Lumbar Disc Disease

• 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

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 stageshelander & others

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

sinu-vertebral nerve

• three branches
• innervate the structures dorsal to the neural canal
  • posterior musculature and skin</li
  • 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

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

Acute herniated lumbar disc

• in lumbar disc disease need to consider:
  • no surgery for psychosocial problems
  • exclude other causes of LBP or sciatica
  • accurate clinical diagnosis
  • unequivocal definition of the lesion on imaging

Clinical

• 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

L4 nerve root compression - L3-L4 disc prolapse

• least common
• pain in lateral thigh, anterior knee, medial leg
• +ve femoral N stretch test
• weak quadriceps, hip adductors
• sensation << over inner side of the leg, anterior knee
• absent knee jerk

L5 nerve root - L4-L5 disc prolapse

• common
• pain at posterolateral thigh, lateral calf & dorsal foot
• weakness of dorsiflexion of foot (can’t heel walk)
  • EHL
  • EDL & B
  • Gluteus medius
• sensory deficit - anterolateral leg, dorsum of foot, great toe
• no reflex deficit

S1 nerve root compression - L5-S1 disc prolapse

• most common
• leg pain > back pain
  • sciatica - mid-gluteal, posterior thigh, calf –> heel
  • >> pain with activity, coughing, sitting, Valsalva
• paraspinal muscle spasm
• loss of lordosis
• +ve SLR
  • pathognomic if well leg SLR produces pain on involved side
• motor loss
  • peroneus longus & brevis
  • triceps surae –> << plantarflexion (can’t tip-toe)
  • gluteus max.
• sensation
  • lateral ankle & foot
• absent ankle jerk

Differential diagnosis of non-mechanical back pain
Extrinsic lesions

• referred
  • abdomen, retroperitoneal
  • aneurism, tumour etc.
• hip dx.
  • OA
  • infection (TB)
• endocrine, metabolic
  • DM
  • Paget’s

Intrinsic lesion - 1° dx. of the spine

• infection - bone, disc, epidural space
• neoplasm
• inflammatory - ankylosing spondylitis
• trauma

Treatment Protocol

• bed rest for 2 to 5 days + NSAID’s (minor analgesics if intolerance to NSAID’s)
• patient education on the disease & postural guidance
• as soon as the pain has improved - physiotherapy
  • extension exercises
  • rationale - re-location of the disc
• if no response to above treatment –> epidural injection of LA + steroids (under image)
  • NB: before epidural must be sure of the diagnosis
  • exclude infection on MRI
  • CI: cauda equina sy., progressive neurology, bleeding disorder
  • after epidural injection - bed rest for 10 to 14 days
  • maximal benefit may only be seen after 2 weeks
• if this fails - LA + steroid infiltration around the nerve root: CT guided
• by 4 to 5 weeks after the onset, should be in a position to make a decision about surgery
• if the patient can tolerate the pain, a 3 month wait before surgery is not detrimental
• ± 5% of patients with an acute back, with or without neurological symptoms should come to surgery
• all patients suffering from LBP require a spine education program (back school)
• treatment should always be conservative to start with

Indications for surgery in acute disc prolapse:

• absolute indications
  • massive prolapse with bladder & bowel paralysis (cauda equina sy.)
  • increasing neurological deficit w/ a significant decrease in SLR test
• relative indications
  • failure after adequate conservative treatment (at least 6 weeks but < 3 months)
    • after 3 months risk of chronic pathology to the nerve root
• incapacitating pain, recurrent episodes of sciatica despite adequate conservative Rx.
  • confirming imaging study (myelogram, CT or MRI) - only indicated if surgery planned
  • must have a radiculopathy, with pain below the knee (> back pain) & the SLR test should reproduce the sciatica
  • sensory disturbances & minor motor signs - should not influence surgical decision

Surgical Options

• open surgery
  • standard laminectomy or laminotomy & discectomy
  • microsurgical discectomy
• closed surgical techniques
  • percutaneous discectomy
  • arthroscopic discectomy
• chemonucleolysis

Principles of surgery in disc prolapse:

• free the nerve root from enchroachment
• nerve root must remain undamaged
• leave as little scar as possible
• do not create instability
  • post-operatively limited walking is permitted, sitting is avoided for 6 weeks
• if surgery indicated - should be done before 4 months
  • << amount of adhesion of disc to nerve root
• failed back rate of about 15% in USA
  • main cause is poor patient selection
• percutaneous discectomy/nucleolysis is not successful - Revrel’s study (1993)
• formal open surgery is better than above - Nachemson 1988
• no benefit from fusion with simple discectomy - Tullbergs study (1993)

Complications of discectomy

• 0-10%

Intra operative

• dural tears, CSF fistula
• neurological complications, nerve root injury
• bleeding
• injury to abdominal vessels, organs

Post-operative

• DVT, PE
• infection
• scarring, arachnoiditis
• ileus
• spinal instability, chr. backache

Recurrence of disc herniation

• usually only presents after a 1 year pain free interval after surgery
• if the pain relief was 6 months or less, other causes such as scar tissue or arachnoiditis or internal nerve injury could be the cause

Symptoms

• multifocal & non mechanical, present at rest
• entire extremity is painful, numb, weak
• extremity gives way
• treatment response
  • no improvement
  • “allergic” to treatment
  • not on treatment
• multiple admissions, multiple doctors, multiple investigations

Signs

• skin or non anatomic distribution
• simulated rotation tests positive
• distraction tests positive
• whole leg is weak or numb