Bilateral ganglion cysts at L4/5 causing central canal stenosis and producing sciatica and neurogenic claudication: a case report

Abstract

Symptomatic bilateral juxtafacet ganglion cysts are relatively uncommon in the degenerated spine. The literature describes 16 cases of bilateral ganglion or synovial cysts, none reported sciatica and neurogenic claudication simultaneously. We present a case of a 60-year-old woman who presented with symptoms of bilateral sciatica and neurogenic claudication. Magnetic resonance imaging of the lumbar spine revealed bilateral lesions related to the facet joints at the L4/5 level, causing bilateral lateral recess stenosis and narrowing of the central canal due to encroachment of these bilateral lesions at the same level. She underwent an elective central canal decompression of the L4/5 level and excision of the facet cysts bilaterally with lateral recess decompression, which resulted in good relief of both the radicular and claudication symptoms.

Background

Lumbar spine degeneration may lead to progressive instability of its structure together with degenerative changes in the ligamentum flavum and facet joints.¹ Intraspinal juxtafacet cysts (both synovial and ganglion cysts) can arise during this process, which can be associated with radiculopathy and, more rarely, neurogenic claudication and myelopathy.^2,3 Synovial cysts are lined with cuboidal epithelium and filled with synovial fluid. They also retain communication with their facet joint of origin. This is the main difference when compared with ganglion cysts which lack a synovial lining and have no communication with the facet joints.¹ Despite this difference, the two terms are used interchangeably within the literature.

Numerous cases of ganglion cysts have been reported in the lumbar spine but, here, we present a rare case of bilateral ganglion cysts at the same level causing central canal stenosis and related sciatica in L5 dermatome together with with neurogenic claudication. A literature search revealed 16 recorded cases of bilateral synovial or ganglion cysts in the lumbar spine,^2–9 with only one post-surgical case reported.³ None of the reported cases so far had presented with both sciatica and neurogenic claudication as in our case.

Case history

A 60-year-old woman attended the neurosurgical outpatient clinic via referral from her general practitioner complaining of a six-month history of sharp radicular pain associated with a burning sensation in her buttocks radiating down to her thighs, calves and feet, bilaterally in an L5 distribution. She also noted that her walking distance had reduced significantly due to increased numbness and pain at the back of the thighs, which was alleviated by bending over or sitting, symptoms which typically fit with neurogenic claudication. The pain initially started on the patient’s right side and progressed to the contralateral side.

She had subsequently sought advice from a physiotherapist, who treated her for piriformis syndrome with exercises and yoga. Unfortunately, despite this treatment, the patient’s pain continued to worsen. There were no clinical features suggestive of cauda equina compression and she had no positive history of previous medical conditions. The patient was regularly taking amitriptyline, naproxen, sertraline and lansoprazole. Clinical examination revealed altered sensation in the L4, L5 and S1 dermatomes on the right side as the only positive finding. The remainder of the neurological examination was normal.

Magnetic resonance imaging (MRI) of the lumbar spine demonstrated the presence of bilateral cyst-like lesions in relation to the facets joints at L4/5 level causing significant bilateral narrowing of the lateral recesses at L4/5, together with with evidence of central canal stenosis (Figures 1 and 2). These findings could explain the sciatica in the L5 distribution bilaterally, as well as the symptom of spinal claudication.

Figure 1 .

Sagittal T2-weighted magnetic resonance imaging of the lumbar spine demonstrating central canal stenosis due to facet joints cysts (arrow) later discovered intraoperatively to be bilateral at L4/5

Figure 2 .

Axial T2-weighted magnetic resonance imaging of the lumbar spine at level L4/5 demonstrating central canal and lateral recess stenosis due to facet joint cysts (arrows)

Subsequently the patient underwent spinous process osteotomy at L4 and excision of bilateral cystic lesions plus decompression of the nerve roots and lateral recess, as well as laminectomy for widening the spinal canal. Intraoperatively the cystic lesions were suggestive of ganglion cysts which did not communicate with the facet joints. The surgery led to improvement of both the radicular pain as well as spinal claudication. The subsequent histology report confirmed that the lesions represented ganglion cysts.

Discussion

Spinal facet cysts are a recognised but rare type of degeneration. The cystic fluid collection is thought to be the result of facet joint degeneration.¹⁰ The cysts can be either true synovial cysts, where the cystic wall is lined by synovium, or ganglion cysts, originating from fibrous tissues around the facet joint.¹¹

Most reported cases of lumbar facet cysts are located at the L4/5 level.¹² The symptoms caused by the facet cysts depending on their relation to the dural sac and nerve roots. It is even more rare to experience symptoms because of bilateral facet joint cysts at the same level. The characteristic features of facet cyst described on MRI include its extradural location, the displacement of the thecal sac and variable signal density indicating high protein content or due to previous internal bleed.¹³

Symptoms of sciatica and claudication are common presentations in degenerative lumbar spine disease. When these symptoms are present in isolation, as commonly encountered in cases of central canal stenosis causing claudication, a central canal decompression alone is sufficient to give relief from symptoms. If the main complaint is sciatic pain due to lateral recess stenosis, then the lateral recess decompression can offer good postoperative results.

It is less frequent, though, to experience both symptoms simultaneously. The presence of both symptoms raises the suspicion of a pathology compromising the lateral recess or the root canal as well as the central spinal canal. In our case, the bilateral ganglion cysts which caused narrowing the central canal and the lateral recesses at L4/5 level clearly caused the unusual combination of simultaneous symptoms of bilateral L5 sciatica as well as neurogenic claudication. The clinical significance of the simultaneous presentation of the above-mentioned symptoms led to surgery being planned.

In our case, the patient experienced bilateral sciatica and claudication symptoms, caused by the cysts occupying the lateral recess and compromising the central canal, which to the best of our knowledge makes it the first reported case of bilateral facets cysts causing a combination of both these symptoms. This case clearly demonstrates that the surgical planning must be tailored differently to take into account both the symptomatology necessitating decompression of the lateral recess and excision of the cysts, but also laminectomy to widen the central canal for best outcome.