Cauda equina syndrome is a well described state of neurologic compromise due to lumbosacral root compression. In most cases, it is due to a
herniated disc,
tumor,
infection, or
hematoma. We report a case of rapid lumbar
synovial cyst expansion leading to acute
cauda equina syndrome and compare it to similar cases in the literature. The patient is a 49-year-old woman with a history of chronic
low back pain who developed
cauda equina syndrome. Serial lumbar magnetic resonance imaging studies demonstrated a significant increase in the size of a lumbar
synovial cyst over a 2 week interval. After an unsuccessful attempt to relieve her acute symptoms with computed tomography-guided
cyst aspiration, an L4-5 posterior spinal
decompression with excision of the
synovial cyst was performed. Postoperatively the patient's perineal
numbness, bladder incontinence, and associated
pain complaints resolved. The only residual symptom at one month follow-up was continued
numbness in the right lower limb in an L5 distribution. This report adds to 6 other well described similar cases found in the literature by illustrating several important points. First, a lumbar
synovial cyst is a rare but possible cause of acute
cauda equina syndrome. Second, magnetic resonance imaging is the test of choice to diagnose and characterize lumbar
synovial cysts; serial imaging can detect fluctuations in
cyst size. Third, percutaneous treatment of lumbar
synovial cysts is variable in efficacy and proved to be unsuccessful in our patient. Finally, surgical management has shown high success rates for symptomatic
cysts. Specifically, in the setting of acute
cauda equina syndrome secondary to a lumbar
synovial cyst, urgent
surgical decompression has led to resolution of
neurologic symptoms in most reported cases. A lumbar
synovial cyst is an uncommon cause of acute
cauda equina syndrome. Prompt diagnosis and treatment may lead to reduced morbidity associated with this condition.