Ligamentum Flavum Cysts Causing Incapacitating Lumbar Spinal Stenosis

Abstract

c c n s . o r gCysts of the ligamentum flavum are unusual causes of spinal compression. Their etiology and histopathologic classification have yet to be fully elucidated. We report our experience of four cases of ligamentum flavum cysts occurring in the lumbar spine and discuss some of the etiologies and possible pathophysiologic mechanisms for their development. CASE REPORTSAn outline of the cases is contained in the Table, and imaging examples are shown in Figure 1. Case 1The patient was an 82-year-old woman referred for recent onset of right-sided sciatica involving mostly the S1 distribution and causing major incapacitation because of severe pain. There was no pain on coughing; however, she had increased urinary frequency at night. On examination, motor function was normal and there was no sensory disturbance on examination of the legs. Reflexes were hypoactive in the right leg with plantar reflexes downgoing.Computerized tomography (CT) imaging of the lumbo-sacral spine showed significant degenerative disease in the lumbar spine, as well as an epidural mass occupying the L5-S1 region, with a small posterocentral subligamentous hernia, possibly representing a synovial or arachnoid cyst but also compatible with a benign cystic tumour such as a schwannoma. Subsequent magnetic resonance imaging (MRI) demonstrated a voluminous epidural cystic lesion compressing the cauda equina to the right of the sac at L5-S1, compatible with a synovial cyst of the ligamentum flavum. In light of the acuity and degree of incapacitation of the disease, the patient was hospitalized for urgent laminectomy with microsurgical removal of the cyst.ABSTRACT: Background: Cysts of the ligamentum flavum are rare and unusual causes of spinal compression. Methods: We report our experience of four cases of ligamentum flavum cysts occurring in the lumbar spine and discuss some of the possible etiologies and pathophysiologic mechanisms according to the available literature. Conclusion: This entity is clearly different from the synovial facetjoints or ganglion cysts.RÉSUMÉ: Sténose spinale lombaire incapacitante causée par un kyste du ligament jaune. Introduction: Les kystes du ligament jaune sont rares et causent très rarement une compression spinale. Méthodes: Nous rapportons notre expérience au sujet de quatre cas de kystes du ligament jaune au niveau lombaire et nous discutons de l'étiologie et de la physiopathologie de cette entité à la lumière de la littérature actuelle. Conclusion: Cette pathologie est nettement différente des kystes synoviaux des articulations facettaires ou des kystes ganglionnaires.

Ligamentum flavum cyst in the lumbar spine: a case report and review of the literature

“…Complete removal of pseudocystic lesions generally has excellent results [2, 9, 14, 27, 28, 30]. Our patient showed complete postoperative resolution of symptoms.…”

“…The tophaceous type of lesion seems to be closely related to previous degeneration of the affected ligament by minor trauma predisposing to calcium deposition. Activity of proteolytic enzymes within the ligament, produced by neutrophils localizing to calcified nodules, has been found [9]. Wildi et al.…”

“…The computed tomography appearance of synovial cysts is often diagnostic and correlates well with pathologic findings. They typically consist of a cystic formation whose walls show calcification, and are located adjacent to facet joints that frequently show signs of degeneration [9]. Ligamentum flavum cysts, conversely, have not been observed to cause rim calcification.…”

“…[30] reported recurrence of the cyst in the remaining ligamentum flavum in two patients 1 year after surgery. While nearly 95% of all operated cysts can be removed in their entirety, a major reported intraoperative difficulty lies in the presence of adhesions to the dural wall, which is the main causative factor of incomplete resection [9]. …”

Electrodiagnosis in Lumbar Spinal Stenosis: A Review

“…form of LSS that results from facet joint capsule hypertrophy, disc degeneration, osteophyte formation, or buckling of the ligamentum flavum (2)(3)(4). These pathologic anatomical conditions may act singularly or as a group to produce the syndrome.…”