Ossification of the ligamenta flava with severe myelopathy in a black patient. A case report

Genetics of Diffuse Idiopathic Skeletal Hyperostosis and Ossification of the Spinal Ligaments

PURPOSE OF REVIEW

The study aims to provide updated information on the genetic factors associated with the diagnoses 'Diffuse Idiopathic Skeletal Hyperostosis' (DISH), 'Ossification of the Posterior Longitudinal Ligament' (OPLL), and in patients with spinal ligament ossification.

RECENT FINDINGS

Recent studies have advanced our knowledge of genetic factors associated with DISH, OPLL, and other spinal ossification (ossification of the anterior longitudinal ligament [OALL] and the yellow ligament [OYL]). Several case studies of individuals afflicted with monogenic disorders, such as X-linked hypophosphatemia (XLH), demonstrate the strong association of fibroblast growth factor 23-related hypophosphatemia with OPLL, suggesting that pathogenic variants in PHEX, ENPP1, and DMP1 are associated with FGF23-phosphate wasting phenotype and strong genetic factors placing patients at risk for OPLL. Moreover, emerging evidence demonstrates that heterozygous and compound heterozygous ENPP1 pathogenic variants inducing 'Autosomal Recessive Hypophosphatemic Rickets Type 2' (ARHR2) also place patients at risk for DISH and OPLL, possibly due to the loss of inhibitory plasma pyrophosphate (PPi) which suppresses ectopic calcification and enthesis mineralization. Our findings emphasize the importance of genetic and plasma biomarker screening in the clinical evaluation of DISH and OPLL patients, with plasma PPi constituting an important new biomarker for the identification of DISH and OPLL patients whose disease course may be responsive to ENPP1 enzyme therapy, now in clinical trials for rare calcification disorders.

Multilevel calcium pyrophosphate dihydrate deposition in cervical ligamentum flavum: clinical characteristics and imaging features

BACKGROUND

Involvement in cervical ligamentum flavum is a rare manifestation of the calcium pyrophosphate dihydrate deposition disease. Only few cases of this condition have been reported. We revealed eighteen cases of CPPD in cervical ligamentum flavum that diagnosed at a single medical center. In our case series, clinical characteristics and magnetic resonance imaging findings of patients are described.

METHODS

We retrospectively reviewed the medical charts and imaging studies of the eighteen patients with pseudogout attack of the cervical ligamentum flavum. In addition, we discussed the differences between this disease and ossification of ligamentum flavum in image manifestations.

RESULTS

There were fourteen men and four women aged between 59 and 87 years. Diabetes mellitus and hypertension were the most common comorbidities. Myelopathy and neck pain were presented in most patients. C4-5 and C5-6 were attacked most frequently, and multiple- rather than single-level involvement could be observed in our series. "Acute on chronic phenomenon" was a specific magnetic resonance image finding in patients whose symptom durations were between 2 to 5 months. Compared to ossification of ligamentum flavum, calcium pyrophosphate dihydrate crystal deposition had different image signs, including morphology, side of the involved ligament, no continuity with the lamina, acute on chronic phenomenon, and presence of retro-odontoid mass.

CONCLUSIONS

Nodular calcifications in cervical ligamentum flavum raise highly suspicion for calcium pyrophosphate dihydrate deposition and must be diagnosed by histological examination and polarized light microscopy. This disease is different from ossification of ligamentum flavum, and it could be recognized by specific image features.

A case of advanced ankylosing spondylitis complicated with cervical myelopathy due to ossification of yellow ligament in which bone histomorphometry demonstrated delayed calcification

There is minimal information available about bone histomorphometric findings in patients with ankylosing spondylitis (AS). Herein, we report a case of advanced AS complicated with cervical myelopathy due to ossification of yellow ligament (OYL). A 37-year-old Japanese man who had been diagnosed with AS was administered adalimumab. Thirty-four months after adalimumab treatment, he reported upper extremity numbness, dexterity impairment and a spastic gait. Magnetic resonance imaging and computed tomography of the cervical spine revealed cervical cord compression at the C5/6 level due to OYL. After surgery including posterior spinal fusion and cervical cord decompression with iliac bone graft at C5 and C6 arches, these symptoms improved. Bone histomorphometry of his ilium revealed marked osteoid formation and reduced mineral apposition, suggesting a calcification disorder. In addition, 25-hydroxy vitamin D was abnormally low (<4 ng/mL), and at 148 pg/mL parathyroid hormone was higher than the reference value, indicating secondary hyperparathyroidism. This case warrants reporting because OYL was complicated with AS and bone histomorphometric findings in AS were evaluated.

Correlation of blood bone turnover biomarkers and Wnt signaling antagonists with AS, DISH, OPLL, and OYL

Background

Wnt signaling plays an important role in development and maintenance of many organs and tissues. The most-studied secreted Wnt inhibitors are sclerostin (SOST), Dickkopf-related protein 1 (DKK-1), and secreted frizzled related protein 1 (SFRP-1) which play important roles in bone turnover. The present study investigated the relationship between serum Wnt inhibitors and diseases with excessive ossification structures, such as ossification of posterior longitudinal ligament (OPLL), ankylosing spondylitis (AS), diffuse idiopathic skeletal hyperostosis (DISH), and ossification of yellow ligament (OYL).

Methods

Twenty-five patients with AS, DISH, OPLL, or OYL were recruited in this study. Fasting peripheral blood samples were collected from all patients and nine controls. Various biomarkers of bone turnover including osteocalcin (OSC), osteoprotegerin (OPG), SFRP-1, DKK-1, and SOST were investigated.

Results

Our data showed that serum levels of OSC were higher, but Dkk-1 levels were lower in AS, DISH, OPLL, and OYL patients than those in the controls. Serum levels of SFRP-1 were significantly higher in DISH patients than those in the controls. Serum levels of SOST were significantly higher in DISH and OPLL patients than both levels in the controls. Serum levels of OPG were lower in AS patients than those in the controls. Serum levels of OSC were higher in the OPLL patients than those in the AS patients. Serum levels of DKK-1, SFRP-1, SOST, and OPG were not significantly different between the different disease groups.

Conclusions

In this exploratory study, both OSC and DKK-1 levels are correlated with the clinical conditions associated with excessive ossification, indicating that blood OSC and DKK-1 levels may serve as diagnostic biomarkers for AS, DISH, OPLL, and OYL. These findings may also help discover potential drug therapies for management of these diseases in the future.

Surgical Technique for Decompression of Severe Thoracic Myelopathy due to Tuberous Ossification of Ligamentum Flavum

STUDY DESIGN

Retrospective review.

OBJECTIVE

To describe a safe surgical procedure, en bloc resection of the posterior wall of the thoracic canal, for the decompression of severe thoracic myelopathy caused by tuberous ossification of the ligamentum flavum (OLF).

SUMMARY OF BACKGROUND DATA

OLF has been widely recognized as a cause of thoracic myelopathy in East Asia. Surgical decompression of thoracic myelopathy caused by OLF is technically demanding. Although several surgical decompression procedures have been described, acute neurological deterioration is common.

MATERIALS AND METHODS

Eighteen patients with severe thoracic myelopathy caused by tuberous OLF underwent posterior decompression via segmental en bloc resection of the posterior wall of the thoracic canal. The ossified ligamentum flavum, laminae, and partial facet joints of each segment were resected en bloc. Ossified dura mater was removed if present. Posterior fixation with pedicle screws was followed by lateral bone graft fusion.

RESULTS

The mean preoperative modified Japanese Orthopaedic Association score (total score, 11) was 4.1 (range, 2-5). Postoperatively, no neurological deterioration occurred, and all patients improved clinically. With an average follow-up of 31.2 months (range, 24-42 mo), the average modified Japanese Orthopaedic Association score was 7.8 (range, 6-10), representing a 2- to 5-point improvement. The average improvement rate was 55.2% (range, 33.3%-83.3%). Most patients were functionally independent at the last follow-up. Forty ossified segments were resected. The average time required for the resection of 1 segment was 77 minutes. Intraoperatively, dural ossification was noted in 11 patients. Complete resection was performed in all patients. Cerebrospinal fluid leakage occurred in 5 patients.

CONCLUSION

Segmental en bloc resection of the posterior wall of the thoracic canal is a safe and effective alternative for OLF-related severe thoracic myelopathy.

Clinical characteristics and surgical outcome of thoracic myelopathy caused by ossification of the ligamentum flavum: a retrospective analysis of 85 cases

STUDY DESIGN

A retrospective comparative study.

OBJECTIVES

To describe the clinical features and radiological findings, to assess the safety and effectiveness of posterior decompressive laminectomy and resection of the ossification of the ligamentum flavum (OLF), and to determine which presurgical and surgical variables were most closely related to postsurgical prognosis of thoracic myelopathy (TM) caused by OLF in China.

METHODS

Eighty-five patients with the diagnosis of TM caused by OLF received surgical treatment from July 1998 to May 2012. Clinical data were collected from medical and operative records. Correlations between the surgical outcome and various factors were also analyzed.

RESULTS

All cases were followed up for a mean of 49.2 months (range, 24-190 months) postoperatively. The mean Japanese Orthopaedic Association score was 3.8 points preoperatively and 8.2 points at the final follow-up, yielding a mean recovery rate of 63.0%. Postoperative complications included transient neurological deficits (9 cases), persistent neurological deficits (4 cases), dural tears (17 cases), cerebrospinal fluid leakage (9 cases), wound dehiscence (2 cases) and wound infection (3 cases). The OLF level (middle thoracic), preoperative duration of symptoms, intramedullary signal change on T2WI and preoperative severity of myelopathy were important predictors of surgical outcome.

CONCLUSIONS

Biomechanical and anatomical factors may have a key role in thoracic OLF progression. Posterior decompressive laminectomy and resection of the OLF can be considered an effective, reliable and safe alternative procedure. The OLF level, preoperative duration of symptoms, intramedullary signal change on T2WI and preoperative severity of myelopathy were confirmed and significantly correlated with the surgical outcome.

Clinical features and surgical outcomes of patients with thoracic myelopathy caused by multilevel ossification of the ligamentum flavum

BACKGROUND CONTEXT

Thoracic myelopathy caused by multilevel (three or more levels) ossification of the ligamentum flavum (OLF) is rare. Little is known about its clinical features, and the surgical outcomes along with its related factors are also unclear.

PURPOSE

To describe the clinical features, assess the safety and effectiveness of surgical decompression, and determine the prognostic factors relevant for patients with thoracic myelopathy caused by multilevel OLF.

STUDY DESIGN/SETTING

A retrospective clinical study.

PATIENT SAMPLE

Seventy-five consecutive multilevel OLF patients who underwent surgical decompression were analyzed.

OUTCOME MEASURES

Modified Japanese Orthopedic Association (JOA) scale and the recovery rate.

METHODS

Patients who underwent surgical decompression for symptomatic multilevel OLF during January 1996 to June 2010 were all included. Clinical data were collected from medical and operative records; patients were evaluated by using the JOA scale preoperatively and during the follow-up. Correlations between the surgical outcome and various factors were also analyzed.

RESULTS

Forty-three men and 32 women with a mean age of 54.7 years (range 36-78 years) were included. The mean number of involved levels is 4.6 and contiguous OLF presented in 73.3% of these patients. The most common involved levels were T10/T11 (15.4%), T9/T10 (13.3%), and T11/T12 (12.5%). Coexisting spinal disorders were found in 41 patients (54.7%). Preoperative evaluation showed the mean JOA score was 5.8±1.7; 37.3% of these patients had mild myelopathy, 53.3% had moderate myelopathy, and 9.3% had severe myelopathy. All patients received posterior laminectomy. The JOA score (mean 8.2±2.1) significantly increased postoperatively (p<.05), and multiple regression analysis showed that preoperative duration of symptoms and preoperative JOA score were important predictors of surgical outcome.

CONCLUSIONS

Laminectomy with partially internal fixation is safe and effective in treatment of patients with symptomatic multilevel OLF. The results of our study show that preoperative JOA score and preoperative duration of symptoms were important predictors for the clinical outcome.

Lumbar spinal stenosis in a young individual as a result of ligamantum flavum ossification: A case report

INTRODUCTION

Symtomatic lumbar ligamantum flavum calcification is quite rare in the young age group.

PRESENTATION OF CASE

The authors report a case of young adult with diagnosis of lumbar spinal stenosis, presenting with leg pain and neurological deficits. Computerized tomography (CT) scan and magnetic resonance (MR) imaging studies revealed ossification of the ligamantum flavum as the causative factor of the disease and the patient recovered completely after the decompressive operation.

DISCUSSION

It is emphasized that attention should be given to this rare etiological factor of lumbar spinal stenosis.

CONCLUSION

Complete relief can be achieved with early and adequate surgery.

Symptomatic myelopathy caused by ossification of the yellow ligament

Objective

This study was performed to describe the clinical presentation, surgical outcome in patients with symptomatic myelopathy caused by ossification of the yellow ligament (OYL).

Methods

The authors reviewed consequent 12 patients in whom posterior decompressive laminectomies were performed for OYL from 1999 to 2005. Diagnostic imagings including simple radiographs, computed tomography and magnetic resonance images were performed in each case. The patients were reviewed to evaluate the clinical presentation, surgical outcome and complications of the operation.

Results

In all patients, OYL was located in the lower thoracic region and all patients presented with numbness on both limbs and pain. Among them, 5 patients presented with gait disturbance due to paraparesis and two patients had sphincter dysfunction. Decompressive laminectomy through a posterior approach using microscope resulted in improvement of symptoms in all patients, but, recovery was incomplete in a half of the patients. The mean postoperative Japanese orthopaedics association (JOA) score was 7.9 when compared with 4.9 in preoperative assessment and the mean recovery rate was 65%. Dural tear was noticed in four patients, so dural repair was performed, but there were no neurological deficits related to neural injury.

Conclusion

OYL is an uncommon cause of myelopathy but it can lead to debilitating thoracic myelopathy. Careful decompressive laminectomy can achieve favorable results.

Epidemiological survey of ossification of the ligamentum flavum in thoracic spine: CT imaging observation of 993 cases

OBJECTIVE

To investigate the characteristics of epidemiological distribution of the ossification of the ligamentum flavum (OLF) in the thoracic spine including the incidence, segmental distribution, and shape.

METHODS

Chest spiral computed tomography scans of 993 cases (male 506, female 487, mean age 60 years, range 5-102 years) who presented due to chest symptoms were analyzed with axial slices combined with sagittal slices. The conditions of OLF in the thoracic spine, including segments, thickness, location, and dural sac compression, were recorded. Prevalence was standardized according to the "Age Structure of Population in Beijing 2008".

RESULTS

Among the population investigated, the standardized prevalence rate was 63.9 %. The standardized prevalence rate for males (68.5 %) was higher than that for females (59.0 %). The highest prevalence rate of OLF was in the 50-59 years age group (79.2 %); however, high density originated it can be found in individuals aged 10-19 years. The comparison of different thoracic segments showed that T10-11 (44.0 %) and T11-12 (41.6 %) had the highest prevalence rates.

CONCLUSION

The prevalence of ossification of the ligamentum flavum was highest in the 50-59 years group, but also occurred in early years. OLF occurs more frequently in the lower than in the upper and middle thoracic regions and its prevalence increases with aging.

Thoracic myelopathy caused by ossification of the yellow ligament in patients with posterior instrumented lumbar fusion

PURPOSE

The objective of this study was to investigate thoracic myelopathy caused by ossification of the yellow ligament (OYL) in patients with posterior instrumented lumbar fusion.

METHODS

Seven patients, who had undergone posterior instrumented lumbar fusion, presented with thoracic myelopathy caused by OYL. No patient had a history of thoracic myelopathy at previous surgery. Instrumented fusions were performed from L1-5 in two patients, L2-5 in three patients and L1-S1 and L2-S1 in one patient each, respectively. MRI and CT scans were performed to confirm cord compression by OYL. Of the seven patients, six patients underwent decompressive laminectomy and OYL removal while one was treated conservatively.

RESULTS

The average time to presentation after first surgery was 63.4 months. OYL was located at T9-10 in two patients, T11-12 in three patients, and T10-11 and T9-11 in one patient each, respectively. All patients had a myelopathic gait and the average Japanese Orthopaedic Association (JOA) score was 3.9, preoperatively. The average JOA score improved from 3.7 to 8 and the average recovery rate was 58.9 % in the six patients who underwent surgical intervention. However, the JOA score fell from 5 to 4 in the one patient who was treated conservatively.

CONCLUSIONS

We report seven patients who suffered from thoracic myelopathy after instrumented lumbar fusion. Surgeons must be aware of the possibility of thoracic myelopathy caused by OYL at the thoracolumbar junction, especially in patients with a complaint of gait disturbance after long instrumented lumbar fusion.

Cyclic tensile strain facilitates the ossification of ligamentum flavum through β-catenin signaling pathway: in vitro analysis

STUDY DESIGN

Histological, immunohistochemical, and real-time reverse transcription-polymerase chain reaction analyses of the expression of cell signaling and transcriptional factors in human ossification of ligamentum flavum (OLF).

OBJECTIVE

To test the hypothesis that β-catenin plays a role in the ossification of OLF cells in response to cyclic tensile strain.

SUMMARY OF BACKGROUND DATA

Several studies have investigated the roles of biomechanical and metabolic factors in the development and progression of OLF, based on the importance of genetic and biological factors. The process of ossification includes enchondral ossification, although such pathology remains poorly defined.

METHODS

Using real-time reverse transcription-polymerase chain reaction, we analyzed the mRNA expression levels of signaling factors known to be involved in the ossification process (β-catenin, Runx2, Sox9, and osteopontin) in cultured OLF cells subjected to cyclic tensile strain. Cyclic tensile strain was produced by Flexercell FX-3000 (Flexercell International, Hillsborough, NC), applied for 0, 6, 12, or 24 hours. The localization of these factors was examined in decalcified paraffin OLF sections by immunohistochemistry. Controlled samples were harvested from nonossified ligamentum flavum of patients who underwent thoracic posterior surgical procedures.

RESULTS

Under resting conditions (no tensile strain), the mRNA levels of β-catenin, Runx2, Sox9, and osteopontin in cultured OLF cells were significantly higher than in the control non-OLF cells. Application of cyclic tensile strain to OLF cells resulted in significant increases in mRNA expression levels of β-catenin, Runx2, Sox9, and osteopontin at 24 hours. Hypertrophic chondrocytes present around the calcification front were immunopositive for Runx2 and osteopontin. Immunoreactivity of β-catenin and Sox9 was strongly present in premature chondrocytes in the fibrocartilage area.

CONCLUSION

Our results indicated that cyclic tensile strain applied to OLF cells activated their ossification through a process mediated by the β-catenin signaling pathway.

Ossification of ligamentum flavum in Middle East Arabs: a hospital-based study

OBJECTIVE

To investigate the frequency of ossification of the ligamentum flavum (OLF) in the spine among the Arab population in Kuwait using magnetic resonance imaging (MRI) surveillance of the whole spine.

SUBJECTS AND METHODS

A consecutive series of 102 patients with low back pain were recruited from the outpatient clinic of Mubarak Al-Kabeer Hospital, Kuwait. MRI of the whole spine in the sagittal plane was obtained in at least two sequences (T(1) and T(2)). The OLF was defined as low signal intensity thickening of the ligament in both T(1) and T(2) sequences on the posterior margin of the spinal canal, causing indentation of the theca with or without cord compression.

RESULTS

Of the 102 cases, 19 (18.6%) patients had OLF. Of the 19 positive cases, 12 (63.2%) were present at a single level, and 7 (36.8%) at multiple levels. A total of 26 OLF segments were identified in the following anatomical distribution: cervical: 15 (57.7%); upper thoracic (T1-T4): 1 (3.8%); mid thoracic (T5-T8): 4 (15.4%); lower thoracic (T9-T12): 4 (15.4%), and lumbar region: 2 (7.7%). Of the 19 OLF patients, 2 (10.5%) had tandem ossification of the posterior longitudinal ligament in the cervical spine and were symptomatic.

CONCLUSIONS

The frequency of OLF appears to be high among this hospital-based cohort of the Arab population. OLF should be kept in mind if a patient presents with radiculopathy, particularly in the cervical region, for which surgical intervention is contemplated.

En bloc resection of lamina and ossified ligamentum flavum in the treatment of thoracic ossification of the ligamentum flavum

OBJECTIVE

We performed a retrospective patient chart review to determine the feasibility and safety of en bloc resection of lamina and ossified ligamentum flavum in the treatment of thoracic ossification of ligamentum flavum (OLF).

METHODS

From January 2000 to June 2006, 36 patients with thoracic OLF underwent en bloc resection of lamina and ossified ligamentum flavum by a burr-grinding technique. The range of resection included one lamina superior and one lamina inferior to the diseased segments. Ossified dura mater was removed if present, and simultaneous repair was carried out.

RESULTS

The mean preoperative Japanese Orthopedic Association (JOA) score (an evaluation system for thoracic myelopathy with a total score of 11 points) was 5 points (range, 3-9 points). The mean JOA score at the last follow-up visit (mean follow-up period, 3.9 years) was 8.44 points (range, 6-11 points). The range of improvement was from 2 to 6 points, and the mean improvement rate was 60.5% (range, 33.3%-100%). No postoperative aggravation of neurological dysfunction, leakage of cerebrospinal fluid (CSF), wound infection, kyphosis, or recurrence occurred. A CSF cyst found in one patient 3 weeks postoperatively was absorbed automatically after 10 months.

CONCLUSION

The en bloc resection technique described here is both safe and effective.

Effect of ligamenta flava hypertrophy on lumbar disc herniation with contralateral symptoms and signs: a clinical and morphometric study

INTRODUCTION

The purpose of this study was to determine whether ligamentum flavum hypertrophy among disc herniated patients causes contralateral pain symptoms. For this reason we measured the thickness of the ligament in disc herniated patients with ipsilateral or contralateral symptoms.

MATERIAL AND METHODS

Two hundred disc herniated patients with ipsilateral symptoms as group I were compared with five disc herniated patients with only contralateral symptoms as group II. Ligamenta flava thicknesses and spinal canal diameters of both groups were measured on magnetic resonance imaging (MRI) with a micro-caliper.

RESULTS

Both groups underwent surgery only on the disc herniated side. The total thicknesses of the ligamenta flava in group II was thicker than in group I. There was no spinal stenosis in either group and no significance difference between the groups. Statistically significant differences were found for both ipsilateral and contralateral thickness of the ligament flava in both groups. We also compared thickness of the ligamenta flava for each level of disc herniation in group I; ligamenta flava hypertrophy was more common at L3-L4 and L4-L5 levels of vertebrae in females.

CONCLUSIONS

Aetiology of contralateral sciatica among disc herniated patients may be related to hypertrophy of the ligamenta flava, especially on the opposite side. Surgical approaches of the disc herniated side alone may be sufficient for a good outcome.

Prevalence, distribution, and morphology of ossification of the ligamentum flavum: a population study of one thousand seven hundred thirty-six magnetic resonance imaging scans

STUDY DESIGN

Large scale, cross-sectional imaging study of a general population.

OBJECTIVES

To evaluate the prevalence, morphology, and distribution of ossification of the ligamentum flavum (OLF) in a population, and synthesize the scientific literature on the prevalence of OLF and some factors associated with its occurrence.

SUMMARY OF BACKGROUND DATA

OLF is a rare disease in which the pathogenesis has not been conclusively established. Little is known about its epidemiology. To date, there is no study that comprehensively assessed the distribution and prevalence of OLF in the whole spine using magnetic resonance imaging (MRI).

METHODS

A total of 1736 southern Chinese volunteers (1068 women; 668 men) between 8 and 88 years of age (mean, 38 years) were recruited by open invitation. MRI was administered to all the participants. T2-weighted, 5-mm spin-echo MRI sequences of the whole spine were obtained. Presence of OLF was identified as an area of low signal intensity in the T2 sagittal sequence located in the posterior part of the spinal canal, and subsequently confirmed by computed tomography scans showing areas of ossification within the ligamentum flavum. The distribution of OLF was classified into 3 types: the isolated type, continuous type, and noncontinuous type. While the morphology of the lesion was classified into triangular, round, and beak shapes based on the pattern of ossification on T2-weighted sagittal MRIs.

RESULTS

OLF was identified in a total of 66 subjects or 3.8% of the population (52 women and 14 men). In 45(68.2%) cases, OLF was present at a single-level (isolated type), whereas in 21 (31.8%) cases OLF was present at multiple levels. The isolated type was found in 45 (68.2%) cases, continuous type in 11 (16.7%), and noncontinuous type in 10 (15.2%). The most common site of involvement is the lower thoracic spine, but they can also occur in the upper thoracic spine. The majority of the segments had a round morphology (n = 75: 81.5%), while 17 (18.5%) segments were triangular in shape. A literature review of the past 26 years showed only 4 reports on the prevalence of OLF, all were in special patient groups.

CONCLUSION

Case reports have described postoperative paraplegia from failure to identify and decompress all stenotic segments of OLF. This study demonstrated that OLF is not uncommon, and that some 15% of the lesions are noncontinuous, and therefore could be missed. The authors recommend that for patients undergoing surgical decompression for 1 level of OLF, the whole spine should be routinely screened for other stenotic segments. Failure to do so could result in paraplegia from the nondecompressed levels.

Ossification of the ligamentum flavum in a Caucasian man

Abnormal ossification of spinal ligaments is a well-known cause of myelopathy in East Asian populations, with ossification of the ligamentum flavum (OLF) and the posterior longitudinal ligament being the most prevalent. In Caucasian populations, OLF is rare, and there has been only 1 documented case of the disease affecting more than 5 spinal levels. In this report, the authors describe the clinical presentation, imaging characteristics, and management of the second published case of a Caucasian man with OLF affecting almost the entire thoracic spine. The literature is then reviewed with regard to OLF epidemiology, pathogenesis, presentation, and treatment.

Symptomatic ossification of the ligamentum flavum at the lumbar spine: a retrospective study

STUDY DESIGN

A retrospective study on 9 patients treated for ossification of the ligamentum flavum (OLF) at the lumbar spine.

OBJECTIVE

To evaluate the clinical and radiologic findings as well as the postoperative results of the patients.

SUMMARY OF BACKGROUND DATA

Ossification of ligamentum flavum (OLF) in the lumbar region causing neurologic impairment is a rare pathologic entity described mainly in Japanese literature. The present study represents the largest surgical series of European patients with OLF at the lumbar spine.

METHODS

A retrospective study of 9 consecutive patients was conducted between 2000 and 2005. The clinical status was evaluated according to the Japanese Orthopedic Association scale. Potential associated disorders were also recorded. Diagnosis in each case was established using computed tomography and magnetic resonance imaging. Whole-spine magnetic resonance imaging was routinely used in order to reveal possible coexisting spinal lesions. Pathologic confirmation was available in all cases.

RESULTS

Radicular pain was the most common presenting symptom. Myotomal weakness was found in most of the cases. A majority of our patients had lesions located at the L3-L5 levels. Thoracic OLF was recorded as a spinal coexisting ossified lesion. Surgery led to neurologic improvement with a statistically significant increase in the Japanese Orthopedic Association score (P = 0.007). The median recovery rate was 91.60% +/- 43.85%.

CONCLUSION

It is possible that OLF is underreported in the Greek population. Surgical treatment is important in order to improve functional outcomes.

COL6A1 polymorphisms associated with ossification of the ligamentum flavum and ossification of the posterior longitudinal ligament

STUDY DESIGN

A case-control association study was conducted to investigate the genetic etiology for ossification of the ligamentum flavum (OLF) and ossification of the posterior longitudinal ligament of the spine (OPLL).

OBJECTIVE

To determine whether COL6A1 polymorphisms are associated with susceptibility to OLF and OPLL in Chinese Han population.

SUMMARY OF BACKGROUND DATA

The COL6A1 has been identified as a susceptibility gene for OPLL in Japanese. The susceptibility gene for OPLL may be different among various populations, so we investigated whether COL6A1 polymorphisms are also associated with OPLL in Chinese Han population. OLF and OPLL are similar in epidemiology, etiology, and pathology, and common coexist. Hereditary factors may be implicated in OLF and COL6A1 may be a potential susceptibility gene for OLF, so we investigated the relations between COL6A1 polymorphisms and OLF.

METHODS

Four known single nucleotide polymorphisms (SNPs) of COL6A1 were genotyped among 338 Chinese Han subjects by high throughput GenomeLab SNPstream genotyping system. Allele frequency and genotype distribution of each polymorphism were compared using a contingency chi2 test between 183 cases (90 OPLL, 61 OLF, and 32 OPLL coexisting with OLF) and 155 controls.

RESULTS

Among 4 studied SNPs, allele frequency of promoter (-572T) SNP demonstrated the most significant difference not only between OPLL cases and controls (P = 2.65E-4), but also between OLF cases and controls (P =7.38E-4). Moreover, the overall frequency of haplotypes constructed from promoter (-572), intron 32 (-29), and intron 33 (+20) SNPs showed significant difference not only between the patients with OPLL and controls, but also between the patients with OLF and controls (P = 5.86E-3, P = 1.5E-8, respectively).

CONCLUSION

This is the first report on SNPs of COL6A1 in OLF that suggests polymorphisms may be a risk factor for OLF. Our findings indicate that COL6A1 may be a common susceptibility gene for OLF and OPLL in Chinese Han population.

Surgical outcome of thoracic myelopathy secondary to ossification of ligamentum flavum

OBJECTIVES

Thoracic myelopathy secondary to OLF is a rare disease described almost exclusively in Japanese patients. Few series of OLF in South Korean subjects has previously been published. This study is to describe the clinical and radiologic aspects, as well as surgical outcomes in a group of South Korean patients.

METHODS

A retrospective study of 8 consecutive patients, including 4 men and 4 women (mean age, 55.6 years), was conducted from 2002 to 2005. Diagnosis in each case was established using CT. Magnetic resonance imaging was also performed in every case. All patients treated surgically and pathologic studies were performed. A comparison between the preoperative neurological status and the status at follow-up was done using Japanese Orthopaedic Association (JOA) scoring system.

RESULTS

Walking difficulties were the most common presenting complaint. A picture of spastic paraparesis associated with sphincter dysfunction was the most common finding on initial examination. In each case, CT provided sufficient information to establish a diagnosis of OLF, while magnetic resonance imaging was helpful for showing spinal cord involvement. In most of the patients, OLF was located in the lower thoracic spine (T10-T11). Decompressive laminectomy with excision of the OLF resulted in significant improvement in motor weakness and gait in 5 (2 excellent, 3 good) patients who had short duration and no hyperintense intramedullary lesion of spinal cord on MRI. All patients improved in their gait and spasticity, but 2 patients had persistent sensory deficit.

CONCLUSION

OLF is a rare cause of thoracic myelopathy. The frequency appears to have been rarely reported in South Korean subjects. CT with sagittal reconstructions and MRI are helpful for diagnosis and spinal cord involvement. When neurologic symptoms develop, decompressive laminectomy should be done immediately and the surgical outcome is generally good if hyperintense intramedullary signal changes of spinal cord have not yet developed.

Pathophysiology of cervical myelopathy

BACKGROUND CONTENT

Cervical myelopathy is a group of closely related disorders usually caused by spondylosis or by ossification of the posterior longitudinal ligament and is characterized by compression of the cervical spinal cord or nerve roots by varying degrees and number of levels. The decrease in diameter of the vertebral canal secondary to disc degeneration and osteophytic spurs compresses the spinal cord and nerve roots at one or several levels, producing direct damage and often secondary ischemic changes.

PURPOSE

Clinicians who treat cervical myelopathy cord injuries should have a basic understanding of the pathophysiology and the processes that are initiated after the spinal cord has been injured.

STUDY DESIGN/SETTING

Literature review.

METHODS

Literature review of human cervical myelopathy and clinically relevant animal models to further our understanding of the pathological mechanisms involved.

RESULTS

The pathophysiology of cervical myelopathy involves static factors, which result in acquired or developmental stenosis of the cervical canal and dynamic factors, which involve repetitive injury to the cervical cord. These mechanical factors in turn result in direct injury to neurons and glia as well as a secondary cascade of events including ischemia, excitotoxicity, and apoptosis; a pathobiology similar to that occurring in traumatic spinal cord injury.

CONCLUSIONS

This review summarizes some of the significant pathophysiological processes involved in cervical myelopathy.

Surgical treatment of 40 patients with thoracic ossification of the ligamentum flavum

OBJECT

The authors evaluated different surgical methods used to treat thoracic ossification of the ligamentum flavum (OLF).

METHODS

Data obtained in 40 patients who underwent posterior decompression for thoracic myelopathy caused by thoracic OLF were studied retrospectively. There were 32 men and eight women. All patients underwent posterior decompression in which laminoplasty was performed or laminectomy combined with lateral fusion. Every surgical specimen was stained with H & E, and scanning electron microscopy was performed in 20 cases. The mean follow-up period was 28 months. Postoperative outcomes were evaluated using a recovery scale based on the Japanese Orthopaedic Association classification. There were a total of 168 ossified segments in this series, 77.4% of which were located in the lower thoracic spine. Marginal osteophyte formation was found in 36 patients; in 32 of the 36 patients, these marginal osteophytes were located at the intervertebral space either higher or lower than the ossified segment. Scanning electron microscopy showed elastic fiber breakdown, proliferation of collagenous fibers, calcification, and OLF in the same microscopy region. Laminoplasty was performed in four patients. In three cases surgery resulted in unchanged or worse outcome (increased kyphotic deformity in two), and in one it resulted in good outcome. Laminectomy combined with lateral fusion was performed in 36 patients, in 30 cases of which it resulted in a good or fair outcome, and increased kyphotic deformity in only one. Of these 36 laminectomy-treated patients, an en bloc laminectomy-treated procedure was performed in 16 patients; in 11 of the 12 patients with lateral or diffuse-type lesions the surgery resulted in a good or fair outcome. En bloc laminectomy, however, seems ineffective in the treatment of patients with thickened, nodular-type thoracic OLF, as the procedure resulted in worse outcome in two of the four patients. The authors have thus developed a new modality of laminectomy that they have termed "separating laminectomy," which they performed in 16 patients with thickened, nodular-type OLF; in 13 cases it resulted in a good or fair outcome, and in only one case did it result in a worse outcome.

CONCLUSIONS

The pathogenesis of thoracic OLF is mainly due to the localized mechanical stress on the ligament. Laminectomy combined with lateral fusion is the treatment of choice for thoracic OLF; furthermore, in terms of the configuration of the ossified lesion, en bloc laminectomy is suitable for the treatment of lateral-type and diffuse-type OLF, and the separating laminectomy is suitable for the thickened, nodular-type OLF.

Spinal compression due to ossified yellow ligament: a short series of 5 patients and literature review

BACKGROUND

Ossification of ligamentum flavum in the thoracic region causing compressive myelopathy among middle-aged patients is a poorly described entity.

CASE DESCRIPTION

Five patients of Indian origin with OYL are described. Their clinical presentations, surgical options, and long-term outcome are presented. Radiologic and clinical follow-up of one of the patient is described over a span of 10 years.

CONCLUSIONS

Decompressive laminectomy and excision of the OYL is the commonly performed surgical procedure. A rapid neurologic improvement follows decompression. The persistent spasticity in certain patients is attributed to irreversible changes within the cord. The disease is thought to be progressive in nature. The prolonged follow-up of these patients suggests that the long-term prognosis is poor. Selective racial involvement and variable clinical presentations, with treatment options, are discussed.

Clinical and prognostic analysis of ossified ligamentum flavum in a Chinese population

OBJECT

The authors performed a retrospective study of clinical and radiological data obtained in 27 Chinese patients with myelopathy induced by ossification of the ligamentum flavum (OLF) who underwent surgery between March 1990 and March 2002. The factors related to surgical outcome of thoracic OLF-induced myelopathy were also assessed.

METHODS

The preoperative clinical features and radiological findings were reviewed retrospectively. Preoperative and postoperative neurological status was assessed using the Japanese Orthopaedic Association (JOA) scoring system and the Nurick Scale. The ossified lesions were classified into five types (lateral, extended, enlarged, fused, and tuberous). Multiple linear regression and logistic regression analyses were performed to establish the factors affecting surgical outcome. The patients' chief complaints were lower-limb weakness and gait disturbance (93%), numbness and sensory deficit (89%), and low-back pain (48%). The coexisting pathological entities were disc herniation, canal stenosis, and ossification of posterior longitudinal ligament. The ossified ligamentum flavum was mainly located at the T10-12 (67%) and T1-3 (15%) levels. Symptoms in 26 patients improved but resolved completely in only 14 after surgery. The mean overall JOA score was 5.3 +/- 1.9 preoperatively and 7.9 +/- 2.3 postoperatively. There is a significant difference between the pre- and postoperative neurological status (p < 0.05) determined by the Student t-test. The recovery rate was 46.3 +/- 9.4%. Multiple regression analysis revealed negative correlation between the duration of preoperative symptoms and surgical outcome as well as a positive correlation between the preoperative JOA score and surgical outcome. Logistic regression analysis demonstrated that fecal and/or urinary incontinence, positive patellar and/or ankle clonus, and intramedullary high T2-weighted magnetic resonance (MR) imaging signal change had negative effects on the surgical outcome.

CONCLUSIONS

The clinical and radiological features of OLF in the Chinese population are similar to those observed in the Japanese population. The duration of preoperative symptoms and JOA score are the most important predictors of the postoperative JOA score and recovery rate. The patients with fecal and/or urinary incontinence, positive patellar and/or ankle clonus, and intramedullary high T2-weighted MR imaging signal change were at higher risk of poor outcome after surgery.

Symptomatic ossification of the ligamentum flavum: a clinical series from the French Antilles

STUDY DESIGN

A series of 14 patients from the French Antilles treated for ossification of the ligamentum flavum (OLF).

OBJECTIVES

To describe the clinical and radiologic aspects, as well as disease course in a group of Caribbean patients. Also describe the use of sagittal computerized tomography (CT) reconstructions to distinguish OLF from calcification of the ligamenta flava.

SUMMARY OF BACKGROUND DATA

OLF is a rare disease described almost exclusively in Japanese patients. Only rarely are patients of African descent affected. No series of OLF in African American or African Caribbean subjects has previously been published.

METHODS

A retrospective study of 14 consecutive patients, including 7 men and 7 women (mean age, 66.8 years), was conducted from 1996 to 2003. Diagnosis in each case was established using CT. Magnetic resonance imaging was also performed in every case. For the 11 patients treated surgically, pathology studies were performed.

RESULTS

Walking difficulties were the most common presenting complaint. A picture of spastic paraparesis associated with sphincter dysfunction was the most common finding on initial examination. In each case, CT provided sufficient information to establish a diagnosis of OLF, while magnetic resonance imaging was helpful for showing spinal cord involvement. In most of the patients, OLF was located in the lower thoracic spine. Surgical decompression through a posterior approach resulted in regression of symptoms in all 11 patients treated surgically.

CONCLUSIONS

This study is the first reported series of OLF in a group of Caribbean patients. The disease appears to be underreported in the African Caribbean population. OLF can lead to debilitating thoracic myelopathy. Surgery is frequently indicated and achieves favorable results.

Cough induced by ossification of the ligamentum flavum in the high cervical spine

✓ The authors report a very rare case of high cervical ossification of the ligamentum flavum (OLF) in a 40-year-old woman who developed an intractable cough after a traffic accident. The patient's symptoms subsided immediately after decompressive laminectomy and removal of the lesion. To the authors' knowledge, this is the first reported case of high cervical OLF in a patient who presented with a cough. The pathophysiological mechanism underlying the cough was determined to be symptomatic of high cervical spine OLF.

Radiculopathy due to ossification of the yellow ligament at the lower lumbar spine

STUDY DESIGN

A case report.

OBJECTIVES

To report a rare case of a 27-year-old female with ossification of yellow ligament at the lower lumbar spine presenting radiculopathy with a drop foot.

SUMMARY OF BACKGROUND DATA

The majority of cases of ossification of yellow ligament occur at the lower third of the thoracic or the thoracolumbar spine. There are only a few reports of ossification of yellow ligament in the lumbar spine and radiculopathy due to ossification of yellow ligament at L4-L5 and L5-S1 levels is very uncommon.

METHODS

A 27-year-old female with a prior fracture of posterior ring apophysis of L5 presented with leg pain and a drop foot. Magnetic resonance imaging demonstrated stenosis with compression of the cauda equina at the L4-L5 and L5-S1 levels.

RESULTS

Decompressive laminectomy of L5 and removal of the ossified yellow ligaments were performed. Histologic examination of en bloc specimen of ossification of yellow ligament revealed degenerative changes of the elastic fibers in the yellow ligament with adjacent chondrosis and ossification. The patient's severe leg pain disappeared completely, although the extent of the drop foot had not fully recovered at the final follow-up examination.

CONCLUSIONS

The mechanism of ossification of yellow ligament in the present case was unclear. The patient did not have any previous generalized disorders besides the history of a ring apophysial fracture or any family history of treatment for ossification of the posterior longitudinal ligament or ossification of yellow ligament. Therefore, localized mechanical stress might have influenced the development of ossification of yellow ligament at lower lumbar spine.

Thoracic myelopathy caused by ossification of the ligamentum flavum: a report of 18 cases

OBJECT

Thoracic myelopathy caused by ossification of the ligamentum flavum (OLF) is a rare entity, most evident in Japan. The authors studied the clinical manifestations, radiological aspects, surgical treatment, and pathogenesis of this disease.

METHODS

Eighteen patients with OLF-induced thoracic myelopathy underwent laminectomy. The severity of myelopathy varied. Complete paraplegia was seen in three cases. Compression of the upper and middle third of the thoracic spine was evident in six cases and of the lower third in 12 cases. Multilevel OLF was demonstrated in 13 cases. In most cases, the ossified ligamentum flavum appears as a V-shaped lesion on computerized tomography and magnetic resonance images. In all patients the diameter of the posterior spinal canal, already narrowed, was further exacerbated by the OLF. Laminectomy was limited to the levels of compression, and the ligamentum flavum was resected in all cases. The symptoms and signs improved in 13 cases and stabilized in four cases. In one case symptoms recurred as a result of ossified lesions forming at other sites. Histological examination showed that the mode of development of the ossified ligaments was endochondral ossification.

CONCLUSIONS

Reports of OLF-induced myelopathy are rare and mainly described in Japan. The incidence also seems high in North Africa. An early laminectomy limited to the level of compression is recommended. Ossified ligamentum flavum is different from the calcification of the ligamentum flavum, which is due to crystal deposits.

Paraparesis in a black man brought on by ossification of the ligamentum flavum: case report and review of the literature

We present the second case of paraparesis secondary to ossification of the ligamentum flavum at the midthoracic region in a black man. Ossification of the ligamentum flavum is frequently described in the Japanese population where the presentation is often in the lower thoracic region. The patient is a 37-year-old black man who, over the 6 months before admission, noticed progressive paraparesis. CT myelogram revealed severe thoracic stenosis by an ossified ligamentum flavum from T4 to T7 with most severe involvement at the T5, T6, and T7 levels. The patient underwent multilevel laminectomies and medial facetectomies from T4 to T7. Over the past decade, ossification of the ligamentum flavum has been reported with increasing frequency in non-Asian patients. This is the third case report in a black man. In addition, ossification of the ligamentum flavum in this particular location is rarely reported. The increased use of advanced neuroimaging techniques in the evaluation of "back pain" may reveal that the prevalence of this condition is higher than expected in non-Asian populations. Improvement in neurologic symptoms secondary to decompressive laminectomies will depend on the degree and duration of spinal cord compression.

Myelopathy caused by ossification of ligamentum flavum

STUDY DESIGN

Retrospective study of seven cases of ossification of ligamentum flavum from two urban hospitals in a Chinese population.

OBJECTIVES

To inspect the epidemiology, clinical presentation, pathology, and treatment outcome in these Chinese patients with ossification of ligamentum flavum.

SUMMARY OF BACKGROUND DATA

Ossification of ligamentum flavum involving the lower thoracic region is relatively common in the Japanese population. It is usually presented with myelopathy of progressive nature.

MATERIALS AND METHODS

Five patients were male and two were female. The mean age was 52 years (range 41-73 years). Diagnosis was made by CT scan, MRI, and subsequent histology. Six patients have been treated by laminectomy and one by laminoplasty. The average follow-up duration is 34 months (range 26-44 months). The outcome is evaluated by Japanese Orthopaedics Association (JOA) score.

RESULTS

The average time of presentation from the onset of symptoms was 9 months (range 3-12 months). Most of the patients presented with lower limb numbness and gait disturbance. One case was presented after a minor trauma. Mean JOA score was 4.8 (range 2-7, of 11). The lower thoracic level was the most frequently involved region. One case was associated with ossification of the posterior longitudinal ligament. Two patients had transient postoperative neurologic deterioration, which improved subsequently. Mean percentage of recovery after surgery in terms of JOA score is 65% (25-100%), with a mean final JOA score of 7.8.

CONCLUSION

Ossification of ligamentum flavum is an uncommon cause of myelopathy in the Chinese population. It can present acutely after minor trauma. Posterior decompression, especially with en bloc dissection of laminae, gives satisfactory results.

Six cases of cervical ligamentum flavum calcification in Blacks in the French West Indies

OBJECTIVE

Calcification of the ligamentum flavum at the cervical spine is an uncommon condition reported mainly in Japanese patients. We describe the clinical manifestations, imaging study findings, and outcomes in six cases seen in the French West Indies.

MATERIAL AND METHODS

We retrospectively reviewed the medical charts of six patients admitted to an orthopedics department for spinal cord compression shown upon computed tomography to be caused by calcification of the ligamentu flavum. There were five women and one man, mean age at admission was 71.7 years (range, 64-79 years) and all six patients were Black.

RESULTS

Five patients had cervical myelopathy and one was asymptomatic. All five symptomatic patients had cervical spinal stenosis, explaining the rapid symptom onset (within six and a half months) and severe motor loss. Computed tomography reconstruction in the sagittal plane ruled out ossification of the ligamentum flavum. Magnetic resonance imaging of the neck failed to demonstrate the calcifications but was useful in evaluating the severity of the spinal cord compression. One patient had articular chondrocalcinosis in both knees and another had calcifications in the basal ganglia. Surgical decompression by the posterior route was performed in two patients and was effective in both, whereas two of the three symptomatic patients who did not have surgery experienced worsening neurological loss. Analysis of the operative specimens from the two surgically treated patients showed a mixture of calcium pyrophosphate dihydrate crystals and apatite microcrystals.

CONCLUSION

Calcification of the ligamentum flavum is probably underrecognized in blacks. This condition causes severe neurological loss. Imaging studies provide the diagnosis. The pathogenesis remains unclear.

Ossification of the ligamentum flavum as a cause of myelopathy in North America: report of three cases

Myelopathy caused by ossification of the ligamentum flavum is a rare condition in North America. The authors describe three patients whose myelopathy was attributed to posterior cord compression warranting laminectomy to decompress the cervical spine (in one patient) and the thoracic spine (in two patients). The spinal computed tomographic scan (especially after myelography) can be instrumental in guiding the management of this condition.

Thoracic myelopathy due to enlarged ossified yellow ligaments. Case report and review of the literature

Enlarged ossified yellow ligaments are a rare and poorly understood cause of thoracic myelopathy. The authors report the case of a patient in whom thoracic myelopathy was caused by enlarged ossified yellow ligaments.