Acute Cauda Equina Syndrome Secondary to a Lumbar Synovial Cyst

Abstract

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. Key words: Acute pain, cauda equina syndrome, lumbar, polyradiculopathy, synovial cyst, zygapophyseal joint

Lumbar Facet Cyst Causing Incomplete Cauda Equina Syndrome: A Case Report and Review of Literature

“…7 Various hypotheses have been proposed regarding the development of these cysts including synovial herniation through a defective capsule, periarticular fibrous tissue undergoing mucinous degeneration, and pluripotent mesenchymal cells in ligamentum flavum undergoing proliferation and focal hemorrhage due to repetitive microtrauma. 2,8 Despite the histological distinction between synovial and ganglion cysts, the clinical presentation, management, and prognosis are similar. 4 The incidence of synovial cysts is 0.6% based on a study of 1,800 CT and MRI scans 5 being more common in the lumbar spine (94%) and a majority occurring at the L4-L5 level.…”

“…12 While a majority present with unilateral or bilateral radiculopathy (55-97%), 25-44% present with neurological claudication, 26-40% present with motor deficits, and 13% present with cauda equine syndrome. 3,[6][7][8] Facet cysts can cause cauda equine syndrome due to hemorrhage within synovial cyst or rapidly expanding cysts. 2,4,9 Nonsurgical management in the form of rest, analgesics, and spinal exercises and epidural steroids have been generally unsatisfactory, 3,6,13 although there is a few reports of spontaneous regression of facet cysts.…”

“…5 These cysts, seen more commonly in the mobile lower lumbar spine, 6 can cause low back pain, radicular leg pain, and in rare cases cauda equina syndrome. 3,[6][7][8] Cauda equina syndrome may occur due to hemorrhage into the cyst 2,4 or rapid expansion of a cyst. 9 In this report, we would like to present the occurrence of incomplete cauda equine syndrome resulting from a facet synovial cyst in a 65-year-old woman who presented with weakness in both lower limbs, difficulty in walking, and saddle anesthesia.…”

Surgically managed symptomatic intraspinal lumbar facet synovial cyst outcome of surgical treatment with resection and instrumented posterolateral fusion, a case series

“…When they present as symptomatic SC (SSC), they require treatment either conservative or surgical [ 7 ]. The latter is currently subject to debate, with the optimal approach still lacking consensus.…”