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)