Adjacent Segment Degeneration after Short-Segment Lateral Lumbar Interbody Fusion (LLIF).

Purpose: To investigate the influence on the adjacent segment degeneration (ASD) of short-segment lateral lumbar interbody fusion (LLIF) at 2 years postoperatively. Methods: Ninety-seven consecutive patients who underwent one- or two-level LLIF were included from two institutions. We diagnosed radiographical adjacent segment degeneration with the appearance of adjacent spondylolisthesis (>3 mm) or deterioration of adjacent disk height (>3 mm) on plain radiographs or decrease of the intervertebral angle (>5 degrees). The differences between the two groups with and without radiographical ASD were investigated using univariate and multivariate analyses to determine the risk factors for ASD. The variables included extent of adjacent decompression, posterior fixation method (open method or percutaneous method), and facet violation on postoperative CT. Results: In total, 19 patients (19.6%) were diagnosed as radiographical ASD 2 years after surgery. Univariate analysis showed that the ASD (+) group had a high frequency of adjacent decompression (21.1 vs. 3.8%, p = 0.035) compared with the ASD (-) group. There were no differences between the two groups in posterior fusion method (percutaneous method 42.1 vs. 57.7%, p = 0.221) or facet joint violation (15.8 vs. 14.1%, p = 0.860). The multivariate analysis found adjacent intervertebral decompression to be a risk factor for ASD 2 years after surgery (odds ratio: 9.95; 95% confidence interval: 1.2-82.1). Conclusions: Adjacent intervertebral decompression was considered to be a potential risk factor for the development of ASD after spinal fusion with LLIF.

A Study of Risk Factors for Early-Onset Adjacent Vertebral Fractures After Kyphoplasty.

STUDY DESIGN: Retrospective study. OBJECTIVES: To elucidate risk factors for early-onset (2 months after initial kyphoplasty) adjacent vertebral fracture (EO-AVF) after kyphoplasty. METHODS: A total of 108 vertebral bodies (95 patients) were included in this study. We examined patient backgrounds, the spinal level of EO-AVFs, surgery-related factors, and imaging findings. We divided the cases into 2 groups: patients with EO-AVF and patients without EO-AVF. Univariate, correlation, and multivariate analyses were conducted to reveal the risks factors for EO-AVFs for these 2 groups. RESULTS: EO-AVFs developed in 28 vertebral bodies; they did not develop in 80 vertebral bodies. The overall EO-AVF incidence rate was 26%. The spinal level was the thoracolumbar junction for 93% of patients and another level for 7%, thus demonstrating the concentration of EO-AVFs in the thoracolumbar junction. For patients without EO-AVF and those with EO-AVF, there were significant differences in age (76 and 80 years, respectively), preoperative vertebral angles (VAs) (17.8° and 23°, respectively), and corrected VAs (7.3° and 12.7°, respectively). Significant differences were not observed for other factors. Pearson's correlation coefficient was 0.661 (P < .000), thereby showing a significantly positive correlation between preoperative VAs and corrected VAs. Logistic regression analysis indicated that age (odds ratio, 1.112; 95% CI, 1.025-1.206) and preoperative VAs (odds ratio, 1.08; 95% CI, 1.026-1.135) were covariates and that the presence of an EO-AVF was a dependent variable. Therefore, both were predictable risk factors for EO-AVFs. CONCLUSION: Age, preoperative VAs, and corrected VAs are risk factors for EO-AVFs after kyphoplasty.

Sarcopenia and physical function are associated with inflammation and arteriosclerosis in community-dwelling people: The Yakumo study.

OBJECTIVES: Sarcopenia reduces physical function, while chronic inflammation causes arteriosclerosis and decreases skeletal muscle. We conducted a cross-sectional study to elucidate the associations among sarcopenia, physical function, arteriosclerosis, and inflammation in community-dwelling people. METHODS: We recruited 335 participants in an annual health checkup. We diagnosed sarcopenia based on appendicular skeletal muscle mass index (aSMI) assessed by bioelectrical impedance analysis. We measured several physical function tests, blood pressure, and serum levels of high-sensitivity C-reactive protein (hs-CRP), total cholesterol, and low-density lipoprotein cholesterol. RESULTS: After controlling for age, sex, and BMI, participants in the sarcopenia group showed lower performance in all measured physical tests than the normal group. Arteriosclerosis risk factors, including blood pressure, cholesterol levels, and hs-CRP, were significantly higher in the sarcopenia group than in the normal group. hs-CRP and total cholesterol levels were significant risk factors of sarcopenia. The aSMI, grip strength, and maximum stride length were negatively related to hs-CRP level. CONCLUSIONS: Community-dwelling people with sarcopenia had higher levels of hs-CRP and a higher risk for arteriosclerosis. The serum level of hs-CRP was an independent risk factor for sarcopenia and was associated with physical function. These findings indicate that chronic inflammation may relate arteriosclerosis and sarcopenia simultaneously.

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.

Spinal sagittal balance substantially influences locomotive syndrome and physical performance in community-living middle-aged and elderly women.

OBJECTIVES: Spinal sagittal imbalance has been well known risk factor of decreased quality of life in the field of adult spinal deformity. However, the impact of spinal sagittal balance on locomotive syndrome and physical performance in community-living elderly has not yet been clarified. The present study investigated the influence of spinal sagittal alignment on locomotive syndrome (LS) and physical performance in community-living middle-aged and elderly women. METHODS: A total of 125 women between the age of 40-88 years (mean 66.2 ± 9.7 years) who completed the questionnaires, spinal mouse test, physical examination and physical performance tests in Yakumo study were enrolled in this study. Participants answered the 25-Question Geriatric Locomotive Function Scale (GLFS-25), the visual analog scale (VAS) for low back pain (LBP), knee pain. LS was defined as having a score of >16 points on the GLFS-25. Using spinal mouse, spinal inclination angle (SIA), thoracic kyphosis angle (TKA), lumbar lordosis angle (LLA), sacral slope angle (SSA), thoracic spinal range of motion (TSROM), lumbar spinal range of motion (LSROM) were measured. Timed-up-and-go test (TUG), one-leg standing time with eyes open (OLS), and maximum stride, back muscle strength were also measured. The relationship between spinal sagittal parameters and GLFS-25, VAS and physical performance tests were analyzed. RESULTS: 26 people were diagnosed as LS and 99 were diagnosed as non-LS. LBP and knee pain were greater, physical performance tests were poorer, SIA were greater, LLA were smaller in LS group compared to non-LS group even after adjustment by age. SIA significantly correlated with GLFS-25, TUG, OLS and maximum stride even after adjustment by age. The cutoff value of SIA for locomotive syndrome was 6°. People with a SIA of 6° or greater were grouped as "Inclined" and people with a SIA of less than 6° were grouped as "Non-inclined". 21 people were "Inclined" and 104 were "Non-inclined". Odds ratio to fall in LS of Inclined group compared to Non-inclined group is 5.0. GLFS-25 were significantly higher, VAS for LBP were greater, TUG, OLS and maximum stride were poorer in Inclined group compared to Non-inclined group even after adjustment by age. CONCLUSIONS: The present study demonstrated that spinal sagittal balance influences the LS and physical performance in community-living middle-aged and elderly women. SIA is a useful spinal parameter to evaluate the risk of LS, and its cutoff value is 6°.

Posterior Surgery for Adolescent Idiopathic Scoliosis With Pedicle Screws and Ultrahigh-Molecular Weight Polyethylene Tape: Achieving the Ideal Thoracic Kyphosis.

STUDY DESIGN: Prospective clinical case series. OBJECTIVES: To describe our surgical procedure and results for posterior correction and fusion with a hybrid approach using pedicle screws, hooks, and ultrahigh-molecular weight polyethylene tape with direct vertebral rotation (DVR) (the PSTH-DVR procedure) for treatment of adolescent idiopathic scoliosis (AIS) with satisfactory correction in the coronal and sagittal planes. SUMMARY OF BACKGROUND DATA: Introduction of segmental pedicle screws in posterior surgery for AIS has facilitated good correction and fusion. However, procedures using only pedicle screws have risks during screw insertion, higher costs, and decreased postoperative thoracic kyphosis. We have obtained good outcomes compared with segmental pedicle screw fixation in surgery for AIS using a relatively simple operative procedure (PSTH-DVR) that uses fewer pedicle screws. METHODS: The subjects were 30 consecutive patients with AIS who underwent the PSTH-DVR procedure and were followed for a minimum of 2 years. Preoperative flexibility, preoperative and postoperative Cobb angles, correction rates, loss of correction, thoracic kyphotic angles (T5-T12), coronal balance, sagittal balance, and shoulder balance were measured on plain radiographs. Rib hump, operation time, estimated blood loss, spinal cord monitoring findings, complications, and scoliosis research society (SRS)-22 scores were also examined. RESULTS: The mean preoperative curve of 58.0 degrees (range, 40-96 degrees) was corrected to a mean of 9.9 degrees postoperatively, and the correction rate was 83.6%. Fusion was obtained in all patients without loss of correction. In 10 cases with preoperative kyphosis angles (T5-T12) <10 degrees, the preoperative mean of 5.8 degrees improved to 20.2 degrees at the final follow-up. Rib hump and coronal, sagittal and shoulder balances were also improved, and good SRS-22 scores were achieved at final follow-up. CONCLUSIONS: The correction of deformity with PSTH-DVR is equivalent to that of all-pedicle screw constructs. The procedure gives favorable correction, is advantageous for kyphosis compared with segmental screw fixation, and uses the minimum number of pedicle screws. Therefore, the PSTH-DVR procedure may be useful for treatment of idiopathic scoliosis.

Variety of the Wave Change in Compound Muscle Action Potential in an Animal Model.

STUDY DESIGN: Animal study. PURPOSE: To review the present warning point criteria of the compound muscle action potential (CMAP) and investigate new criteria for spinal surgery safety using an animal model. OVERVIEW OF LITERATURE: Little is known about correlation palesis and amplitude of spinal cord monitoring. METHODS: After laminectomy of the tenth thoracic spinal lamina, 2-140 g force was delivered to the spinal cord with a tension gage to create a bilateral contusion injury. The study morphology change of the CMAP wave and locomotor scale were evaluated for one month. RESULTS: Four different types of wave morphology changes were observed: no change, amplitude decrease only, morphology change only, and amplitude and morphology change. Amplitude and morphology changed simultaneously and significantly as the injury force increased (p<0.05) Locomotor scale in the amplitude and morphology group worsened more than the other groups. CONCLUSIONS: Amplitude and morphology change of the CMAP wave exists and could be the key of the alarm point in CMAP.

Influence of spinal imbalance on knee osteoarthritis in community-living elderly adults.

Previous studies evaluated various risk factors for knee OA; however, no study has examined the association between spinal factors, such as total spinal alignment and spinal range of motion (ROM), with knee OA. The purpose of this study was to examine the influence of spinal factors including total spinal alignment and spinal ROM on knee OA in community-living elderly subjects. A total of 170 subjects ≥60 years old (mean age 69.4 years, 70 males and 100 females) enrolled in the study (Yakumo study) and underwent a basic health checkup. We evaluated A-P knee radiographs, sagittal parameters (thoracic kyphosis angle, lumbar lordosis angle, and spinal inclination angle) and spinal mobility (thoracic spinal ROM, lumbar spinal ROM and total spinal ROM) as determined with SpinalMouse(®). The radiological assessment of knee OA was based on the Kellgren and Lawrence classification, and the knee flexion angle was measured while the subject was standing. Spinal inclination angle and thoracic spinal ROM correlated significantly with knee OA on univariate analyses. Multivariate logistic regression analysis indicated that an increase in spinal inclination angle (OR 1.073, p<0.05) was significantly associated with knee OA. Spinal inclination angle had significant positive correlation with knee flexion angle (r=0.286, p<0.001). The spinal inclination angle is the most important factor associated with knee OA.

Fatal case of cervical blunt vascular injury with cervical vertebral fracture: a case report.

Blunt cerebrovascular injury (BCVI) is usually caused by neck trauma that predominantly occurs in high-impact injuries. BCVI may occur due to damage to both the vertebral and carotid arteries, and may be fatal in the absence of appropriate treatment and early diagnosis. Here, we describe a case of cerebral infarction caused by a combination of a lower cervical spinal fracture and traumatic injury to the carotid artery by a direct blunt external force in a 52-year-old man. Initially, there was no effect on consciousness, but 6 hours later loss of consciousness occurred due to traumatic dissection of the carotid artery that resulted in a cerebral infarction. Brain edema was so extensive that decompression by emergency craniectomy and internal decompression were performed by a neurosurgeon, but with no effect, and the patient died on day 7. This is a rare case of cerebral infarction caused by a combination of a lower cervical spinal fracture and traumatic injury to the carotid artery. The case suggests that cervical vascular injury should be considered in a patient with a blunt neck trauma and that additional imaging should be performed.

Utility of a 3-dimensional full-scale NaCl model for rib strut grafting for anterior fusion for cervicothoracic kyphosis.

In severe spinal deformity, pain and neurological disorder may be caused by spinal cord compression. Surgery for spinal reconstruction is desirable, but may be difficult in a case with severe deformity. Here, we show the utility of a 3D NaCl (salt) model in preoperative planning of anterior reconstruction using a rib strut in a 49-year-old male patient with cervicothoracic degenerative spondylosis. We performed surgery in two stages: a posterior approach with decompression and posterior instrumentation with a pedicle screw; followed by a second operation using an anterior approach, for which we created a 3D NaCl model including the cervicothoracic lesion, spinal deformity, and ribs for anterior reconstruction. The 3D NaCl model was easily scraped compared with a conventional plaster model and was useful for planning of resection and identification of a suitable rib for grafting in a preoperative simulation. Surgery was performed successfully with reference to the 3D NaCl model. We conclude that preoperative simulation with a 3D NaCl model contributes to performance of anterior reconstruction using a rib strut in a case of cervicothoracic deformity.

Surgically treated cases of lumbar spondylolysis and isthmic spondylolisthesis: a multicenter study.

STUDY DESIGN: Prospective database study. OBJECTIVES: To grasp the characteristics of surgically treated cases with lumbar spondylolysis or isthmic spondylolisthesis. SUMMARY OF BACKGROUND DATA: A detailed analysis of surgically treated cases with spondylolysis or isthmic spondylolisthesis has never been reported. An epidemiological study in Japan conducted on 2000 subjects found the incidence of lumbar spondylolysis in the Japanese general population (population-based study) to be 5.9% (males: 7.9%, females: 3.9%). Among 124 vertebrae with spondylolysis, there were 0.8% L2 lesions, 3.2% L3 lesions, 5.6% L4 lesions, and 90.3% L5 lesions, including 5 cases (4.3%) with multiple-level lesions. METHODS: We have been registering surgically treated spine cases in our database since 2000. From this database, we prospectively collected cases with lumbar spondylolysis or isthmic spondylolisthesis that were treated surgically between January 2000 and December 2009. We determined the age at surgery, sex, and vertebral level of spondylolysis. RESULTS: Of the 564 spondylolysis patients treated surgically, 66.8% were male and 33.2% were female. The mean age at surgery was 52.5 years (range, 13-84 y). There were 585 vertebrae with spondylolysis including 21 cases (3.7%) with multiple-level lesions. L5 spondylolysis affected 432 vertebrae and was the most common location (73.8%), followed by 125 L4 lesions (21.4%), 24 L3 lesions (4.1%), and 2 L2 lesions (0.7%). CONCLUSIONS: The percentage of L4 lesions in our study was significantly higher and of L5 lesions was significantly lower than those lesions' percentages in the population-based study. L4 spondylolysis may be more unstable or cause clinical symptoms more frequently leading to more surgical intervention. The percentage of multiple-level spondylolysis was similar between the 2 studies, suggesting these patients respond relatively well to conservative treatment. The male/female ratio was 2:1 in both studies, indicating that males and females require surgery at a similar frequency.

Appropriate timing of surgical intervention for the proximal type of cervical spondylotic amyotrophy.

PURPOSE: The purposes of this study were to evaluate the clinical outcome after surgical treatment of patients with the proximal type of cervical spondylotic amyotrophy (CSA) and to explore the appropriate timing for surgical intervention. MATERIALS AND METHODS: A retrospective review was performed on a consecutive cohort of 41 patients who underwent surgical treatment for the proximal type of CSA between 1995 and 2011 at the Nagoya Spine Group Hospitals. We collected information regarding age, type of muscle atrophy, preoperative and final manual muscle test, duration of symptoms, high-intensity areas on T2-weighted MRI images, low-intensity areas on T1-weighted MRI images, levels of spinal canal stenosis, the compression lesion site, cervical kyphosis and surgical procedures (laminoplasty, anterior spinal fusion and posterior spinal fusion). Univariate analyses and multivariate logistic regression analysis were performed to identify correlates of a poor outcome. To explore the appropriate timing for performing surgery, we analyzed the data using receiver operating characteristic (ROC) analysis. RESULTS: The duration of CSA symptoms was 11.6 months on average. The surgical results were excellent for 25 patients, good for six, fair for nine and poor for one. On multivariate logistic regression analysis, the duration of symptoms was statistically associated with a poor surgical outcome (OR 1.393, p = 0.011). ROC analysis demonstrated that 4.3 months from the onset of CSA symptoms was the appropriate time to undergo surgery. CONCLUSIONS: Our results indicate that we should recommend surgical intervention to patients with the proximal type of CSA within about 4 months after the onset of symptoms if conservative treatment has not been successful.

Intraoperative neurological deterioration secondary to spinal kyphotic change after cervicothoracic junction laminectomy.

STUDY DESIGN: Case report. OBJECTIVE: We report a case in which intraoperative spinal kyphosis after laminectomy led to neurological deterioration during intramedullary spinal cord tumor surgery at the cervicothoracic junction (CTJ). SUMMARY OF BACKGROUND DATA: CTJ is a transitional zone between the cervical and thoracic spine; this region can be easily affected by mechanical stress. Although postoperative spinal instability or kyphosis after laminectomy at CTJ has been reported, no reports of intraoperative neurological deterioration after laminectomy exist. METHODS: The patient was a 40-year-old female with an intramedullary spinal cord tumor at T2-T4, which was suspected to be an ependymoma. She had no neurological deficit before the surgery. Although tumor removal surgery using a posterior approach was planned, the waves observed on intraoperative neurophysiological monitoring in the bilateral lower extremity disappeared soon after laminectomy. RESULTS: The waveform reappeared when we manually corrected the kyphosis at CTJ by pushing the spine. However, when we stopped the manual correction, the waveform disappeared again. The cause of neurological deterioration was strongly suspected to be a spinal kyphosis secondary to laminectomy. We removed the tumor after posterior instrumentation, and her neurological status was restored in 3 months postoperatively. CONCLUSION: A minimal change in spinal alignment secondary to laminectomy could be a cause of intraoperative neurological deterioration during surgery at CTJ. Spinal fixation using spinal instrumentation should be performed before laminectomy, particularly in patients with preoperative neurological damage or severe spinal cord compression at CTJ. LEVEL OF EVIDENCE: 4.

Intradural disc herniation: radiographic findings and surgical results with a literature review.

OBJECTIVE: To report a series of four cases of intradural disc herniation (IDH) with a review of the literature. SUMMARY OF BACKGROUND DATA: IDH is a rare type of disc herniation. Preoperative diagnosis is difficult and IDH is only confirmed during surgery in most cases. Here, we describe four cases of IDH, including three with lumbar hernia and one with thoracic hernia. METHODS: A retrospective chart review, surgical database query, and review of radiology reports are presented for each case, along with a literature review of IDH. RESULTS: Two of the four patients had a history of surgery at the same spinal level. Ring enhancement in gadolinium-enhanced MRI, an air image in computed tomography, and complete block in myelography were observed in the series. Surgery was performed with a transdural approach in all patients. One patient underwent transforaminal lumbar interbody fusion after postoperative recurrence. Three patients with lumbar involvement had nerve root symptoms preoperatively, but showed symptomatic improvement in the early postoperative period. In contrast, the patient with thoracic involvement had preoperative muscle weakness due to myelopathy symptoms, and had residual symptoms after surgery. CONCLUSIONS: IDH is a rare disease and characteristic imaging findings can be useful for diagnosis. Intraoperative findings lead to a definitive diagnosis in many cases and recognition of the pathological characteristics of IDH is important.

Chronic spontaneous lumbar epidural hematoma simulating extradural spinal tumor: a case report.

Spinal epidural hematoma (SEH) is an uncommon disorder, and chronic SEHs are rarer than acute SEHs. However, there is few reported involving the bone change of the vertebral body in chronic SEHs. We present a case report of lumbar epidural hematoma that required differentiation from extramedullary spinal tumors by a long process because the CT scan revealed scalloping of the vertebral body and review the relevant literature. A 78-year-old man had experienced a gradual onset of low back pain and excruciating pain in both legs. Lumbar MRI on T1-weighted images revealed a space-occupying lesion with a hyperintense signal relative to the spinal cord with no enhancement on gadolinium adminisration. Meanwhile, T2-weighted images revealed a heterogeneous intensity change, accompanying a central area of hyperintense signals with a hypointense peripheral border at the L4 vertebra. Moreover, the CT scan demonstrated scalloping of the posterior wall of the L4 vertebral body which is generally suspected as the CT finding of spainal tumor. During the epidural space exploration, we found a dark red-colored mass surrounded by a capsular layer, which was fibrous and adhered to the flavum and dura mater. Microscopic histological examination of the resected mass revealed a mixture of the relatively new hematoma and the hematoma that was moving into the connective tissue. Accordingly, the hematoma was diagnosed as chronic SEH. The particular MRI findings of chronic SEHs are helpful for making accurate preoperative diagnoses of this pathology.

Recurrence of solitary fibrous tumor of the cervical spinal cord.

Solitary fibrous tumor (SFT) mostly originates from the pleura because of proliferation of fibroblast cells. It is extremely rare for the tumor to originate from the spinal cord. Here, we report a rare case of SFT in the spinal cord that recurred repeatedly and progressed from intramedullary to extramedullary. A 40-year-old man underwent C4-5 intramedullary and extramedullary tumor resection in another hospital. Eighteen years later, he experienced symptoms of myelopathy because of tumor recurrence; therefore, he consulted with our hospital and underwent tumor resection again. During surgery, we found that the tumor had an intramedullary and extramedullary location. Only partial resection was possible because of intraoperative deterioration in the compound motor action potential (CMAP). After resection, the pathological diagnosis was SFT. The postoperative course was good. However, two years later, a third tumor resection was required because of dysuria and tumor growth. In this surgery, total resection of the tumor was possible without intraoperative deterioration of the CMAP. The tumor has not subsequently recurred. However, SFT recurrence is relatively common and careful follow-up is required for early detection of recurrence, even after successful removal of the tumor.

Radiologic evaluation after posterior instrumented surgery for thoracic ossification of the posterior longitudinal ligament: union between rostral and caudal ossifications.

STUDY DESIGN: Retrospective clinical study. OBJECTIVE: To investigate, using multislice CT images, how thoracic ossification of the posterior longitudinal ligament (OPLL) changes with time after thoracic posterior fusion surgery. SUMMARY OF BACKGROUND DATA: Few studies have evaluated thoracic OPLL preoperatively and post using computed tomography (CT). METHODS: The subjects included 19 patients (7 men and 12 women) with an average age at surgery of 52 years (38-66 y) who underwent indirect posterior decompression with corrective fusion and instrumentation at our institute. Minimum follow-up period was 1 year, and averaged 3 years 10 months (12-120 mo). Using CT images, we investigated fusion range, preoperative and postoperative Cobb angles of thoracic fusion levels, intraoperative and postoperative blood loss, operative time, hyperintense areas on preoperative MRI of thoracic spine and thickness of the OPLL on the reconstructed sagittal, multislice CT images taken before the operation and at 3 months, 6 months and 1 year after surgery. The basic fusion area was 3 vertebrae above and below the OPLL lesion. RESULTS: The mean operative time was 7 hours and 48 min (4 h 39 min-10 h 28 min), and blood loss was 1631 mL (160-11,731 mL). Intramedullary signal intensity change on magnetic resonance images was observed at the most severe ossification area in 18 patients. Interestingly, the rostral and caudal ossification regions of the OPLLs, as seen on sagittal CT images, were discontinuous across the disk space in all patients. Postoperatively, the discontinuous segments connected in all patients without progression of OPLL thickness by 5.1 months on average. CONCLUSIONS: All patients needing surgery had discontinuity across the disk space between the rostral and caudal ossified lesions as seen on CT. This discontinuity was considered to be the main reason for the myelopathy because a high-intensity area on magnetic resonance imaging was seen in 18 of 19 patients at the same level. Rigid fixation with instrumentation may allow the discontinuous segments to connect in patients without a concomitant thickening of the OPLL.

Characteristics and surgical results of the distal type of cervical spondylotic amyotrophy.

OBJECT: Cervical spondylosis that causes upper-extremity muscle atrophy without gait disturbance is called cervical spondylotic amyotrophy (CSA). The distal type of CSA is characterized by weakness of the hand muscles. In this retrospective analysis, the authors describe the clinical features of the distal type of CSA and evaluate the results of surgical treatment. METHODS: The authors performed a retrospective review of 17 consecutive cases involving 16 men and 1 woman (mean age 56.3 years) who underwent surgical treatment for the distal type of CSA. The condition was diagnosed on the basis of cervical spondylosis in the presence of muscle impairment of the upper extremity (intrinsic muscle and/or finger extension muscles) without gait disturbance, and the presence of a compressive lesion involving the anterior horn of the spinal cord, the nerve root at the foramen, or both sites as seen on axial and sagittal views of MRI or CT myelography. The authors assessed spinal cord or nerve root impingement by MRI or CT myelography and evaluated surgical outcomes. RESULTS: The preoperative duration of symptoms averaged 11.8 months. There were 14 patients with impingement of the anterior horn of the spinal cord and 3 patients with both anterior horn and nerve root impingement. Twelve patients were treated with laminoplasty (plus foraminotomy in 1 case), 3 patients were treated with anterior cervical discectomy and fusion, and 2 patients were treated with posterior spinal fixation. The mean manual muscle testing grade was 2.4 (range 1-4) preoperatively and 3.4 (range 1-5) postoperatively. The surgical results were excellent in 7 patients, good in 2, and fair in 8. CONCLUSIONS: Most of the patients in this series of cases of the distal type of CSA suffered from impingement of the anterior horn of the spinal cord, and surgical outcome was fair in about half of the cases.

The cutoff amplitude of transcranial motor evoked potentials for transient postoperative motor deficits in intramedullary spinal cord tumor surgery.

STUDY DESIGN: Retrospective clinical study of intraoperative transcranial motor evoked potential (TcMEP) amplitudes and postoperative motor deficits (PMDs). OBJECTIVE: To determine the quantifiable cutoff amplitude of TcMEP for predicting transient PMDs in intramedullary spinal cord tumor (IMSCT) surgery. SUMMARY OF BACKGROUND DATA: The "presence or absence" criterion is reliable and widely used the alarm criterion for preventing permanent PMDs in IMSCT surgery. However, we wanted to prevent PMDs even if it is transient. The cutoff amplitude for transient PMDs should be identified. METHODS: We conducted a retrospective study to identify the cutoff amplitude for predicting transient PMDs in IMSCT surgery. Thirty-seven patients were included in the study. We examined intraoperative electrophysiological changes and perioperative motor status in these patients. Receiver operating characteristic analyses were performed to identify the cutoff amplitudes for predicting transient PMDs in IMSCT surgery. The incidence of PMDs and cutoff TcMEP amplitude in cervical and thoracic lesions were compared. RESULTS: Thirteen cases demonstrated transient PMDs. Among 280 monitorable muscles in 37 cases, 51 muscles in 13 patients showed PMDs. Through receiver operating characteristic analysis, the relative and the absolute cutoff amplitudes at the intraoperative point of deterioration were identified to be 12% residual of baseline amplitude and 3.2 µV, respectively. Sensitivity/specificity for those cutoff points are 86%/74% and 88%/78%, respectively. The incidence of PMD was significantly higher, and the cutoff amplitude was lower in the thoracic lesions than in the cervical lesions. CONCLUSION: We determined the cutoff TcMEP amplitude for predicting transient PMDs in IMSCT surgery. The cutoff amplitude for the cervical lesions was higher than that for the thoracic lesions. The results suggest the need for setting different alarm criteria in different level of spine. LEVEL OF EVIDENCE: 3.