Keiichi Katsumi

Can prophylactic bilateral C4/C5 foraminotomy prevent postoperative C5 palsy after open-door laminoplasty?: a prospective study.

Study Design. A prospective study. Objective. To evaluate the effectiveness of prophylactic C4/C5 microforaminotomy with open-door laminoplasty for cervical myelopathy in preventing postoperative C5 palsy. Summary of Background Data. Postoperative C5 palsy is a common complication of cervical laminoplasty. Although the etiology of C5 palsy and preventive measures remain unclear, we hypothesize that C5 palsy is caused by C5 nerve root impairment induced by potential C4/C5 foraminal stenosis and posterior shifting of the spinal cord after laminoplasty. Methods. The study included 141 consecutive patients with cervical myelopathy (103 men and 38 women) who underwent open-door laminoplasty with prophylactic bilateral C4/C5 foraminotomy between 2009 and 2010. These were designated as the foraminotomy group (FG). One hundred forty-one consecutive patients (100 men and 41 women) who underwent open-door laminoplasty without prophylactic foraminotomy during 2006 to 2008 served as a control group. This was the nonforaminotomy group (NFG). The incidence of C5 palsy, operation time, blood loss, and the number of decompressed disc levels were recorded. Results. The incidence of C5 palsy was 1.4% (2 of 141 cases) in the FG, and 6.4% (9 of 141 cases) in the NFG. The mean operation times were 129 and 102 minutes, respectively. There were significant differences in the incidence of C5 palsy and operation time (both comparisons, P < 0.05). There were no significant differences in blood loss or the number of decompressed disc levels (both comparisons, P > 0.05). Conclusion. Prophylactic bilateral C4/C5 microforaminotomy significantly decreased the incidence of postoperative C5 palsy. These results suggest that the main etiology of C5 palsy was C5 root impairment. However, 2 patients experienced C5 palsy despite undergoing prophylactic foraminotomy, which indicated that other factors including spinal cord impairment after acute decompression against cervical canal stenosis may also be considered as minor etiologies of C5 palsy. We conclude that prophylactic C4/C5 foraminotomy was an effective preventive measure against postoperative C5 palsy after laminoplasty.

Analysis of C5 palsy after cervical open-door laminoplasty: relationship between C5 palsy and foraminal stenosis.

Study Design: A retrospective study. Objective: To determine the clinical and imaging characteristics of postoperative C5 palsy after cervical open-door laminoplasty. Summary of Background Data: Postoperative C5 palsy is a common complication of cervical laminoplasty, and although there are several hypotheses regarding its etiology, the pathogenesis and preventive measures remain unidentified and many controversies remain. Methods: A total of 141 consecutive patients (100 men and 41 women) who had undergone open-door laminoplasty for cervical myelopathy between 2006 and 2009 were included in this study. Postoperative C5 palsy was defined as deltoid muscle weakness of a grade <3 in manual muscle test. The patients were divided into 2 groups: 1 that had experienced C5 palsy (PG; the palsy group) and the other that had not (NPG; the nonpalsy group). The parameters evaluated were the incidence of C5 palsy, the level at which spinal cord compression appeared preoperatively, the spinal cord level showing a T2 high-signal intensity lesion on magnetic resonance imaging, T2 high-signal intensity lesions newly appearing postoperatively, and the diameters of the C4/5 and C5/6 foramens. Results: The incidence of C5 palsy was 6.4% (9/141 cases). There were no significant differences between the 2 groups in sex, age, diagnosis, operation time, blood loss, level of spinal cord compression, level of T2 high-signal lesion, or new T2 high-signal lesions. The average diameter of the C4/5 foramen was 1.99 mm in the PG and 2.76 mm in the NPG (P<0.005). In contrast, the average diameter of the C5/6 foramen was 2.35 mm in PG and 2.50 mm in the NPG. Conclusions: There was a significant difference in the diameter of the C4/5 foramen between the PG and the NPG. The results suggest that the main etiology of C5 palsy is impairment of the C5 nerve root induced by preexisting C4/5 foraminal stenosis.

Clinical outcomes of posterior lumbar interbody fusion for lumbar foraminal stenosis: preoperative diagnosis and surgical strategy.

Study Design A retrospective case study of the use of posterior lumbar interbody fusion (PLIF) to treat lumbar foraminal stenosis (LFS). Objectives To characterize the features of clinical symptoms, radiographic evaluation, and surgical outcomes of PLIF in LFS. Summary of Background Data There is no gold standard for the surgical treatment of foraminal stenosis, which occurs in 8% to 10% of surgical cases of lumbar degenerative disease. Methods Data from 31 patients (33 segments) who underwent PLIF from 2001 to 2005 at our institution were analyzed. Exclusion criteria included the patients having both LFS and central canal stenosis, plus extraforaminal or intraforaminal disc herniation. There were 22 males and 9 females, with an average age of 61 (31∼78 y). The affected levels were as follows: L3/4 in 1 patient, L4/5 in 4, and L5/S1 in 28. All patients underwent PLIF with the combination of segmental pedicle screws, interbody cages, and autogenous local bone graft. Results The frequencies of Kemp sign (+), intermittent claudication, leg pain in a sitting position, and leg pain at night, were high. Radiographic evaluation showed severe disc degeneration such as loss of disc height, massive osteophyte formation, and transverse offset angles of the nerve root at the corresponding level. Magnetic resonance imaging and 3D-reconstraction computed tomography clearly showed intraforaminal stenosis in sagittal, axial, and coronal planes. The PLIF procedure provided complete root decompression, restoration of disc height, and preservation of lumbar lordosis at final follow-up. The Japanese Orthopedic Association score improved from 17.1 points preoperatively to 24.9 points at final follow-up, and the overall fusion rate was 100%. Conclusion Lumbar foraminal stenosis could be reliably diagnosed by distinctive clinical symptoms, and various radiographic examinations such as plain x-ray, Magnetic resonance imaging, and 3D-reconstraction computed tomography. The PLIF procedure, in combination with segmental pedicle screws, interbody cages, and autogenous local bone graft provides excellent clinical outcomes, and is a rational and useful surgical option for lumbar foraminal stenosis.

Plexiform schwannoma of the forearm

We report a case of plexiform schwannoma located in the flexor muscles of the forearm in the absence of other signs of neurofibromatosis or schwannomatosis. Magnetic resonance examination revealed a multinodular irregular inhomogeneous mass. Some nodules displayed a peripheral, high intensity rim and a central low intensity (target sign) on T2-weighted images. Pre-operative diagnosis of the rare plexiform schwannoma may be possible with careful imaging examination for the target sign.

Two-year clinical and radiological outcomes of open-door cervical laminoplasty with prophylactic bilateral C4-C5 foraminotomy in a prospective study.

Study Design. A prospective study. Objective. To evaluate the 2-year outcomes of open-door cervical laminoplasty with prophylactic bilateral C4–C5 foraminotomy. Summary of Background Data. A prospective trial of prophylactic bilateral C4–C5 foraminotomy with open-door laminoplasty for cervical compression myelopathy showed a significant efficacy for preventing postoperative C5 palsy. However, in bilateral foraminotomy, there are concerns such as postoperative instability, hinge fracture, or nonunion, which may cause deterioration of neurological symptoms and neck pain. Methods. A prospective trial was performed in 141 patients between 2009 and 2010 (group F). A group of 141 patients who underwent open-door laminoplasty without prophylactic foraminotomy from 2006 to 2008 served as a control group (group NF). Here, we report 2-year radiological and clinical data for 121 patients (follow-up rate: 85.8%) in group F and 115 patients (81.6%) in group NF. The 2 groups were demographically similar, except for the operation time. Results. In group F, the mean rate of facet joint preservation was 71.4%. C2–C7 and C4–C5 lordosis and C4 translational movement were maintained postoperatively in both groups. The range of motion of C2–C7 and C4–C5 significantly decreased to about 80% of the preoperative values in both groups (P < 0.01). These radiological parameters and the incidence of hinge fracture and nonunion did not differ significantly between the groups. Visual analogue scale scores for neck pain were unchanged and significant recoveries (P < 0.001) in Japanese Orthopaedic Association scores were found in both groups. There were no significant differences in these clinical scores between the groups. The incidences of C5 palsy were 1.7% and 7.0% in groups F and NF, respectively (P = 0.043). Conclusion. Prophylactic bilateral C4–C5 foraminotomy did not adversely affect the 2-year radiological and clinical outcomes. Therefore, we conclude that this approach is an effective and desirable procedure for preventing postoperative C5 palsy. Level of Evidence: 3

Hydrogen peroxide modulates synaptic transmission in ventral horn neurons of the rat spinal cord

Excessive production of reactive oxygen species (ROS) is implicated in many central nervous system disorders; however, the physiological role of ROS in spinal ventral horn (VH) neurons remains poorly understood. We investigated how pathological levels of H2O2, an abundant ROS, regulate synaptic transmission in VH neurons of rats using a whole‐cell patch clamp approach. H2O2 increased the release of glutamate and GABA from presynaptic terminals. The increase in glutamate release involved N‐type voltage‐gated calcium channels (VGCCs), ryanodine receptors (RyRs), and inositol trisphosphate receptors (IP3Rs); the increase in GABA release, which inhibited glutamatergic transmission, involved IP3R. Inhibiting N‐type VGCCs and RyRs attenuates excitotoxicity resulting from increased glutamatergic activity while preserving the neuroprotective effects of GABA, and may represent a novel strategy for treating H2O2‐induced motor neuron disorders resulting from trauma or ischaemia–reperfusion injury.

False-negative transcranial motor evoked potentials (TcMEPs) during surgery for congenital lumbar kyphoscoliosis: a case report

Introduction: Transcranial motor evoked potential (TcMEP) monitoring is the gold standard for intra-operative neurological monitoring (IOM) of motor pathways during complex spine surgery because of its high sensitivity and specificity. However, although it is very low, the rate of false-negatives in TcMEP monitoring is not zero. Therefore, over-reliance on TcMEP monitoring can cause potentially preventable motor deficits.Case presentation: We report a case of motor deficits due to nerve root stretch after surgical correction of a congenital lumbar kyphoscoliosis in a 56-year-old woman. TcMEPs did not show any significant changes during surgery, whereas free-run electromyography (EMG) demonstrated a long-lasting train activity in the left quadriceps femoris muscle (QF) after correction at the osteotomy area. According to the normal findings on TcMEP monitoring, we did not release the correction. Postoperatively, a significant decrease (grade 2-) in the manual muscle test for the left QF and iliopsoas muscle and hypesthesia of the left anterior thigh was revealed. Fortunately, muscle strength was fully recovered without revision surgery at 6 months postoperatively; however, numbness in the left anterior thigh persisted at 2 years after surgery.Discussion: Our report suggests that the possibility of false-negative TcMEPs should be kept in mind, especially during surgery with a risk of nerve root injury. When abnormal findings in the free-run EMG, including long-lasting train activity, are observed, surgeons should consider performing appropriate responses, such as the release of the correction, even when no substantial changes are seen in the TcMEPs.

The Influence of Lumbar Muscle Volume on Curve Progression After Skeletal Maturity in Patients With Adolescent Idiopathic Scoliosis: A Long-Term Follow-up Study

STUDY DESIGN A retrospective cohort study. OBJECTIVES To investigate the relationship between skeletal muscle status of the trunk and the progression of adolescent idiopathic scoliosis (AIS) during adulthood. To date, studies evaluating the risk factors for progression of AIS have principally focused on radiographic parameters. METHODS Eighty-two women with AIS managed conservatively, who had a major curve ≥30° at skeletal maturity (Risser grade ≥4), were enrolled. Patients had been followed-up, on average, over 23.5 years (range, 12-37 years) after skeletal maturity, and were ≥30-years-old at the time of the survey (mean, 40.1 years). The ratio of the cross-sectional area (CSA) and signal intensity (SI) of muscles (multifidus [MF], erector spinae [ES], and psoas major [PM]) were evaluated using axial T2-weighted magnetic resonance images at the level of L4. RESULTS The mean progression of the main thoracic and thoracolumbar/lumbar (TL/L) curves after skeletal maturity was 8.2° (mean annual rate of 0.4°) and 7.2° (mean annual rate of 0.3°), respectively. The mean CSA ratio was as follows: MF, 23.3%; ES, 79.6%; and PM, 40.5%. The mean SI ratio was as follows: MF, 34.9%; ES, 31.7%; and PM, 20.9%. On multivariate logistic regression, a higher SI ratio of the MF was predictive of a progression of the Cobb angle and translation of the apical vertebra, with a lower CSA ratio of the ES contributing to the progression of the Cobb angle for the TL/L curve. CONCLUSIONS In patients with AIS who have a major curve ≥30° at skeletal maturity, patients with greater TL/L curve progression have lower skeletal muscle volume and higher fatty degeneration of the lumbar extensor muscles in adulthood. However, further longitudinal or prospective studies are necessary to clarify the causal relationship between scoliosis progression and trunk muscular status. LEVEL OF EVIDENCE Level III, retrospective cohort study.STUDY DESIGN A retrospective cohort study. OBJECTIVES To investigate the relationship between skeletal muscle status of the trunk and the progression of adolescent idiopathic scoliosis (AIS) during adulthood. SUMMARY OF BACKGROUND DATA To date, studies evaluating the risk factors for progression of AIS have principally focused on radiographic parameters. METHODS Eighty-two women with AIS managed conservatively, who had a major curve ≥30° at skeletal maturity (Risser grade ≥4), were enrolled. Patients had been followed-up, on average, over 23.5 years (range, 12-37 years) after skeletal maturity, and were ≥30-years-old at the time of the survey (mean, 40.1 years). The ratio of the cross-sectional area (CSA) and signal intensity (SI) of muscles (multifidus [MF], erector spinae [ES], and psoas major [PM]) were evaluated using axial T2-weighted magnetic resonance images at the level of L4. RESULTS The mean progression of the main thoracic and thoracolumbar/lumbar (TL/L) curves after skeletal maturity was 8.2° (mean annual rate of 0.4°) and 7.2° (mean annual rate of 0.3°), respectively. The mean CSA ratio was as follows: MF, 23.3%; ES, 79.6%; and PM, 40.5%. The mean SI ratio was as follows: MF, 34.9%; ES, 31.7%; and PM, 20.9%. On multivariate logistic regression, a higher SI ratio of the MF was predictive of a progression of the Cobb angle and translation of the apical vertebra, with a lower CSA ratio of the ES contributing to the progression of the Cobb angle for the TL/L curve. CONCLUSIONS In patients with AIS who have a major curve ≥30° at skeletal maturity, patients with greater TL/L curve progression have lower skeletal muscle volume and higher fatty degeneration of the lumbar extensor muscles in adulthood. However, further longitudinal or prospective studies are necessary to clarify the causal relationship between scoliosis progression and trunk muscular status. LEVEL OF EVIDENCE Level III, retrospective cohort study.

Risk Factors for Proximal Junctional Fracture following Fusion Surgery for Osteoporotic Vertebral Collapse with Delayed Neurological Deficits: A Retrospective Cohort Study of 403 Patients

Introduction Approximately 3% of osteoporotic vertebral fractures develop osteoporotic vertebral collapse (OVC) with neurological deficits, and such patients are recommended to be treated surgically. However, a proximal junctional fracture (PJFr) following surgery for OVC can be a serious concern. Therefore, the aim of this study is to identify the incidence and risk factors of PJFr following fusion surgery for OVC. Methods This study retrospectively analyzed registry data collected from facilities belonging to the Japan Association of Spine Surgeons with Ambition (JASA) in 2016. We retrospectively analyzed 403 patients who suffered neurological deficits due to OVC below T10 and underwent corrective surgery; only those followed up for　≥2 years were included. Potential risk factors related to the PJFr and their cut-off values were calculated using multivariate logistic regression analysis and receiver operating characteristic (ROC) analysis. Results Sixty-three patients (15.6%) suffered PJFr during the follow-up (mean 45.7 months). In multivariate analysis, the grade of osteoporosis (grade 2, 3: adjusted odds ratio (aOR) 2.92; p=0.001) and lower instrumented vertebra (LIV) level (sacrum: aOR 6.75; p=0.003) were independent factors. ROC analysis demonstrated that lumbar bone mineral density (BMD) was a predictive factor (area under curve: 0.72, p=0.035) with optimal cut-off value of 0.61 g/cm2 (sensitivity, 76.5%; specificity, 58.3%), but that of the hip was not (p=0.228). Conclusions PJFr was found in 16% cases within 4 years after surgery; independent risk factors were severe osteoporosis and extended fusion to the sacrum. The lumbar BMD with cut-off value 0.61 g/cm2 may potentially predict PJFr. Our findings can help surgeons select perioperative adjuvant therapy, as well as a surgical strategy to prevent PJFr following surgery.

Data for: Perioperative factors associated with favorable outcomes of posterior decompression and instrumented fusion for cervical ossification of the posterior longitudinal ligament: a retrospective multicenter study

PURPOSE Posterior decompression with instrumented fusion (PDF) is a suitable surgical treatment for K-line (-)-type cervical ossification of the posterior longitudinal ligament (OPLL). However, the adequate indications of PDF have not been clarified yet. The purpose of this study was to investigate the surgical results of PDF and perioperative factors that influence the surgical outcome, and to clarify the adequate indications of PDF. METHODS Twenty-seven patients (21 men and 6 women, mean age: 61.4 years) who were diagnosed with a K-line (-)-type OPLL that was treated with PDF were included in this study. We evaluated these patients clinically and radiologically to investigate the outcomes of PDF and perioperative factors that influence improvements in the Japanese Orthopedic Association (JOA) score. RESULTS The mean recovery rate of JOA score at the final follow-up examination was 53.3%. In the statistical analysis, the preoperative C2-C7 angle and the C2-C7 angle immediately postoperatively significantly predicted the surgical outcome. The C2-C7 angle immediately postoperatively was the only most important predictor. Using a receiver operating characteristic curve analysis, we found that the cutoff value of the C2-C7 angle immediately postoperatively for good outcomes (recovery rate of JOA score ≥50%) was -2.0°. CONCLUSIONS PDF for K-line (-)-type OPLL patients with preoperative lordotic alignment can be expected to have favorable outcomes, which is the adequate indication for PDF. Since the C2-C7 angle immediately postoperatively was the most important predictor, the physician should pay attention to maintain the cervical lordotic alignment to enhance the surgical outcomes in surgical planning.