Kazuhiko Satomi

Operative results and postoperative progression of ossification among patients with ossification of cervical posterior longitudinal ligament.

Although the pathogenesis of ossification of the cervical posterior longitudinal ligament (OPLL) has not yet been clarified, it has come to be widely recognized that severe cervical myelopathy or radiculopathy is caused by OPLL. Fifty-three cases who were operated on for OPLL with myelopathy or radiculopathy in our clinic over the past 16 years were followed up. A recovery rate of approximately 70% was observed. Postoperative progressions of the ossification were observed among 75% of the cases of continuous and mixed type but seldom among those with segmental and other types. As causative factors for these postoperative progressions of the ossification, the authors would like to advocate biological, structural, and mobility-related elements. We concluded that in the ossified stage it is desirable to apply anterior decompression for the segmental and other type, posterior decompression for the continuous and mixed type, and, if necessary, two-stage combined decompression for the mixed type.

Expansive Open-door Laminoplasty for Cervical Spinal Stenotic Myelopathy

Although the operative results have been improving since the air drill was introduced for cervical laminectomy instead of an ordinary rongeur, post-laminectomy complications, such as postoperative fragility of the cervical spine to acute neck trauma, posterior spur formation at the vertebral body, and malalignment of the lateral curvature have still remained as unsolved problems. In order to avoid these disadvantages, a new surgical technique called “expansive open-door laminoplasty” was devised by the author in 1977, which is relatively easier, safer, and better than the ordinary laminectomy from the standpoint of structural mechanics of the cervical spine. The operative procedure is described in detail. Operative results in the patients with cervical OPLL, spondylosis, and canal stenosis were satisfactory, and optimal widening of the AP diameter of the spinal canal is considered to be over 4 mm. From this procedure a bilateral, open-door laminoplasty has been devised for extensive exploration at the intradural space.

Short-term complications and long-term results of expansive open-door laminoplasty for cervical stenotic myelopathy

BACKGROUND CONTEXT Laminoplasty has been reported to achieve good operative results for treatment of cervical stenotic myelopathy. However, long-term results and prognostic factors have not been well documented. Among postoperative complications, weakness of the shoulder girdle muscles has been reported as a particular complication of laminoplasty, but the cause is still poorly understood. PURPOSE Our aim was to clarify the short-term complications and long-term operative results after unilateral open-door laminoplasty and to identify the predictors for operative outcome. STUDY DESIGN We retrospectively reviewed short-term complications and long-term operative results associated with cervical stenotic myelopathy treated by unilateral open-door laminoplasty. PATIENT SAMPLE There were 162 men and 42 women with an average age of 57 years who were treated by unilateral open-door laminoplasty in the two institutions. Pathogenesis of myelopathy was cervical spondylosis in 88 patients, cervical disk herniation with a narrow spinal canal in 10, and ossification of the posterior longitudinal ligament in 106. OUTCOME MEASURES Postoperative complications and their outcomes were examined clinically in 204 patients, and causes of motor paresis were sought with postoperative computed tomography after myelography. Postoperative improvement of clinical symptoms was assessed by recovery rate calculated with the scores of the Japanese Orthopaedic Scoring System in 80 patients. METHODS The occurrence rate of short-term postoperative complications, causes of motor paresis, and their outcomes were reviewed in 204 patients. Clinical condition was assessed with the Japanese Orthopaedic Scoring System, recovery rate was calculated with the score, and prognostic factors for outcome were studied in 80 patients who were followed up for 5 years or longer (average, 8 years; range, 5-17 years). RESULTS Occurrence rate of complications, such as muscle weakness, deep infection, closure of opened laminae, and others, was 10.8%. Muscle weakness was observed in 7.8% of the patients. However, this rate decreased in recent years. The cause of motor paresis is not known with certainty, but it may be secondary to operative trauma, posterior shift of the spinal cord, or to displacement of the lamina in the hinge side. Recovery rate of clinical symptoms was 62.1% at the final follow-up. Rates were 63.6% for cervical spondylosis, 87.1% for cervical disk herniation, and 61.3% for ossification of the posterior longitudinal ligament. There was no significant difference between pathologies. Patient age younger than 60 years at the time of operation and less than 1 years duration of symptoms before surgery were significantly associated with recovery rate of clinical symptoms. Recovery rate was not correlated with either preoperative function judged by the Japanese Orthopaedic Association score or spinal sagittal diameter. CONCLUSIONS The main cause of postoperative motor paresis of upper extremities is thought to be operative trauma, resulting from such procedures as air-drill and Kerrison rongeur handling. Short-term complications may decrease with the use of nontraumatic procedures. Better operative outcomes may be achieved with careful operative procedures and early operative treatment in the patients with myelopathy.

Idiopathic spinal cord herniation: Report of two cases and review of the literature

The authors experienced unique cases of spinal cord herniation. Only eight cases of spinal cord herniation have been reported formerly. The authors report two cases of spinal cord herniation accompanied with double structure of dura mater (duplicated dura mater). The causes of their condition are discussed in this report.

Predictability of operative results of cervical compression myelopathy based on preoperative computed tomographic myelography

The transverse area and flattening ratio of the spinal cord were determined with preoperative computed tomographic myelography in 103 patients with cervical compression myelopathy: cervical spondylotic myelopathy (n = 44); ossification of the posterior longitudinal ligament (n = 39); and cervical disc herniation (n = 20). With these values and other clinical items (eg, age, duration of symptoms, preoperative severity), a linear model to predict postoperative recovery was attempted by multiple regression analysis. In cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament, the transverse area of the spinal cord and the duration of symptoms were accepted as effective explanatory variables to predict recovery. In cervical disc herniation, regardless of the transverse area or duration, the recovery was good, and pathologic state was considered essentially different.

A CLINICAL STUDY OF DEGENERATIVE SPONDYLOLISTHESIS. RADIOGRAPHIC ANALYSIS AND CHOICE OF TREATMENT

Surgical treatment of degenerative spondylolisthesis in 27 patients by means of anterior lumbar interbody fusion and in 14 patients by means of posterior decompression yielded average degrees of recovery of 77% and 56%, respectively. Preoperative analysis of myelograms, and computed tomographies after myelography indicated taht anterior shifting of the inferlor articular process of the slipping vertebra was the main factor responsible for compresion of the nervous tissue in the early stages of degenerative spondylolisthesis. Patients in these stages should be treated by anterior lumbar interbody fusion. In the later stages of degenerative spondylolisthesis, osteophytes on the superior articular processes of the lower vertebra were an additional factor in compression, and patients should be treated by posterior decompression. Computed tomographies after myelography provided the key images for identifying pathologic proceses in degenerative spondylolisthesis and selecting appropriate surgical procedures.

Radiographic predictors for the development of myelopathy in patients with ossification of the posterior longitudinal ligament: a multicenter cohort study.

Study Design. A multicenter cohort study was performed retrospectively. Objective. To identify radiographic predictors for the development of myelopathy in patients with ossification of the posterior longitudinal ligaments (OPLL). Summary of Background Data. The pathomechanism of myelopathy in the OPLL remains unknown. Some patients with large OPLL have not exhibited myelopathy for a long periods of time. Predicting the course of future neurologic deterioration in asyptomatic patients with OPLL is difficult at their initial visit. Methods. A total of 156 OPLL patients from 16 spine institutes with an average of 10.3 years of follow-up were reviewed. Subjects underwent a plain roentgenogram, computed tomography (CT), and magnetic resonance imaging of the cervical spine during the follow-up. The trauma history of the cervical spine, maximum percentage of spinal canal stenosis in a plain roentgenogram and CT, range of motion of the cervical spine, and axial ossified pattern in magnetic resonance imaging or CT were reviewed in relation to the existence of myelopathy. Results. All 39 patients with greater than 60% spinal canal stenosis on the plain roentgenogram exhibited myelopathy. Of 117 patients with less than 60% spinal canal stenosis, 57 (49%) patients exhibited myelopathy. The range of motion of the cervical spine was significantly larger in patients with myelopathy than in those of without it. The axial ossified pattern could be classified into 2 types: a central type and a lateral deviated type. The incidence of myelopathy in patients with less than 60% spinal canal stenosis was significantly higher in the lateral deviated-type group than in the central-type group. Fifteen patients of 156 subjects developed trauma-induced myelopathy. Of the 15 patients, 13 had mixed-type OPLL and 2 had segmental-type OPLL. Conclusion. Static and dynamic factors were related to the development of myelopathy in OPLL.

S3-4. New alarm point of transcranial electrical stimulation motor evoked potentials for intraoperative spinal cord monitoring. A prospective multicenter study of the Spinal Cord Monitoring Working Group of the Japanese Society for Spine Surgery and Related Research (JSSR)

Transcranial electrical stimulation motor evoked potentials (TcMEPs) became the gold standard for intraoperative spinal cord monitoring. However there is no definite alarm point of TcMEPs due to a lack of multicenter study. Thus we set 70% decrease of amplitude as the alarm point of TcMEPs from the experience of our 48 true positive cases from 2007 to 2009. 959 cases of spinal deformity, spinal cord tumor and ossification of the posterior longitudinal ligament (OPLL) were included in this prospective multicenter study from our 18 institutes related to the Japanese Society for Spine Surgery and Related Research monitoring working group from 2010 to 2012. There were only two false negative cases which were intramedullary spinal cord tumor. This new alarm criterion provided higher sensitivity (95%) and specificity (91.1%) for intraoperative spinal cord monitoring and good accuracy except for intramedullary spinal cord tumor. This study is the first prospective multicenter research to investigate the alarm point of TcMEPs. We recommend the alarm point to be a 70% decrease of amplitude for routine spinal cord monitoring, especially in surgery for spinal deformity, OPLL and extramedullary spinal cord tumor.

Level diagnosis of cervical myelopathy using evoked spinal cord potentials

The ESCPs (evoked spinal cord potentials) resulting from both median nerve and spinal cord stimulation were recorded from the interlaminar yellow ligaments posteriorly or intervertebral discs anteriorly on patients with cervical myelopathy in order to determine the most significant lesion in the spinal cord electrophysiologically. The normal median-nerve-evoked spinal cord potential (MN-ESCP) consisted of P1N1 and N2(P2) deflections, while normal spinal cord-ascending evoked spinal cord potential (SC-AESCP) consisted of N1 and N2 deflections. The abnormal ESCPs obtained from 65 patients were classified into three grades. The spinal level recording the highest grade of ESCP, which was mostly positive wave, generally corresponded to the level that was clearly diagnosed as the main lesion by neurologic and radiologic examinations, such as a case of single level disc hernia. With these techniques, the level diagnostic rates of primary lesions were 94.7% in posterior recordings and 74.1% in anterior recordings.

Postoperative deep infection in tumor endoprosthesis reconstruction around the knee

BackgroundAlthough deep infection remains one of the most difficult complications to manage in the treatment of musculoskeletal tumor reconstructed with an endoprosthesis, limited information with respect to its incidence and risk factors has been reported.MethodsThis multicenter, retrospective, uncontrolled study reviewed the medical records of 82 patients who underwent reconstruction with an endoprosthesis or temporary spacer for bone-immature patients after resection of malignant bone tumor around the knee. Risk factors for deep infection and the impact of deep infection on prosthesis survival and oncological outcomes were analyzed. Deep infection was defined according to the Centers for Disease Control and Prevention (CDC) guidelines with minor modification.ResultsDeep infection occurred in 14 cases (17%), identified at a mean of 10.9 months (range <1 to 48 months) after initial surgery. Univariate analysis identified surface infection (P < 0.001) and skin necrosis (P < 0.001) as risk factors associated with deep infection. Conversely, tumor origin, chemotherapy, number of postoperative antibiotics, and length of bone resection were not associated with infection. Subclass analysis in femur cases identified a correlation between infection and the extent of partial resection of the quadriceps muscle (P = 0.04). In the multivariate analysis, surface infection represented an independent risk factor for deep infection (P = 0.03). Deep infection was a risk for endoprosthesis survival (P = 0.003) but did not affect the oncological outcome.ConclusionsA strong correlation between the condition of soft tissue and establishment of deep infection is suggested in this study. Although practical options for preventing deep infection seem limited, the present data allow a form of perioperative evaluation for patients with a higher risk of deep infection.