Extraforaminal Lumbar Synovial Cyst Causing Sudden Foot Drop -Case Report-

Abstract

A 52-year-old female presented with extraforaminal lumbar synovial cyst at the L4-5 level causing sudden foot drop on the right. Computed tomography, magnetic resonance (MR) imaging, and coronal MR myelography source images identified the cystic mass in the extraforaminal zone. The patient underwent microdecompression via a lateral transmuscular route, and the extraforaminal cyst compressing L4 ganglion was successfully removed. The histological diagnosis was synovial cyst. This unique case of surgically proven extraforaminal lumbar synovial cyst causing sudden foot drop indicates that extraforaminal synovial cyst should be included in the differential diagnosis of patients presenting with sudden foot drop.

Intradural Invasion of Lumbar Synovial Cyst

“…2,4,12,19,27) The differential diagnosis of synovial cyst in the lumbar spine includes migrated herniated disk, schwannoma, cystic neurofibroma, extradural arachnoid cyst, perineural cyst, meningioma, ganglion cyst, and ligamentum flavum cyst, among others. 3,7,12,17,27) In the present case, we could not definitely confirm that synovial cyst was the causative pathology based only on the findings of MR imaging and CT. CT showed a small amount of gas in the mass. Gas-filled synovial cysts have been reported, presumably originating from the contiguous vacuum in the facet joint, 1,10,11,15,18,24,25) but the diagnostic value is limited due to the polymorphism of radiologic presentation of synovial cysts and lack of sensitivity of CT. 21) Surgery has been considered for the treatment of symptomatic lumbar synovial cyst.…”

“…2,17,19) The most common presenting symptoms are radiculopathy, neurogenic claudication, or cauda equina syndrome, with associated sensory loss and motor weakness, whereas back pain usually precedes radiculopathy. 4,6,14,16,17,19,20,27) Neuroimaging investigations such as MR imaging have been advocated to accurately identify synovial cyst. MR imaging shows synovial cyst as a sharply marginated epidural mass, located posterolateral to the thecal sac near the facet joint, and in lateral recess.…”

“…Conservative treatments including percutaneous needle aspiration of the synovial cyst and intra-articular steroid injection have been advocated, but the outcome of surgical excision has been superior to nonsurgical treatment. 2,4,6,9,14,16,17,19,20,26,27) The surgical technique varies depending on the cyst size, local pathology, and adhesion to the dura. Cyst excision only is a sufficient first line of treatment, even though underlying spinal instability remains.…”

L2 Radicular Compression Caused by a Foraminal Extradural Gas Pseudocyst

“…The gas pseudocyst was removed using the lateral transmuscular approach 6) . During the surgery, a well-demarcated oval-shaped pseudocyst filled with gas, which was compressing the L2 root, was detected in the foraminal zone.…”

“…We present a case of a 67-year-old woman who suffered from severe pain in the right leg caused by an extradural gas pseudocyst in the intervertebral foramen. The patient underwent cyst excision using the lateral transmuscular approach 6,7) and her leg pain was significantly improved after the operation.…”