2026 年 13 巻 p. 301-306
Cervical calcification of the ligamentum flavum is a relatively rare disease that causes myelopathy due to calcification within the ligament. We recently encountered a patient with rapid progression of cervical calcification of the ligamentum flavum after anterior fixation surgery, resulting in spinal cord symptoms. An 81-year-old woman had a history of anterior decompression and fixation surgery (Williams-Isu method) at C3-4 and C5-6 at the age of 58 years, with no sequelae. Eighteen months preoperatively, the patient developed walking difficulties, arm pain, and weakness in both arms. Magnetic resonance imaging showed C4-5 anterior spinal cord compression, and C4-5 anterior decompression and fixation surgery were performed. Postoperatively, the patient's condition improved, and she was discharged from the hospital, able to walk unaided. However, 17 months postoperatively, the patient rapidly developed right arm pain, walking difficulties, and urinary and rectal incontinence. There was a rapid progression within 18 months in cervical calcification of the ligamentum flavum at the C6-7 level on magnetic resonance imaging and severe compression of the spinal cord; therefore, urgent laminectomy was performed. Postoperatively, the symptoms improved, and there was no recurrence for 3 years. In addition to the previously performed C3-4 and C5-6 fusion procedures, the addition of a C4-5 fusion resulted in a longer fusion spanning from C3 to C6, and it is thought that mechanical stress was concentrated on the adjacent intervertebral space of C6-7. Although the cause of cervical calcification of the ligamentum flavum has not been determined, this case strongly suggests that mechanical stimulation may exacerbate the condition.
Cervical calcification of the ligamentum flavum (CCLF) is a relatively rare disease that causes myelopathy due to calcification within the ligament. With the widespread use of computed tomography (CT) and magnetic resonance imaging (MRI), the number of reported cases has increased, and previous reports have indicated that it is more common among Southeast Asian ethnic groups.1-7) There are scattered reports on this condition, but there is no established etiology.4-6) Compared with ossification of the ligamentum flavum in the thoracolumbar spine, rapid progression of CCLF has been reported, requiring caution in clinical practice.8-10) We encountered a patient with cervical ligament calcification, which rapidly increased in the adjacent vertebral space after anterior decompression and fixation surgery, resulting in spinal cord symptoms. Here, we report the first images to capture this sudden increase in calcification, with a literature review.
Written informed consent was obtained from the patient for the publication of this case report and the accompanying images.
The patient was an 81-year-old woman with a primary complaint of walking difficulties and had no history of smoking or alcohol consumption.
At 58 years of age (23 years prior to presentation), she had undergone anterior decompression and fusion surgery (Williams-Isu method) at C3-4 and C5-6 for cervical spondylotic myelopathy and radiculopathy. Her symptoms resolved without complications. Also, there was no significant family history. At the time of presentation, the patient had experienced walking difficulties for 17 months and had repeatedly fallen. The patient also had difficulty raising both arms, fine motor impairment, and pain that gradually worsened. The patient visited the Department of Neurosurgery at Fukuoka University Hospital and underwent CT and MRI. MRI of the cervical spine revealed severe compression of the anterior cervical spinal cord at the C4-5 level. Cervical spine CT showed bone fusion at C3-4 and C5-6 due to the previous surgery (Figure 1). Calcification of the ligamentum flavum was observed at C6-7; however, no significant spinal cord compression was identified. Although the patient was older, pain control with medication was poor, and motor impairment worsened; therefore, surgical treatment was deemed appropriate. Spinal cord compression was mainly caused by the anterior element of the C4-5 single intervertebral space, and anterior decompression and fixation procedures were performed.
A. Sagittal T2-weighted MRI images before C4-5 anterior decompression and fixation surgery. Severe cervical spinal cord compression is observed at the C4-5 level, caused by anterior component. Findings were suggestive of CCLF with low T2 signal intensity at the C6-7 level and mild spinal cord compression. B, C. Cervical spine plain CT, sagittal and axial view, prior to C4-5 anterior decompression and fixation surgery. C3-4 and C5-6 are fused. Ligamentum flavum calcification is observed at C6-7, with mild ligament thickening.
CCLF: cervical calcification of the ligamentum flavum; CT: computed tomography; MRI: magnetic resonance imaging
Two months after visiting our hospital, C4-5 anterior decompression and fusion were performed. The procedure was performed using a surgical microscope. The vertebral spur was removed using a drill, and the intervertebral foramen was enlarged. A titanium cage (M-cageSR; HOYA Technosurgical Company, Tokyo, Japan) was used for intervertebral fixation. There were no postoperative complications, and the walking impairment improved. The patient was discharged from the hospital.
Eighteen months postoperatively, she began experiencing pain and instability in her right upper limb, and one month later, she suddenly developed difficulty in walking and had urinary and rectal incontinence. She developed quadriplegia and fine motor skill impairment, and was admitted to the hospital on an emergency basis for surgery. Her neurological findings at admission included manual muscle testing of the arms (right 4, left 4+) and of the legs (right 3, left 4+) as well as decreased tactile sensation and thermal pain sensation of the left lower limb.
Blood tests revealed no significant abnormalities. MRI of the cervical spine revealed severe compression of the spinal cord at the posterior portion of C6-7, and CT showed calcification of the ligamentum flavum at the same level (Figure 2). Surgery was considered to address the adhesion between the calcified ligamentum flavum and dura mater, and laminectomy was chosen rather than laminoplasty.
A. Sagittal T2-weighted MRI images when the CCLF increased. Severe cervical spinal cord compression is seen at the C6-7 level, caused by posterior compression. High T2 signal intensity within the spinal cord is observed at the same site. With low T2 signal intensity, CCLF and ossification were suspected at C6-7 posteriorly. This was a significant increase compared with that in the previous examination. B, C. CT sagittal image when CCLF increased; B (sagittal image) and C (axial image). The findings were suggestive of ligamentum flavum calcification at C6-7. This was a significant increase compared with that in the previous examination.
CCLF: cervical calcification of the ligamentum flavum; CT: computed tomography; MRI: magnetic resonance imaging
The lamina of C6-7 was resected using a drill, and the calcified ligamentum flavum was removed. Adhesion to the dura mater was mild, and it could be carefully divided and completely removed without damaging the dura mater (Figure 3A). Nodular lesions were observed, which on pathological analysis (Figure 3B) consisted of partially degenerated fibrocartilage and granulomatous tissue mixed with giant cells, accompanied by island-like deposits of calcium pyrophosphate dihydrate (CPPD) crystals at the center.
Intraoperative finding and pathological findings of the ligamentum flavum. A. Calcified ligamentum flavum is observed, with mild adhesion to the dura mater. B. Ossification and nodular lesions are observed in the ligamentum flavum. The nodular areas consisted of fibrocartilage, and were accompanied by partial degeneration, mixed granulation tissue with giant cells, and island-like deposits of calcium pyrophosphate dihydrate (CPPD) crystals.
Postoperative cervical spine CT confirmed successful spinal cord decompression. There were no postoperative complications, and the patient's condition improved. The urinary and rectal incontinence and walking difficulties improved, and after being transferred to a rehabilitation hospital, the patient was discharged and was able to walk independently. Three years postoperatively, the patient has shown no new spinal cord-related or neurological symptoms.
This case report describes a rapid increase in cervical ligament calcification observed on imaging that progressed over a short period of 18 months. Causes of CCLF include aging, nutritional and endocrine disorders, and chronic mechanical stimulation.11,12) Cases with detailed descriptions of clinical symptoms and MRI/CT findings were extracted from the cited literature and are presented in Table 1. Previous reports indicate that it is mainly seen in older people, particularly in women of Asian descent in the sixth and seventh decades of life.10,13) According to previous reports, the sites of occurrence are the middle and lower cervical vertebrae.1-21)
Summary of Previously Reported Cases of Cervical Ligamentum Flavum Calcification
| Case | Age/ sex | Symptoms | Preoperative symptoms at the time of surgery | Level | Treatment | Presentation to surgery | Factor | Histology | Radiological findings of CT | Postoperative course | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| CPPD: calcium pyrophosphate dihydrate; CT: computed tomography; F: female; HA: hydroxyapatite; M: male; N/A: not applicable | |||||||||||
| Pascal-Moussellard et al. (1999), [17] | 1 | 72/F | Numbness in hands, ataxic gait, lower limb weakness | Numbness in hands, ataxic gait lower limb weakness, hyperreflexia, positive Hoffmann sign | C4-5 | C4-5 laminectomy | 3 months | Mechanical stress | CPPD, HA, island-like calcification | Egg-shaped carciformation | Symptomatic improvement with no recurrence at 1 year. |
| Kobayashi et al. (2016), [16] | 2 | 70/F | Cervical pain | Cervical pain | C5-6 | C6 laminectomy | 6 weeks | Pseudogout | CPPD | Egg-shaped carciformation | Symptomatic improvement with no recurrence at 7 years. |
| Nishikawa et al. (2018), [9] | 3 | 78/F | Gait disturbance, numbness in hands | Gait disturbance, numbness in hands | C4-6 | C3-6 laminoplasty | 6 months | Mechanical stress | CPPD, HA, island-like calcification | Egg-shaped carciformation, disc hernia, spondylosis | Symptoms improved postoperatively. |
| Nishikawa et al. (2018), [9] | 4 | 87/F | Gait disturbance, numbness in hands | Gait disturbance, numbness in hands, inability to ambulate | C4-6 | C3-6 laminoplasty | 6 months | Mechanical stress | CPPD, HA, island-like calcification | Diffuse and speck-like calcification, spondylosis | Symptomatic improvement with no recurrence at 1 year. |
| Cao et al. (2019), [18] | 5 | 74/M | Left limb weakness | Inability to ambulate | C3-4 | C3-4 laminectomy | 4 days | N/A | CPPD | Egg-shaped carciformation | Ambulatory at 2 weeks postoperatively. Symptomatic improvement with no recurrence at 5 years. |
| Kimura et al.(2020), [15] | 6 | 78/M | Mild tetraplegia | Severe tetraplegia | C4-5 | C3 laminectomy C4-5 laminoplasty | 4 days | Trauma/pseudogout | CPPD | Speck-like calciformation | Symptomatic improvement with no recurrence at 1 year. |
| Lu et al. (2021), [19] | 7 | 70/M | Cervical pain, hand clumsiness | Cervical pain, hand clumsiness | C3-7 | C3-7 laminoplasty C3-7 fusion | 2 months | N/A | CPPD | Egg-shaped carciformation | Symptoms improved postoperatively. |
| Present case | 8 | 81/F | Upper limb pain, gait disturbance | Mild tetraplegia following falling bladder and bowel dysfunction | C6-7 | C6-7 laminectomy | 1 month | Mechanical stress | CPPD | Egg-shaped carciformation | Symptomatic improvement with no recurrence at 1 year. |
Calcification of the ligamentum flavum results in the formation of an occupying lesion that compresses the spinal cord anteriorly and causes neurological symptoms. Previously, CCLF was considered a chronic progressive condition associated with age-related degeneration, and it was generally assumed that disease progression was slow. However, in recent years, there have been reports of rapidly progressive cases with significant spinal symptoms appearing in a few weeks to a few months.8-10) Clinically, CCLF is broadly categorized into two patterns of progression. The attack type is characterized by day-scale progression, in which an acute CPPD attack induces inflammatory swelling of the ligamentum flavum, resulting in severe neurological deterioration within several days.15) On the other hand, the mechanical degenerative type is characterized by week-to-month progression, in which pre-existing mild calcification gradually enlarges under altered local mechanical stress or in the presence of canal stenosis, eventually becoming symptomatic.20,21) This case would be categorized as a rapidly progressive example of the mechanical degenerative type.
Currently, there are no established tests or findings that can predict rapid progression, and there are no clear guidelines regarding surgical treatment for rapidly progressing CCLF, such as whether decompression alone is sufficient or posterior fixation should also be used. However, in general, the first choice of treatment is posterior decompression surgery using laminectomy or laminoplasty. For this patient, instability was minimal; therefore, decompression alone would be sufficient. Additionally, for patients in whom calcific lesions strongly adhere to the dura mater, careful microscopic dissection is required.3) For this patient, laminectomy was chosen rather than laminoplasty because it allowed careful dissection.
CCLF is detected on CT as an oval or spotted area of high absorption within the ligamentum flavum, and on MRI as an area of low T2 signal compressing the spinal cord. In patients with rapid progression of CCLF, high signal changes in the spinal cord appear early on MRI scans, indicating the need for urgent decompression surgery.8,9) In our patient, we considered the rapid increase in calcification to be caused by the two surgeries that resulted in a long fusion from C3 to C6, which placed significant mechanical stress on the directly inferior C6-7 level. Spinal symptoms progressed rapidly, causing difficulty in walking and bladder and bowel dysfunction; however, early surgical intervention resulted in improvement of the neurological symptoms. Multiple case reports have reported improvement rates in Japanese Orthopaedic Association scores postoperatively, ranging from 60% to 87%, with a tendency toward favorable outcomes in patients with short duration of preoperative neurological symptoms.9,14) Therefore, in rapidly progressive CCLF, early determination of surgical indications based on imaging diagnosis is an important factor in improving prognosis. From this patient, it can be concluded that caution is necessary in patients in whom mechanical stress is predicted.
Previous reports and studies have revealed that in CCLF, calcium deposits mainly remain within the ligamentum flavum and do not extend to the surface.1-7,11) Kawano et al.6) reported pathological findings showing that the center of the calcification was hydroxyapatite (HA) and the surrounding area was CPPD, suggesting that CPPD may become chemically stable HA crystals over time. Considering the role of the ligamentum flavum in the cervical spine, chronic mechanical stimulation (particularly traction and rotation) damages the ligamentous fibers. During the inflammatory process that repairs this damage, ligamentous fibers proliferate and thicken, and multiple small calcifications occur independently within the ligamentum flavum. It is speculated that these small calcifications gradually fuse, leading to enlargement of the calcifications. In this patient, there was partial degeneration, with granulation tissue mixed with giant cells, and accompanied by island-like deposits of CPPD crystals; however, no HA was observed. This patient experienced rapid enlargement, and possibly, there was insufficient time for HA crystals to form. When our patient visited the hospital with spinal symptoms after undergoing fixation surgery at C3-4 and C5-6, calcification of the ligamentum flavum at C6-7 was suspected, and there were no significant findings of compression. If we had predicted an increase in CCLF after fixation surgery, we could have considered posterior decompression instead of anterior decompression and fixation of C4-5 at this point. As a result, calcification of the ligamentum flavum in the adjacent C6-7 intervertebral space progressed rapidly after C4-5 fusion surgery, causing spinal cord symptoms. For this patient, early surgical intervention led to an improvement in the condition; however, it is important to note that calcification of the ligamentum flavum can rapidly increase owing to mechanical stress.
We encountered a patient with rapidly progressing CCLF, who presented with significant spinal symptoms. Following two previous procedures for cervical spondylotic myelopathy, a long fusion was performed from C3 to C6, and it is thought that mechanical stress was concentrated on the adjacent C6-7 intervertebral space directly below. Although the cause of calcification and ossification of the ligamentum flavum has not yet been determined, this case strongly suggests that mechanical stimulation exacerbates these conditions. Early surgery is considered effective for patients with CCLF and rapidly worsening neurological symptoms, and is important for determining the treatment plan.
We would like to thank Editage (www.editage.jp) for English language editing.
Ethical approval was not required for this case report. Written informed consent was obtained from the patient for publication of this case report and accompanying images. All authors have no conflict of interest.
