A novel computed tomography scoring system for evaluating the risk of dural defects in anterior surgery for cervical ossification of the posterior longitudinal ligament.

OBJECTIVE: To develop and validate a computed tomography (CT)-based scoring system for evaluating the risk of dural defects (DDs) in anterior surgery for cervical ossification of the posterior longitudinal ligament (OPLL). METHODS: We retrospectively analyzed CT imaging features of 114 OPLL patients in our institute who received anterior decompression surgery. Intraoperative DDs were found in 16 patients. A multivariable logistic regression was used to evaluate the predictors. According to the odd ratio of the included risk factors, we developed a CT scoring system for evaluating the risk of DDs in anterior OPLL surgery. The system was further validated in an independent group of 39 OPLL patients. RESULTS: We developed a CT scoring system as follows: hook sign (2 points), K-line (-) (1 point) and broad base (1 point). Thus, the system comprised 4 total points, and patients were at high risks of dural defects when the score ≥3 points. The operating characteristics of a score ≥3 for predicting DDs in the validation group were: sensitivity of 0.83, specificity of 0.94, LR positive of 13.75, LR negative of 0.18 and AUC of 0.886. The discriminatory ability of the proposed score could be demonstrated in the validation cohort. CONCLUSIONS: The relatively simple and easy-to-use scoring system we propose integrates the 3 most reliable spinal CT findings observed in patients with OPLL and a DD. The likelihood to identify the underlying risks of spinal CSF leaks may be useful to triage patients who may benefit from indirect decompression techniques.

Effect of simultaneous surgical treatment in scoliosis associated with intraspinal abnormalities: A retrospective study.

To evaluate the outcomes of single-stage surgical treatment for spinal deformity and coexisting intraspinal pathologies, 12 patients who underwent single-stage surgical treatment for spinal deformity and co-existing intraspinal abnormalities between October 2016 and January 2017 were enrolled in the present study. Treatment for intraspinal abnormalities, posterior correction, osteotomy and internal fixation were performed simultaneously. The clinical and radiological outcomes, surgical details, complications and postoperative outcomes were evaluated. The mean fusion length was 11.0±2.8. Both scoliosis Cobb angle (pre-surgery 65.9±13.4 vs. post-surgery 21.7±9.4) and kyphosis (pre-surgery 71.1±19.5 vs. post-surgery 31.4±10.4) were significantly improved post-surgery. Tethered cords were released and epidermoid cysts, gangliogliomas, meningiomas and lipomas were resected. Muscle strength in all patients was improved. The muscular tone of 8 patients was improved. No severe complications occurred postoperatively. None of the patients experienced deterioration in their neurological status nor loss of correction during the 12-24 months' follow-up. The simultaneous surgical treatment for spinal deformity and intraspinal pathology seems to be a safe and effective approach. Neurological deficits were improved postoperatively. Osteotomy produces satisfactory correction results.

Magnetic Resonance Imaging of Chiari Malformation Type I in Adult Patients with Dysphagia.

OBJECTIVE: To explore the magnetic resonance imaging (MRI) characteristics of Chiari malformation type I (CMI) in patients with dysphagia. METHODS: Adult patients diagnosed with CMI were retrospectively and consecutively reviewed from January 2013 to December 2016. Symptoms and medical characteristics were recorded. According to the clinical manifestations, we divided the patients into two groups. The first group had 21 patients with symptoms of dysphagia and the second group had 71 patients with nondysphagia symptoms. Various length or angle measurements of the posterior cranial fossa (PCF), syringomyelia, and degree of cerebellar tonsillar herniation were investigated using magnetic resonance imaging (MRI). Univariate, correlation, and multivariate logistic regression analyses were used to compare and analyze the data of the two groups. RESULTS: The mean length of the clivus, height of PCF, and slope inclination angle of clivus significantly decreased in the dysphagia group compared to the nondysphagia group. The mean cranial spinal angle (CSA) and degree of cerebellar tonsillar herniation were significantly larger in the dysphagia group. There were no correlations between the age, sex, disease duration, and the length of cerebellar tonsillar herniation or CSA. There was a positive correlation between dysphagia level and CSA (r=-0.50; p=0.021). Among CSA, age, sex, the degree of tonsillar herniation, syringomyelia, and disease duration, CSA was the individual sign that correlated significantly with dysphagia (OR: 1.447; 95% CI: 1.182-1.698; P<0.001). Interactions between CSA and the degree of cerebellar tonsillar herniation, syringomyelia, and dysphagia existed (OR: 1.104; 95% CI: 1.042-1.170; P=0.001 and OR: 1.081; 95% CI: 1.023-1.142; P=0.006, respectively). CONCLUSIONS: The CMI patients with dysphagia were more likely to have a large CSA on MRI compared with CMI patients without dysphagia. An increased probability with syringomyelia or length of cerebellar tonsillar herniation can enhance the contribution of CSA to dysphagia in patients with CMI.

Spondylolisthesis with Uncommon Congenital Deformity of L4-L5 Vertebral Fusion Treated by Oblique Lumbar Interbody Fusion.

BACKGROUND: Diagnosis and management of congenital anomalies of the spine can be a challenge because of their complex presentations. We present an uncommon case of congenital deformity of the spine with L4-L5 vertebral fusion, mimicking a single vertebra, and L3 spondylolisthesis treated by oblique lumbar interbody fusion (OLIF). CASE DESCRIPTION: A 69-year-old woman presented with increasing lower back pain radiating to the left leg, with aggravation of symptoms for the past 6 months, causing difficulty in walking. She also complained of paresthesia along the L3-L5 dermatomes in both legs, with more prominence on the left side. Imaging revealed fusion deformity of the L4-L5 vertebrae, as well as degenerative spondylolisthesis at the L3-L4 level. After treatment with OLIF, the patient had an uneventful recovery period. Comparisons were made between the preoperative and 6-month follow-up visual analog scale and the Oswestry Disability Index scores. The patient showed significant improvement in the scores, as well as in her symptoms. CONCLUSIONS: OLIF is a promising technique that can be applied in the management of degenerative disk diseases and also for deformities that may be formidable to treat by adopting the traditional posterior approach.

Predictors for Development of Symptomatic Myelopathy in Patients with Radiculopathy Caused by Cervical Ossification of Posterior Longitudinal Ligament.

OBJECTIVE: To identify clinical factors predicting the development of myelopathy in cervical ossification of the posterior longitudinal ligament (OPLL) patients with radiculopathy. METHODS: We retrospectively reviewed 83 cervical OPLL patients who presented with radiculopathy. On the basis of the symptoms and physical findings, we divided patients into 2 groups: myelopathy group and nonmyelopathy group. Demographic, clinical, and radiologic characteristics were reviewed and analyzed among the 2 groups. Predictors for the development of myelopathy were assessed via univariate and multivariate analysis. RESULTS: Univariate analysis demonstrated that a high occupying ratio and the presence of an intramedullary high signal were risk factors for development of myelopathy from radiculopathy in OPLL patients. Multivariate analysis further identified that a high occupying ratio was the only independent predictor (odds ratio 1.05, 95% confidence interval 1.003-1.091, P = 0.035). The cervical range of motion and minor trauma were not related to the development of myelopathy in our study. CONCLUSIONS: Nonmyelopathic OPLL patients with radiculopathy and a high occupying ratio were at higher risk of developing myelopathy, and surgical intervention should be recommended in these cases. However, for elderly patients with significant comorbid conditions, the risks and benefits of surgery should be carefully considered.

Carotid Artery-Related Perioperative Stroke Following Anterior Cervical Spine Surgery: A Series of 3 Cases and Literature Review.

BACKGROUND: Vascular complications following anterior cervical spine surgery are rare but potentially devastating. Complications associated with the carotid artery are even more disastrous but largely anecdotal, with no more than 4 reported cases. MATERIALS AND METHODS: We report 3 new cases of carotid artery-related perioperative stroke following anterior cervical spine surgery. All 3 patients had carotid artery atherosclerosis and the time of intraoperative carotid artery retraction was longer than 1 hour. One patient underwent hypotension during surgery. Risk factors as well as prevention and management protocols of carotid artery-related perioperative stroke based on the literature review and our clinical experience are discussed. CONCLUSIONS: Carotid artery-related perioperative stroke following anterior cervical spine surgery is extremely rare. Prolonged traction, carotid artery atherosclerosis, and intraoperative hypotension can produce cerebral hypoperfusion and cause ischemic stroke. Preoperative risk assessment, adequate perioperative manipulation, and postoperative management can minimize overall morbidity and mortality.

Computed Tomography Imaging Study of Basilar Invagination and Atlantoaxial Dislocation.

OBJECTIVE: We sought to analyze axis deformities and the biomechanics related to atlantoaxial dislocation (AAD) in patients with basilar invagination (BI). METHODS: Seventy-six patients were retrospectively analyzed including 21 patients who had BI (group B), 32 patients with BI and AAD (group C), and 23 nondeformity control subjects (group A). Using 3-dimensional computed tomography imaging the distance from the tip of the dens above the Chamberlain line in the sagittal plane, atlantodental interval, sagittal inclination, coronal inclination, and craniocervical tilt, the height of the odontoid and ratio of the height to the odontoid basal width were measured in each patient. We statistically analyzed the resulting data for correlations among physiologic measurements and disease state. RESULTS: The height of the odontoid process in groups A, B, and C was 13.38 ± 1.50 mm, 10.87 ± 1.48 mm, and 8.49 ± 2.49 mm, respectively. The ratio of height-to-basal width of the odontoid in groups A, B, and C was 1.32 ± 0.21, 0.91 ± 0.21, and 0.65 ± 0.17, respectively. The sagittal inclination in groups A, B, and C was 85.85 ± 4.55 degrees, 105.76 ± 10.72 degrees, and 123.48 ±12.43 degrees, and the coronal inclination was 108.95 ± 24.09 degrees, 105.40 ± 25.16 degrees, and 108.82 ± 21.41 degrees, respectively. The craniocervical tilt in groups A, B, and C was 60.31 ± 6.98 degrees, 84.53 ± 18.94 degrees, and 71.79 ± 11.69 degrees, respectively. The height of the odontoid, height-to-basal width, and sagittal inclination were significantly correlated with both BI and AAD (P < 0.001). Odontoid height and height-to-basal width ratio were significantly correlated with BI, AAD, and sagittal inclination (P < 0.001). Finally, craniocervical tilt was correlated only with the BI severity (P < 0.001). CONCLUSION: This study confirms that deformities of the odontoid process and the lateral joint correlate with severity of BI, while deformity of the odontoid process may be a primary factor in AAD for patients with BI.

Risk Factors and Management of Dural Defects in Anterior Surgery for Cervical Ossification of the Posterior Longitudinal Ligament.

OBJECTIVE: To investigate risk factors and outcomes and to develop a cogent perioperative management algorithm for dural defects (DDs) in anterior surgery for cervical ossification of the posterior longitudinal ligament (OPLL). METHODS: Ninety OPLL patients who had undergone anterior cervical decompression between January 2014 and December 2016 were reviewed. DDs occurred in 12 patients. Demographic, clinical, and radiologic data; intraoperative and postoperative management; and complications were analyzed. Risk factors for DDs were assessed with multivariate analysis. A treatment algorithm was identified based on these findings and our experience. RESULTS: The prevalence of DDs was 13.3% (12/90). Univariate and multivariate analyses showed that the ratio of OPLL base to spinal canal (odds ratio [OR] 1.09, P = 0.012), kyphotic cervical alignment with thick OPLL masses (OR 9.44, P = 0.026), and lateral, curved, and irregular OPLL masses (OR 8.28, P = 0.037) could be risk factors for DDs. DDs were repaired intraoperatively with onlay grafts, and lumbar drains were placed in all DD patients. The treatment was successful in all DD patients, and outcome measures did not differ between the DD and no DD groups. No patient had experienced complications associated with DDs and CSF leaks at the final follow-up visit. CONCLUSIONS: Patients with broad-based OPLL, kyphotic cervical alignment with thick OPLL masses, and lateral, curved, and irregular OPLL masses have a higher risk of DD in anterior surgery for OPLL. Intraoperative primary repair with onlay grafts combined with early lumbar drains is a simple, safe, and effective strategy for DDs. The outlook for the long-term sequelae of DDs is optimistic if they are managed adequately.

A case of fourth atlanto-axial facet joint: anatomical description.

PURPOSE: To report a rare fourth atlanto-axial joint. METHODS: A cadaveric specimen of a young male adult from occiput to C4 was dissected for anatomical study of craniocervical region. A true fourth atlanto-axial joint was confirmed. Its morphological characteristics were described. RESULTS: The fourth atlantoaxial joint is rarely seen. The possible embryogenesis is discussed. This case raises an anatomical possibility of a new variant in this region. CONCLUSIONS: A unique case with an anatomically proven fourth atlantoaxial joint is reported. This anomaly can lead to misdiagnosis. CT scan coupled with MRI can facilitate accurate diagnosis.

Dural dissection cyst: a more accurate term for extradural meningeal cyst.

AIMS: Spinal extradural meningeal cyst (EMC) aetiology remains unclear. Based on our in-depth analysis of EMC clinical characters, we propose the alternative term 'dural dissection cyst' (DDC), which is more consistent with its aetiology and pathological manifestations. METHODS: We examined the clinical, imaging and operative findings of four patients with spinal EMC (type I A) and analysed the aetiology and treatment of the cyst. RESULTS: Spinal DDC was observed between T10 and L3 in our series. Patients presented with low back pain, lower extremity numbness and weakness, and segmental muscle atrophy. Small clefts were found on the inner wall of all cysts. Microscopic suture of the cleft successfully improved patient's symptoms and neurological deficits. CONCLUSIONS: Spinal EMC (type I A) is characterized by dural dissection, so the term DDC can best reflect its aetiology. Because it is a dissection cyst, the most reasonable treatment is to suture the fistula.

[An analysis of surgical outcome and influencing factors in patients of congenital basilar invagination with atlantal-axial dislocation: report of 120 cases].

OBJECTIVE: To investigate the surgical outcome and its influencing factors in patients of congenital basilar invagination (BI) with atlanto-axial dislocation (AAD). METHODS: From May 2004 to August 2010, 120 patients who had BI with AAD were surgically treated with direct posterior intraoperative distraction-reduction and fixation technique, 93 patients were successfully followed up by means of questionnaire survey, telephone and clinical evaluation. Pre- and postoperative dynamic cervical X-rays, computed tomographic scans, 3-dimentional reconstruction views and magnetic resonance imaging were performed. Pre- and postoperative Japanese Orthopaedic Association (JOA) score, distance between odontoid tip and Chamberlain's line and atlantodental interval were measured to evaluate the surgical result. Statistical analysis was performed by means of paired t test and Pearson Correlation analysis. RESULTS: There were 93 cases were followed up for 24-99 months with an average of 46.5 months. Until the final follow-up, clinical symptoms were improved in 79 patients (84.9%), and were stable in 7 patients (7.5%) and deteriorated in 4 patients (4.3%). Three patients died postoperatively (3.2%). Patients without intramedullary signal intensity change (ISIC) had better surgical outcome. Patients with compression from anterior odontoid tip and posterior bone margin of occipital foramen had the worst surgical outcome (F = 3.987, P < 0.01). Overall, good decompression and bone fusion were shown on postoperative image in 87 patients (93.5%). There were 3 deaths in this series because of basilar artery thrombosis, posterior fossa hematoma and unknown reasons each. CONCLUSIONS: The direct posterior intraoperative distraction-reduction and fixation technique is an effective simple and safe method for the treatment of BI with AAD. Anterior compression from odontoid tip and posterior compression from bone margin of occipital foramen-atlantal posterior arch play important roles in its developing mechanism. ISIC on MRI is a predictive factor for the worse surgical outcome.

Feasibility and limitations of C1 lateral mass screw placement in patients of atlas assimilation.

BACKGROUND: C1 lateral mass is a common place for screw fixation in normal anatomy; whereas there is no research about whether screw placement is suitable in patients of C1 assimilation (C1A). OBJECTIVE: To study the feasibility and limitations of C1 lateral mass screw placement in patients with C1A. PATIENTS AND METHODS: From April 2008 to March 2009, C1 lateral mass of 17 C1A patients with atlantoaxial instability (AAI) or dislocation (AAD) was observed and measured using CT reconstruction; and factors determining C1 lateral mass screw placement were studied before and during the operation. RESULTS: A screw of 3.5mm in diameter could be virtually inserted in 31 C1 lateral masses of total 17 C1A patients with maximal length of the screw 18.1±2.7mm; but the entry point of screw had to be modified in the posterior part of inferior facet of C1 instead of posterior middle wall of C1 lateral mass. Clinically, abnormal course of vertebral artery in 6 of 30 (20%) and abundance of venous plexi prevented the proper exposure of C1 lateral mass and screw placement. Hypoglossal canal also had potential risk of injury during screw placement. CONCLUSION: In patients of C1A, when C1 lateral mass screw placement is programmed, factors limit its use should be well studied, and CT angiography is essential.

Recurrent hemorrhage of ligamentum flavum cyst: case report.

A 39-year-old man presented with recurrent lower back and leg pain for 8 months due to repeated hemorrhage into an L5 ligamentum flavum cyst. Lumbar MR imaging showed an extradural cystic mass originating from the ligamentum flavum on the right side in the L5 segment. Microsurgical laminotomy and flavectomy were performed. The symptoms resolved completely and the patient had an uneventful postoperative recovery.

Direct posterior reduction and fixation for the treatment of basilar invagination with atlantoaxial dislocation.

OBJECTIVE: To report the surgical technique and clinical results for the treatment of basilar invagination (BI) with atlantoaxial dislocation (AAD) by direct posterior reduction and fixation using intraoperative distraction between the occiput and C2 pedicle screws. METHODS: From May 2004 to June 2008, 29 patients who had BI with AAD were surgically treated in our department. Pre- and postoperative dynamic cervical x-rays, computed tomographic scans, and 3-dimensional reconstruction views were performed to assess the degree of dislocation. Ventral compression of the cervicomedullary junction was evaluated by magnetic resonance imaging. For all patients, reduction of the AAD was conducted by intraoperative distraction between the occiput and C2 pedicle screws using a direct posterior approach. RESULTS: Follow-up ranged from 6 to 50 months in 28 patients. Clinical symptoms improved in 26 patients (92.9%) and were stable in 2 patients (7.1%) without postoperative deterioration. Radiologically, complete or more than 50% reduction was achieved in 27 of 28 patients (96.4%). In 1 patient, the reduction was less than 50% because the direction of the facets on 1 side of the C1-C2 joint was vertically oriented, instead of horizontal. Overall, good decompression and bone fusion were shown on postoperative magnetic resonance imaging, computed tomography, or x-ray scans for all patients. There was 1 death in the series because of basilar artery thrombosis 1 week after the operation. CONCLUSION: The direct posterior distraction technique between occiput and C2 pedicle screws is an effective, simple, fast, and safe method for the treatment of BI with AAD. Transoral odontoidectomy and cervical traction for the treatment of BI with AAD should be reconsidered.

[Different methods of intracranial-extracranial bypass surgery for the treatment of intracranial aneurysms].

OBJECTIVE: To investigate the effects and methods of intracranial-extracranial (IC-EC) bypass surgery in the treatment of intracranial aneurysms. METHODS: The clinical material of 9 cases, who performed IC-EC bypass surgery before occlusion of the parental arteries of intracranial aneurysms, was studied retrospectively, especially how to evaluate the co-lateral circulation of the parental arteries and how to select the different methods of IC-EC bypass surgery. RESULTS: The co-lateral circulation in 9 cases was not enough to meet the need of the cerebral blood flow after occlusion of the parental arteries of the aneurysms. Revascularization by different methods of IC-EC bypass surgery and then occlusion of the parental arteries, ischemia in the brain area feeding by occluded parental arteries of the aneurysms did not occurred. CONCLUSION: When the co-lateral circulation of the parental arteries of intracranial aneurysm is not enough, the revascularization by different methods of IC-EC bypass surgery is needed before occlusion of these arteries.

[Minimally invasive surgery of the spinal cord hemangioblastoma].

OBJECTIVE: To clarify and discuss the diagnosis and minimally invasive surgery of spinal cord hemangioblastoma. METHODS: The clinical data of 16 patients with spinal cord hemangioblastoma who were operated on between 1992 and 2001 were analyzed retrospectively with a review of the literature. RESULTS: Twelve patients were subjected to MRI examination, nine to spinal cord angiography, and six to preoperative embolization. Thirteen patients underwent complete excision, and three underwent partial excision due to massive bleeding and anterior location of the tumor in spinal cord. Eleven patients showed improvement of their symptoms, four no change at all, and tumor recurrence was seen in one patient with aggravation. CONCLUSION: MRI and spinal angiography are essential for preoperative diagnosis and surgical planning. Early diagnosis and microsurgical resection greatly preserve the neurological function of the patients. Preoperative embolization sometimes is helpful in surgery.