Koichi Kasahara

Lumbar multilevel degenerative spondylolisthesis: radiological evaluation and factors related to anterolisthesis and retrolisthesis.

Radiographs of 3,259 outpatients with low back disorders were examined for age, gender, level, direction, degree of slip, lumbar lordosis, pedicle–facet (P-F) angle, facet shape, and disc height. Degenerative lumbar spondylolisthesis was found in 284 (8.7%) of the patients, of which 83 were excluded. Single-level spondylolisthesis was present in 132 of the 201 patients studied, including 93 cases of anterolisthesis and 39 of retrolisthesis, the former being predominant at L4 and in women and the latter at L2 and equal between the genders. Multilevel spondylolisthesis in 69 patients included 65 (94%) of two-segment slip, 21 anterior, 25 posterior, and 19 combined, and 4 cases of three-segment retrolisthesis. Factors related to anterolisthesis were increased P-F angle and W-shaped facet joint; statistically, however, no factors were found statistically related to retrolisthesis. Multilevel anterolisthesis was considered to occur from factors similar to those previously reported for single-level anterolisthesis, and the pathomechanism of retrolisthesis is different from that of anterolisthesis.

Lumbar instability and clinical symptoms: which is the more critical factor for symptoms: sagittal translation or segment angulation?

Background: The relationship between radiologic instability and its symptoms is controversial. Previous authors consider flexion–extension radiographs to be of little value in evaluating instability; however, the current authors consider the variation of results in evaluating radiologic instability to be the result of limitations in previous researchers’ methods. Methods: In this report, sagittal translation and angulation at the L4–L5 segment were measured in flexion–extension films in 1090 outpatients with low back and/or leg pain using a three-landmark measuring method. The symptoms of four groups with and without 3-mm translation and with and without 10° angulation were compared for all the patients and for 280 age-matched patients using a scoring system. The age-matched patients were followed up for 4.6 years. Results: Results showed that patients with ≥3-mm translation had significantly lower scores, indicating a limitation in their daily activities due to pain, than patients <3-mm translation; however, no difference was observed between the groups in terms of angulation. The group with ≥3-mm translation and ≥10° angulation significantly demonstrated the lowest scores at both evaluations during the initial visit and follow-up. This group had been suffering from low back and/or leg pain the longest and had visited the hospital significantly more often than other groups. Conclusion: In conclusion, translation of the lumbar segment has a greater influence than angulation on lumbar symptoms. The presence of both radiologic factors could be an indicator for persistence of the symptoms.

Prospective study and multivariate analysis of the incidence of C5 palsy after cervical laminoplasty.

Study Design. A prospective comparative study about the incidence of postoperative C5 palsy and multivariate analysis of the risk factors of C5 palsy. Objective. To clarify the risk factors of occurrence of C5 palsy after laminoplasty (LP) by comparing the 2 surgical procedures of open-door and double-door LP prospectively. Summary of Background Data. The incidence of C5 palsy has been reported to average 4.6%, and there has been no difference of the incidence among surgical procedures. However, there were only indirect retrospective studies. Methods. A total of 146 patients who underwent the LP procedure between 2006 and 2007 were studied prospectively. In 2006, the patients were assigned to undergo the open-door LP, and in 2007, they were assigned to undergo the double-door LP. The incidence of postoperative C5 palsy was compared prospectively between these 2 LP procedures, and the risk factors of C5 palsy were detected with multivariate logistic regression analysis. Results. Postoperative C5 palsy occurred in 7 of 73 cases after open-door LP (9.6%) and in 1 of 73 cases after double-door LP (1.4%). The incidence of C5 palsy after open-door LP was statistically higher than the one after double-door LP (P = 0.029), and open-door LP was recognized as a significant risk factor for postoperative C5 paralysis (odds ratio: 69.6, P = 0.043). In addition, ossification of posterior longitudinal ligament (OPLL) was recognized as a significant risk factor for postoperative C5 paralysis (odds ratio: 43.8, P = 0.048). Conclusion. This study showed significant evidence indicating the higher risk of postoperative C5 palsy in open-door LP than double-door LP. Because OPLL as well as open-door LP were recognized as the risk factors of C5 palsy, asymmetric decompression by open-door LP might introduce imbalanced rotational movement of spinal cord and result in C5 palsy. We recommend double-door LP to minimize the postoperative C5 palsy, in particularly, if the patient has OPLL.

Age distribution of three radiologic factors for lumbar instability: probable aging process of the instability with disc degeneration.

Study Design. Cross-sectional study of 880 outpatients with low back and/or leg pain regarding age distribution of three radiologic factors. Objectives. To investigate the proportion and relationship of three individual radiologic factors with age on segmental instability in sagittal plane in consecutive age groups. Summary of Background Data. Previous studies revealed relationships between radiologic factors for instability and symptoms; however, little is known about the relationship between factors and age except in degenerative spondylolisthesis. Methods. Excessive segmental motion, defined as more than 10° angulation, more than 3 mm translation, and more than 3 mm slip in neutral position, at the L4–L5 segment in 880 outpatients (389 men, 491 women) with low back and/or leg pain aged from 14 to 84 years was investigated by 3 observers. The number and rate of the patients with each excessive motion were evaluated in continuous age groups of 5 years. Results. The mean ages of patients with excessive angulation, translation, and slip in neutral position were 41.7, 50.0, and 62.8 years, respectively. Both rates of excessive angulation and translation showed two peak patterns demonstrating peaks in the teens and 20s groups and in the over 46 age groups; however, angulation was predominant in younger age groups and translation was predominant in older age groups. Slip in neutral position was frequently observed in age groups over 46 and increased with age. Conclusions. The presence of patients with excessive angulation and translation in younger age groups suggests they have a hypermobile segment with least degenerated discs. Different predominant patterns of these radiologic factors may reveal the probable aging process of the instability.

Delayed dural laceration by hydroxyapatite spacer causing tetraparesis following double-door laminoplasty.

OBJECT The authors describe 4 cases of delayed dural laceration by hydroxyapatite (HA) spacer causing tetra-paresis following double-door laminoplasty. There are few reports of iatrogenic spinal cord lesions developing after double-door laminoplasty, although some complications such as postoperative C-5 paralysis or axial symptoms have been reported. The purpose of this report is to draw attention to the possibility of delayed dural laceration and its triggering mechanism. METHODS One hundred thirty patients treated for cervical myelopathy were followed up for an average of 2 years and 9 months after laminoplasty. RESULTS Four patients experienced aggravation of cervical myelopathy. Anterior dislodgement of HA spacers was shown on plain lateral radiographs. Follow-up T2-weighted magnetic resonance imaging demonstrated that the dislodged HA spacers were surrounded by cerebrospinal fluid at the time of aggravation. The dislodged HA spacers were removed and the dural membrane defects were repaired by patching with the fascia of the gluteus maximus muscle. The preoperative symptoms improved after the second operation in all patients. CONCLUSIONS It is hypothesized that the loosening of the HA spacer in split spinous processes could occur with the movement of the cervical spine and/or the breakage of the suture before bone bonding. Anterior dislodgement of the HA spacer toward the spinal canal would cause dural laceration by direct friction between the dural membrane and the dislodged HA spacer, resulting in clinical aggravation. Despite the well-documented advantages of using HA spacers for double-door laminoplasty, possible laceration due to a dislodged HA spacer should be considered as a late complication.

Symptomatic hematoma of lumbar facet joint: joint apoplexy of the spine?

Study Design. A case report. Objectives. To report and discuss a rare case of epidural hematoma that was considered to be formed as a result of idiopathic bleeding occurring at the facet joint (joint apoplexy). Summary of the Background Data. Spontaneous spinal epidural hematoma is a relatively rare condition. According to a review article of 199 spontaneous spinal epidural hematomas in the last 2 decades, the majority of these conditions are thought to result from a rupture of the epidural vascular network. Recently, a hemorrhagic lumbar synovial cyst and a hematoma occurring from the ligamentum flavum were reported as rare types of epidural hematoma. Methods. The authors describe the treatment and the clinical, radiologic, surgical, and pathologic findings in one patient with a rare epidural hematoma. Results. Magnetic resonance imaging revealed that the extradural mass lesion was continuous with the right L4-5 facet joint; this was confirmed by surgery when the extradural hematoma was directly visualized. The joint cavity was also filled with the hematoma. There was no evidence of preceding cyst formation macroscopically or microscopically. The excised capsule of the left L4-5 facet joint revealed moderate hyperplasia of the synovium with an increased number of capillary vessels. Conclusions. This is the first reported case of radiculopathy considered to be a result of facet joint apoplexy in the absence of any preceding synovial cyst formation. The pathomechanism of the hemorrhage at the lumbar facet joint is unclear, but it is speculated that there could be an association with degenerative change of the facet joint. Surgical excision of this mass was considered to be the definitive treatment.

The influence of sagittal instability factors on clinical lumbar spinal symptoms.

Study Design Cross-sectional and prospective study. Objective To find the critical order of 3 radiographic factors observed in standing flexion-extension films and to discover their combined effect on lumbar symptoms. Summary of Background Data Many previous reports have described relationships between degenerative change in the lumbar disc and segmental instability; however, few reports have attempted to show any relationship between instability and symptoms. Little is known about which type of instability is the most critical in the sagittal plane of the lumbar spine. Methods Excessive segmental motion (factors): >3 mm slip, >3 mm translation, and >10 degrees angulation, at the L4/5 segment in 880 patients (389 men and 491 women; mean age, 49.4 y) with low back and/or leg pain were investigated at initial visit. Symptoms of low back and leg pain, and walking ability were evaluated at initial visit and 4.6-year follow-up using Japanese Orthopaedic Associations scoring system. Severity and continuity of symptoms were evaluated and compared among the groups according to various combinations of excessive motion. Results Of the 3 factors, patients with >3 mm slip had the lowest scores, and patients with >10 degrees angulation had the highest, both at initial visit and follow-up (P<0.001). In the comparative study of various factors, the groups with >3 mm slip had significantly lower scores than the group with no factors, and these groups had significantly lower scores in leg pain and walking ability than the nonfactor group (P<0.05). Conclusions Of the 3 factors, >3 mm slip had the strongest effect on symptoms followed by >3 mm translation and then >10 degrees angulation. Therefore, patients with low back and/or leg pain at initial visit and >3 mm slip, may expect symptoms of a duration exceeding 4 years. More than 10 degrees angulation had the least effect on symptoms as shown by the similarity in scores with the nonfactor group.

Radiculopathy due to ossification of the yellow ligament at the lower lumbar spine.

Study Design. A case report. Objectives. To report a rare case of a 27-year-old female with ossification of yellow ligament at the lower lumbar spine presenting radiculopathy with a drop foot. Summary of Background Data. The majority of cases of ossification of yellow ligament occur at the lower third of the thoracic or the thoracolumbar spine. There are only a few reports of ossification of yellow ligament in the lumbar spine and radiculopathy due to ossification of yellow ligament at L4–L5 and L5–S1 levels is very uncommon. Methods. A 27-year-old female with a prior fracture of posterior ring apophysis of L5 presented with leg pain and a drop foot. Magnetic resonance imaging demonstrated stenosis with compression of the cauda equina at the L4–L5 and L5–S1 levels. Results. Decompressive laminectomy of L5 and removal of the ossified yellow ligaments were performed. Histologic examination of en bloc specimen of ossification of yellow ligament revealed degenerative changes of the elastic fibers in the yellow ligament with adjacent chondrosis and ossification. The patient’s severe leg pain disappeared completely, although the extent of the drop foot had not fully recovered at the final follow-up examination. Conclusions. The mechanism of ossification of yellow ligament in the present case was unclear. The patient did not have any previous generalized disorders besides the history of a ring apophysial fracture or any family history of treatment for ossification of the posterior longitudinal ligament or ossification of yellow ligament. Therefore, localized mechanical stress might have influenced the development of ossification of yellow ligament at lower lumbar spine. Spine 2003;28:E401–E404

Preliminary Evaluation of the Pathomechanisms of Dysphagia After Occipitospinal Fusion: Kinematic Analysis by Videofluoroscopic Swallowing Study.

Study Design. Kinematic analysis of swallowing function using videofluoroscopic swallowing study (VFSS). Objectives. The aims of this study were to analyze swallowing process in the patients who underwent occipitospinal fusion (OSF) and elucidate the pathomechanism of dysphagia after OSF. Summary of Background Data. Although several hypotheses about the pathomechanisms of dysphagia after OSF were suggested, there has been little tangible evidence to support these hypotheses since these hypotheses were based on the analysis of static radiogram or CT. Considering that swallowing is a compositive motion of oropharyngeal structures, the etiology of postoperative dysphagia should be investigated through kinematic approaches. Methods. Each four patients with or without postoperative dysphagia (group D and N, respectively) participated in this study. For VFSS, all patients were monitored to swallow 5-mL diluted barium solution by fluoroscopy, and then dynamic passing pattern of the barium solution was analyzed. Additionally, O-C2 angle (O-C2A) was measured for the assessment of craniocervical alignment. Results. O-C2A in group D was −7.5 degrees, which was relatively smaller than 10.3 degrees in group N (P = 0.07). In group D, all cases presented smooth medium passing without any obstruction at the upper cervical level regardless of O-C2A, whereas the obstruction to the passage of medium was detected at the apex of mid-lower cervical ocurvature, where the anterior protrusion of mid-lower cervical spine compressed directly the pharyngeal space. In group N, all cases showed smooth passing of medium through the whole process of swallowing. Conclusion. This study presented that postoperative dysphagia did not occur at the upper cervical level even though there was smaller angle of O-C2A and demonstrated the narrowing of the oropharyngeal space towing to direct compression by the anterior protrusion of mid-lower cervical spine was the etiology of dysphagia after OSF. Therefore, surgeon should pay attention to the alignment of mid-cervical spine as well as craniocervical junction during OSF. Level of Evidence: 4

The Prediction and Prevention of Dysphagia after Occipitospinal Fusion by Use of the S-line (swallowing line).

Study Design. Clinical case series and risk factor analysis of dysphagia after occipitospinal fusion (OSF). Objective. The aim of this study was to develop new criteria to avoid postoperative dysphagia by analyzing the relationship among the craniocervical alignment, the oropharyngeal space, and the incidence of dysphagia after OSF. Summary of Background Data. Craniocervical malalignment after OSF is considered to be one of the primary triggers of postoperative dysphagia. However, ideal craniocervical alignment has not been confirmed. Methods. Thirty-eight patients were included. We measured the O-C2 angle (O-C2A) and the pharyngeal inlet angle (PIA) on the lateral cervical radiogram at follow-up. PIA is defined as the angle between McGregors line and the line that links the center of the C1 anterior arch and the apex of cervical sagittal curvature. The impact of these two parameters on the diameter of pharyngeal airway space (PAS) and the incidence of the dysphagia were analyzed. Results. Six of 38 cases (15.8%) exhibited the dysphagia. A multiple regression analysis showed that PIA was significantly correlated with PAS (&bgr; = 0.714, P = 0.005). Receiver-operating characteristic curves showed that PIA had a high accuracy as a predictor of the dysphagia with an AUC (area under the curve) of 0.90. Cases with a PIA less than 90 degrees showed significantly higher incidence of dysphagia (31.6%) than those with a 90 or more degrees of PIA (0.0%) (P = 0.008). Conclusion. Our results indicated that PIA had the high possibility to predict postoperative dysphagia by OSF with the condition of PIA <90°. Based on these results, we defined “Swallowing-line (S-line)” for the reference of 90° of PIA. S-line (−) is defined as PIA <90°, where the apex of cervical lordosis protruded anterior to the “S-line,” which should indicate the patient is at a risk of postoperative dysphagia. Level of Evidence: 4