A 68-year-old female patient was referred for a lumbar spine MRI examination with intense pain at lumbar region and coexistence of right sciatica, resistant to treatment.
MRI disclosed a clearly demarcated extradural spherical lesion, one cm in diameter close to the right intervertebral foramen at the L4-L5 level. The lesion exhibited low signal intensity on T1-Weighted images (WI) (Figure 1a) with peripheral post gadolinium contrast uptake (Figure 2), while on T2-WI it showed a rim of low signal intensity (Figure 1b, Figure 3). The continuity of the lesion with the facet articulation arose the possibility of a synovial cyst, compressing neighbouring right L5 root. There was considerable clinical improvement after cyst removal and decompression of the spinal root.
Facets synovial cysts (FSCs) are considered an extrusion of the synovium through a capsular defect from a degenerated or unstable facet joint. These cysts occur most often at the L4-L5 level which is known to be the most mobile part of the lumbar spine. These space-occupying lesions may produce compression to a nerve root and subsequent sciatica resistant to conservative treatment. FSCs may be left untreated if asymptomatic. Otherwise surgical excision is the treatment of choice. Alternatively intraarticular injection of steroids under imaging guidance may be curative. Currently, MR imaging is the examination of choice for the diagnosis of FSCs and previously used imaging methods such as myelography, CT and CT myelography, facet arthrography and CT facet arthrography are almost abandoned. Variable signal intensities for the lumbar FSCs’ contents on MRI have been reported in the literature. FSCs are usually hypointense on T1-WI; however they may present iso- or slightly hyper-intensity related to high protein content or small amounts of paramagnetic breakdown products of haemorrhage within the cyst. Cyst content on T2-weighted images is most frequently mildly hyperintense in comparison with the CSF; in most cases. FSCs may have similar appearance with ganglia on MRI, although in the latter communication with the intraarticular space is lacking. Also synovial lining is evident in FSCs on histology, that is lacking in ganglia cases. However, preoperative distinction between these two entities is not mandatory, when surgical decompression is required. Spontaneous resolution of FSCs may occur and cyst rupture has been served as an explanation. Specific location and MR imaging characteristics may facilitate correct diagnosis of FSCs that should be differentiated from solid extradural spinal neoplasms.
Lumbar Facet Synovial Cyst
Based on the lumbar spine MRI sequences provided by the patient, at the L4-L5 vertebral level on the right side near the interlaminar space or the intervertebral foramen, a round or oval cystic lesion can be observed. On T1-weighted images, this lesion typically appears hypointense or slightly isointense, while on T2-weighted images, it demonstrates relatively high signal intensity with a well-defined cystic appearance. The lesion is adjacent to and may be associated with the corresponding facet joint, and in some cases, there is evidence of significant degeneration in the facet joint. The cystic lesion exerts a certain degree of compression on the surrounding nerve roots, which may correlate with the patient’s right-sided sciatica. Other intervertebral discs show varying degrees of degenerative changes, but no obvious large disc herniations are noted.
Considering the patient’s age (68 years), clinical presentation (persistent low back pain and right-sided sciatica), and imaging findings showing a cystic lesion around the L4-L5 facet joint with evidence of nerve root compression, the most likely diagnosis is: Right L4-L5 Facet Synovial Cyst.
1. Conservative Treatment
- Trial of non-steroidal anti-inflammatory drugs (NSAIDs) and analgesics for pain control, in conjunction with physical therapy modalities, monitoring symptom changes over a short period.
- If the cyst is small and symptoms are tolerable, regular follow-up observation may be sufficient.
2. Interventional Treatment
- Under imaging guidance, steroid injection into the facet joint or cyst, combined with local anesthesia, can potentially reduce intracystic pressure and inflammatory reaction, thereby alleviating symptoms.
- Suitable for patients who have inadequate responses to conservative therapy but are not yet considering surgery or have higher surgical risks.
3. Surgical Treatment
- If conservative and interventional treatments fail, or if the cyst exerts significant pressure on the nerve root and severely impacts quality of life, surgical removal of the cyst and decompression is recommended.
- Facet stabilization may be performed during surgery to reduce the risk of recurrence.
4. Rehabilitation / Exercise Prescription (FITT-VP Principle)
F (Frequency): 3–5 times per week, gradually increasing to daily short sessions.
I (Intensity): Start with low-intensity exercises (e.g., flat-ground walking, basic lumbar strengthening exercises), and increase gradually based on pain tolerance.
T (Time): Begin each session with a 5–10 minute warm-up, followed by 10–15 minutes of the main training, and end with a 5-minute cool-down. As rehabilitation progresses, extend the main training to 20–30 minutes.
T (Type): Emphasize low-impact aerobic exercises (walking, swimming, low-impact aerobics) and core muscle strengthening (e.g., bird-dog exercises, bridge poses, etc.).
V (Volume): Adjust according to the duration and frequency of each session, increasing the total weekly exercise by about 10% incrementally.
P (Progression): As pain subsides and lumbar strength improves, gradually increase workout intensity, such as reducing rest intervals or adding resistance training.
Special Note: Because the patient is older, ensure safety during initial exercises, preferably under the supervision of a professional (e.g., physical therapist). Avoid high-impact or excessive flexion-extension movements of the lumbar spine. If severe pain or worsening neurological symptoms occur, seek medical evaluation promptly.
Disclaimer: This report is based solely on the current imaging and available information for reference purposes. It cannot replace an in-person clinical diagnosis or professional medical advice. If you have any concerns or if symptoms worsen, please consult a specialist promptly for further evaluation and treatment.
Lumbar Facet Synovial Cyst
