Neurosurgery notes/Spine/Spinal Degenerative Diseases/Lumbar degenerative disease/Lumbar canal stenosis

Lumbar canal stenosis

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Lumbar degenerative disease

General

  • Any condition involving narrowing of the spinal canal or neural foramen.

Numbers

  • Prevalence 1% of the population
  • patients undergoing surgery for this condition increasing eightfold over the last 30 years
    • predominantly in the over 65 age group.

Pathology

  • Spinal degeneration causes
    • Buckling of ligaments
      • Accentuated in lumbar extension.
    • Disc degeneration
    • Spondylolisthesis
  • All the above causes lumbar canal stenosis → Longstanding compression of the cauda equina →
    • Reduced CSF delivery
    • Microvascular changes
      • Venous congestion impairs metabolism and nerve root arterioles lose the ability to vasodilate in response to increased metabolic demand during exercise.
    • Inflammation

Classification

  • Congenital (idiopathic or achondroplastic)
    • Rare
    • Between 30 and 40 years of age.
  • Acquired (degenerative, spondylolytic, traumatic, or metabolic).
    • Common
    • Presents predominantly in the over 60- year- old age group.

Clinical feature

  • Neurogenic claudication: which develops on standing and walking
    • Features
      • Symptoms develops on standing and walking
      • Radicular leg pain
      • Heaviness
      • Numbness
      • Paresthesia
    • Due to mechanical compression and vascular insufficiency.
  • Differentiate from peripheral vascular disease
    • Clinical features include back pain with associated radiation into the buttocks on walking and standing associated with heaviness and numbness.
    • Relief of symptoms occurs with flexion of the lumbar spine and rest.
    • Check for pulse/cap refill.
      • Signs and symptoms
      Vascular
      Neurogenic
      walking distance
      fixed
      variable
      type of pain
      cramps, tightness
      dull ache, numbness
      relief at cessation of activity
      immediate
      delayed
      back pain
      rarely
      occasionally
      pain relief
      standing
      flexion and sitting
      posture provocation
      uncommon
      common
      walking up hill
      pain
      no pain
      bicycle riding
      pain
      no pain
      pulses
      absent
      normal
      trophic changes
      likely
      absent
      muscle atrophy
      rarely
      occasionally

CES

  • Rare but patients may present with a chronic picture or coexisting acute disc herniation.

Examination findings

  • may be subtle
  • precipitated by exercise.
  • Assessment of sagittal balance may reveal flexion of the knees and hyperextension of the hip to compensate for increased lumbar flexion.

Radiology

  • Poor correlation between
    • Degree of radiological compression
    • Severity of clinical symptoms

Management

  • Conservative
    • Indication
      • Presence of significant comorbidities, lack of radiological and clinical concordance, and mild or intermittent symptoms.
    • In most patients, symptoms of LCS progress but a small percentage of patients improve with non- operative treatment.
    • Options include
      • Nonsteroidal anti-inflammatory
      • Muscle relaxants
      • Physiotherapy
      • Postural education
      • Epidural steroid infiltration
    • Evidence
      • A direct comparison of patients undergoing surgical and conservative management of LCS is misleading due to lack of class 1 evidence and heterogeneity of the two groups.
  • Surgery
    • Indication
      • experiencing moderate to severe symptoms
      • Progressive neurological deficit and sphincteric disturbance are absolute indications for surgery
    • Options:
      • Laminectomy
        • Less used as it can be detabilizing. Instead perform unilateral under cutting of midline.
        • Central compression is treated surgically through laminectomy at the stenotic segment.
        • Favoured in severe stenosis, deformity, and when a wide lateral decompression is required.
        • The greatest degree of compression is sublaminal where the flavum is thickest.
      • Selective decompression
        • In cases of moderate compression resection of the flavum may be performed through a unilateral approach (preserving the midline ligaments and contralateral muscles), laminotomy and an ‘over- the- top’ technique to decompress the contralateral canal.
        • Moderate lateral recess and extraforaminal stenosis can be addressed using selective decompressive techniques such as laminotomy, medial facetectomy, and extraforaminal muscle splitting approaches.
      • Laminoplasty
        • Laminoplasty techniques have been described similar to those initially described in the cervical spine however, it is not commonplace in the treatment of LCS with increased operative time and no evidence to suggest benefit over other approaches.
      • Interspinous process distraction devices,
        • insertion of a spacer through the interspinous ligament, maintaining the supraspinous ligament → decreases intradiscal pressure, distracts the facets and neural foramen, unbuckles the flavum, and reduces abnormal segmental motion.
        • They can be inserted at multiple levels, L4/ 5 being most common with a small S1 spinous process precluding placement at L5/ S1.
        • Contraindications include
          • Spondylolisthesis
          • Tumours
          • Trauma
          • Unstable or high-grade degenerative spondylolisthesis
          • Osteoporosis
        • Current evidence and NICE guidance (2010) suggest ISD devices are efficacious for carefully selected patients in the short and medium term, although failure may occur and further surgery may be needed.
        • There are no major safety concerns.
        • Therefore, these procedures may be used provided that normal arrangements are in place for clinical governance, consent and audit.
      • Decompression alone
        • Combined decompression and fusion is recommended when there is evidence of segmental instability.
          • This is somewhat theoretical and may be difficult to prove radiologically.
          • Limited evidence suggests decompression and non- instrumented fusion in the context of degenerative spondylolisthesis results in significantly improved back and leg pain when comparing decompression alone.
        • Decompression vs fusion
      • Decompression + fusion (non- instrumented vs. instrumented).
        • Indication
          • It is generally accepted that fusion should be considered in cases of deformity, moderate to severe low back pain, recurrent and junctional stenosis, or when greater than 50% bilateral facetectomy is required for decompression.
        • Instrumented fusion Vs non- instrumented fusion
          • Fischgrund et al 1997 (n=67, 2 yr f/u) symptomatic spinal stenosis associated with degenerative lumbar spondylolisthesis
              • instrumentation
              non instrumentation
              p
              Excellent or good clinical outcome
              76%
              85%
              0.45
              Successful fusion
              82%
              45%
              0.0015
            • Overall, successful fusion did not influence patient outcome (P = 0.435).
      • Interbody fusion
        • There is no evidence to suggest that interbody fusion (ALIF, PLIF, TLIF, and XLIF) improves overall outcome.
        • Said et al 2022 Meta-analysis provide a comparison between PLF and PLIF based on RCTs.
          • PLIF had higher fusion rates,
          • both fusion methods achieve similar clinical outcomes with equal complication rate, revision rate, operation time and blood loss at 1-year minimum follow-up.