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British Medical Books Health Issues Computerized Tomography

Incidence

  • 80% of the population affected at some time in life
  • 40% also has sciatica
  • most frequent claim for disability in USA (1990) involved back disorders
    • approximately 19%
    • enormous financial costs
    • loss of productivity
  • Nachemson (1993) - cost of LBP was 5% of Sweden’s GNP
  • clear correlation between welfare benefits & stay away from work

Causes Mechanical Failure

Gross

  • i.e. plain X ray diagnosis
    • spondylolisthesis
    • scoliosis with facet joint arthritis
    • trauma #’s & dislocations
    • spinal osteoporosis

Subtle

  • instability - like to rest
    • disc pathology - discogram or MRI diagnosis
    • ligament & facet joint capsule sprains & strains
  • facet arthrosis - like to move
    • diagnosed on facet arthrography, CT

Nerve root compression

  • disc prolapse
  • stenosis

Rarer causes

  • inflammation
    • i.e. ankylosing spondylitis
  • infection
  • metabolic
  • neoplastic
    • malignant - primary or secondaries
    • benign

Non-orthopaedic

  • gynae
  • intra-abdominal
  • vascular

Natural history of lumbar disc disease

  • natural history of the disc sy. is towards resolution
    • Holmes & Rothman - 90% resolve spontaneously within 3 months
    • Singer - similar findings
    • Weber (Spine 1983) - results of disc dx treated operatively at 1 year was far better than those treated non-operatively BUT, at 4 & 10 year follow-up, the results were the same
  • neurological results improved just as well in the conservatively treated group as the operative group
  • natural course of herniated discs - decrease in size (serial CT scans) - Thelander & others

Theory of spinal degeneration

  • all spines degenerate
  • present methods of treatment are for symptomatic relief, not for a cure
  • degenerative process divided into three separate stages

1st stage - dysfunction

  • age group - 15-45 years
  • tears in the disc anulus & localized synovitis of the facet joints
  • familial predisposition to lumbar disc herniation in patients who had herniation before age 21 years

2nd stage - instability

  • 35-70-year-old patients
  • internal disruption of the disc progressive disc resorption, degeneration of the facet joints with capsular laxity, subluxation & joint erosion

Final stage - stabilization

  • patients older than 60 years
  • development of hypertrophic bone about the disc and facet joints
  • leads to segmental stiffening or frank ankylosis
  • each spinal segment degenerates at a different rate
  • one level is in dysfunction, another may be entering stabilization stage
  • disc herniation a complication of disc degeneration in dysfunction & instability stages
  • spinal stenosis from degenerative arthritis is a complication of bony overgrowth compromising neural tissue in the late instability & early stabilization stages
  • males were found to have more degeneration than females
  • L4-5 & L3-4 disc levels showed the greatest degree of disc degeneration

Pain transmitting structures

  • at the level of the intervertebral foramen is the dorsal root ganglion
  • distal to the ganglion three distinct branches arise from the dorsal root

Ventral ramus

  • supplies all structures ventral to the neural canal

Sinu-vertebral nerve

  • originates from the ventral ramus
  • innervating posterior aspect of disc, vertebral bodies & posterior longitudinal ligament

Dorsal ramus

  • three branches
  • innervate the structures dorsal to the neural canal
  • posterior musculature and skin
  • facet joint

Results of surgery

  • failure rate of surgery for pain relief d/t disc herniation is high (reported by several authors)
  • significant morbidity also present post-op

Why surgery often fails

  • main cause of surgical failure = poor patient selection
  • inaccurate diagnosis
  • back pain & sciatica can originate from a number of sites
  • X rays, CT scans & MRI’s are only of relevance if the findings are supported by clinical findings
  • to operate on the basis of special investigations only is unacceptable
  • must also remember:
    • diabetes can mimic a herniated disc
    • ischaemia of the cauda equina & nerve roots are a cause of intermittent claudication
    • psychogenic factors

Investigations

  • straight x-ray
  • blood tests
  • myelogram
  • CT scan
  • MRI scan
  • bone scan

Special investigations

  • CT & MRI
    • low specificity: 30% of the N population have positive scans which are of no importance
  • EMG
    • has a very high accuracy: helpful test when surgery is considered
  • fibrinolytic activity test
    • a low fibrinolytic response favours a bad surgical result
    • the plasminogen activator inhibitor 1 test is sufficient to assess this
  • discogram
    • valuable pre-operative examination

Treatment modalities

  • manipulation
    • if it has a role
  • traction
    • no proof that it has a beneficial role
  • chemonucleolysis
    • unpopular because of severe complications:
    • transverse myelitis
    • allergic reactions
    • persisting attacks of muscle spasm
  • facet joint infiltration
    • useful, may exclude a facet joint arthropathy as a cause of pain
  • epidural injections (cortisone)
    • recommended
  • spinal corsets
    • have a place in the treatment of low backache

Indications for surgery in discogenic disease

  • all compatible
    • symptom complex
    • clinical signs
    • investigations
  • advanced neuro deficit
  • progressive neuro deficit
  • sphincter involvement
  • incapacitating pain
  • failed conservative management

Lumbar Spinal Stenosis

  • elderly patients
  • smaller than normal spinal canal + spondylosis
  • local pain in back
  • relief by flexion
  • claudication of the cauda equina
  • random neurological signs in legs
  • good surgical outcome

Ankylosing spondylitis

  • young males
  • non-specific “lumbago” symptoms
  • morning stiffness
  • typical radiological signs
  • later signs
    • poker spine
    • respiratory difficulty
    • cardiac and other systems

Non-specific (mechanical) low back pain

  • site
    • discomfort across lower back
    • central pain, usually over L5
    • leg pain or paraesthesia within “sciatic” distribution
    • unilateral or bilateral buttock or lateral back pain
  • character
    • episodic or cyclical pain in the middle years of life
    • arises from L3-S 1
    • early morning stiffness or pain eases when patient is up and about
  • relation to posture
    • often aggravated by sitting or standing still
    • eased by walking normally
  • pain that is greatly aggravated by walking raises the possibility of vascular claudication or spinal or lateral canal stenosis