Degenerative Disease

Epidemiology

  • Men > Women
  • 40-50 years onset
  • Risk factors:
    • Smoking
    • Manual labour
    • Driving

Pathoanatomy

  • Ageing:
    • Keratin Sulphate to Chondroitin Sulphate ratio of disc increases
    • Water content decreases
  • Leads to a cascade of:
    • Loss of disc height – causes kyphosis
    • Disc herniation
    • Facet arthrosis
    • Subluxation (listhesis)
    • Ligament calcification (ALL/PLL) and hypertrophy (flavum)
    • Compensatory osteophyte formation:
      • Uncovertebral joints
      • Foramina
      • Anterior and posterior aspect of end plates

Clinical Presentation

History

  • Gradual onset
  • Occipital headache
  • Activity/position related pain – extension & rotation
    • Flexion opens up canal & relieves symptoms
  • Radiculopathy:
    • Unilateral dermatomal pain or weakness
    • Trapezius, upper back pain
  • Myelopathy:
    • Clumsiness of hands – buttons, writing, eating
    • Gait disturbance – ataxic, broad-based
    • Burning/shooting pain up & down neck (Lhermitte’s sign)
  • Late & uncommon symptoms of myelopathy:
    • Bladder/bowel dysfunction
    • Subjective weakness
    • Significant motor weakness – if in legs is late & worrying sign
  • Constant achy pain rare
  • Radicular pain

Examination

  • Spurling’s Sign:
    • For radiculopathy
    • Maximal extension & rotation towards side of symptoms replicates symptoms
      • Narrows exit foramina and impinges root further
  • Signs of Myelopathy:
    • Hoffman Reflex: Flicking tip of middle finger = thumb IPJ flexion
      • May be present in people with normally brisk reflexes
    • Babinski Sign: Big toe elevation when sole stroked
      • False positive in infants
    • Inverted Radial Reflex: BR reflex causes finger flexion
    • Gait: Ataxia & broad-based stance
    • Upper motor neuron signs: Hyper-reflexia, clonus, spasticity
      • May have mixed picture with predominantly UMN in legs & LMN in arms

Imaging

X-Ray

  • 70% of 70-year-olds have asymptomatic XR changes
  • AP:
    • Uncovertebral osteophytes, alignment
  • Lateral:
    • Canal diameter - <14mm is relative stenosis; <10mm absolute
    • Torg Ratio (vertebral body/canal ratio) <0.8 = stenosis
    • Alignment – is spine kyphotic (limits treatment options)
  • Oblique:
    • Foraminal stenosis
  • Flexion/Extension views:
    • If instability suspected – usually stiff rather than unstable

MRI

  • Signal change in cord
  • Neural compression
  • CT Myelogram – for those who can’t have MRI – delineates OPLL better

Management

Axial Neck Pain

  • Non-operative where at all possible:
    • Physio
    • Aerobic exercise
    • Weight loss
    • Isometric C-spine strengthening – decreases the neutral zone
    • Moist heat
  • Results of surgery unpredictable

Radiculopathy

  • Natural history of radiculopathy is good with non-operative treatment
  • Indications for surgery:
    • Progressive weakness
    • Intractable pain
    • Failure of non-operative treatment

Myelopathy

  • No real place for non-surgical treatment
  • Natural history shows stepwise deterioration with time
  • Best results are while myelopathy is mild and present for short time:
    • Aim is to halt progression, not restore neurology
    • Gait changes frequently do not resolve

Surgical Options

  • Current evidence shows 3% yearly rate of adjacent level disease whatever the index surgery
  • Decision-making should be based on which will give best symptomatic relief with lowest complications

Motion Sparing

  • Disc replacement
  • Foraminotomy
  • Laminoplasty

Motion Sacrificing

  • ACDF (Anterior Cervical Discectomy & Fusion)
  • Corpectomy & Fusion
  • Laminoplasty & Fusion

Anterior Cervical Discectomy & Fusion (ACDF) / Anterior Corpectomy & Fusion

  • Gold standard – first choice answer almost always
  • Allows direct decompression of all pathologic lesions:
    • Disc
    • Uncovertebral osteophytes
    • Vertebra (corpectomy)
    • OPLL
  • Indirect decompression of foramina by using allograft to restore lordosis
  • Results: 90% symptom relief

Principles

  • Anterior approach
  • Remove disc and osteophytes
  • Use allograft to restore lordosis (equal to autograft) & less morbidity
  • Fusion improved with plating
  • Use strut graft/cages if corpectomy done
  • If >2 level surgery, consider supplementary posterior instrumentation
    • Modern systems may be ok up to 3 levels

Complications

  • Recurrent & superior laryngeal nerves
  • Oesophageal damage
  • Pseudoarthrosis – often asymptomatic: leave alone
  • Haematoma
  • Neurologic complications <1% - rare

Posterior Foraminotomy

  • Low morbidity
  • For isolated radiculopathy affecting one root due to foraminal stenosis
  • Foraminal osteophytes removed to open up space for root
  • Not for myelopathy
  • Not to be done if patient is kyphotic – does not change alignment

Disc Replacement

  • Same as ACDF approach and indications
  • Preserves motion by placing prosthesis
  • Unproven yet to alter course of adjacent level disease
    • Comparable results to ACDF for symptom relief

Laminectomy with or without Fusion

  • If a laminectomy is done, perform a fusion
    • Avoids post-laminectomy kyphosis
    • Swan neck deformity (without fusion)
  • Easier surgery
  • Less favourable results as compared to other procedures
  • Not to be done if patient is kyphotic – does not change alignment

Laminoplasty

  • Lower morbidity and easier surgery – C3 to C7 usually performed
  • Can be secured with laminoplasty plates
  • Increases room for cord – relieves symptoms
  • Maintains stability
  • Not indicated if axial pain present as no fusion is performed

Complications

  • Recurrent myelopathy
  • Stiffness – autofusion occurs
  • C5 root damage
  • Not to be done if patient is kyphotic – does not change alignment

Combined Anterior & Posterior Approaches

  • If multilevel surgery is performed
  • Consider if >2 and certainly >3 levels
    • Especially if multilevel corpectomy
  • Supplements anterior instrumentation while graft consolidates
  • HALO does not adequately immobilise sub-axial spine

OPLL (Ossification of the Posterior Longitudinal Ligament)

  • Potential cause of myelopathy
  • More common in Oriental Asians
  • Unknown aetiology but:
    • Genetic, occupational, dietary (high salt intake), diabetes, obesity implicated
  • Narrows space for cord
  • Predisposes to myelopathy after extension injuries
  • XR shows ossification posterior to the vertebral body only
  • Mainly affects C Spine

Surgery for OPLL

  • Anterior or posterior
  • Posterior may be safer than trying to excise OPLL tethered to cord

Diffuse Idiopathic Skeletal Hyperostosis (DISH)

  • Ossification of the Anterior Longitudinal Ligament
  • Forrestier’s disease is isolated ALL ossification
  • DISH includes ALL ossification as well as other skeletal hyperostoses
  • Typically affects lower thoracic spine but may be in cervical or lumbar
  • Ossification is actually along anterolateral aspect of bodies on axial CT
    • Looks similar to ankylosing spondylitis

Differentiated by:

  • Sparing of Facet joints
  • Sparing of SI joints

Diagnostic Criteria for DISH

  • Bridging syndesmophytes across 4 contiguous vertebrae (3 disc spaces)
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