Surgical treatment for thoracic spinal stenosis

Degenerative Thoracic Myelopathy: A Scoping Review of Epidemiology, Genetics, and Pathogenesis

STUDY DESIGN

Literature Review.

OBJECTIVE

Myelopathy affecting the thoracic spinal cord can arise secondary to several aetiologies which have similar presentation and management. Consequently, there are many uncertainties in this area, including optimal terminology and definitions. Recent collaborative cervical spinal research has led to the proposal and subsequent community adoption of the name degenerative cervical myelopathy(DCM), which has facilitated the establishment of internationally-agreed research priorities for DCM. We put forward the case for the introduction of the term degenerative thoracic myelopathy(DTM) and degenerative spinal myelopathy(DSM) as an umbrella term for both DCM and DTM.

METHODS

Following PRISMA guidelines, a systematic literature search was performed to identify degenerative thoracic myelopathy literature in Embase and MEDLINE.

RESULTS

Conditions encompassed within DTM include thoracic spondylotic myelopathy, ossification of the posterior longitudinal ligament, ossification of the ligamentum flavum, calcification of ligaments, hypertrophy of ligaments, degenerative disc disease, thoracic osteoarthritis, intervertebral disc herniation, and posterior osteophytosis. The classic presentation includes girdle pain, gait disturbance, leg weakness, sensory disturbance, and bladder or bowel dysfunction, often with associated back pain. Surgical management is typically favoured with post-surgical outcomes dependent on many factors, including the causative pathology, and presence of additional stenosis.

CONCLUSION

The clinical entities encompassed by the term DTM are interrelated, can manifest concurrently, and present similarly. Building on the consensus adoption of DCM in the cervical spine and the recent proposal of degenerative cervical radiculopathy(DCR), extending this common nomenclature framework to the terms degenerative spinal myelopathy and degenerative thoracic myelopathy will help improve recognition and communication.

A single centre service evaluation of degenerative cervical and thoracic myelopathy

BACKGROUND

Degenerative cervical myelopathy (DCM) and degenerative thoracic myelopathy (DTM) present with leg, bladder and bowel symptoms. If imaging confirms spinal cord compression both conditions are usually managed surgically. Surgical timing is important in patient management as it affects post-operative recovery and long-term outcomes. This service evaluation aims to explore whether that patients with DTM are more likely to be treated urgently than those with DCM and to examine whether any differences in management are justified.

METHODS

A retrospective service evaluation was registered and approved by the Cambridge University Hospitals NHS Foundation Trust (CUH) Clinical Audit Department (Clinical Project ID4455 PRN10455). All patients who had undergone surgery for DTM at CUH from January 2015 until April 2022 were included. Comparison was made to a cohort of DCM patients who underwent surgery at CUH from June 2016 to January 2019. Data analysis was conducted in R.

RESULTS

A total of 130 DCM patients and 78 DTM patients were included. Our DCM and DTM patient cohorts had comparable demographics, but DTM patients had fewer spinal levels affected. Despite equivalent disease severity, DTM patients had a shorter time to diagnosis, shorter wait for surgery and were more likely to be operated on as an emergency case.

CONCLUSIONS

Despite comparable demographics and pathophysiology, DTM was diagnosed and managed more quickly than DCM. Better defined diagnostic pathways for degenerative spinal myelopathy may hold opportunities to optimise diagnosis and management, ensuring consistent high quality, efficient and equitable care.

Prevalence of and factors associated with stenotic thoracic ligamentum flavum hypertrophy

INTRODUCTION

Stenotic thoracic ligamentum flavum hypertrophy can cause leg and/or low back pain similar to that caused by lumbar spinal stenosis. However, the thoracic spine may occasionally be overlooked in patients with leg and/or low back pain. An accurate understanding of the prevalence of stenotic thoracic ligamentum flavum hypertrophy and its associated factors is necessary.

METHODS

In this prevalence study, we reviewed whole-spine MRI scans of patients who visited the pain clinic complaining of leg and/or low back pain between 2010 and 2019. We analyzed the overall prevalence and prevalence according to the age group, sex, grade of lumbar disc degeneration, and thoracic level. In addition, we identified factors independently associated with stenotic thoracic ligamentum flavum hypertrophy occurrence.

RESULTS

Among 1896 patients, the overall prevalence of stenotic thoracic ligamentum flavum hypertrophy was 9.8% (185/1896), with the highest prevalence observed in the ≥80-year-old age group among all age groups (15.9%, 14/88). The region with the highest prevalence was the T10/11 level (3.0%, 57/1896). Multivariable logistic regression analysis revealed that when compared with the <50-year-old age group, all other age groups were significantly associated with stenotic thoracic ligamentum flavum hypertrophy (p<0.01). In addition, grade 5 of lumbar disc degeneration was significantly associated with stenotic thoracic ligamentum flavum hypertrophy (p=0.03).

CONCLUSIONS

Given the possibility for missed stenotic thoracic ligamentum flavum hypertrophy to potentially result in neurological complications, extending lumbar spine MRI covering the lower thoracic region may be considered for patients over 50 years of age with suspected severe lumbar disc degeneration.

Navigation-Assisted Micro-Window Excision of Thoracic Ossification of Ligamentum Flavum (Mishima Surgery) in Professional Baseball Pitchers: A Case Report and Technical Note

Background and Objectives: Thoracic ossification of the ligamentum flavum (OLF) often causes myelopathy and/or radiculopathy. The disease is frequently observed in East Asian populations. Although thoracic OLF in young athletes who have underwent decompression surgery has been reported, the removal of posterior spinal bony elements and ligamentous complex may often cause postoperative thoracolumbar instability. We established a novel surgical technique that preserves the posterior spinal elements, including the spinous processes, facet joints, and supraspinous and interspinous ligaments for thoracic OLF. This is the first case report to describe a navigation-assisted micro-window excision of thoracic OLF. Case: A 32-year-old male right-handed professional baseball pitcher with significant weakness and numbness in the left leg was referred to our hospital. The patient was diagnosed with thoracic OLF at T10-11 based on radiographic and magnetic resonance images in August 2022. After exposure of the left T10-11 laminae via a small unilateral incision, the location of T10-11 OLF was detected over the lamina by O-arm navigation. Then, the micro-window was made directly above the OLF using a navigated air drill, and the OLF was removed on the ipsilateral side. The contralateral side of OLF was also resected through the same micro-window, achieving complete spinal cord decompression. Results: The next day of the surgery, his leg weakness and numbness were significantly improved. Six weeks after the surgery, he started pitching. Three months after surgery, his symptoms had gone completely, and he pitched from the mound. Approximately 6 months after surgery, he successfully pitched in a professional baseball game. Conclusions: A navigation-assisted micro-window excision of thoracic OLF effectively preserved the spinal posterior bony elements and ligamentous complex. However, long-term clinical outcomes should be evaluated in future studies.

Value of Additional Instrumented Fusion in the Treatment of Thoracic Ossification of the Ligamentum Flavum

Objective

The ossification of the ligamentum flavum (OLF) is one of the major causes of thoracic myelopathy. Surgical decompression with or without instrumented fusion is the mainstay of treatment. However, few studies have reported on the added effect of instrumented fusion. The objective of this study was to compare clinical and radiological outcomes between surgical decompression without instrumented fusion (D-group) and that with instrumented fusion (F-group).

Methods

A retrospective review was performed on 28 patients (D-group, n=17; F-group, n=11) with thoracic myelopathy due to OLF. The clinical parameters compared included scores of the Japanese Orthopedic Association (JOA), the Visual analogue scale of the back and leg (VAS-B and VAS-L), and the Korean version of the Oswestry disability index (K-ODI). Radiological parameters included the sagittal vertical axis (SVA), the pelvic tilt (PT), the sacral slope (SS), the thoracic kyphosis angle (TKA), the segmental kyphosis angle (SKA) at the operated level, and the lumbar lordosis angle (LLA; a negative value implying lordosis). These parameters were measured preoperatively, 1 year postoperatively, and 2 years postoperatively, and were compared with a linear mixed model.

Results

After surgery, all clinical parameters were significantly improved in both groups, while VAS-L was more improved in the F-group than in the D-group (-3.4±2.5 vs. -1.3±2.2, p=0.008). Radiological outcomes were significantly different in terms of changes in TKA, SKA, and LLA. Changes in TKA, SKA, and LLA were 2.3°±4.7°, -0.1°±1.4°, and -1.3°±5.6° in the F-group, which were significantly lower than 6.8°±6.1°, 3.0°±2.8°, and 2.2°±5.3° in the D-group, respectively (p=0.013, p<0.0001, and p=0.037). Symptomatic recurrence of OLF occurred in one patient of the D-group at postoperative 24 months.

Conclusion

Clinical improvement was achieved after decompression surgery for OLF regardless of whether instrumented fusion was added. However, adding instrumented fusion resulted in better outcomes in terms of lessening the progression of local and regional kyphosis and improving leg pain. Decompression with instrumented fusion may be a better surgical option for thoracic OLF.

Should asymptomatic cervical stenosis be treated in the setting of progressive thoracic myelopathy? A systematic review of the literature

PURPOSE

Unlike tandem stenosis of the cervical and lumbar spine, tandem cervical and thoracic stenosis (TCTS) of the spine is less common, and the approach and order of intervention are controversial. We aim to review the literature to evaluate the incidence and interventions for patients with cervical and thoracic stenosis. We provide illustrative cases to demonstrate that thoracic myelopathy in the setting of asymptomatic cervical stenosis can be treated safely.

METHODS

A systematic review of the literature through electronic databases of PubMed, EMBASE, Web of Science, and Cochrane Library was performed to present the current literature that evaluates TCTS as it relates to incidence and surgical interventions. We also present two cases of patients undergoing operative intervention for thoracic myelopathy in the setting of concurrent cervical stenosis.

RESULTS

A total of 26 English original studies and case reports were identified. Nine studies evaluated the incidence of TCTS. 20 studies with a total of 168 patients with TCTS presented information on surgical intervention options. There is an overall aggregate incidence of 11.6% (530/4751) based on incidence studies. 165 patients underwent thoracic intervention. Of these patients, 63 patients underwent cervical intervention first, 29 underwent thoracic intervention first, and 73 underwent simultaneous, single-stage intervention.

CONCLUSIONS

In patients presenting with myelopathy, both cervical and thoracic spine should be evaluated for TCTS. Order of operative intervention is tailored to clinical and radiographic information. In cases of thoracic myelopathy with asymptomatic cervical stenosis, thoracic intervention can be pursued with precautions to prevent further cervical cord injury.

Total en bloc spondylectomy is worth doing in complete paralysis spinal giant cell tumor, a minimum 1-year follow-up

OBJECTIVE

To investigate the neurological recovery of Frankel A spinal giant cell tumor (GCT) patients after they had received a Total En Bloc Spondylectomy (TES).

MATERIALS AND METHODS

We retrospectively recorded data of three patients (two females) with mobile spine GCT (T6, T10, and L2) Enneking stage III with complete paralysis before surgery, who had undergone TES in our institute from January 2018 to September 2020. The duration of neurologic recovery to Frankel E was the primary outcome. The intra-operative blood loss, operative time, operative-related complications, and the local recurrence were the secondary outcomes.

RESULTS

The duration of suffering from Frankel A to TES surgery was 2 months for the T6 patient, 3 weeks for the T10 patient, and 1 month for the L2 patient. Three patients had achieved full neurological recovery to Frankel E within 6 months after TES (T6 for 5 months, T10 for 3 months, and L2 for 3 months). The average blood loss was 2833.33 ml and the mean operative time was 400 min. Up until the last follow-up (13-25 months), no evidence of local recurrences had been found in any of the three patients.

CONCLUSION

Frankel A spinal GCT patients can achieve full neurological recovery after TES, if the procedure is performed within 3 months after complete paraplegia. TES can effectively control any local recurrences.

Comparison of Anterior and Posterior Surgical Approaches for Treatment of Thoracic Myelopathy

OBJECTIVE

To study a large multi-institutional sample of patients undergoing anterior versus posterior approaches for surgical decompression of thoracic myelopathy.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program was queried for patients who underwent decompression for thoracic myelopathy between 2007 and 2015 via anterior or posterior approaches. Patients were excluded if they were undergoing surgery for tumors to isolate a degenerative cohort. Demographics, patient comorbidities, operative details, and postoperative complications were compared between the 2 cohorts.

RESULTS

Although there were no differences in age (P = 0.06), sex (P = 0.72), or American Society of Anesthesiologists class (P = 0.59), there were higher rates of steroid use (P = 0.01) and hematologic disorders that predispose to bleeding (P = 0.04) at baseline in the posterior approach cohort. The posterior approach patients had longer operative times (P = 0.03), but there were no differences in length of stay (P = 0.64). Although there were no significant differences in the rates of major organ system complications or return to the operating room (P = 0.52), the posterior approach cohort displayed a trend toward increased severe adverse complications (29.8% vs. 17.6%, P = 0.28) compared with the anterior approach cohort.

CONCLUSION

Although the anterior approach to surgical decompression of thoracic myelopathy demonstrated a lower complication rate, this result did not reach statistical significance. The anterior approach was associated with significantly shorter mean operative time, but otherwise there were no significant differences in operative or postoperative outcomes. These findings may support the favorability of the anterior approach but warrant further investigation in a larger study.

Microendoscopic Posterior Decompression for Treating Thoracic Myelopathy Caused by Ossification of the Ligamentum Flavum: Case Series

Background and Objectives: Ossification of the ligamentum flavum (OLF) is a relatively common cause of thoracic myelopathy. Surgical treatment is recommended for patients with myelopathy. Generally, open posterior decompression, with or without fusion, is selected to treat OLF. We performed minimally invasive posterior decompression using a microendoscope and investigated the efficacy of this approach in treating limited type of thoracic OLF. Materials and Methods: Microendoscopic posterior decompression was performed for 19 patients (15 men and four women) with thoracic OLF with myelopathy aged between 35 to 81 years (mean age, 61.9 years). Neurological examination and preoperative magnetic resonance imaging (MRI) and computed tomography (CT) were used to identify the location and morphology of OLF. The surgery was performed using a midline approach or a unilateral paramedian approach depending on whether the surgeon used a combination of a tubular retractor and endoscope. The numerical rating scale (NRS) and modified Japanese Orthopedic Association (mJOA) scores were compared pre- and postoperatively. Perioperative complications and the presence of other spine surgeries before and after thoracic OLF surgery were also investigated. Results: Four midline and 15 unilateral paramedian approaches were performed. The average operative time per level was 99 min, with minor blood loss. Nine patients had a history of cervical or lumbar spine surgery before or after thoracic spine surgery. The mean pre- and postoperative NRS scores were 6.6 and 5.3, respectively. The mean recovery rate as per the mJOA score was 33.1% (mean follow-up period, 17.8 months), the recovery rates were significantly different between patients who underwent thoracic spine surgery alone (50.5%) and patients who underwent additional spine surgeries (13.7%). Regarding adverse events, one patient experienced dural tear, another experienced postoperative hematoma, and one other underwent reoperation for adjacent thoracic stenosis. Conclusion: Microendoscopic posterior decompression was applicable in limited type of thoracic OLF surgery including beak-shaped type and multi vertebral levels. However, whole spine evaluation is important to avoid missing other combined stenoses that may affect outcomes.

Full-endoscopic decompression for thoracic ossification of ligamentum flavum: surgical techniques and clinical outcomes: A retrospective clinical study

BACKGROUND

Many complications are associated with thoracic open decompression surgery, such as dural tears and neurological deficits. The clinical outcomes are also not satisfactory. Full-endoscopic decompression of the lumbar spinal canal has achieved satisfactory results for the treatment of lumbar spinal stenosis. This surgery may be used for the treatment of thoracic ossification of the ligamentum flavum (OLF) under local anesthesia. The aim of our study is to introduce the surgical techniques used for full-endoscopic decompression for thoracic OLF and to evaluate its safety and efficacy.

METHODS

Fourteen patients with thoracic OLF (4 combined with dural ossification) underwent full-endoscopic decompression surgery. An interlaminar approach was performed. The anchoring method was used to establish the working passage. Spinal cord exposure began at a space between the ossification and the spinal cord, and dorsal and contralateral decompression were performed with the "Over the Top" technique. The modified Japanese Orthopedic Association score (11 points) was used to evaluate the efficacy during follow-up. At the same time, the visual analogue scale score for assessing back pain before and after the operation was evaluated.

RESULTS

The average operation time was 159.73 ± 62.09 minutes, and the hospitalization time was 7.43 ± 1.79 days. The follow-up period ranged from 8 to 22 months. Neurological function was improved. There were no serious complications. Dural tears occurred in 5 patients, intraoperative neurological deterioration occurred in 1 patient, and intraoperative headache and neck pain occurred in 1 patient.

CONCLUSION

Full-endoscopic decompression is an effective, safe surgical technique for thoracic OLF even the cases combined with dural ossification.

Surgery of degenerative thoracic spinal stenosis-long-term outcome with quality-of-life after posterior decompression via an uni- or bilateral approach

BACKGROUND

The rate of degenerative thoracic spinal stenosis (TSS) as underlying pathology for myelopathy is not precisely known, and larger case series are only available for the Asian region. We present one of the largest European series to evaluate rate and clinical outcome after dorsal decompression via a uni- or bilateral approach.

METHOD

We investigated patients' characteristics, imaging/surgical parameters, and outcomes with quality-of-life (QOL) in all patients who underwent surgical treatment for TSS between 2013 and 2018 in a university neurosurgical clinic.

RESULTS

From 645 patients with surgery for degenerative spondylotic myelopathy within 6 years, 28 patients (4.3%) suffered from TSS. Median age was 70.4 years with a slight predominance of the female sex (m:f = 1:1.3). The most frequent symptoms (mean duration 7.6 months) were ataxia (61%) and sensory changes (50%). The stenoses (median Naganawa score 3) mostly resulted from a combined osseous/ligamentous hypertrophy and disc prolapse, the majority located below Th8 (75%). Nineteen patients with lateralized compression underwent bilateral decompression via a unilateral approach (fenestration/hemilaminectomy with "undercutting" procedure), and 9 patients with circular pathology underwent bilateral-approached decompression (laminectomy). There were no significant differences of patients' characteristics, blood loss, operation time, and in-patient stay between both surgical groups. Independent from the mode of surgery, the spinal canal was significantly (p < 0.001) widened (median Naganawa score 0), and pain (p = 0.04), myelopathy (mJOA score p = 0.01), and QOL (Oswestry Disability Index, p = 0.03; SF-36-MCS, p = 0.01) were significantly improved at long-term follow-up (mean 35.1 months).

CONCLUSIONS

Non-tumorous myelopathy is caused in about 4% of patients by TSS and can be effectively treated by surgical decompression via both a uni- or bilateral approach.

Surgical results and prognostic factors following percutaneous full endoscopic posterior decompression for thoracic myelopathy caused by ossification of the ligamentum flavum

Minimally invasive surgery (MIS) has shown satisfactory surgical results for the treatment of thoracic myelopathy (TM) caused by ossification of the ligamentum flavum (OLF). This study investigated the prognostic factors following MIS and was based on the retrospective analysis of OLF patients who underwent percutaneous full endoscopic posterior decompression (PEPD). Thirty single-segment OLF patients with an average age of 60.4 years were treated with PEPD under local anaesthesia. Clinical data were collected from the medical and operative records. The surgical results were assessed by the recovery rate (RR) calculated from the modified Japanese Orthopaedic Association (mJOA) score. Correlations between the RR and various factors were analysed. Patients’ neurological status improved from a preoperative mJOA score of 6.0 ± 1.3 to a postoperative mJOA score of 8.5 ± 2.0 (P < 0.001) at an average follow-up of 21.3 months. The average RR was 53.8%. Dural tears in two patients (6.7%, 2/30) were the only observed complications. Multiple linear regression analysis showed that a longer duration of preoperative symptoms and the presence of a high intramedullary signal on T2-weighted MRI (T2HIS) were significantly associated with poor surgical results. PEPD is feasible for the treatment of TM patients with a particular type of OLF. Patients without T2HIS could achieve a good recovery if they received PEPD early.

Design of mulitlevel OLF approach ("V"-shaped decompressive laminoplasty) based on 3D printing technology

PURPOSE

To introduce a new surgical approach to the multilevel ossification of the ligamentum flavum (OLF) aided by three-dimensional (3D) printing technology.

METHODS

A multilevel OLF patient (male, 66 years) was scanned using computed tomography (CT). His saved DICOM format data were inputted to the Mimics14.0 3D reconstruction software (Materialise, Belgium). The resulting 3D model was used to observe the anatomical features of the multilevel OLF area and to design the surgical approach. At the base of the spinous process, two channels were created using an osteotomy bilaterally to create a "V" shape to remove the bone ligamentous complex (BLC). The decompressive laminoplasty using mini-plate fixation was simulated with the computer. The physical model was manufactured using 3D printing technology. The patient was subsequently treated using the designed surgery.

RESULT

The operation was completed successfully without any complications. The operative time was 90 min, and blood loss was 200 ml. One month after the operation, neurologic function was recovered well, and the JOA score was improved from 6 preoperatively to 10. Postoperative CT scanning showed that the OLF was totally removed, and the replanted BLC had not subsided.

CONCLUSION

3D printing technology is an effective, reliable, and minimally invasive method to design operations. The technique can be an option for multilevel OLF surgical treatment. This can provide sufficient decompression with minimum damage to the spine and other intact anatomical structures.

Predictors of surgical outcome in thoracic ossification of the ligamentum flavum: focusing on the quantitative signal intensity

The association between intramedullary increased signal intensity (ISI) on T2-weighted magnetic resonance imaging (MRI) and surgical outcome in thoracic ossification of the ligamentum flavum (OLF) remains controversial. We aimed to determine the impact of signal change ratio (SCR) on thoracic OLF surgical outcomes. We retrospectively reviewed 96 cases of thoracic OLF surgery and investigated myelopathy severity, symptom duration, MRI and computed tomographic findings, surgical technique and postoperative recoveries. Surgical outcomes were evaluated according to the modified Japanese Orthopaedic Association (JOA) score and recovery rate. JOA recovery rate <50% was defined as a poor surgical outcome. By multivariate logistic regression analysis, we identified risk factors associated with surgical outcomes. Forty patients (41.7%) had a recovery rate of <50%. In receiver operating characteristic (ROC) curves, the optimal preoperative SCR cutoff value as a predictor of poor surgical outcome was 1.54. Multivariate logistic regression analysis revealed that a preoperative SCR ≥1.54 and symptom duration >12 months were significant risk factors for a poor surgical outcome. These findings suggest that preoperative SCR and duration of symptoms were significant risk factors of surgical outcome for patients with thoracic OLF. Patients with preoperative SCR ≥1.54 can experience poor postoperative recovery.

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.

Microendoscopic posterior decompression for the treatment of thoracic myelopathy caused by ossification of the ligamentum flavum: a technical report

PURPOSE

Ossification of the ligamentum flavum (OLF) is a common cause of progressive thoracic myelopathy in East Asia. Good surgical results are expected for patients who already show myelopathy. Surgical decompression using a posterior approach is commonly used to treat OLF. This study investigated the use of microendoscopic posterior decompression for the treatment of thoracic OLF.

METHODS

Microendoscopic posterior decompression was performed on 9 patients with myelopathy. Patients had a mean age of 59.8 years and single-level involvement, mostly at the T10-11 and T11-12 vertebrae. Computed tomography and magnetic resonance imaging were used to classify the OLF. A tubular retractor and endoscopic system were used for microendoscopic posterior decompression. Midline and unilateral paramedian approaches were performed in 2 and 7 patients, respectively. Intraoperative motor evoked potentials (MEPs) of 7 patients were monitored. Pre- and postoperative neurological status was evaluated using the modified Japanese Orthopaedic Association (mJOA) score.

RESULTS

Thoracic OLF for all patients were classed as bilateral type with a round morphology. Improvement of MEPs at least one muscle area was recorded in all patients following posterior decompression. A dural tear in one patient was the only observed complication. The mean recovery rate was 44.9 %, as calculated from mJOA scores at a mean follow-up period of 20 months.

CONCLUSIONS

Microendoscopic posterior decompression combined with MEP monitoring can be used to treat patients with thoracic OLF. The optimal surgical indication is OLF at a single vertebral level and of a unilateral or bilateral nature, without comma and tram track signs, and a round morphology.

Treatment strategies for the surgical complications of thoracic spinal stenosis: a retrospective analysis of two hundred and eighty three cases

PURPOSE

Our aim was to investigate the causes of and treatment strategies for surgical complications of thoracic spinal stenosis.

METHODS

Between May 1990 and May 2010, 283 patients with thoracic spinal stenosis were treated in our department. Three physicians were assigned to patient follow-up. Patient medical records and radiographs were reviewed. Complications were categorised as perioperative, mid- to long-term and donor-site.

RESULTS

Follow-up was completed for 254 patients; 249 patients survived. Follow-up time ranged from one to 19 years, with a mean of six years and two months. There were 107 cases with complications an incidence rate of 42.1%. Eleven cases were pulmonary infection, seven transient nerve-root injury, three pulmonary injury and one vertebral canal haematoma, all of which resolved. Thirteen cases of spinal cord injury postoperatively were treated using dehydration and corticosteroid therapy; eight recovered to the preoperation level, and five deteriorated. Eleven cases resulted in dural injury, and four led to cerebrospinal fluid leakage. There were five cases of wound-fat liquefaction and one of wound infection. Seven cases with deep venous thrombosis of the lower limb resolved by elevating the affected limb and administration of low-molecular-weight dextran. Seven cases of delayed wound healing recovered following change of dressings and antibiotic administration. Four cases of delayed bone-graft fusion recovered by extending the external fixation time. One case of bone-graft absorption was treated by iliac bone grafting and bracing. Two cases of internal fixation breakage were treated by removing the internal fixation.

CONCLUSIONS

Thoracic spinal stenosis surgery may result in various complications but has a good prognosis with proper treatment. The key points in reducing complications are the surgeon's familiarity with operative imperatives and the appropriate surgical approach.

Surgical results and prognostic factors for thoracic myelopathy caused by ossification of ligamentum flavum: posterior surgery by laminectomy

BACKGROUND

Thoracic ossification of ligamentum flavum (TOLF) of the spine is characterized by a heterotopic bone formation in the thoracic ligamentum flavum, which causes slowly progressing spinal cord injury. Surgical decompression is the most common treatment of choice for patients with compressive myelopathy due to TOLF. However, the surgical outcome is not always satisfactory.

METHODS

To identify the predictors of surgical outcome, we retrospectively studied the associations between various clinical and radiological parameters and postoperative recovery in 78 patients who underwent decompressive laminectomy for thoracic myelopathy due to TOLF between October 1998 and June 2011. Surgical outcomes were assessed using modified Japanese Orthopedic Association (mJOA) recovery rate (RR)/outcome scores.

RESULTS

At a minimum of 1 year after surgery for TOLF treatment, the postoperative clinical scores showed statistically significant changes with improvement in the JOA scores. The results indicated that a longer duration of preoperative symptoms, fused-type TOLF, and the degree of compression of the anteroposterior diameter and ossified region (middle thoracic OLF) was related to poor prognosis.

CONCLUSION

Early diagnosis and sufficient surgical decompression improved the functional outcomes of TOLF patients. The surgical risk is relatively higher due to the tenuous blood supply of the spinal cord and the limited spinal canal volume of the middle thoracic spine extending from T4 to T9.

Upper facet joint en bloc resection for the treatment of thoracic myelopathy caused by ossification of the ligamentum flavum

OBJECT

The authors introduce a novel technique to treat thoracic myelopathy caused by ossification of the ligamentum flavum (OLF): upper facet joint en bloc resection. This surgical procedure avoids surgery to the most heavily compressed cord surface, contact with the cord, and cord injury. The epidural venous plexus bleeding point can be directly seen and easily controlled during the decompression.

METHODS

Between January 2007 and January 2009, thoracic myelopathy caused by OLF was diagnosed in 38 patients using plain radiography, CT, and MRI, and diagnoses were confirmed by postoperative pathological examination. All upper facet joint en bloc resection procedures were performed in 2 steps. First, the bony structures above the upper facet joint surfaces were resected and the upper facet joints were isolated. Second, en bloc resection of the upper facet joint was performed by dissection of the junction between the pedicle and upper facet joint. Intraoperative neurological monitoring was performed in all cases. The modified Japanese Orthopaedic Association (mJOA) scoring system was used to assess neurological status. The degree of postoperative expansion of the spinal cord was calculated on axial MR images. The pre- and postdecompression Cobb angle was applied to assess the magnitude of local kyphosis.

RESULTS

Of the 38 cases of OLF, 6 were single level, 12 were double level, and 20 were multilevel. Of the 92 ossified segments in this study, 23 (25.0%) were located in the upper thoracic spine (T1-4), 13 (14.1%) were located in the midthoracic spine (T5-8), and 56 (60.9%) were located in the lower thoracic spine (T9-L1). The mean intraoperative blood loss was 340 ± 54 ml. The neurological status improved during follow-up (mean 46.1 months) from a preoperative mean mJOA score of 5.39 ± 1.52 to 8.97 ± 1.22 points (t = 18.39, p < 0.05). The neurological function recovery rate ranged from 28.6% to 100%. The mean increase in pre- and postoperative kyphosis of the involved vertebrae was only 1.3° ± 1.6°. The increase in the cross-sectional area of the dural sac at the level of maximum compression suggested that decompression was complete.

CONCLUSIONS

Upper facet joint en bloc resection is effective and may be a reasonable alternative treatment choice for thoracic myelopathy caused by OLF.

Lamina osteotomy and replantation with miniplate fixation for thoracic myelopathy due to ossification of the ligamentum flavum

Lamina osteotomy and replantation with miniplate fixation is often used to treat benign intradural tumors, effectively preventing nerve entrapment and postoperative spinal deformities. However, no studies report using this technique to treat thoracic myelopathy due to ossification of the ligamentum flavum (OLF). This article reports the clinical outcome of a series of 18 cases of contiguous multilevel OLF treated by lamina osteotomy and replantation with miniplate fixation.Eighteen consecutive patients at the authors' institution were treated between 2008 and 2010 for contiguous multilevel OLF. Clinical efficacy, operative time, blood loss, sagittal alignment, and complications were investigated. Japanese Orthopaedic Association scale scores improved from 4.7±1.4 preoperatively to 7.9±1.3 three months postoperatively and 8.8±1.3 at final follow-up (P<.01), with a mean recovery rate of 67.8%±13.1%. No significant kyphotic deformity occurred postoperatively, and local kyphosis in the treated area increased by a mean of only 1.9°±1.0° at final follow-up. No patient required additional surgery due to spinal canal reobstruction and progressive spinal deformity. Cerebrospinal fluid leakage occurred in 4 patients and resolved after repair. Pulmonary infection and deep venous thrombosis occurred in 1 patient who was discharged with no complications after routine treatment.Lamina osteotomy and replantation with miniplate fixation is an effective therapeutic option for thoracic myelopathy due to contiguous multilevel OLF compression. The technique provides adequate decompression and stabilized sagittal alignment and avoids invasion of the spinal canal by scar tissue.

Imaging of spinal stenosis: neurogenic intermittent claudication and cervical spondylotic myelopathy

Spinal stenosis in either the cervical or lumbar spinal segments is one of the most common indications for spine imaging and intervention, particularly among the elderly. This article examines the pathophysiology and imaging of the corresponding clinical syndromes, cervical spondylotic myelopathy or neurogenic intermittent claudication. The specificity fault of spine imaging is readily evident in evaluation of spinal stenosis, as many patients with anatomic cervical or lumbar central canal narrowing are asymptomatic. Imaging also may be insensitive to dynamic lesions. Those imaging features that identify symptomatic patients, or predict response to interventions, are emphasized.

Clinical characteristics and surgical outcome of the symptomatic ossification of ligamentum flavum at the thoracic level with combined lumbar spinal stenosis

STUDY DESIGN

Retrospective study.

OBJECTIVE

To identify the clinical significance of coexistence of lumbar spinal stenosis (LSS) with thoracic ossification of ligamentum flavum (OLF), and to study the surgical outcome of the thoracic OLF patients with or without LSS.

SUMMARY OF BACKGROUND DATA

The OLF at the thoracic level (thoracic OLF) is a rare disease that causes acquired thoracic spinal canal stenosis. Thoracic OLF is frequently combined with other spinal disorders, such as LSS, and it is not uncommon for thoracic OLF to be misdiagnosed as LSS, resulting in delayed diagnosis. However, clinical impacts of the coexistence of LSS with thoracic OLF remain unknown.

METHODS

In the present study, 36 patients who underwent posterior decompression for OLF-induced thoracic myelopathy were retrospectively reviewed, and the adverse influence of the copresence of LSS with thoracic OLF was studied with regard to clinical features such as clinical symptoms and surgical outcome.

RESULTS

Out of 36 patients, 18 patients had LSS (combined group: C-group), and the remaining 18 patients had thoracic OLF only (thoracic group: T-group). No significant inter-group differences were found in terms of gender, age, follow-up period, and preoperative duration of symptoms. Regarding the etiology of LSS in the C-group, 12 cases had degenerative LSS, two cases had lumbar OLF, one case had degenerative LSS with lumbar OLF, one case had had degenerative LSS with lumbar OPLL, and two cases had traumatic LSS due to lumbar kyphosis after vertebral fracture. Clinical examination revealed that the T-group was significantly more likely to demonstrate Achilles hyper-reflexia, while the C-group was significantly more likely to demonstrate Achilles hypo-reflexia. The mean preoperative and postoperative JOA scores were not statistically different between the two groups. However, the mean recovery rate of the JOA score was 17.3% in the C-group, and 30.4% in the T-group. Statistical analysis revealed that the recovery rate of the C-group was significantly lower than that of the T-group.

CONCLUSION

Thoracic OLF with LSS will show a more severe clinical manifestation than that without LSS. In this study, we clearly indicated that the coexisting LSS in thoracic OLF will have adverse effects on the surgical results in thoracic OLF.

Laminectomy in patients with achondroplasia: the impact of time to surgery on long-term function

STUDY DESIGN

Retrospective analysis, survey.

OBJECTIVE

To describe a cohort of individuals with achondroplasia undergoing thoracolumbar laminectomy and to examine if shorter time to surgery was related to improvement in long-term functional outcome.

SUMMARY OF BACKGROUND DATA

Data on the long-term benefits of laminectomy are mixed for such patients. Earlier intervention may be associated with greater likelihood of long-term benefit, but quantified data are lacking.

METHODS

We retrospectively studied 49 patients with achondroplasia who underwent primary laminectomy for spinal stenosis. Patients completed a questionnaire to assess symptoms, walking distance, and independence (per Modified Rankin Scale), before surgery and currently. Responses were analyzed for the likelihood of improved walking distance or Rankin level.

RESULTS

Our patients had the following mean values: age, 37.7 ± 10.6 years; body mass index, 31.8 ± 5.5; symptom duration, 74.0 ± 100.1 months; preoperative symptom severity score, 2.7 ± 1.0 points; mean changes in blocks walked, +0.39 ± 2.0; and Rankin level, +0.08 ± 1.47. Patients with a time-to-surgery interval of <6 months were 7.13 times (95% confidence interval [CI], 1.39-36.66) more likely to experience improvement in walking distance and 4.00 times (95% CI, 1.05-15.21) more likely to experience Rankin level improvement than patients whose interval was >6 months. Intervals of up to 12 and 24 months were associated with increased likelihoods of 4.95 (95% CI, 1.41-17.41) and 3.43 (95% CI, 1.05-11.22), respectively, of improved walking distance compared with those with longer time-to surgery intervals, but those Rankin level improvements were not statistically significant.

CONCLUSION

Time from symptom onset to surgery in patients with achondroplasia is an important predictor of long-term functional outcome. For sustained long-term postsurgical improvement, the window of opportunity might be relatively narrow. Patients with achondroplasia should seek medical advice for spinal stenotic symptoms as soon as possible.

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.

Thoracic myelopathy due to ossification of ligamentum flavum: a retrospective analysis of predictors of surgical outcome and factors affecting preoperative neurological status

Despite good posterior decompression of thoracic myelopathy due to ossification of ligamentum flavum (OLF), recovery varies widely from 25 to 100%. Neurological status on presentation also varies widely in different patients. We, therefore retrospectively studied relation of various clinical and magnetic resonance imaging (MRI) parameters with preoperative neurological status and postoperative recovery in 25 patients who underwent decompressive laminectomy for thoracic myelopathy due to OLF. Patients were assessed using leg-trunk-bladder scores of JOA scale and recovery rate (RR) was calculated as RR = postoperative score - preoperative score/11 - preoperative score × 100. With Pearson's correlation, postoperative recovery rate (RR) significantly correlated with preoperative duration of symptoms, JOA score, sensory JOA score, canal grade, dural canal-body ratio (DCBR), intramedullary signal size (ISS), and intramedullary signal type (IST) on MRI. On MRI, two types of signal changes were identified: normal in T1/hyperintense in T2 representing cord edema and hypointense in T1/hyperintense in T2 representing cystic changes indicating lesser and higher grades, respectively. Presence or absence of signal changes did not correlate with postoperative recovery; but whenever present, ISS greater than 15 mm significantly compromised recovery. Multiple regression analysis (MRA) identified preoperative duration of symptoms and preoperative ISS as significant predictors of postoperative outcome. Based on MRA, we formulated a multiple regression equation to predict RR as Predicted RR = 83.4 + (0.1 × age in years) - (0.7 × preoperative duration of symptoms in months) + (1.5 × preoperative JOA score) + (0.2 × preoperative canal grade in percentage) - (2.5 × ISS in mm) - (1.5 × IST in grade). Though age, preoperative anal sensations, spasticity, canal grade, DCBR, ISS, and IST significantly correlated with preoperative neurological status, MRA identified ISS as most important factor determining preoperative neurological status. Preoperative duration of symptoms and developmentally narrow canal had no influence on preoperative neurological status. Patients with developmentally narrow canal showed significant correlation with younger age at onset of myelopathy. To conclude, only independent factor determining preoperative neurological status is ISS. Predictors of postoperative recovery are preoperative duration of symptoms and ISS. Postoperative recovery can be predicted by formulated equation.

Thoracic myelopathy caused by ossification of the ligamentum flavum

OBJECTIVE

Ossification of the ligamentum flavum (OLF) is a rare cause of thoracic myelopathy. The aim of this study was to identify factors associated with the surgical outcome on the basis of preoperative clinical and radiological findings.

METHODS

Data obtained in 26 patients whot underwent posterior decompression for thoracic myelopathy, caused by thoracic OLF, were analyzed retrospectively. Patient age, duration of symptoms, OLF type, preoperative and postoperative neurological status using the Japanese Orthopedic Association (JOA) scoring system, surgical outcome, and other factors were reviewed. We compared the various factors and postoperative prognosis. All patients had undergone decompressive laminectomy and excision of the OLF.

RESULTS

Using the JOA score, the functional improvement was excellent in 8 patients, good in 14, fair in 2, and unchanged in 2. A mean preoperative JOA score of 6.65 improved to 8.17 after an average of 27.3 months. According to our analysis, age, gender, duration of symptoms, the involved spinal level, coexisting spinal disorders, associated trauma, intramedullary signal change, and dural adhesions were not related to the surgical outcome. However, the preoperative JOA score and type of OLF were the most important predictors of the surgical outcome.

CONCLUSION

Early diagnosis and sufficient surgical decompression could improve the functional prognosis for thoracic OLF. The postoperative results were found to be significantly associated with the preoperative severity of myelopathy and type of OLF.

Two-stage decompression for combined epiconus and cauda equina syndrome due to multilevel spinal canal stenosis of the thoracolumbar spine: a case report

INTRODUCTION

A case of combined epiconus and cauda equina syndrome due to multilevel spinal canal stenosis of the thoracolumbar spine is reported.

METHODS

A 76-year-old man with multilevel spinal canal stenosis of the thoracolumbar spine (Th11-12, L2-S) who showed symptoms of epiconus syndrome was reported. First, we performed anterior decompression and fusion at the thoracolumbar junction (decompression: Th11-12, fusion: Th10-L2), which ameliorated his symptom partially. However, he presented cauda equina symptoms. Then, he underwent posterior spinal decompression (L3-5) and fusion (Th12-L5).

RESULTS

After anterior decompression, several symptoms disappeared. However, motor and sensory disturbance below L4 and bladder-bowel disturbance remained. We then performed a secondary operation. At three years' follow-up, he was able to walk with the aid of a cane.

CONCLUSIONS

Combined epiconus and cauda equina syndrome due to multilevel spinal canal stenosis was treated by combined two-stage anterior and posterior decompression. In this case, multilevel decompression via anterior and posterior approaches was necessary to relieve the symptoms.

Concomitant noncontiguous level (thoracic & lumbar) spinal stenosis

Presented here is a prospective study assessing the efficacy of decompression of concomitant noncontiguous level (thoracic & lumbar) stenosis in accordance with neurological findings, nerve root blocks, and myelographically proven disease. The objective was to determine the efficacy, clinical outcome, and functional recovery in patients undergoing simultaneous decompression. No previous study has focussed on the clinical outcome of such simultaneous decompression. Twenty-one patients with neurological claudication, progressive gait disturbance, upper motor neuron symptoms, and findings of myelopathy in both the lower extremities underwent simultaneous decompression and were assessed. The average follow-up was 32 months (range, 24-40 months). At the last examination,13 patients (82%) had excellent or good clinical results. Postoperative improvement correlated inversely with the duration of symptoms. The patients usually had satisfactory outcomes when the correct diagnosis was made and management was implemented. Functional recovery depends on early diagnosis and timely surgical intervention.

Thoracic ossification of ligamentum flavum caused by skeletal fluorosis

Thoracic ossification of ligamentum flavum (OLF) caused by skeletal fluorosis is rare. Only six patients had been reported in the English literature. This study reports findings from the first clinical series of this disease. This was a retrospective study of patients with thoracic OLF due to skeletal fluorosis who underwent surgical management at the authors' hospital between 1993 and 2003. Diagnosis of skeletal fluorosis was made based on the epidemic history, clinical symptoms, radiographic findings, and urinalysis. En bloc laminectomy decompression of the involved thoracic levels was performed in all cases. Cervical open door decompression or lumbar laminectomy decompression was performed if relevant stenosis was present. Neurological status was evaluated preoperatively, at the third day postoperatively, and at the end point of follow-up using the Japanese Orthopaedic Association (JOA) scoring system of motor function of the lower extremities. A total of 23 cases were enrolled, 16 (69.6%) males and 7 (30.4%) females, age ranging from 42 to 72 years (mean 54.8 years). All patients came from a high-fluoride area, and 22 (95.7%) had dental fluorosis. Medical imaging showed OLF together with ossification of many ligaments and interosseous membranes, including interosseous membranes of the forearm (18/23 patients 78.3%), leg (14/23 patients 60.9%), and ribs (11/23 patients 47.8%). OLF was classified into five types based on MRI findings: localized (4/23 patients 17.4%), continued (12/23 patients 52.2%), skip (3/23 patients 13.0%), combining with anterior pressure (2/23 patients 8.7%), and combining with cervical and/or lumbar stenosis (2/23 patients, 8.7%). Urinalysis showed a markedly high urinary fluoride level in 14 of 23 patients (60.9%). Patients were followed up for an average duration of 4 years, 5 months. Paired t-test showed that the JOA score was slightly but nonsignificantly increased relative to preoperative measurement 3 days after surgery (P = 0.0829) and significantly increased at the end of follow-up (P = 0.0001). In conclusion, Fluorosis can cause ossification of thoracic ligamentum flavum, as well as other ligaments. Comparing with other OLF series, a larger number of spinal segments were involved. The diagnosis of skeletal fluorosis was made by the epidemic history, clinical symptom, imaging study findings, and urinalysis. En bloc laminectomy decompression was an effective method.

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.

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.

Unilateral atlantal lateral mass hypertrophy

✓ The authors report the cases of four patients in whom they diagnosed an extremely rare and hitherto unreported clinical condition—unilateral hypertrophy of the C-1 lateral mass causing symptomatic cord compression. All patients presented with long-standing torticollis and progressive myelopathy. Three patients underwent posterior decompressive surgery and one underwent resection of the part of the lateral mass invading into the spinal canal and subsequent atlantoaxial plate and screw fixation. Clinical improvement of varying degrees occurred in all cases following surgery. The clinical recovery, however, was most remarkable in the patient who underwent resection of the bone portion indenting the cord. The follow-up periods ranged from 2 to 14 years.

The remarkable similarity in the presenting clinical and radiological/neuroimaging features in all four patients suggests that unilateral hypertrophy of the lateral mass of atlas may be a defined clinical entity. The treatment strategy needs to be evaluated; however, resection of the compression-causing portion of the hypertrophic bone appears to be the best treatment option.

Contributing factors affecting the prognosis surgical outcome for thoracic OLF

The thoracic ossification of ligamentum flavum (OLF) is a disease that produces spastic paraparesis, and there are various factors that may affect the surgical outcome of thoracic OLF patients. The authors of this study treated 19 of these thoracic OLF patients from 1998 to 2002, and retrospectively reviewed the patients' age, sex, symptom duration, involved disease level, preoperative clinical features, neurological findings, radiological findings, the other combined spinal diseases and the surgical outcomes. There were excellent or good surgical outcomes in 16 patients, but 3 patients did not improve after thoracic OLF surgery: this included 1 patient, whose motor function worsened after decompressive thoracic OLF surgery. The favorable contributing factors of surgical outcome in thoracic OLF are a short preoperative symptom duration, single-level lesion, and unilateral lesion type on CT axial scan. On the contrary, the poor prognostic factors are beak type lesion and intramedullary signal changes on T(2)-weighted sagittal MRI. The complete preoperative evaluation including radiologic findings will provide valuable aid in presuming the surgical outcome for the thoracic OLF patients.

Surgical experience with symptomatic thoracic ossification of the ligamentum flavum

Object. Symptomatic thoracic ossification of the ligamentum flavum (OLF) is rare, and its prognostic factors remain unclear. The authors retrospectively studied 24 patients with surgically treated thoracic OLF to delineate its prognostic factor.

Methods. The clinical manifestations, radiological studies, surgical records, and pathological findings were reviewed. Preoperative and postoperative neurological data were reappraised using the American Spinal Injury Association and modified Japanese Orthopaedic Association (JOA) scoring systems. Spearman rank-correlation coefficients and nonparametric tests were used to analyze the correlations between the variables of patient characteristics, preoperative duration of symptoms, preoperative neurological status, associated spinal disorder(s) other than thoracic OLF, and the final functional outcome.

Conclusions. Decompressive surgery is indicated in patients in whom symptomatic thoracic spinal cord compression is caused by intruding OLF. Magnetic resonance imaging can provide sufficient clues for the diagnosis of thoracic OLF. Higher preoperative modified JOA scores of 3 and 4 are positively correlated with better postoperative functional recovery than lower scores. Surgery should be performed as soon as possible before independent ambulatory function is impaired.

Outcome of late surgical treatment in patients with incomplete paraplegia due to spinal degenerative diseases

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

To assess the outcome of late surgical intervention in patients with incomplete paraplegia due to spinal degenerative diseases.

SETTING

Three men and four women with cervical or thoracic spinal degenerative diseases, who preoperatively were unable to walk for more than 6 months in Mie prefecture, Japan.

METHODS

Review of clinical records and questionnaire survey regarding the walking ability of patients 2 years after surgery.

RESULTS

All seven patients were unable to walk postoperatively.

CONCLUSION

A late surgical intervention may not lead to functional recovery in patients with spinal degenerative disease who were unable to walk for at least 6 months.

Transient paraparesis after laminectomy in a patient with multi-level ossification of the spinal ligament

Acute neurologic deterioration is not a rare event in the surgical decompression for thoracic spinal stenosis. We report a case of transient paraparesis after decompressive laminectomy in a 50-yr-old male patient with multi-level thoracic ossification of the ligamentum flavum and cervical ossification of the posterior longitudinal ligament. Decompressive laminectomy from T9 to T11 was performed without gross neurological improvement. Two weeks after the first operation, laminoplasty from C4 to C6 and additional decompressive laminectomies of T3, T4, T6, and T8 were performed. Paraparesis developed 3 hr after the second operation, which recovered spontaneously 5 hr thereafter. CT and MRI were immediately performed, but there were no corresponding lesions. Vascular compromise of the borderlines of the arterial supply by microthrombi might be responsible for the paraparesis.