Synovial Facet Cyst - Spine

Introduction

A degenerative lesion of the lumbar spine that often presents with radicular symptoms
Epidemiology
- incidence
  - rare
- location
  - usually in lumbar spine
    - 60% to 89% occur at the L4-L5 level (most mobile segment)
Pathophysiology
- possible etiologies
  - trauma (controversial)
  - microinstability of the facet leading to
    - extruded synovium through joint capsules
    - myxoid degeneration of collagen tissue
    - proliferation of fibroblasts with increased hyaluronic acid production
Associated conditions
- degenerative spondylolisthesis

Presentation

Symptoms
- mechanical back pain
- radicular symptoms (leg pain)
- neurogenic claudication (buttock/leg pain with walking)
Physical exam
- may see nerve root deficits at associated spinal levels

Imaging

Radiographs
- recommended views
  - required
    - AP lateral, lateral, flexion and extension of spine
  - findings
    - usually normal
    - look for segmental instability
MRI
- indications
  - significant leg pain
- views
  - best seen on T2 axial and sagittal images

Treatment

Complications

Cyst recurrence
- high incidence of recurrence with resection alone
- new studies favor facetectomy and fusion as first line of operative treatment