Risk factors for intraoperative lateral mass fracture of lateral mass screw fixation in the subaxial cervical spine.

OBJECT: Although lateral mass screw fixation for the cervical spine is a safe technique, lateral mass fracture during screw fixation is occasionally encountered intraoperatively. This event is regarded as a minor complication; however, it poses difficulties in management that may affect fixation stability and clinical outcome. The purpose of this study is to determine the incidence and etiology of lateral mass fractures during cervical lateral mass screw fixation. METHODS: A retrospective clinical review of patient records was performed in 117 consecutive patients (mean age 57 years, range 15-86 years) who underwent lateral mass screw fixation using a modified Magerl method from 1997 to 2010 at a single institution. A total of 555 lateral masses were included in this study. The outer diameters of the screws were 3.5 or 4.0 mm. In the retrospective clinical analysis, the incidence of intraoperative lateral mass fractures was reviewed. Potential risk factors for this complication were assessed using multivariate analysis. RESULTS: The incidence of lateral mass fractures during cervical lateral mass screw fixation was 4.7% (26 lateral masses) among all cases. Among the disorders, the incidence was highest in patients with destructive spondyloarthropathy (DSA) (18.8%, 12 lateral masses). There was no significant difference with respect to lateral mass fracture between the use of 4.0-mm screws (5.6%) and 3.5-mm screws (3.6%). Independent risk factors identified by logistic regression were DSA (OR 7.89, p < 0.001) and screw insertion in the C-6 lateral masses (OR 2.80, p = 0.018). CONCLUSIONS: The overall incidence of lateral mass fracture during cervical lateral mass screw fixation was 4.7%. Destructive spondyloarthropathy as an underlying cause of morbidity and screw placement in the C-6 lateral mass were identified as independent risk factors. Use of a 4.0-mm screw in patients with DSA may be a principal risk factor for this complication.

C-5 palsy after cervical laminoplasty with instrumented posterior fusion.

OBJECT: Postoperative C-5 palsy is known as a common complication after cervical laminoplasty. The authors of this article have encountered postoperative C-5 palsy more often when laminoplasty was combined with instrumented posterior spinal fusion than when it was performed alone. The purpose of this clinical study was to examine the incidence of fifth cervical nerve root palsy (C-5 palsy) and surgical results in patients with cervical myelopathy who had undergone laminoplasty with or without instrumented spinal fusion. METHODS: The authors retrospectively studied patients with cervical myelopathy who had undergone laminoplasty with or without instrumented posterior spinal fusion. RESULTS: Clinical data on 58 patients were evaluated and analyzed. Preoperative diagnoses were cervical spondylotic myelopathy or ossification of the posterior longitudinal ligament of the cervical spine. Twenty-four patients with spondylolisthesis or kyphosis underwent laminoplasty combined with posterior spinal fusion using instrumented lateral mass fixation (fusion group), while the remaining 34 patients underwent laminoplasty without posterior spinal fusion (no-fusion group). In the fusion group, C-5 palsy developed in 6 patients; in the no-fusion group, it occurred in only 1 patient. There was a significant difference in the rate of this complication between the 2 groups. In the fusion group, local kyphosis and spondylolisthesis level were reduced at the fusion level, and all patients with C-5 palsy underwent C4-5 spinal fusion. CONCLUSIONS: The incidence of postoperative C-5 palsy is significantly higher after laminoplasty when it is combined with spinal fusion. Correction of kyphosis and spondylolisthesis using posterior instrumentation may be a risk factor for iatrogenic intervertebral foraminal stenosis leading to C-5 palsy.

Postoperative spinal cord herniation with pseudomeningocele in the cervical spine: a case report.

BACKGROUND CONTEXT: Postoperative spinal cord herniation with pseudomeningocele is a rare disease, with only five cases reported before the present study. PURPOSE: To describe the clinical features and radiologic findings of postoperative spinal cord herniation with pseudomeningocele. STUDY DESIGN: Case report. METHODS: A case of a 51-year-old man who suffered from postoperative spinal cord herniation with pseudomeningocele was reported, and previous reports on this subject are reviewed. RESULTS: He had undergone excision of a spinal cord tumor in the cervical spine 10 years previously. He had progressive paraparesis and urinary disturbance 10 years later. The Computed Tomography Multi Planner Reconstruction myelogram showed dilation of the ventral subarachnoid space with left deviation of the spinal cord into the pseudomeningocele at C7. On observation at surgery, the spinal cord appeared displaced dorsally and herniated through the defect of the dorsal dura mater. The spinal cord was tightly adhesive around the dural defect. We released the adhesion of the spinal cord and the dural defect under the spinal cord, and the dural defect was repaired using an artificial dura mater. CONCLUSIONS: The release of adhesion around dural defect and repair of dural defect under spinal cord monitoring resulted in a satisfactory neurologic recovery. Surgical repair of the dural defect with a dural substitute was necessary.

Comparison of clinical features and outcomes of staphylococcus aureus vertebral osteomyelitis caused by methicillin-resistant and methicillin-sensitive strains.

The causative organism of vertebral osteomyelitis (VO) was almost exclusively Staphylococcus aureus. The purpose of this study was to delineate the differences in clinical features and outcomes between patients with methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) VO. This study retrospectively reviewed 85 consecutive patients with VO treated between 2005 and 2011. Surgical site infections were excluded. Diagnosis was made by cultures of either blood or biopsied samples. We identified 16 cases of MRSA VO and 14 cases of MSSA VO. The average follow-up period was 18.5 months. Clinical features and outcomes were analyzed. Males were more likely to have MRSA VO than MSSA VO (87.5% vs. 35.7%). In regards to the number of co-morbidities, patients with MRSA VO had significantly more co-mobidities than patients with MSSA VO. Additionally, the rate of patients who underwent surgical procedure (excluding spinal surgeries in the affected region) within 3 months were significantly higher in the MRSA VO group than the MSSA VO group (56.3% vs. 14.3%). White blood cell counts and C-reactive protein levels in patients with both strains significantly improved 4 weeks after the initial treatment compared with the pretreatment values. The recurrence rate within 6 months tended to be higher for MRSA VO (37.5% vs. 7.1%), but no significant difference in mortality was observed between the two VO types. In conclusion, male sex, multiple co-morbidities and previous non-spine surgery were significant risk factors for VO due to MRSA as compared to MSSA. The recurrence rate within 6 months tended to be higher for MRSA VO. Patients with MRSA VO should be monitored carefully for recurrence by sequential clinical, radiographic, and laboratory examinations during the treatment course.

Cervical lateral mass screw fixation without fluoroscopic control: analysis of risk factors for complications associated with screw insertion.

OBJECTIVE: To examine the outcome of cervical lateral mass screw fixation focusing on analysis of the risk factors for screw-related complications. METHODS: Ninety-four patients who underwent posterior cervical fixation with a total of 457 lateral mass screws were included in the study. The lateral mass screws were placed using a modified Magerl method. Computed tomographic (CT) images were taken in the early postoperative period in all patients, and the screw trajectory angle was measured on both axial and sagittal plane images. RESULTS: In the postoperative CT analysis for the screw trajectory, 56.5 % of the screws were directed within the acceptable range (within 21-40° on both axial and sagittal planes). As intraoperative screw-associated complications, 9.6 % of the screws were found to contact with or breach the vertebral artery foramen. In this group, the screw trajectory angle on axial plane was significantly lower than in the group without contact. Facet violation was observed in 13 screws (2.8 %). This complication was associated with a significantly lower trajectory angles in the sagittal plane, predominantly at C6 level (69.2 %). In the patient chart review, no serious neurovascular injuries were documented. CONCLUSIONS: In the analysis of potential risk factors for violation of the VA foramen as well as FV during screw insertion, the former incidence was significantly related to the screw trajectory angle (lack of lateral angulation) in the axial plane, while the latter incidence was related to a poor screw trajectory angle in the sagittal plane.

Rest-induced suppression of anterior horn cell excitability as measured by F waves: comparison between volitionally inactivated and control muscles.

To test the hypothesis that the anterior horn cells become hypoexcitable in the absence of central drive, we recorded F waves simultaneously from the first dorsal interosseous (FDI) and the abductor digiti minimi (ADM) before and after volitionally inactivating one muscle (target) while periodically contracting the other muscle (control). In 14 healthy subjects, F waves recorded from the target muscle showed a progressive decrease in persistence and amplitude (whether counting all 100 trials or only detectable responses) after muscle relaxation for 1, 3, and 6 hours, followed by a quick recovery upon brief muscle contraction. We conclude that volitional inactivation suppresses the F waves of the target muscle without equally affecting the control muscle innervated by the same nerve. The history of activity of a muscle should therefore be taken into account in clinical testing, especially when the study of a paretic muscle shows abnormal F-wave excitability.

[The effect of particle size and amount of inhalation on the pulumonary function testsn in asthmatic children].

The effect of three nebulizers, Nisshou and LC plus, were compared by the particle size and amount of inhalation. The improvement of FEV1 at 15 minutes after the inhalation was significantly higher in LC plus than Nisshou (MMD: 7.43microm, 10.76microm). The amount of inhlation were compared between Nisshou with/without Y tube and LC plus nebulizer with/without LC valve system. Nisshou nebulizer with Y tube and LC plus nebulizer with LC valve systems were significantly better than that of LC plus nebulizer without LC valve system. Small loss of inhalation gave us better efficacy. The urinary excretion of disodium cromoglycate (DSCG) was highest in LC plus with LC valve system, Nisshou with Y tube and lowest in Nisshou without Y tube. The elecctric nebulizers produced better in MMD of 5microm and a smaller loss of inhalation. These results suggested that MMD less than 5microm and small loss from nebulizer are very important for inhalation therapy.