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Annular Tear

Summary

  • Annular tear refers to a disruption of the annulus fibrosus of an intervertebral disc
  • Typically occurs due to degenerative changes or acute trauma
  • Imaging findings include high-intensity zones on MRI and contrast enhancement of the outer annulus

Pathophysiology

  • Annulus fibrosus consists of concentric layers of collagen fibers
  • Tears can be:
    • Concentric: Separation between annular layers
    • Radial: Extend from nucleus pulposus to outer annulus
    • Transverse: Separate the annulus from the endplate
  • Annular tears can lead to disc herniation and discogenic pain

Demographics

  • Most common in adults aged 30-50 years
  • Higher prevalence in:
    • Males
    • Individuals with physically demanding occupations
    • Those with a history of trauma or repetitive stress

Diagnosis

  • Clinical presentation:
    • Low back pain, often with radicular symptoms
    • Pain may worsen with certain movements or positions
  • Physical examination:
    • Limited range of motion
    • Positive straight leg raise test (for lower lumbar tears)
  • Diagnostic tests:
    • MRI is the gold standard for diagnosis
    • Discography may be used in select cases

Imaging

  • MRI findings:
    • High-intensity zone (HIZ) on T2-weighted images
    • Focal hyperintensity in the posterior annulus on T2-weighted images
    • Contrast enhancement of the outer annulus on post-gadolinium T1-weighted images
  • CT discography:
    • Contrast leakage into the annular tear
    • Useful for correlating pain with specific disc levels

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  • A 45-year-old patient presented with an acute radiculopathy in the left L4 distribution.
  • While there was only minimal intervertebral foraminal narrowing, the L4-5 disc that contained a T2-hyperintense annular tear made contact with the left L4 nerve root.

Treatment

  • Conservative management:
    • Physical therapy and exercise
    • Nonsteroidal anti-inflammatory drugs (NSAIDs)
    • Activity modification
  • Interventional procedures:
    • Epidural steroid injections
    • Intradiscal electrothermal therapy (IDET)
    • Radiofrequency ablation
  • Surgical options (for persistent symptoms):
    • Microdiscectomy
    • Disc replacement
    • Spinal fusion (in select cases)

Differential diagnosis

Differential Diagnosis Differentiating Feature
Disc Herniation Focal protrusion of disc material on MRI; may have associated nerve root compression
Facet Joint Arthropathy Pain typically worse with extension; facet joint hypertrophy on imaging
Spinal Stenosis Symptoms worsen with extension and improve with flexion; narrowing of spinal canal on imaging
Spondylolisthesis Forward slippage of vertebra visible on X-ray or CT; may have associated instability
Myofascial Pain Syndrome Presence of trigger points; no specific imaging findings
Sacroiliac Joint Dysfunction Pain localized to SI joint area; may show inflammation on MRI
Vertebral Compression Fracture Visible fracture on imaging; often associated with osteoporosis or trauma
Spinal Tumor Mass lesion visible on MRI; may have associated systemic symptoms
Ankylosing Spondylitis Fusion of sacroiliac joints on imaging; often affects younger males
Infection (Discitis/Osteomyelitis) Fever, elevated inflammatory markers; visible infection on MRI with contrast