summary Synovial facet cysts are degenerative lesions of the lumbar spine that can lead to lumbar spinal stenosis, resulting in low back pain and radicular symptoms Diagnosis is made with MRI of the lumbar spine Treatment is a trial of nonoperative management with NSAIDs and physical therapy. Surgical management is indicated for progressive disabling pain that has failed nonoperative management and/or the presence of progressive neurological deficits Epidemiology Incidence rare Anatomic location usually in the lumbar spine 60-89% occur at L4-5 (most mobile segment) ~14% occur at L3-4 ~12% occur at L5-S1 Etiology Pathophysiology possible etiologies trauma (controversial) microinstability of the facet joint, leading to: extruded synovium through the joint capsule myxoid degeneration of collagen tissue proliferation of fibroblasts with increased hyaluronic acid production cyst composition ganglion cysts flavum cysts serous contents mucoid contents hemorrhagic contents Associated conditions degenerative spondylolisthesis Presentation Symptoms mechanical back pain radicular symptoms (leg pain) rapid onset or sudden deterioration suggest a facet cyst hematoma neurogenic claudication (buttock/leg pain with walking) Physical exam neurovascular may have nerve root deficits at associated spinal levels Imaging Radiographs recommended views AP, lateral, flexion, and extension findings usually normal look for segmental instability MRI indications significant leg pain views best seen on axial and sagittal T2-weighted images traditionally hyperintense centers with hypointense rims on T2 and hypointense inner cores on T1 sequences peripheral rim enhancement with gadolinium contrast improved detection rate with positional MRI 89% sensitivity when supine 97% sensitivity when standing cysts may increase in size while standing high-signal intensity on T2-weighted images synovial content higher success rate with CT-guided cyst rupture low-signal intensity on T2-weighted images gelatinous or calcified contents lower success rate with CT-guided cyst rupture Treatment Nonoperative NSAIDs, rest, immobilization, physical therapy, and epidural steroid injections indications first-line treatment mild symptoms radicular pain without motor weakness outcomes no natural history studies have been conducted to date CT-guided cyst rupture, facet steroid injection, and cyst injection indications second-line management after failure of conservative measures radicular symptoms correlate with facet cyst location outcomes 50-75% pain relief at 1-year ~39% of patients will require surgical intervention at 7 months Operative laminectomy with decompression and cyst excision indications persistent symptoms despite nonoperative management unilateral symptoms can be performed in patients with spondylolisthesis who have unilateral symptoms as long as they are aware of the higher risk of slip progression outcomes high incidence of recurrent back pain and cyst formation within 2 years 80-90% success rate in improving back and leg pain risk of iatrogenic spondylolisthesis facetectomy and instrumented fusion indications some consider this to be the first-line of surgical treatment due to high recurrence rates symptomatic recurrence following laminectomy with decompression bilateral symptoms central canal stenosis wider decompression will likely lead to iatrogenic instability presence of instability (i.e. degenerative spondylolisthesis) outcomes demonstrated to have the lowest risk of persistent back pain and recurrence of cyst formation in recent studies complete resolution of symptoms in 80-90% of patients Techniques NSAIDs, rest, immobilization, physical therapy, and epidural steroid injections technique recommended for 6-8 weeks prior to proceeding with surgical treatment or CT-guided rupture CT-guided cyst rupture, facet steroid injection, and cyst injection technique fluoroscopic guidance commonly used secondary surgery rate is roughly 50% CT guidance improved visualization of spinal anatomy slightly improved patient outcomes compared to fluoroscopic guidance laminectomy with decompression and cyst excision approach posterior approach to the spine technique unilateral laminotomy and medial facetectomy with a high-speed burr create a plane between the dura and cyst grab cyst with Allis clamp or forceps and apply gentle traction separate cyst from the underlying dura with Epstein curet or Woodson elevator facetectomy and instrumented fusion approach posterior approach to the spine technique place pedicle screws at the intersection of the superior border of the transverse process and midline of the superior articular process perform decompressive laminectomy and facetectomy excise cyst after developing an interval between cyst and dura partial excision in cases of cysts adherent to the dura Complications Cyst recurrence incidence high recurrence rate with resection alone treatment new studies favor facetectomy and fusion as first-line operative treatment Iatrogenic spondylolisthesis risk factors decompressive laminectomy without fusion treatment posterior instrumented fusion +/- spondylolisthesis reduction Dural tear incidence risk factors revision surgery cyst adherent to the dura 50-55% of cases limited cyst resection in these cases minimizes the risk of dural tear partial cyst excision results in an 88% success rate in treating lumbar spinal stenosis while minimizing the risk of dural tear