Transient paraparesis after laminectomy for thoracic ossification of the posterior longitudinal ligament and ossification of the ligamentum flavum

White Cord Syndrome: A Treatment Dilemma

Spinal cord reperfusion injury following decompressive surgery is extremely rare. This complication is known as white cord syndrome (WCS). A 61-year-old male presented with chronic neck stiffness associated with left C6/C7 radiculopathy and numbness. Magnetic resonance imaging (MRI) of the cervical spine reported a severely narrowed left C6/C7 neural exit canal. C6/C7 anterior cervical decompression and fusion (ACDF) was performed. There was no significant intraoperative injury. On postoperative day 6, the patient developed bilateral C8 numbness, which started post-operation. He was treated for surgical site inflammation and was prescribed prednisolone and amitriptyline. However, his condition progressively worsened. At postoperative six weeks, there was right hemisensory loss, right triceps atrophy, and positive right Lhermitte's and Hoffman's tests. This subsequently progressed to right C7 weakness and bilateral lower limb radiculopathy at postoperative eight weeks. Postoperative MRI of the cervical spine revealed a new focal gliosis/edema within the spinal cord at C6/C7. The patient was treated conservatively with pregabalin and was referred for rehabilitation. Early diagnosis and treatment initiation are crucial in the management of WCS. Surgeons should be aware of this potential complication and counsel patients on the risk prior to surgery. Magnetic resonance imaging (MRI) remains the gold standard in the diagnosis of WCS. The current mainstay of treatment is high-dose steroids, intraoperative neurophysiological monitoring, and early recognition of postoperative WCS.

"White cord syndrome after cervical or thoracic spinal cord decompression. Haemodynamic complication or mechanical damage? An understimated nosographic entity"

The ischemia-reperfusion mechanism is believed to be responsible for parenchymal damage caused by temporary hypoperfusion and worsened by the subsequent attempt of reperfusion. This represents a true challenge for physicians of several fields, including neurosurgeons. A limited number of papers have shed the light on a rare pathological condition that affects patients experiencing an unexplained neurological deficit after spine surgery, the so-called "white cord syndrome". This entity is believed to be caused by an "ischemia-reperfusion" injury on the spinal cord, documented by a post-operative intramedullary hyperintensity on T2 weighted MRI sequences. To date, the cases of white cord syndrome reported in literature mostly refer to cervical spine surgery. However, the analysis of several reviews focusing on spine surgery outcome suggest that post-operative neurological deficits of new onset could be charged to a mechanism of ischemia-reperfusion, even if the physiopathology of this event is seldom explored or at least discussed. The same neuroradiological finding can suggest a mechanical damage due to surgical inappropriate manipulation. On this purpose, we performed a systematic revision of literature with the aim to identify and analyze all the factors potentially contributing to ischemic-reperfusion damage of the spinal cord that may potentially complicate any spinal surgery, without distinction between cervical or thoracic segment. Finally, we believe that post-operative neurological deficit after spinal surgery constituting the "white cord syndrome", could be underreported, while both neurosurgeons and patients should be fully aware of this rare but potentially devasting complication burdening cervical and thoracic spine surgery.

Top 50 Most Cited Articles on Thoracic Ossification of Posterior Longitudinal Ligament

Study Design

Bibliometric analysis.

Objective

Over the last several decades, the field of thoracic ossification of the posterior longitudinal ligament (T-OPLL) has evolved unprecedentedly, and the literature on T-OPLL has increased significantly. The purpose of this study is to identify and review the top 50 most cited publications related to T-OPLL.

Methods

The most frequently cited 50 articles in this field until 30 October 2021 were identified by searching Web of Science. We ranked the articles based on the citation number. Through the bibliometric method, we evaluated the following information: article title, first author, year of publication, journal of publication, total number of citations, country, and study topic.

Results

The number of citations of included studies ranged from 20 to 108, with a mean number of 45.4. The journal Spine published most articles (20), followed by Spinal Cord (5), and European Spine (5). All of these articles were contributed by 38 first authors, Yamazaki (4), Fujimura (3), and Aizawa (3) who published more than 2 articles. In the respect of productive countries, Japan (39) contributed most papers. Tomita contributed the most cited article in 1990 on Spine, which was the first-ever report of circumferential decompression for thoracic myelopathy due to T-OPLL.

Conclusion

The top 50 influential articles on T-OPLL were identified and analyzed in this study. It will undoubtedly provide a comprehensive and detailed basis for the orthopedic and neurosurgery physicians to make a clinical decision and assimilate the research focus of spine surgery.

Postoperative progression of ligamentum flavum ossification after posterior instrumented surgery for thoracic posterior longitudinal ligament ossification: long-term outcomes during a minimum 10-year follow-up

OBJECTIVE

The authors sought to investigate clinical and radiological outcomes after thoracic posterior fusion surgery during a minimum of 10 years of follow-up, including postoperative progression of ossification, in patients with thoracic ossification of the posterior longitudinal ligament (T-OPLL).

METHODS

The study participants were 34 consecutive patients (15 men, 19 women) with an average age at surgery of 53.6 years (range 36-80 years) who underwent posterior decompression and fusion surgery with instrumentation at the authors' hospital. The minimum follow-up period was 10 years. Estimated blood loss, operative time, pre- and postoperative Japanese Orthopaedic Association (JOA) scores, and JOA score recovery rates were investigated. Dekyphotic changes were evaluated on plain radiographs of thoracic kyphotic angles and fusion levels pre- and postoperatively and 10 years after surgery. The distal junctional angle (DJA) was measured preoperatively and at 10 years after surgery to evaluate distal junctional kyphosis (DJK). Ossification progression at distal intervertebrae was investigated on CT.

RESULTS

The Cobb angles at T1-12 were 46.8°, 38.7°, and 42.6°, and those at the fusion level were 39.6°, 31.1°, and 34.1° pre- and postoperatively and at 10 years after surgery, respectively. The changes in the kyphotic angles from pre- to postoperatively and to 10 years after surgery were 8.0° and 7.2° at T1-12 and 8.4° and 7.9° at the fusion level, respectively. The DJA changed from 4.5° postoperatively to 10.9° at 10 years after surgery. There were 11 patients (32.3%) with DJK during follow-up, including 4 (11.8%) with vertebral compression fractures at lower instrumented vertebrae or adjacent vertebrae. Progression of ossification of the ligamentum flavum (OLF) on the caudal side occurred in 8 cases (23.6%), but none had ossification of the posterior longitudinal ligament (OPLL) progression. Cases with OLF progression had a significantly lower rate of DJK (0% vs 38.5%, p < 0.01), a lower DJA (3.4° vs 13.2°, p < 0.01), and a smaller change in DJA at 10 years after surgery (0.8° vs 8.1°, p < 0.01).

CONCLUSIONS

Posterior decompression and fusion surgery with instrumentation for T-OPLL was found to be a relatively safe and stable surgical procedure based on the long-term outcomes. Progression of OLF on the caudal side occurred in 23.6% of cases, but cases with OLF progression did not have DJK. Progression of DJK shifts the load in the spinal canal forward and the load on the ligamentum flavum is decreased. This may explain the lack of ossification in cases with DJK.

Spinal reperfusion syndrome. A literature review and medicolegal implications

Aim. To consider the diagnosis of spinal reperfusion syndrome (SRS) and its medicolegal implications.Materials and Methods. . A PRISMA guided PubMed search was performed to identify cases of possible SRS following spinal surgery.Result. Fourteen papers suggested that SRS might be the cause of neurological deterioration. In patients undergoing surgery for cervical degenerative disorders there were 7 patients who had new deficits immediately on awakening from the anaesthetic. There were 6 patients who had no new deficit immediately post-surgery with new deficits occurring within hours, or up to 3 days post-surgery.Conclusion. There is no agreed clinical definition of the SRS and the radiological abnormalities are not defined. The diagnosis of SRS can potentially be made by exclusion or inclusion. If there is a known cause of new neurological deficits intra- or immediately post-operatively, such as for example intraoperative cord injury, inadequate decompression or a haematoma, that is the probable diagnosis, not SRS. If a patient awakes with new deficits the most likely cause (if no other cause is identified) is intraoperative injury to the cord. If there is delayed deterioration with no cause identified SRS is a possible explanation. New deficits occur in 0.5 to 1.0% of patients undergoing anterior cervical spine surgery i.e. overall this is common whereas SRS is rare. The medicolegal implications are discussed.

Efficacy of Intraoperative Intervention Following Transcranial Motor-evoked Potentials Alert During Posterior Decompression and Fusion Surgery for Thoracic Ossification of the Posterior Longitudinal Ligament: A Prospective Multicenter Study of the Monitoring Committee of the Japanese Society for Spine Surgery and Related Research

STUDY DESIGN

Prospective, multicenter, observational study.

OBJECTIVE

The aim of this study was to investigate the efficacy of intervention after an alert in intraoperative neurophysiological monitoring (IONM) using transcranial motor-evoked potentials (Tc-MEPs) during surgery for thoracic ossification of the posterior longitudinal ligament (T-OPLL).

SUMMARY OF BACKGROUND DATA

T-OPLL is commonly treated with posterior decompression and fusion with instrumentation. IONM using Tc-MEPs during surgery reduces the risk of neurological complications.

METHODS

The subjects were 79 patients with a Tc-MEP alert during posterior decompression and fusion surgery for T-OPLL. Preoperative muscle strength (manual muscle testing [MMT]), waveform derivation rate at the start of surgery (baseline), intraoperative waveform changes; and postoperative motor paralysis were examined. A reduction in MMT score of ≥1 on the day after surgery was classified as worsened postoperative motor deficit. An alert was defined as a decrease in Tc-MEP waveform amplitude of ≥70% from baseline. Alerts were recorded at key times during surgery.

RESULTS

The patients (35 males, 44 females; age 54.6 years) had OPLL at T1-4 (n = 27, 34%), T5-8 (n = 50, 63%), and T9-12 (n = 16, 20%). The preoperative status included sensory deficit (n = 67, 85%), motor deficit (MMT ≤4) (n = 59, 75%), and nonambulatory (n = 26, 33%). At baseline, 76 cases (96%) had a detectable Tc-MEP waveform for at least one muscle, and the abductor hallucis had the highest rate of baseline waveform detection (n = 66, 84%). Tc-MEP alerts occurred during decompression (n = 47, 60%), exposure (n = 13, 16%), rodding (n = 5, 6%), pedicle screw insertion (n = 4, 5%), posture change (n = 4, 5%), dekyphosis (n = 2, 3%), and other procedures (n = 4, 5%). After intraoperative intervention, the rescue rate (no postoperative neurological deficit) was 57% (45/79), and rescue cases had a significantly better preoperative ambulatory status and a significantly higher baseline waveform derivation rate.

CONCLUSION

These results show the efficacy of intraoperative intervention following a Tc-MEP alert for prevention of neurological deficit postoperatively.Level of Evidence: 2.

Novel Simultaneous Decompression Through Single-stage Mini-thoracotomy for Concurrent Ossification of the Posterior Longitudinal Ligament and Ossification of the Ligamentum Flavum at the Same Thoracic Level: A Technical Report and Literature Review

STUDY DESIGN

Technical case report.

OBJECTIVE

To describe a novel technique of decompression through single-stage mini-thoracotomy for removing concurrent ossification of the posterior longitudinal ligament (OPLL) and ossification of the ligamentum flavum (OLF) at the same thoracic level simultaneously.

SUMMARY OF BACKGROUND DATA

Concurrent OPLL and OLF at the same thoracic level is not common. Because these conditions lead to severe thoracic myelopathy, however, they require surgical decompression.To date, several cases with concurrent OPLL and OLF at the same thoracic level and surgical methods to treat these conditions have been described. However, no consensus on the surgical methods for the treatment these conditions has been established and these surgical methods have been also reported to be linked with the incidence of complication like neurological deterioration and the requirement of bone grafting and instrumentation.

METHODS

Three consecutive patients who presented with thoracic myelopathy caused by concurrent OPLL and OLF at the same thoracic level were treated by our novel surgical technique of decompression through single-stage mini-thoracotomy.

RESULTS

Simultaneous complete removal of OPLL and OLF through single-stage mini-thoracotomy was performed successfully in the three patients. All patients' preoperative symptoms gradually improved during the follow-up period, and no additional complications were associated with removal of OLF through thoracotomy. And there was no kyphotic change or instability in the thoracic spine after more than a year of follow-up although both bone grafting and instrumentation were not performed.

CONCLUSION

This novel surgical technique is considered to be able to be a safe and effective alternative to the conventional treatment of selective cases of thoracic myelopathy caused by concurrent OPLL and OLF at the same thoracic level.Level of Evidence: 4.

Bilateral translaminar osseous-channel assisted percutaneous full-endoscopic ligamentectomy decompression for thoracic myelopathy due to ossification of the ligamentum flavum: a technical note

Introduction

A variety of surgical procedures have been introduced to treat patients with thoracic myelopathy (TM) caused by ossification of the ligamentum flavum (OLF). However, they are accompanied by significant trauma and risk, and their surgical outcomes are not always satisfactory.

Aim

To describe a bilateral translaminar osseous-channel assisted posterior percutaneous full-endoscopic ligamentectomy decompression (p-PELD) technique as a novel minimally invasive procedure for treating patients with TM due to OLF.

Material and methods

A 51-year-old female patient with persistent thoracolumbar back pain and progressive numbness in the bilateral lower extremities for 2 years underwent percutaneous vertebroplasty (PVP) for T11 osteoporotic compression fractures (OCF) in a regional hospital one week prior to hospitalization. TM caused by canal stenosis and dorsal spinal cord compression at T10/11 secondary to OLF and an OCF at T11 were diagnosed based on clinical presentations and radiologic examinations. After bilateral p-PELD for TM was performed at T10/11, the result was confirmed based on postoperative radiographic and clinical results.

Results

The bilateral OLF was completely removed by the p-PELD technique. No complications were encountered, and her symptoms were sufficiently improved after surgery. The VAS score was 6 points preoperatively and decreased to 0 points at the last follow-up (24 months). The modified Japanese Orthopaedic Association (mJOA) score improved from 2 points preoperatively to 10 points at the final follow-up.

Conclusions

As a minimally invasive technique, the bilateral translaminar osseous-channel assisted p-PELD procedure provided precise and sufficient decompression for the treatment of OLF-related TM.

'White cord syndrome', a rare but disastrous complication of transient paralysis after posterior cervical decompression for severe cervical spondylotic myelopathy and spinal stenosis: A case report

Transient paralysis following spinal decompression surgery is a rare but devastating postoperative complication. Spinal cord ischemia-reperfusion injury has been identified as one of the crucial pathogenic factors contributing to the sudden neurological deterioration associated with spinal decompression surgery. 'White cord syndrome' is a characteristic imaging manifestation of spinal cord ischemia-reperfusion injury, referring to high intramedullary signal changes in the sagittal T2-weighted MRI scan with unexplained neurological deficits following surgical decompression. The present study reported on the case of a 51-year old male patient who suffered from acute left limb hemiplegic paralysis following posterior cervical laminectomy decompression for severe cervical spondylotic myelopathy and spinal stenosis, which were caused by ossification of the posterior longitudinal ligament. The patient's neurological function gradually improved after the immediate administration of high-dose methylprednisolone therapy combined with mannitol and neurotrophic drugs. At the 2-month follow-up, the intensity of the spinal cord signal on MRI had almost returned to normal and the 'white cord syndrome' had disappeared. However, the patient complained of postoperative neck swelling pain caused by cerebrospinal fluid leakage; therefore, an additional cerebrospinal fluid leakage exploration and neoplasty were performed. At 2 weeks after the second surgery, the patient's neck swelling pain was relieved and the area of cerebrospinal fluid leakage was significantly reduced. Despite the low incidence rate, surgeons should be aware of this complication, particularly when treating chronic severe cervical spinal stenosis with anterior or posterior decompression. Once transient paralysis occurs, early diagnosis and interventions are essential to reverse the neurological deficit.

Surgical technique modification of circumferential decompression for thoracic spinal stenosis and clinical outcome

Progressive thoracic myelopathy caused by ossification of posterior longitudinal ligament (OPLL) responds poorly to conservative therapy. The most direct decompression is extirpation of ossified posterior longitudinal ligament (PLL). Surgical outcomes of posterior approaches to remove ossified PLL are not always satisfactory because of the risk of neurological deterioration. In this study, we modified the conventional anterior decompression technique via a posterior approach for thoracic OPLL. From an anterior approach, the posterior cortex of vertebral body was exposed and the ossified PLL was removed. Then kyphosis correction was done via posterior instrumentation to reduce cord compression between dura under tension and the anterior canal wall. From the back, the distal end of the ossified PLL was displaced anteriorly to create a gap between ossified PLL and dura, remaining adhesions were divided and the ossified PLL was manipulated through this gap under direct vision. The surgical technique was applied in 20 patients with thoracic myelopathy caused by OPLL. One case of postoperative neurological deterioration was encountered but this recovered fully. Our outcomes were relatively favorable.

Connection of discontinuous segments in early functional recovery from thoracic ossification of the posterior longitudinal ligament treated with posterior instrumented surgery

OBJECTIVE

The objective of this study was to investigate the relationship between morphological changes in thoracic ossification of the posterior longitudinal ligament (T-OPLL) and postoperative neurological recovery after thoracic posterior fusion surgery. Changes of OPLL morphology and postoperative recovery in cases with T-OPLL have not been examined.

METHODS

In this prospective study, the authors evaluated data from 44 patients (23 male and 21 female) who underwent posterior decompression and fusion surgery with instrumentation for the treatment of T-OPLL at our hospital. The patients’ mean age at surgery was 50.7 years (range 38–68 years). The minimum duration of follow-up was 2 years. The location of thoracic ossification of the ligamentum flavum (T-OLF), T-OLF at the OPLL level, OPLL morphology, fusion range, estimated blood loss, operative time, pre- and postoperative Japanese Orthopaedic Association (JOA) scores, and JOA recovery rate were investigated. Reconstructed sagittal multislice CT images were obtained before and at 3 and 6 months and 1 and 2 years after surgery. The basic fusion area was 3 vertebrae above and below the OPLL lesion. All parameters were compared between patients with and without continuity across the disc space at the OPLL at 3 and 6 months after surgery.

RESULTS

The preoperative morphology of OPLL was discontinuous across the disc space between the rostral and caudal ossification regions on sagittal CT images in all but one of the patients. Postoperatively, these segments became continuous in 42 patients (97.7%; occurring by 6.6 months on average) without progression of OPLL thickness. Patients with continuity at 3 months had significantly lower rates of diabetes mellitus (p < 0.05) and motor palsy in the lower extremities (p < 0.01). The group with continuity also had significantly higher mean postoperative JOA scores at 3 (p < 0.01) and 6 (p < 0.05) months and mean JOA recovery rates at 3 and 6 months (both p < 0.01) after surgery.

CONCLUSIONS

Preoperatively, discontinuity of rostral and caudal ossified lesions was found on CT in all patients but one of this group of 44 patients who needed surgery for T-OPLL. Rigid fixation with instrumentation may have allowed these segments to connect at the OPLL. Such OPLL continuity at an early stage after surgery may accelerate spinal cord recovery.

Surgery-related predictable risk factors influencing postoperative clinical outcomes for thoracic myelopathy caused by ossification of the posterior longitudinal ligament: a multicenter retrospective study

OBJECTIVE

Compression of the spinal cord by thoracic ossification of the posterior longitudinal ligament (T-OPLL) often causes severe thoracic myelopathy. Although surgery is the most effective treatment for T-OPLL, problems associated with surgical intervention require resolution because surgical outcomes are not always favorable, and a small number of patients experience deterioration of their neurological status after surgery. The aim of the present study was to examine the surgery-related risk factors contributing to poor clinical outcomes for myelopathy caused by T-OPLL.

METHODS

Data were extracted from the records of 55 patients with thoracic myelopathy due to T-OPLL at institutions in the Fukuoka Spine Group. The mean follow-up period was 5.3 years. Surgical outcomes were assessed using the Japanese Orthopaedic Association (JOA) scale. To investigate the definitive factors associated with surgical outcomes, univariate and multivariate regression analyses were performed with several patient-related and surgery-related factors, including preoperative comorbidities, radiological findings, JOA score, surgical methods, surgical outcomes, and complications.

RESULTS

Neurological status improved in 33 patients (60.0%) and deteriorated in 10 patients (18.2%) after surgery. The use of instrumentation was significantly associated with an improved outcome. In the comparison of surgical approaches, posterior decompression and fusion resulted in a significantly higher neurological recovery rate than did anterior decompression via a posterior approach and fusion or decompression alone. It was also found that postoperative neurological status was significantly poorer when there were fewer instrumented spinal levels than decompression levels. CSF leakage was a predictable risk factor for deterioration following surgery.

CONCLUSIONS

It is important to identify preventable risk factors for poor surgical outcomes for T-OPLL. The findings of the present study suggest that intraoperative CSF leakage and a lower number of instrumented spinal fusion levels than decompression levels were exacerbating factors for the neurological improvement in T-OPLL surgery.

Three-Dimensional Analysis of the Radiological Risk Factors for Progression of the Thoracic Ossification of the Posterior Longitudinal Ligament After Posterior Decompression and Stabilization

BACKGROUND

Although research shows that the ossified masses of ossification of the posterior longitudinal ligament (OPLL) continue to grow postoperatively, information regarding thoracic OPLL (T-OPLL) is lacking. To date, no study has investigated the progression of T-OPLL within each motion segment. The purpose of this study was to analyze the progression of T-OPLL in each motion segment using a 3-dimensional measurement and evaluate whether the type of T-OPLL and surgical methods affect its progression postoperatively.

METHODS

Clinical data from 20 patients (101 segments) with thoracic myelopathy secondary to OPLL were evaluated retrospectively. All patients underwent posterior decompression (laminectomy and stabilization or circumferential decompression [CD] and stabilization) at a single center. The 3-dimensional measurement of OPLL volume was performed using computed tomography scans. The ossified masses were classified into 2 types based on the fusion of each segment at the intervertebral space: type 1 = complete bridging (fused); type 2 = not fused. Statistical analyses were performed to determine the degree of T-OPLL progression according to the types and surgical methods.

RESULTS

Mean OPLL progression was significantly higher in type 2. The mean annual growth rates of OPLL (AGRO) for groups 1 and 2 were 6.21% ± 6.11% per year and 23.50% ± 11.34% per year, respectively (P < 0.01). Further, no statistically significant differences were seen between the fixed and non-fixed groups (P = 0.23), and CD and non-CD segments (P = 0.56).

CONCLUSIONS

The mean AGRO does not decrease even after stabilization and CD. Type 2 intervertebral space was a risk factor for T-OPLL progression. Cases of type 2 without CD need close follow-up.

Benefits and Risks of Subsection Laminectomy with Pedicle Screw Fixation for Ossification of the Ligamentum Flavum of the Thoracic Spine: A Retrospective Study of 30 Patients

BACKGROUND This study aimed to evaluate the effectiveness of subsection laminectomy with pedicle screw fixation (SLPF) for the treatment of ossification of the ligamentum flavum of the thoracic spine. MATERIAL AND METHODS Thirty patients (age, 40-71 years) with ossification of the ligamentum flavum of the thoracic spine underwent SLPF (13 men, 17 women). Operative time, intraoperative blood loss, preoperative and postoperative change in thoracic kyphosis, and perioperative complications were recorded. The Japanese Orthopedic Association (JOA) score for severity of myelopathy and the American Spinal Injury Association (ASIA) motor and sensory impairment scale were used before and after surgery. RESULTS Mean operative time for SLPF was 208.4±38.3 min and mean intraoperative blood loss was 689.3±171.7 ml. The mean JOA score significantly increased from 5.7±1.9 before surgery to 8.8±2.2 at one month after surgery and 9.3±2.7 at the last follow-up (P<0.01). Postoperative improvement in neurological function increased by 68.3±14.4%. The postoperative ASIA grades significantly improved compared with the preoperative grades (P<0.01). The mean local Cobb angle significantly decreased from 17.8±4.3° before surgery to 15.4±3.6° at one month after surgery and 15.8±3.8° at the last follow-up (P<0.01). Three patients (10%) had operative cerebrospinal fluid (CSF) leak. Postoperatively, one patient had neurological deterioration, two patients had deep venous thrombosis (DVT), and one patient developed a wound infection. CONCLUSIONS SLPF was an effective procedure for the treatment of ossification of the ligamentum flavum of the thoracic spine.

Two-Staged Circumferential Decompression and Fusion Surgery for Upper Thoracic Myelopathy Caused by Concurrent Beak-Type Ossification of the Posterior Longitudinal Ligament and Ligamentum Flavum at T1-T2 Level: A Case Report

BACKGROUND

Upper thoracic myelopathy caused by combined ossification of the posterior longitudinal ligament (OPLL) and ossification of the ligamentum flavum (OLF) is relatively rare. This clinical condition is difficult to treat, and a surgical method has not been fully established. We report an extremely rare case of severe thoracic myelopathy caused by concurrent beak-type OPLL and OLF at T1-T2.

CASE DESCRIPTION

A 53-year-old woman with paresthesia of both legs and an inability to hold a standing position presented to our hospital. Radiological images showed a large beak-type OPLL at T1-T2 and an OLF at T1-T7. The spinal cord was severely compressed at T1-T2. First, posterior decompression and instrumentation fusion at C6-T4 was performed, with a T1-T2 bilateral parallel gutter along the dural tube into the vertebral bodies covering the extent of the OPLL. Second, anterior decompression of the OPLL with corpectomy of T1-T2 and fusion using iliac bone grafting was performed after the sternal manubrium splitting approach. In the deep operating field of the second surgery, the gutters created during the first surgery were helpful for judging the width and thickness of the OPLL during the anterior decompression procedure. Postoperatively, her neurological symptoms greatly improved, the patient could walk independently, and the Japanese Orthopaedic Association score had improved from 3 preoperatively to 8 at the final follow-up examination at 16 months postoperatively.

CONCLUSIONS

Two-stage circumferential decompression and fusion surgery can be considered an effective surgical method for upper thoracic concurrent OPLL and OLF. The bilateral gutters created during the first surgery improved the safety and feasibility of this difficult operation.

"U" route transforaminal percutaneous endoscopic thoracic discectomy as a new treatment for thoracic spinal stenosis

PURPOSES

To describe the rationale, surgical technique, and short-term follow-up results of a new minimally invasive treatment for thoracic spinal stenosis (TSS) caused by herniation, ossification of the ligamentum flavum (OLF), and/or ossification of the posterior longitudinal ligament (OPLL) with a "U" route transforaminal percutaneous endoscopic thoracic discectomy (PETD).

METHODS

Fourteen patients, including seven males and seven females, underwent "U" route PETD. Myelopathy was caused by OLF in 14 patients, OPLL in one, combined OLF-OPLL in ten, and intervertebral disc herniation (IDH) in five. Decompression was performed in one segment in 12 patients, and in two segments in two patients. The Japanese Orthopedic Association (JOA) scores, visual analog scale (VAS) scores, and complications were documented.

RESULTS

The JOA scores improved from 4.64 ± 2.31 pre-operatively to 7.07 ± 1.59 one day post-operatively and 11.79 ± 1.85 at final follow-up. The difference between pre-operation and post-operation was statistically significant (P < 0.05). Moreover, the VAS score was 6.07 ± 2.06 points pre-operatively, decreasing to 3.00 ± 1.24 points at one day post-operatively, and 1.14 ± 0.86 points at last follow-up (P < 0.05). Dural tear was observed in two cases during the intervention. No patient had transient worsening of pre-operative paralysis.

CONCLUSIONS

This retrospective analysis shows that "U" route PETD for decompression may be a feasible alternative to treat thoracic spinal stenosis.

Mechanical stress affects the osteogenic differentiation of human ligamentum flavum cells via the BMP‑Smad1 signaling pathway

The aim of the present study was to investigate the effects of mechanical stress on the osteogenic differentiation of human ligamentum flavum cells via the bone morphogenetic protein (BMP)‑Smad1 signaling pathway. Mechanical stress increased cell proliferation and induced osteogenic differentiation of human cells derived from the ossification of the ligamentum flavum (OLF). In addition, mechanical stress activated osteocalcin (OC), alkaline phosphatase (ALP) and runt‑related transcription factor 2 (RUNX‑2) mRNA expression, and suppressed Ets proto‑oncogene 1 (Ets‑1) and sex determining region Y‑box 2 (SOX‑2) mRNA expression in OLF cells. Src protein expression was suppressed by mechanical stress in human OLF cells. In addition, the protein expression levels of BMP, phosphorylated (p)‑mothers against decapentaplegic homolog‑1 (Smad1) and p‑p38‑mitogen‑activated protein kinases (p38MAPK) were increased by mechanical stress. These results demonstrate that mechanical stress effectively increases cell proliferation, promotes the osteogenic differentiation rate of OLF cells, activates OC, ALP and RUNX‑2, and suppresses Ets‑1 and SOX‑2 potentially via the BMP‑Smad1 and Src‑p38MAPK signaling pathways.

Treatment for Thoracic Ossification of Posterior Longitudinal Ligament with Posterior Circumferential Decompression

OBJECTIVE

To report the results of the posterior approach for thoracic ossification of posterior longitudinal ligament (TOPLL) by using a special "L" osteotome.

METHODS

The present study enrolled 16 consecutive patients (9 men and 7 women) between May 2009 and September 2013. All patients underwent a posterior circumferential decompression osteotomy and segmental instrumentation with interbody fusion. The mean age at surgery was 57.3 years (range, 37-68 years). Patients' data, clinical manifestation, blood loss, length of surgery, complications, visual analog scale (VAS), Japanese Orthopedic Association (JOA), and Frankel grading system before and after surgery were collected and evaluated, retrospectively.

RESULTS

The average follow-up period was 30 ± 19 months (range, 12-50 months). All patients were successfully treated with posterior compression and segmental instrumentation with interbody fusion. The average operation time was 261.6 ± 51.3 min (range, 190-310 min). The mean blood loss was 980.3 ± 370.5 mL (range, 600-2100 mL). All patients had subjective improvement of motor power and gait. Average preoperative and postoperative JOA scores were 4.2 ± 1.7 and 7.8 ± 2.5 points, respectively. Differences in the overall JOA scores showed significant postoperative improvement. At the last follow-up, all patients improved either by one or two Frankel grades. There was a significant difference between preoperative VAS scores and those 3 months after surgery (P < 0.05). No significant difference was observed between the 3-month and 12-month results (P > 0.05). Cerebrospinal fluid (CSF) leakage occurred in 3 patients. Acute neurological deterioration was encountered postoperatively in 1 patient.

CONCLUSION

Treatment with posterior transpedicular osteotomy and circumferential decompression was found to be safe, effective, reliable, and technically feasible, and keeping the thoracic cavity intact avoids many shortcomings of anterior surgery and results in a satisfactory spinal decompression.

Ponte Osteotomy During Dekyphosis for Indirect Posterior Decompression With Ossification of the Posterior Longitudinal Ligament of the Thoracic Spine

STUDY DESIGN

Retrospective clinical study.

PURPOSE

To investigate the outcomes after indirect posterior decompression and dekyphosis using multilevel Ponte osteotomies for ossification of the posterior longitudinal ligament (OPLL) of the thoracic spine.

SUMMARY OF BACKGROUND DATA

There are no previous reports on the use of Ponte osteotomy to treat thoracic OPLL.

METHODS

The subjects were 10 patients with an average age at surgery of 47 years, who underwent indirect posterior decompression and dekyphosis using multilevel Ponte osteotomies at our institute. Minimum follow-up period was 2 years, and averaged 2 year 6 months. Using radiographs and CT images, we investigated fusion range, preoperative and postoperative Cobb angles of thoracic fusion levels, intraoperative ultrasonography, and clinical results.

RESULTS

The mean fusion area was 9.8 vertebraes, with average laminectomy of 7.3 laminas. The mean preoperative thoracic kyphosis of fusion levels on standing radiograph measured 35 degrees and was changed to 21 degrees after surgery. The mean number of Ponte osteotomies was 3 levels. The mean preoperative and postoperative (at the 1 y follow-up) JOA scores were 3.5 and 7.5 points, respectively, and the recovery rate was 56%. On intraoperative ultrasonography, 7 of the cases were included in the floating (+) and 3 in the floating (-) groups, and the recovery rates were 66.0% and 33.4%, respectively.

CONCLUSIONS

"The Ponte procedure for indirect spinal cord decompression" is a novel concept used for the first time with thoracic OPLL in our study, and we consider it a useful method to achieve more effectively dekyphosis and indirect spinal cord decompression if there is not the spinal cord free from OPLL on intraoperative ultrasonography after only laminectomies.

Resection of Beak-Type Thoracic Ossification of the Posterior Longitudinal Ligament from a Posterior Approach under Intraoperative Neurophysiological Monitoring for Paralysis after Posterior Decompression and Fusion Surgery

Study Design Prospective clinical study. Objective Posterior decompression and fusion surgery for beak-type thoracic ossification of the posterior longitudinal ligament (T-OPLL) generally has a favorable outcome. However, some patients require additional surgery for postoperative severe paralysis, a condition that is inadequately discussed in the literature. The objective of this study was to describe the efficacy of a procedure we refer to as "resection at an anterior site of the spinal cord from a posterior approach" (RASPA) for severely paralyzed patients after posterior decompression and fusion surgery for beak-type T-OPLL. Methods Among 58 consecutive patients who underwent posterior decompression and fusion surgery for beak-type T-OPLL since 1999, 3 with postoperative paralysis (5%) underwent RASPA in our institute. Clinical records, the Japanese Orthopaedic Association score, gait status, intraoperative neurophysiological monitoring (IONM) findings, and complications were evaluated in these cases. Results All three patients experienced a postoperative decline in Manual Muscle Test (MMT) scores of 0 to 2 after the first surgery. RASPA was performed 3 weeks after the first surgery. All patients showed gradual improvements in MMT scores for the lower extremity and in ambulatory status; all could walk with a cane at an average of 4 months following RASPA surgery. There were no postoperative complications. Conclusions RASPA surgery for beak-type T-OPLL after posterior decompression and fusion surgery resulted in good functional outcomes as a salvage surgery for patients with severe paralysis. Advantages of RASPA include a wide working space, no spinal cord retraction, and additional decompression at levels without T-OPLL resection and spinal cord shortening after additional dekyphosis and compression maneuvers. When used with IONM, this procedure may help avoid permanent postoperative paralysis.

Outcomes of Surgical Treatment for Thoracic Myelopathy: A Single-institutional Study of 73 Patients

STUDY DESIGN

Retrospective study.

OBJECTIVE

The aim was to investigate the clinical outcomes in patients with thoracic myelopathy in a single institution and to identify prognostic factors for poor outcomes.

SUMMARY OF BACKGROUND DATA

Because of the rarity of thoracic myelopathy, a few studies have analyzed a large number of clinical results for patients with thoracic myelopathy treated in a single institution.

METHODS

Seventy-one patients who underwent surgical treatment for thoracic myelopathy between 2000 and 2011 in a single institution were included in this analysis. We investigated the patients' characteristics, surgical outcomes, and prognostic factors for poor outcomes.

RESULTS

Of the 73 patients, eight patients had disc herniation (DH) or spinal stenosis (SS), 10 patients had ossification of the posterior longitudinal ligament (OPLL), 40 patients had ossification of the ligamentum flavum (OLF), and 15 patients had OPLL + OLF. The mean patient age at the time of surgery was 61.9 years. Thoracic myelopathy was caused by OPLL and/or OLF in 65 patients (89%). Fifty-eight patients underwent laminectomy, eight patients underwent laminectomy and posterior fusion, four patients underwent OPLL extirpation and posterior fusion, and three patients underwent OPLL extirpation. The mean Japanese Orthopedic Association Scoring System scores before surgery and at the final follow-up examination were 6.0 ± 1.8 and 7.7 ± 2.0 points, respectively, yielding a mean recovery rate of 30% ± 43%. The JOA score improved significantly postoperatively (P < 0.05). Risk factors for poor outcomes were longer preoperative symptom duration, preoperative JOA score < 7, and OPLL and/or OLF. Large blood loss volume was significantly associated with a worse postoperative JOA score.

CONCLUSION

A considerable degree of neurological recovery was observed after surgical treatment in patients with thoracic myelopathy. Prognostic factors for poor outcomes were longer preoperative duration of symptoms, worse preoperative symptoms, OPLL and/or OLF, and large volume of intraoperative bleeding.

LEVEL OF EVIDENCE

4.

Surgical Treatment for Thoracic Myelopathy Due to Simultaneous Ossification of the Posterior Longitudinal Ligament and Ligamentum Flavum at the Same Level

STUDY DESIGN

Retrospective review.

OBJECTIVE

The aim of this study was to assess the clinical outcomes of surgery in patients with simultaneous ossification of the posterior longitudinal ligament (OPLL) and ossification of the ligamentum flavum (OLF) at the same thoracic spine level and identify the risk factors for poor outcomes.

SUMMARY OF BACKGROUND DATA

OPLL complicated with OLF in the thoracic spine is a rare condition. The optimal treatment option for thoracic myelopathy due to OPLL and OLF remains controversial, and high risk of postoperative paralysis remains a major complication.

METHODS

We conducted a retrospective review of clinical and radiographic records of 15 patients who underwent surgery for simultaneous OPLL and OLF at the same level.

RESULTS

Simultaneous OPLL and OLF occurred in the upper thoracic spine in 3 patients (20%), mid-thoracic spine in 10 patients (67%), and lower thoracic spine in 2 patients (13%). Six, 4, 2, and 3 patients underwent posterior decompression, posterior decompression and fusion, posterior decompression and circumferential decompression through a posterior approach, and circumferential decompression and posterior fusion, respectively. The mean Japanese Orthopaedic Association score before surgery and at the final follow-up was 5.7±1.9 and 7.0±2.1 points, respectively, yielding a mean recovery rate of 16.5%. However, no significant difference was observed between preoperative and postoperative Japanese Orthopaedic Association scores. Two patients with mid-thoracic lesions reported postoperative lower extremity weakness. Mid-thoracic lesions and considerable blood loss were risk factors for poor surgical outcome.

CONCLUSIONS

Simultaneous OPLL and OLF in the mid-thoracic spine was observed in two thirds of the patients. We suggest that simultaneous OPLL and OLF in this area has a relatively poor recovery and may be very challenging and risky to treat, regardless of the surgical method selected, and recommend early surgery for OPLL and OLF in the mid-thoracic spine.

Characteristics of ossification of the spinal ligament; incidence of ossification of the ligamentum flavum in patients with cervical ossification of the posterior longitudinal ligament - Analysis of the whole spine using multidetector CT

BACKGROUND

Ossification of the posterior longitudinal ligament (OPLL) and ossification of the ligamentum flavum (OLF) are characterized by replacement of ligamentous tissue by ectopic new bone formation. Although the background of both diseases might be similar, there are some differences between two diseases. Some patients have both OPLL and OLF. However, the incidence of both OPLL and OLF is still unclear and the precise lesions have not been investigated, yet. This study was conducted to evaluate OLF of the whole spine in patients with cervical OPLL and to analyze the relationship of the ossified lesions between OLF and OPLL.

METHODS

One hundred seventy eight patients who were diagnosed as cervical OPLL by plain radiographs were included. CT images of the whole spine were taken. Ossified lesions were checked at each level of vertebral body and intervertebral disc. The ossification index of OPLL (OPLL OS index) was determined by the sum of the levels of vertebral bodies and intervertebral discs where OPLL existed. The same index was applied for detecting the level of OLF (OLF OS index). Age, gender and OPLL characteristics were compared between the OLF(+) group, OLF was seen at any levels of the spinal canal, and the OLF(-) group, OLF was not seen.

RESULTS

The most frequent level of OPLL was at C5 vertebral level and OLF was predominant at upper and lower thoracic levels. Seventeen patients (9.6%) had OPLL and OLF at the same spinal level. The averaged OPLL OS index of the total spine in these patients was 8.7 ± 6.1, ranged from 1 to 36. The averaged OLF OS index of the total spine was 3.1 ± 2.2 (ranged from 1 to 13) in the patients who had OLF at any levels of the whole spine. One hundred fifteen patients (64.6%) with cervical OPLL had OLF at any levels of the whole spine. No relationship was found between the OPLL OS index and the OLF OS index. There was no significant difference among the data between the OLF(+) group and the OLF(-) group.

CONCLUSIONS

This study demonstrated 64.6% of the patients with cervical OPLL had OLF, mainly in the thoracic spine. However, there was no relationship regarding the severity of the ossified lesions between OPLL and OLF. CT analysis of the whole spine should be carried out for the early detection of OPLL and OLF in patients with cervical OPLL.

Iatrogenic Spinal Cord Injury during Removal of the Inferior Articular Process in the Presence of Ossification of the Ligamentum Flavum

Ossified ligamentum flavum (OLF) is a condition of heterotopic lamellar bone formation within the yellow ligament. Some patients with OLF can be asymptomatic. However, asymptomatic OLF may not be obvious on preoperative MRI and could increase the risk of iatrogenic injury during treatments for unrelated spinal conditions. This report describes a case of spinal cord injury caused by the indirect transmission of force from an osteotome to an asymptomatic OLF during the resection of a thoracic inferior articular process (IAP). To prevent this outcome, we urge careful review of CT imaging in the preoperative setting and advocate the use of a high-speed drill instead of an osteotome during bone removal in the setting of an adjacent area of OLF.

Delayed neurological deterioration with an unknown cause subsequent to surgery for intraspinal meningiomas

Delayed neurological deterioration in the absence of direct cord insult following surgical decompression is rare, but severe post-operative complication occurs in chronically compressive spinal disorders. In the present study, the clinical medical records and radiological findings of 10 patients who underwent surgical removal of intraspinal meningiomas and then experienced delayed post-operative neurological deterioration were reviewed. The cases are presented with consideration of the possible underlying mechanisms. There were five male and five female patients, with a mean age of 46.8 years. The mean duration of illness from the onset of symptoms to diagnosis was 42.8 months. Seven tumors were located in the thoracic region and three in the cervical region of the spine. The tumors compressed the cord severely and gross total removal was achieved in all cases. Immediately subsequent to the surgery, all patients were able to move all extremities, but the onset of the neurological deterioration occurred at post-operative hours 3-8 in all cases (mean, 5 h post-surgery). In four cases, radiological examination revealed an area of high signal changes intrinsic to the cord on T2-weighted images, but without residual compression. The mean follow-up period was 49.6 months. Nine patients reported a marked recovery in status compared with the pre-operative presentation during the several weeks to months following surgery. The surgical removal of intraspinal meningiomas may lead to delayed and severe neurological deterioration in the post-operative period in the absence of direct mechanical cord insult. Ischemia-reperfusion injury may be one potential etiology of this deterioration. Recognition of the neurological deficit following surgical excision of intraspinal meningiomas may improve pre-operative patient counseling and merits further study for the determination of the precise pathophysiology.

Ossification of the ligamentum flavum as cause of thoracic cord compression: Case report of a Latin American man and review of the literature

Background:

Ossification of the ligamentum flavum is a widely described pathology in eastern Asia. Cases have been reported in northern Africa, the Middle-East, India, the Caribbean, Europe, and North America, but no cases from Latin America have been published in the literature. It affects mostly elderly men, with a possible association with obesity and type 2 diabetes.

Case Description:

A 38-year-old previously healthy Latin American male presented to the emergency room department with severe functional disability and a 3/5 paraparesis. Blood reports showed no abnormalities. Computed tomography and magnetic resonance imaging showed a ligamentum flavum ossification with myelopathy. The patient underwent a T3-T9 laminotomy. At hospital discharge, the patient remained with a 3/5 paraparesis, mild hypoesthesia in both lower limbs and bladder incontinence. Rectal sphincter was continent. At 6 months, he was able to walk with a cane, with no sphincter or sensory alterations.

Conclusions:

Ligamentum flavum ossification is rare. To our understanding, this is the first case reported in the Latin American population.

Transient neurological deficit following midthoracic decompression for severe stenosis: a series of three cases

PURPOSE

To report three cases of transient perioperative neurological deficit in the absence of direct cord insult following decompression of the severely stenotic thoracic spine.

METHODS

The clinical and radiographic electronic medical records of three patients who underwent decompression for severe midthoracic stenosis with transient neurological deficits perioperatively were reviewed. The cases are presented with consideration of possible underlying mechanisms and multimodality intraoperative monitoring (IOM) findings.

RESULTS

Two patients had neurologic changes on IOM and Stagnara wake-up test, the remaining patient had absent motor and sensory potentials at baseline and throughout the case. IOM changes were observed immediately following decompression in the absence of direct cord insult or displacement. Postoperatively all patients experienced neurological motor deficits which presented as complete paralysis of the right lower extremity in two of the patients and the left lower extremity in one patient. The deficit was transient-improvement of motor strength occurred between 1 and 13 months of follow-up in all patients.

CONCLUSION

Decompression of a severely stenotic region of the thoracic spinal cord may lead to a complete yet transient motor deficit in the perioperative period in the absence of direct mechanical cord insult. Potential etiologies include ischemia-reperfusion injury, microthrombi, and altered perfusion due to internal recoil of spinal cord architecture following decompression. IOM may show conspicuous findings in such events, however, may not be relied upon when baseline potentials are sub-optimal. Recognition of this short-lived neurological deficit following decompression of the severely stenotic thoracic spine will improve preoperative patient counseling and merits further study for determination of the precise pathophysiology.

Management of thoracic myelopathy caused by ossification of the posterior longitudinal ligament combined with ossification of the ligamentum flavum-a retrospective study

BACKGROUND CONTEXT

Ossification of the posterior longitudinal ligament (OPLL) or ossification of the ligamentum flavum (OLF) is being increasingly recognized as a cause of thoracic myelopathy and is relatively common in the Japanese population and literature. However, no series of OPLL combined with OLF has been previously published. Many different surgical procedures have been used for the treatment of thoracic OPLL or OLF. However, the possibility of postoperative paraplegia remains a major risk, and consistent protocols and procedures for surgical treatment of thoracic OPLL combined with OLF have also not been established.

PURPOSE

To compare the effect of thoracic myelopathy treatment and safety of posterior decompression with or without instrumented fusion and circumferential spinal cord decompression via a posterior approach in Chinese patients of OPLL combined with OLF at a single institution.

STUDY DESIGN

This retrospective clinical study of 31 cases was conducted to investigate the clinical outcomes of three kinds of surgical procedures for thoracic myelopathy caused by OPLL combined with OLF in Chinese population.

PATIENT SAMPLE

Procedure was performed in 31 patients.

OUTCOME MEASURES

Neurologic status was evaluated using the Japanese Orthopaedic Association (JOA) score and Hirabayashi recovery rate before and after surgery.

METHODS

A total of 31 patients who underwent surgery for thoracic OPLL combined with OLF were classified into three groups: posterior decompression group (13 patients); circumferential decompression group (seven patients), which included four who underwent extirpation and the other three underwent the floating procedure; and posterior decompression and fusion group (11 patients), all of whom underwent laminectomy with posterior instrumented fusion. In each group, JOA score was used to evaluate thoracic myelopathy, and Hirabayashi recovery rate was calculated 1 year after surgery and at final examination.

RESULTS

Mean recovery rate at the final follow-up was 46.5% in the posterior decompression group, 65.1% in the circumferential decompression group, and 62.7% in the posterior decompression and fusion group. Postoperative paralysis occurred in three patients in the posterior decompression group, one in the circumferential decompression group, and one in the posterior decompression and fusion group. In the circumferential decompression group, leakage of cerebrospinal fluid occurred in four patients. Urinary tract infection occurred in two patients, and superficial wound disruption occurred in one patient. Late neurologic deterioration occurred in four patients in the posterior decompression group. There were no cases of postoperative paralysis or late neurologic deterioration in the posterior decompression and fusion group.

CONCLUSIONS

Thoracic OPLL combined with OLF is an uncommon cause of myelopathy in the Chinese population. It can present acutely after minor trauma. A considerable degree of neurologic recovery was obtained by posterior decompression with instrumented fusion, despite the anterior impingement of the spinal cord by the remaining OPLL. In addition, the rate of postoperative complications was low with this procedure. We consider that one-stage posterior decompression and instrumented fusion be selected for patients in whom the spinal cord is severely damaged before surgery and/or when circumferential decompression is associated with an increased risk.

Analysis of demographics, risk factors, clinical presentation, and surgical treatment modalities for the ossified posterior longitudinal ligament

OBJECT

Ossification of the posterior longitudinal ligament (OPLL) is a rare disease that results in progressive myeloradiculopathy related to pathological ossification of the ligament from unknown causes. Although it has long been considered a disease of Asian origin, this disorder is increasingly being recognized in European and North American populations. Herein the authors present demographic, radiographic, and comorbidity data from white patients with diagnosed OPLL as well as the outcomes of surgically treated patients.

METHODS

Between 1999 and 2010, OPLL was diagnosed in 36 white patients at Barrow Neurological Institute. Patients were divided into 2 groups: a group of 33 patients with cervical OPLL and a group of 3 patients with thoracic or lumbar OPLL. Fifteen of these patients who had received operative treatment were analyzed separately. Imaging analysis focused on signal changes in the spinal cord, mass occupying ratio, signs of dural penetration, spinal levels involved, and subtype of OPLL. Surgical techniques included anterior cervical decompression and fusion with corpectomy, posterior laminectomy with fusion, posterior open-door laminoplasty, and anterior corpectomy combined with posterior laminectomy and fusion. Comorbidities, cigarette smoking, and previous spine surgeries were considered. Neurological function was assessed using a modified Japanese Orthopaedic Association Scale (mJOAS).

RESULTS

A high-intensity signal on T2-weighted MR imaging and a history of cervical spine surgery correlated with worse mJOAS scores. Furthermore, mJOAS scores decreased as the occupying rate of the OPLL mass in the spinal canal increased. On radiographic analysis, the proportion of signs of dural penetration correlated with the OPLL subtype. A high mass occupying ratio of the OPLL was directly associated with the presence of dural penetration and high-intensity signal. In the surgical group, the rate of neurological improvement associated with an anterior approach was 58% compared with 31% for a posterior laminectomy. No complications were associated with any of the 4 types of surgical procedures. In 3 cases, symptoms had worsened at the last follow-up, with only a single case of disease progression. Laminoplasty was the only technique associated with a worse clinical outcome. There were no statistical differences (p > 0.05) between the type of surgical procedure or radiographic presentation and postoperative outcome. There was also no difference between the choice of surgical procedure performed and the number of spinal levels involved with OPLL.

CONCLUSIONS

Ossification of the posterior longitudinal ligament can no longer be viewed as a disease of the Asian population exclusively. Since OPLL among white populations is being diagnosed more frequently, surgeons must be aware of the most appropriate surgical option. The outcomes of the various surgical treatments among the different populations with OPLL appear similar. Compared with other procedures, however, anterior decompression led to the best neurological outcomes.

Ossification of the posterior longitudinal ligament: a review

Ossification of the posterior longitudinal ligament (OPLL) is most commonly found in men, the elderly, and Asian patients. There are many diseases associated with OPLL, such as diffuse idiopathic skeletal hyperostosis, ankylosing spondylitis, and other spondyloarthropathies. Several factors have been reported to be associated with OPLL formation and progression, including genetic, hormonal, environmental, and lifestyle factors. However, the pathogenesis of OPLL is still unclear. Most symptomatic patients with OPLL present with neurological deficits such as myelopathy, radiculopathy, and/or bowel and bladder symptoms. There are some reports of asymptomatic OPLL. Both static and dynamic factors are related to the development of myelopathy. Plain radiography, CT, and MR imaging are used to evaluate OPLL extension and the area of spinal cord compression. Management of OPLL continues to be controversial. Each surgical technique has some advantages and disadvantages, and the choice of operation should be made case by case, depending on the patient's condition, level of pathology, type of OPLL, and the surgeon's experience. In this paper, the authors attempt to review the incidence, pathology, pathogenesis, natural history, clinical presentation, classification, radiological evaluation, and management of OPLL.

Management of ossification of the posterior longitudinal ligament of the thoracic spine

The management of thoracic ossification of the posterior longitudinal ligament has been studied by many spinal surgeons. Indications for operative intervention include progressive radiculopathy, myelopathy, and neurological deterioration. The ideal surgery for decompression remains highly debatable as various methods of surgical treatment of ossification of the posterior longitudinal ligament have been devised. Although numerous modifications to the 3 main approaches have been identified (anterior, posterior, or lateral), the indication for each depends on the nature of compression, the morphology of the lesion, the level of the compression, the structural alignment of the spine, and the neurological status of the patient. The authors discuss treatment techniques for thoracic ossification of the posterior longitudinal ligament, cite case examples from a single institution, and review the literature.

Ossification of the ligamentum flavum of the thoracic spine in the Korean population

OBJECT

Thoracic ossification of the ligamentum flavum (OLF), a main cause of thoracic myelopathy, is an uncommon disease entity. It is seen mostly in East Asia, although the majority of reports have issued from Japan. In the present study, the clinical features and prognostic factors of thoracic OLF were examined in a large number of Korean patients.

METHODS

Data from 51 consecutive patients who underwent decompressive laminectomy with or without fusion for thoracic OLF between 1998 and 2008 were retrospectively analyzed. Patients were evaluated pre- and postoperatively using the modified Japanese Orthopedic Association (JOA) scale (maximum total score of 11). Patient age, sex, preoperative symptoms, duration of initial symptoms, number of involved segments, duration of follow-up, presence of dural adhesion (dural tearing), intramedullary high signal intensity, morphological classification of OLF (axial or sagittal), coexisting disease, and fusion or no fusion were also evaluated. Surgical outcomes were assessed using JOA recovery rate/outcome scores, and patient satisfaction grades and prognostic factors were analyzed.

RESULTS

There were 18 men and 33 women with a mean age of 60.9 years (range 38-80 years). A mean preoperative JOA score of 5.5 improved to a mean score of 7.4 at the last follow-up (mean 52 months after surgery). The mean duration of the initial symptoms was 34.5 months (range 0.1-240 months) prior to surgery. The most common symptoms were motor dysfunction (80%); sensory deficit (67%); and pain, numbness, and claudication (59%) in the lower extremities. Knee hyperreflexia appeared in 69% of the patients. There were a total of 130 ossified segments, and the mean number of segments per patient was 2.6. Ninety-two (71%) of 130 segments were located below T-8. Recovery outcomes were good (18 patients), fair (16 patients), unchanged (11 patients), or worse (6 patients). Thirty-one patients (61%) were satisfied with their operations. Patients with a beak type of OLF on sagittal MR images experienced a higher recovery rate and a better satisfaction grade than did those with a round OLF. The patients with higher preoperative JOA scores demonstrated significantly higher JOA scores postoperatively (p < 0.001), and the preoperative JOA score had a significant correlation with the recovery rate in patients exhibiting mainly motor dysfunction (p = 0.040, r = 0.330).

CONCLUSIONS

Of the thoracic OLF studies published to date, the present analysis involves the largest Korean population. The most common symptoms of thoracic OLF were motor dysfunction and sensory deficit in the lower extremities, although pain, numbness, and claudication were observed in some patients and were notably accompanied by knee hyperreflexia. At a minimum of 2 years after surgery for thoracic OLF, operative outcomes were generally good, and the prognostic factors affecting good surgical outcomes included a beak type of OLF and a preoperative JOA score > 6.

Clinical analysis of thoracic ossified ligamentum flavum without ventral compressive lesion

The aim of this study was to analyze the clinical characteristics of thoracic ossified ligamentum flavum (OLF) and to elucidate prognostic factors as well as effective surgical treatment modality. The authors analyzed 106 thoracic OLF cases retrospectively from January 1999 to December 2008. The operative (n = 40) and the non-operative group (n = 66) were diagnosed by magnetic resonance imaging (MRI) and/or computed tomography (CT) imaging. We excluded cases exhibiting ventral compressive lesions causing subarachnoid space effacement in thoracic vertebrae as well as those with a coexisting cervical compressive myelopathy. Those in the operative group were treated with decompressive laminectomy as well as resection of OLF. The preoperative neurologic status and postoperative outcomes of patients, as indicated by their modified Japanese Orthopedic Association (mJOA) scores and recovery rate (RR), Modic changes, the axial (fused or non-fused) and sagittal (omega or beak) configurations of OLF, and the ratios of the cross-sectional area (CSA) and anteroposterior diameter (APD) of the most compressed level were studied. The most commonly affected segment was the T10-11 vertebral body level (n = 49, 27.1%) and the least affected segment was the T7-8 level (n = 1, 0.6%). The ratios of the CSA in non-fused and fused types were 77.3 and 59.3% (p < 0.001). When Modic changes were present with OLF, initial mJOA score was found to be significantly lower than those without Modic change (7.62 vs. 9.09, p = 0.033). Neurological status improved after decompressive laminectomy without fusion (preoperative vs. last mJOA; 7.1 ± 2.01 vs. 8.57 ± 1.91, p < 0.001). However, one patient exhibited transient deterioration of her neurological status after surgery. In the axial configuration, fused-type OLF revealed a significant risk for a decreased postoperative mJOA score (0-7, severe and moderate) (Odds ratio: 5.54, χ (2) = 4.41, p = 0.036, 95% CI: 1.014-30.256). The results indicated that the new categorization of axial-type of OLF is a helpful predictor of postoperative patient outcome and fused type was related with poor prognosis. In OLF cases free from ventral lesions compressing the spinal cord, decompressive laminectomy is enough for successful surgical outcome. Therefore, early surgical treatment will be considered in cases with fused-type OLF compressing spinal cord even though they do not have myelopathic symptoms.

Posterior decompression with kyphosis correction for thoracic myelopathy due to ossification of the ligamentum flavum and ossification of the posterior longitudinal ligament at the same level

Object

The object of this study was to evaluate the efficacy and safety of posterior decompression with kyphosis correction for thoracic myelopathy due to ossification of the ligamentum flavum (OLF) and ossification of the posterior longitudinal ligament (OPLL) at the same level.

Methods

Between January 2003 and December 2005, 11 patients (8 men and 3 women) with thoracic myelopathy due to OLF and OPLL at the same level underwent posterior decompressive laminectomy and excision of OLF. Posterior instrumentation was also performed for stabilization of the spine and reducing the thoracic kyphosis angle by approximately 5–15° (kyphosis correction), and spinal fusion was performed in all cases. The follow-up period ranged from 2 to 4 years (mean 2.8 years). The outcomes were evaluated using a recovery scale based on the Japanese Orthopaedic Association classification. The score of each patient was calculated before surgery, 1 year after surgery, and at the final follow-up visit.

Results

After surgery, the thoracic kyphosis in the stabilization area was reduced from 30.0 ± 4.02° to 20.8 ± 2.14° on average. The mean score on the Japanese Orthopaedic Association scale improved from 3.5 ± 1.69 preoperatively to 8.5 ± 1.63 at the final follow-up, with a recovery rate of 68.0%. The results were good in 9 patients and fair in 2 patients. Postoperative MR imaging showed that the spinal cord was shifted posteriorly and decompressed completely in all cases. Myelopathy was not aggravated in any case after surgery.

Conclusions

A considerable degree of neurological recovery was observed after posterior decompression and kyphosis correction. The procedure is easy to perform with a low risk of postoperative paralysis. The authors therefore suggest that the procedure is useful for patients whose spinal cords are severely impinged by OLF and OPLL at the same level.

A modified decompression surgery for thoracic myelopathy caused by ossification of posterior longitudinal ligament: a case report and literature review

STUDY DESIGN

Case report and review.

OBJECTIVE

We report a case with severe thoracic myelopathy because of ossification of the posterior longitudinal ligament (OPLL) of the spine, in which the OPLL was removed via a modified decompression approach, with sufficient decompression of the spinal cord and a satisfactory outcome was achieved.

SUMMARY OF BACKGROUND DATA

Many different decompressive surgeries may be applied for thoracic myelopathy caused by OPLL. However, there are variations among patients with thoracic myelopathy because of OPLL, and the possibility of postoperative paralysis remains a major risk, and to date, the effective treatment option for thoracic myelopathy caused by OPLL is still controversial.

METHODS

The patient was a 60-year-old woman with isolated OPLL at T10/T11 with anteriorly compression in the spinal cord. Posterior decompression by laminectomy and anterior decompression by extirpation of the OPLL were performed by a posterior-lateral approach. First, spinal cord retrocession was achieved to relieve the compression of OPLL by posterior decompression. Second, the posterior 2/3 of involved vertebral bodies and the T10/T11 intervertebral disc were resected with the anterior-lateral approach. Then, the OPLL was extirpated from the anterior direction in order to relieve the spinal cord compression completely, and the resected ribs were used for the anterior column reconstruction. Finally, a titanium device was secured over the area of surgery to stabilize the spinal column.

RESULTS

Complete removal of the ossification was achieved in the present patient. Satisfactory surgical outcome of this patient was confirmed by a follow-up of 3 years after operation.

CONCLUSION

The present case suggests that posterior decompression, anterior extirpation of OPLL, and interbody fusion with spinal instrumentation only via a modified posterior-lateral approach is a novel, safe, and effective procedure for surgical treatment of thoracic OPLL.

Posterior decompression with instrumented fusion for thoracic myelopathy caused by ossification of the posterior longitudinal ligament

We evaluated the clinical results of posterior decompression with instrumented fusion (PDF) for thoracic myelopathy due to ossification of the posterior longitudinal ligament (OPLL). A total of 24 patients underwent PDF, and their surgical outcomes were evaluated by the Japanese Orthopaedic Association (JOA) scores (0-11 points) and by recovery rates calculated at 3, 6, 9 and 12 months after surgery and at a mean final follow-up of 4 years and 5 months. The mean JOA score before surgery was 3.7 points. Although transient paralysis occurred immediately after surgery in one patient (3.8%), all patients showed neurological recovery at the final follow-up with a mean JOA score of 8.0 points and a mean recovery rate of 58.1%. The mean recovery rate at 3, 6, 9 and 12 months after surgery was 36.7, 48.8, 54.0 and 56.8%, respectively. The median time point that the JOA score reached its peak value was 9 months after surgery. No patient chose additional anterior decompression surgery via thoracotomy. The present findings demonstrate that despite persistent anterior impingement of the spinal cord by residual OPLL, PDF can result in considerable neurological recovery with a low risk of postoperative paralysis. Since neurological recovery progresses slowly after PDF, we suggest that additional anterior decompression surgery is not desirable during the early stage of recovery.

Clinical results and complications of circumferential spinal cord decompression through a single posterior approach for thoracic myelopathy caused by ossification of posterior longitudinal ligament

STUDY DESIGN

A retrospective review.

OBJECTIVE

This study examined the clinical outcomes of circumferential spinal cord decompression through a posterior approach for thoracic ossification of posterior longitudinal ligament (OPLL), to determine the efficacy of this procedure and the incidence of complications.

SUMMARY OF BACKGROUND DATA

Since posterior decompressive laminectomy is not always effective in the treatment of thoracic myelopathy caused by OPLL, circumferential spinal cord decompression through a single posterior approach seems to offer an effective treatment option. However, this procedure is technically demanding and has a high risk of postoperative neurologic deterioration. Long-term clinical outcome data and complication rates of this procedure are not well covered in the literature.

METHODS

Medical records of sequentially treated 30 patients, who had undergone circumferential spinal cord decompression through a single posterior approach, were reviewed to determine demographic data, neurologic examination, imaging findings, surgical procedure, and follow-up data. The Japanese Orthopedic Association (JOA) score was used to assess physical dysfunction and neurologic impairment.

RESULTS

The mean follow-up period was 8 years; the average operative time was 389 minutes; the mean blood loss was 1883 mL. An average of 4-level spinal cord decompression was performed on all 30 patients. Posterior spinal fusion was performed on 26 of the 30 patients. The mean preoperative JOA score was 3.4/11, and it improved to an average of 7.1/11 at final evaluation. Clinical symptoms and the JOA score improved in 24 patients, but were unchanged or worsened in the other 6 patients compared to the preoperative conditions. Surgical complications included dural tear in 12 patients (40%), deep infection in 3 (10%), and postoperative neurologic deterioration in 10 (33%). Statistical analysis showed that a risk factor associated with the unfavorable surgical outcomes was multiple level circumferential spinal cord decompression of 5 or more vertebral levels.

CONCLUSION

Despite circumferential spinal cord decompression through posterior approach for thoracic OPLL providing effective neurologic recovery, there was a high rate of complications such as postoperative neurologic deterioration. Risk factor analysis shows that multiple level circumferential decompression of 5 or more vertebral levels to be associated with unfavorable surgical outcome.

Circumspinal decompression with dekyphosis stabilization for thoracic myelopathy due to ossification of the posterior longitudinal ligament

STUDY DESIGN

Circumspinal decompression with dekyphosis stabilization was prospectively performed with thoracic myelopathy due to ossification of posterior longitudinal ligament (OPLL). Neurologic outcome was reviewed.

OBJECTIVE

To evaluate how easily, safely, and completely the thoracic OPLL can be removed or floated by circumspinal decompression with dekyphosis stabilization.

SUMMARY OF BACKGROUND DATA

Anterior decompression is the best for the spinal cord recovery to treat thoracic myelopathy caused by OPLL on the concave side of the spinal cord. However, anterior approach for removal of OPLL plaque is technically demanding.

METHODS

This is an operative procedure. Wide laminectomy is performed. Bilateral gutters along the dural tube are made using a diamond drill into the vertebral body covering the extent of the OPLL to be removed anteriorly. Posterior instrumentation is applied for stabilization of the spine and reducing thoracic kyphosis by approximately 5 to 10 degrees (dekyphosis stabilization). Four weeks after the first step, anterior decompression is performed with direct vision with the landmark of gutters using an operative microscope, followed by interbody fusion. Fifteen patients with thoracic myelopathy due to OPLL had the first-step operation, and 11 patients underwent circumspinal decompression (both the first and second operation).

RESULTS

Kyphosis in the stabilization area reduced from 30.7 to 24.7 degrees on average in 15 patients. In 2 of the 15 patients, the spinal cord was shifted posteriorly and completely decompressed by only the first-step operation in the postoperative myelography or magnetic resonance imaging. The second-step operation was cancelled, and their Japanese Orthopedic Association scores improved from 6 to 10 points and from 4 to 10.5 point, respectively at final follow-up. In other 13 patients, the spinal cord was still compressed by the OPLL plaque. In 2 of the 13 patients, the second-step operation was cancelled because their general condition was impaired. Their preoperative Japanese Orthopedic Association scores were 2.0 and 2.5, and final scores were 5.5 and 5.5 points, respectively. Remaining 11 patients who underwent circumspinal decompression (both the first and second operation) neurologically improved and maintained from 4.0 points to 9.1 points on average at final follow-up.

CONCLUSION

The OPLL plaque in the thoracic spine might be most easily, safely, and completely removed or floated, and the spinal cord is circumferentially decompressed through circumspinal decompression with dekyphosis stabilization.

An analysis of factors causing poor surgical outcome in patients with cervical myelopathy due to ossification of the posterior longitudinal ligament: anterior decompression with spinal fusion versus laminoplasty

OBJECTIVE

We compared the surgical outcome of anterior decompression with spinal fusion (ASF) with the surgical outcome of laminoplasty for patients with cervical myelopathy due to ossification of the posterior longitudinal ligament.

METHODS

The study group comprised 19 ASF patients (A-group) and 40 laminoplasty patients (P-group) treated from 1993 to 2002 with 1 year or longer follow-up. The Japanese Orthopedic Association scoring system was used to evaluate cervical myelopathy, and the recovery rate calculated 1 year after surgery.

RESULTS

The mean recovery rate was 68.4% in the A-group and 52.5% in the P-group (P<0.05). Fifteen patients had a recovery rate less than 40%: 2 in the A-group and 13 in the P-group. One P-group patient and none of the A-group patients developed postoperative aggravation of their neurologic status. The P-group was divided into 2 subgroups: a good outcome group comprising patients whose recovery rate was 40% or higher (n=27) and a poor outcome group comprising patients whose recovery rate was less than 40% (n=13). The mean age at surgery was 59.9 years in the good outcome group and 68.0 years in the poor outcome group (P<0.05). The mean range of intervertebral mobility at maximum cord compression level before surgery was 6.9 degrees in the good outcome group and 10 degrees in the poor outcome group (P<0.05).

CONCLUSIONS

These results demonstrated that the surgical outcome of ASF was superior to the surgical outcome of laminoplasty. Elderly patients treated with laminoplasty showed an especially poor surgical outcome. We suggest that hypermobility of vertebrae at the cord compression level is a risk factor for poor surgical outcome after laminoplasty. Based on these results, we recommend that ASF should be the first choice of treatment for patients with significant ossification of the posterior longitudinal ligament and a hypermobile cervical spine. When laminoplasty is used for such cases, the addition of posterior instrumented fusion would be desirable for stabilizing the spine and decreasing damage to the spinal cord.

A review of factors predictive of surgical outcome for ossification of the ligamentum flavum of the thoracic spine

OBJECT

Ossification of the ligamentum flavum (OLF) is a pathological condition that affects the ligament and causes slowly progressive myeloradiculopathy in adults. Although OLF has been regarded as endemic to East Asian countries, studies from outside these areas have increasingly been reported. Because of long-standing compression of the spinal cord by OLF, a patient's functional prognosis may not always be favorable, and attempts have been made in recent studies to identify clinical factors that are predictive of the surgical outcome of patients with thoracic OLF.

METHODS

The authors conducted a review of the literature published in the English, Japanese, and Korean languages. They examined studies in which correlation between clinical factors and outcome was statistically evaluated. The clinical factors included sex, age, level of the ossified ligamentum flavum, number of segments affected by OLF, coexisting ossification of the posterior longitudinal ligament (OPLL) or other spinal disorders, preoperative duration of symptoms, preoperative neurological score, computed tomography (CT)-based classification, and the presence of intramedullary high signal intensity on T2-weighted magnetic resonance images.

CONCLUSIONS

The clinical factors that are unlikely to be predictive of outcome include sex, age, level of the ossified lesion, number of OLF-affected segments, coexisting OPLL, CT classification, and the presence of high signal intensity. It is unclear whether the preoperative duration of symptoms or neurological score is predictive of outcome because the results have been inconsistent among the studies. Analysis of the more recent literature, however, suggests that these two factors are predictive of outcome. The use of a neurological score should be standardized so that compilation and comparison of data can be facilitated.

Clinical results of surgery for thoracic myelopathy caused by ossification of the posterior longitudinal ligament: operative indication of posterior decompression with instrumented fusion

STUDY DESIGN

This retrospective study was conducted to investigate the clinical outcomes of several surgical procedures for thoracic myelopathy caused by ossification of the posterior longitudinal ligament (OPLL).

OBJECTIVE

To evaluate the effect of myelopathy treatment and safety of posterior decompression with instrumented fusion.

SUMMARY OF BACKGROUND DATA

Many different surgical procedures have been used for the treatment of thoracic OPLL. However, the possibility of postoperative paraplegia remains a major risk, and consistent protocols and procedures for surgical treatment of thoracic OPLL have also not been established.

METHODS

A total of 51 patients who underwent surgery for thoracic OPLL were classified into 3 groups: (1) posterior decompression group (18 patients), which included 12 who underwent laminectomy and 6 who underwent cervicothoracic laminoplasty; (2) OPLL extirpation group (16 patients), which included 4 who underwent anterior decompression through thoracotomy and 12 who underwent anterior decompression through the posterior approach; and (3) posterior decompression and fusion group (17 patients), all of whom underwent laminectomy with posterior instrumented fusion. In each group, the Japanese Orthopedic Association score was used to evaluate thoracic myelopathy, and the recovery rate calculated 1 year after surgery and at final examination.

RESULTS

Mean recovery rate at final follow-up was 41.9% in the posterior decompression group, 62.1% in the OPLL extirpation group, and 59.3% in the posterior decompression and fusion group. Postoperative paralysis occurred in 3 patients in the posterior decompression group and in 3 in the OPLL extirpation group. In the OPLL extirpation group, leakage of cerebrospinal fluid occurred in 8 patients and hydrothorax in 2. Late neurologic deterioration occurred in 7 patients in the posterior decompression group. There were no cases of postoperative paralysis or late neurologic deterioration in the posterior decompression and fusion group.

CONCLUSIONS

A considerable degree of neurologic recovery was obtained by posterior decompression with instrumented fusion, despite the anterior impingement of the spinal cord by OPLL remaining. In addition, the rate of postoperative complications was extremely low with this procedure. We recommend that 1-stage posterior decompression and instrumented fusion be selected for patients in whom the spinal cord is severely damaged before surgery and/or when extirpation of OPLL is associated with increased risk.