Presented at the 2012 AAPM Annual Meeting « Back

Lumbar Synovial Cyst: An Unusual Cause of Acute Cauda Equina Syndrome

Jeffery Muir, MD, muir.jeffery@mayo.edu¹, Matthew J. Pingree, MD¹, Susan M. Moeschler, MD¹, Mayo Clinic, Rochester, Minnesota

Introduction: Cauda equina syndrome is a well-described state of neurologic compromise due to lumbosacral root compression. It is most often caused by mass effect from disc herniation, tumor, infection, stenosis, or hematoma.1 We report a case of rapid lumbar synovial cyst expansion leading to acute cauda equine syndrome. Material/Methods: A 49-year-old female with a history of chronic low back pain primarily attributed to L4-5 facet degenerative arthritis presented with new onset saddle anesthesia, bladder incontinence, and lower limb pain as well as paresthesias. Neurologic exam revealed positive straight leg raise bilaterally, right peronei and bilateral toe extensor muscle weakness, right greater than left perineal numbness, diminished rectal tone, and decreased ankle reflexes. Lumbar MRI was obtained and compared to a study from 2 weeks earlier. It demonstrated new moderate spinal canal narrowing at the L4-5 level due to a dorsal epidural cyst contiguous with the right L4-5 facet. After an unsuccessful attempt to relieve her symptoms with CT-guided cyst aspiration, an L4-5 posterior spinal decompression with excision of the synovial cyst was performed. Results: Postoperatively, the patient's perineal numbness, bladder incontinence, and associated pain complaints resolved. The only residual symptom at 1 month follow-up was continued numbness in the right lower limb in a L5 distribution. Conclusions: A lumbar synovial cyst is a rare but possible cause for acute cauda equina syndrome. Morbidity associated with this condition can be minimized through prompt recognition and treatment. References: 1)Fraser S, Roberts L, Murphy E. Cauda equina syndrome: a literature review of its definition and clinical presentation. Arch Phys Med Rehabil. 2009 Nov;90(11):1964-8.

Funding: None