summary Synovial Facet Cysts are degenerative lesions of the lumbar spine that can lead to lumbar spinal stenosis and cause low back pain and radicular symptoms. Diagnosis is made with MRI studies 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 progressive neurological deficits. Epidemiology Incidence rare Anatomic location usually in lumbar spine 60% to 89% occur at the L4-L5 level (most mobile segment) ~14% occurrence at L3-4 ~12% occurrence at L5-S1 Etiology 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 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 suggests a facet cyst hematoma neurogenic claudication (buttock/leg pain with walking) Physical exam neurovascular may see nerve root deficits at associated spinal levels Imaging Radiographs recommended views required AP lateral, lateral, flexion and extension views of spine findings usually normal look for segmental instability MRI indications significant leg pain views best seen on T2 axial and sagittal 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 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, epidural steroid injections indications mild symptoms first-line treatment radicular pain without motor weakness outcomes no natural history studies have been conducted to date CT-guided cyst rupture, facet steroid injection, cyst injection indications second-line management after failing conservative measures radicular symptoms correlate with facet cyst location outcomes 50-75% pain relief at 1-year approximately 39% of patients will require surgical intervention at 7 months Operative laminectomy with decompression and cyst excision indications persistent symptoms despite non-operative management unilateral symptoms can be performed in patients with spondylolisthesis with 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 two years 80-90% success rate in back and leg pain risk of iatrogenic spondylolisthesis facetectomy and instrumented fusion indications some consider 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 (e.g. 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, 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, cyst injection technique fluoroscopic guidance commonly used secondary surgery rate 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 plane between dura and cyst grab cyst with allis clamp or forceps and apply gentle traction separate cyst from 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 process perform decompressive laminectomy and facetectomy excise cyst after developing interval between cyst and dura partial excision in cases of cysts adherent to the dura Complications Cyst recurrence incidence high incidence of recurrence with resection alone treatment new studies favor facetectomy and fusion as first line of 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 dura 50-55% of cases the facet cyst is adherent to the dura limited cyst resection in these cases minimizes dural tear risk partial cyst excision results in 88% success rate for lumbar spinal stenosis while minimizing risk of dural tear