
  • Screening radiography:
    • Compression fractures (lateral view)
    • Spondylolisthesis (lateral view)
    • Pedicle destruction in metastatic bone disease (AP view)
    • Scoliosis (AP view)
    • Tumors of the pelvis (AP view of the pelvis)
  • MRI is procedure of choice for detecting and defining anatomy of:
    • Herniated discs
    • Compression from vertebral body fractures
    • Marrow involvement from neoplastic processes, spinal cord tumors
  • CT is effective and used primarily for patients:
    • Who cannot undergo MRI
    • With previous surgery who have metal implants
Pathological Findings
Nuclear pulposus extruded through a weakened annular fibrosis
Differential Diagnosis
  • Diabetic neuropathy
  • Disc space infection or epidural abscess
  • Spondylogenic: Disc rupture, spinal stenosis, muscle sprain
  • Psychogenic: Vague and stocking-glove type pain
  • Neurogenic: Spinal cord tumor or cysts
Treatment
General Measures
  • A systematic approach is necessary to identify the correct diagnosis and minimize disability.
  • Noninvasive treatment:
    • Highly successful
    • Patient education:
      • Limit bending, heavy lifting
      • Teach and encourage back strengthening and cardiovascular fitness.
    • Limited bed rest (1-3 days), then gradual increase in activity
  • Invasive treatment:
    • Epidural steroids may provide relief of variable duration.
Special Therapy
Physical Therapy
Physical therapy can be useful for back exercises, healthy-back educational programs, and aerobic conditioning.
Medication
First Line
  • Muscle relaxants
  • NSAIDs
  • Avoid narcotics.
Surgery
  • If nonoperative treatment fails after 6 weeks
  • If neurologic deficit, cauda equina
  • Microdiscectomy
  • Current standard is laminotomy and discectomy.
  • Minimally invasive microdiscectomy is performed with greater frequency through various tubular and expandable retractor systems.
    • The procedure may result in less tissue damage than current procedures.
    • Prospective studies comparing this technique to conventional microdiscectomy are underway.
Follow-up
Prognosis
Good; most patients recover spontaneously with some reports of a >70% rate of recovery with nonoperative treatment.
Complications
  • Cauda equina syndrome: Large central disc herniation causing bowel/bladder symptoms and findings
  • Persistent pain
  • Progressive spondylosis (disc degeneration)
Patient Monitoring
The patient should be seen at 2-4-week intervals to document strength and recovery.
Miscellaneous
Codes
ICD9-CM
722.10 Displacement of herniated disc
Patient Teaching
Patients are instructed on care of the back, to minimize disability.
FAQ
Q: What are the symptoms of sciatica?
A: Sciatica is a symptom itself. The patient may experience burning, pain, or a tingling sensation in the back and legs as a result of pressure on the sciatic nerve.
Q: What are the main causes of sciatica?
A: The most common cause of sciatica is a herniated intervertebral disc.
Q: What are the treatment options for patients with sciatica?
A: Physical therapy, exercise, and anti- inflammatory medications should be tried 1st, followed by spinal injections and surgery.

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