, Introduction
Degenerative changes in the aging spine often lead to complex clinical presentations, particularly in elderly patients with comorbidities. Juxta-facet cysts, though commonly observed in the lumbar spine, are generally asymptomatic but may occasionally cause neurological symptoms. Among these, ligamentum flavum cysts (LFC) are a rare variant and pose a unique diagnostic and management challenge, especially when hemorrhagic. This case report highlights the unique presentation, diagnosis, and surgical management of a hemorrhagic LFC in an 84-year-old male patient. Due to his advanced age, concurrent use of an antiplatelet agent, and active physical therapy (PT) due to previous spinal surgeries, this case offers critical insights into the clinical challenges and considerations of treating hemorrhagic LFC in older patients. Understanding the interaction between age-related degeneration, medication, and cyst development is essential to managing similar cases in geriatric patients effectively.
Case Report
An 84-year-old man visited the outpatient clinic with a chief complaint of left buttock pain that began 3 days prior. He was on clopidogrel for peripheral arterial occlusive disease. Due to severe pain, rated as an 8 on the numerical rating scale (NRS), he was unable to walk or perform daily activities normally. The pain did not improve with medication, physiotherapy, or rest. In 2009, he had undergone a C5 corpectomy with C4-6 fusion for cervical ossification of the posterior longitudinal ligament with myelopathy (Fig. 1). In August 2023, he presented with quadriplegia and a modified Japanese Orthopedic Association (JOA) score of 7, leading to a laminoplasty at C3 and C4 due to stenosis with myelopathy at these levels (Fig. 1). Post-laminoplasty, his modified JOA score improved to 12 and he was able to walk on flat surfaces with the assistance of a walking aid. He was then admitted to a rehabilitation hospital for active PT, during which he suddenly experienced severe left buttock pain.
On examination, he had no motor weakness in the lower limbs, with a negative straight leg raising test bilaterally. Reflexes in the left lower limb were diminished, and paresthesia was noted in the left buttock area. A magnetic resonance imaging (MRI) from August 2023 showed no abnormalities at the L4/5 level (Fig. 2). However, an MRI from October 2024, following the sudden onset of symptoms, revealed newly developed extradural cystic masses near both facet joints, displaying layered intensity on T1-weighted and T2-weighted images (Fig. 3). Magnetic resonance neurography showed the lesions compressing the thecal sac (Fig. 3). A left-sided extradural cystic mass was identified as the likely cause of the neurological symptoms.
The patient consented to surgery and was scheduled for left unilateral laminectomy with bilateral decompression (ULBD) and cyst removal on L4/5 level under general anesthesia. Initially, a partial hemilaminectomy was performed on the left side, with the left facet joint preserved as much as possible. This approach revealed the left-sided ligamentum flavum, which contained a cystic mass. After excising the left-sided ligamentum flavum along with the cystic mass, the right-sided ligamentum flavum with a cystic mass was removed by maneuvering instruments through the left-sided incision. During the procedure, the excised cystic masses contained dark brownish hematoma and were found to originate from the ventral surface of the ligamentum flavum (Fig. 4). Complete decompression of the thecal sac was achieved after mass removal. Histopathological analysis showed a cystic lesion containing blood clots without synovial lining, suggestive of a degenerative hemorrhagic cyst, likely an LFC with hemorrhage (Fig. 5). Postoperatively, the patient reported improvement in his buttock pain, with an NRS of 3, was able to ambulate with cane assistance, and was discharged on the fourth postoperative day.
Discussion
Juxta-facet cysts are a well-known pathology typically found in the lumbar spine. Based on their location, they are categorized into facet joint cysts, posterior longitudinal ligament cysts, and LFC [1,2]. Although facet joint cysts are the most common type, LFC are rarely reported and can present a diagnostic challenge on initial imaging. LFC, first described by Moiel et al. [3] in 1967, are uncommon causes of neurological deficit and predominantly located in the lower lumbar spine [4]. The L4/5 level, being the most mobile segment, is the most common site for LFC in this region, followed by the L5/S1 level [5]. Additionally, hemorrhagic complications occur in less than 10% of juxta-facet cysts [6] and are rare in LFC or any type of juxta-facet cyst [7].
The ligamentum flavum primarily consists of elastic fibers with a smaller amount of collagen fibers, distinguishing it from other spinal ligaments. Collagen fibers in the spine contribute tensile strength and stiffness, while elastic fibers provide compliance and resilience during multiaxial movement [8]. Although the exact mechanism of cyst formation in the ligamentum flavum remains unclear, chronic microtrauma to the ligament is thought to play a role, potentially leading to cyst development [9]. These microtraumas may trigger regenerative processes, resulting in type-2 collagen deposition, reduced elasticity, and further degeneration with myxoid changes [10]. Furthermore, degenerative changes in the ligamentum flavum are believed to increase its susceptibility to bleeding following trauma, stretching forces, or repetitive micromotions involving the spine [11]. One report documented a clear history of physical trauma in patients with hemorrhagic synovial cysts [12], while another indicated that anticoagulant therapy could be a contributing factor for hemorrhagic facet cysts [13].
LFC lack specific clinical symptoms and are often found incidentally. When symptomatic, LFC commonly present with radiculopathy and may initially be mistaken for intervertebral disc herniation [14]. Clinical presentation varies depending on the cyst’s location, size, and growth. Asymmetric compression by the cyst may cause unilateral radicular pain similar to foraminal stenosis, while centrally located cysts that obstruct the spinal canal can lead to canal stenosis and claudication-like leg pain. Common symptoms include radicular pain in 97% of patients, sometimes accompanied by sensory changes, motor deficits, a positive Lasègue sign, or abnormal reflexes [15]. Although rare, cauda equina syndrome may occur in cases of cyst infection or hemorrhage, constituting a surgical emergency [16].
MRI is the gold standard for distinguishing LFC from other intraspinal cystic lesions. LFC appear as a well-defined, thin-walled lesion contained within the ligamentum flavum, exhibiting the typical signal intensity of a cyst or fluid on all sequences [13]. The MRI appearance of a hemorrhagic juxta-facet cyst depends on factors such as protein content, blood products, and the timing of the hemorrhage within the cyst [17]. T2-weighted images of these cysts display varying signal intensities due to prior hemorrhages, increased protein content, and calcification [18]. Differential diagnoses include discal cysts, facet joint cysts, perineural cysts, dermoid cysts, schwannomas, ependymal cysts, or infected cysts. Magnetic resonance neurography, another diagnostic tool, allows direct imaging of LFC and their relationship to surrounding structures.
In our case, MRI revealed newly developed extradural cystic masses that appeared to originate from the facet joint or ligamentum flavum. These cystic masses were isointense on computed tomography and displayed layered intensity with a gradational fluid level on MRI, strongly suggesting hemorrhagic cysts. Magnetic resonance neurography showed extradural cystic masses in the dorsal area of both facets, compressing the thecal sac. Intraoperative findings revealed that the cystic mass contained hemorrhage and was located solely on the ventral surface of the ligamentum flavum, with no connection to the facet joint. Histopathological examination confirmed hemorrhage within the ligamentum flavum. Active PT can subject the spine to repetitive microtrauma, potentially leading to degenerative changes in the ligamentum flavum and contributing to the formation of LFC. The use of antiplatelet agents, such as clopidogrel, can increase the bleeding tendency in the already-degenerative ligamentum flavum, resulting in hemorrhagic changes within the cyst. The hemorrhagic nature of this cystic mass may lead to rapid expansion, causing neurological symptoms.
Operative management of LFC depends significantly on the patient's neurological condition. Asymptomatic and incidentally discovered cases typically do not require surgery, while symptomatic cases generally do to relieve neurological symptoms. Conservative treatments have shown limited long-term effectiveness. Although percutaneous steroid injections into synovial and juxta-facet cysts can offer short-term relief, percutaneous cyst aspiration is generally ineffective [19]. Surgical excision is the preferred approach when conservative measures are unsuccessful. The main goal of surgery is spinal decompression with complete cyst and ligamentum flavum excision. Most cysts are non-adherent to the dura, allowing for careful dissection and removal, which lowers recurrence risk; however, dura adhesions may lead to incomplete resection and recurrence [18,20]. During surgery, adequate exposure is essential for visualization and mobilization to minimize nerve root and thecal sac traction risk. Surgical outcomes are generally favorable, with significant improvement in pain and neurological function.
Although the patient did not exhibit any neurological deficits, such as motor weakness, surgical intervention was necessary due to the sudden onset of large cystic masses, which caused severe stenosis. The pain from these masses was so intense that the patient was unable to perform daily activities, making conservative treatment impractical. A complete excision of the LFC was achieved through ULBD, a commonly performed surgical procedure in spinal surgery that does not require long-term hospital stay. The patient experienced immediate symptom relief following the surgery. Additionally, the removal of the ligamentum flavum through ULBD helps prevent the recurrence of LFC.
In conclusion, this case underscores the importance of recognizing rare spinal pathologies, such as hemorrhagic LFC, as a potential cause of acute neurological symptoms in elderly patients, especially those with a history of degenerative spinal changes or use of antiplatelet or anticoagulant therapy. The rapid expansion of hemorrhagic cysts can exacerbate spinal compression, leading to sudden and debilitating symptoms. Given the limited effectiveness of conservative treatments in symptomatic LFC, prompt surgical decompression should be considered, particularly in cases involving hemorrhage. In this patient, advanced imaging and histopathological confirmation were crucial for accurate diagnosis, and surgical intervention provided substantial relief from debilitating symptoms. This case serves as a reminder to clinicians of the need for vigilance in diagnosing rare cystic lesions in older patients, where early recognition and management can have profound benefits in alleviating pain, restoring mobility, and enhancing overall patient outcomes.
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