The fate of heterotopic ossification associated with cervical artificial disc replacement.

STUDY DESIGN: This is a retrospective study designed to observe the progressive appearance of heterotopic ossification (HO) after cervical artificial disc replacement (ADR). OBJECTIVE: To investigate the development and progressive appearance of HO at cervical ADR sites. SUMMARY OF BACKGROUND DATA: HO is defined as the formation of bone outside the skeletal system. The reported HO occurrence rate in cervical ADR is high and varied. However, the long-term outcome of HO has not been investigated by longitudinal observation. METHODS: Sixty-seven consecutive patients undergoing cervical ADR with complete radiological data were selected for this study. Cervical lateral radiographs and computed tomographic scans were obtained during the first and second studies and compared to identify any transitions in HO. The change in the HO occurrence rate, distribution, and grade of HO were investigated at 2 follow-up time points (18.6 and 36.9 mo postsurgery). To compare the amount of progression between participants' HO rates, the relative increase rate was calculated. RESULTS: HO showed a progressive pattern. The grade of HO was redistributed toward a higher grade in the second study. The number of patients with HO had increased from 31 (46.3%) to 43 (64.2%) of 67 patients at the final follow-up with statistically significant difference (P = 0.037). Twenty-six patients (39.4%) had progressed toward a higher HO grade, but 41 patients (60.6%) showed no change in HO grade. The overall RI rate and the weighted RI rate were 39.4% and 48.7%, respectively. CONCLUSION: This study found that HO has a progressive appearance and determined that HO is not a static but rather a dynamic phenomenon with progressive pattern. Future elucidation of the environmental factors affecting HO, including genetic or proteomic analyses, is recommended. LEVEL OF EVIDENCE: 3.

Stand-alone cervical cages versus anterior cervical plate in 2-level cervical anterior interbody fusion patients: clinical outcomes and radiologic changes.

STUDY DESIGN: Retrospective study. OBJECTIVES: To compare the efficacy of 2-level anterior cervical discectomy and fusion with cage alone (ACDF-CA) and with cage and plate construct (ACDF-CPC) with regard to clinical outcome and radiologic changes. SUMMARY OF BACKGROUND DATA: The use of stand-alone cervical interbody cages in ACDF has become popular, but high subsidence rates have been reported in the literature. METHODS: A total of 54 consecutive patients who underwent 2-level ACDF-CA or ACDF-CPC after suffering from cervical radiculopathy were divided into 2 groups: group A (n = 28) underwent ACDF-CA, group B (n = 26) underwent ACDF-CPC. Fusion rate, global and segmental kyphosis, disk height, and subsidence rate were assessed by radiolographs. Clinical outcomes were assessed using Robinson's criteria. RESULTS: Solid fusion was achieved in 96.43% (27/28) in group A and in 96.15% (25/26) in group B. Fusion segmental kyphosis of >5 degrees occurred in 14.29% (4/28) of group A and in 7.69% (2/26) of group B; however, there was no statistical difference between the 2 groups (P>0.05). Subsidence occurred in 35.71% (10/28) of group A as compared with 11.54% (3/26) of group B (P<0.05). Clinical outcomes were similar in the 2 treatment groups. CONCLUSIONS: The use of cage and plate construct in 2-level ACDF results in a shorter fusion duration and a lower subsidence rate than that of cage alone; however, there is no significant difference in the postoperative global and segmental alignment and clinical outcomes between groups.

Spinal cord hemangioblastomas in von hippel-lindau disease: management of asymptomatic and symptomatic tumors.

PURPOSE: Standard treatment of asymptomatic spinal cord hemangioblastoma in von Hippel-Lindau (VHL) disease has yet to be established. The purpose of this study was to propose guidelines for the treatment of asymptomatic spinal cord hemangioblastomas in VHL disease. MATERIALS AND METHODS: VHL disease patients treated for spinal cord hemangioblastomas between 1999 and 2009 were included. All spinal cord hemangioblastomas were divided into three groups: Group 1, asymptomatic tumors at initial diagnosis followed with serial imaging studies; Group 2, asymptomatic tumors at initial diagnosis that were subsequently resected; and Group 3, symptomatic tumors at initial diagnosis, all of which were resected. RESULTS: We identified 24 spinal cord hemangioblastomas in 12 patients. Groups 1, 2 and 3 comprised 13, 4 and 7 tumors, respectively. Group 1 exhibited a smaller tumor volume (257.1 mm³) and syrinx size (0.8 vertebral columns) than those of Group 2 (1304.5 mm³, 3.3 vertebral columns) and Group 3 (1787.4 mm³, 6.1 vertebral columns). No difference in tumor volume or syrinx size was observed between Groups 2 and 3. Five tumors in Group 1 were resected during follow-up because symptoms had developed or the tumor had significantly grown. Finally, among 17 asymptomatic tumors at the initial diagnosis, nine tumors were resected. Only one tumor of these nine tumors resulted in neurological deficits, while five of seven symptomatic tumors caused neurological deficits. CONCLUSION: Selective resection of asymptomatic tumors before they cause neurological deficits might bring about better outcomes.

The clinical features and surgical outcomes of pediatric patients with primary spinal cord tumor.

BACKGROUND: Primary spinal cord tumors (PSCTs) in pediatric patients are rare, with a reported overall incidence rate of 1-2.6 per one million children. We reviewed our experience of surgically treated 27 pediatric patients with PSCT and discussed the clinical features, radiological findings, surgical outcomes, and prognostic factors. METHODS: Between March 1999 and March 2010, a total of 27 pediatric patients with PSCT were surgically treated in a single institution. We retrospectively analyzed their data. RESULTS: There were 13 females and 14 males, and their ages ranged from 6 months to 19 years (mean age, 12.1 years). The most common presenting symptom was motor weakness, and the histologic type of the tumors were mainly schwannoma, astrocytoma, and ependymoma. The tumor was completely resected in 17 patients, subtotally resected in 7 patients, and partial resection or biopsy was performed in 3 patients. Adjuvant chemotherapy was performed in 9 patients, and radiotherapy in 12 patients, respectively. The average follow-up period was 33.5 months (1.17-129). Five patients experienced the progression of disease, and three of them expired. The mean time for disease progression was 19.0 months (4.5-48.7). CONCLUSIONS: PSCT in pediatric patients can be surgically removed with an acceptable low surgical morbidity. Progression-free survival was found to be related to the grade of tumor and the extent of tumor resection. Early diagnosis and treatment anticipate good functional neurologic outcome.

Effects of lumbar arthrodesis on adjacent segments: differences between surgical techniques.

STUDY DESIGN: A finite element analysis. OBJECTIVE: To evaluate the differences between surgical techniques in terms of the effects of arthrodesis on adjacent segments. SUMMARY OF BACKGROUND DATA: Augmentation with posterior rigid fixation combined with transpedicular screw insertion, which is one of the most popular techniques for lumbar arthrodesis, shows benefits in immediate stabilization and a higher fusion rate but is reportedly correlated with greater stress on adjacent segments. However, the increased stress on adjacent segments needs further evaluation because the differences of the effects on adjacent segments between surgical techniques, including anterior lumbar interbody fusion, posterior lumbar interbody fusion, and semirigid fixation, have not yet been determined. METHODS: A finite element model of the human lumbar spine was developed. Three spinal segments (L2-L5) were used to investigate. The intact spinal model was validated by comparing it with previously reported models. Then, 4 arthrodesis models were analyzed and compared: (1) anterior lumbar interbody fusion model; (2) posterior lumbar interbody fusion model; (3) semirigid fixation model combined with posterior lumbar interbody fusion; and (4) rigid fixation model combined with posterior lumbar interbody fusion. RESULTS: Among these 4 models, the rigid fixation model showed the greatest amount of stress, with increased intervertebral disc pressure and contact force of the facet joints of both upper and lower adjacent segments. The second highest stress levels were seen in the semirigid fixation model and the lowest stress levels were seen in the anterior lumbar interbody fusion model. CONCLUSION: Although bony fusion had been completed, the effects of lumbar arthrodesis on adjacent segments could vary according to the surgical technique used for arthrodesis. Semirigid fixation combined with arthrodesis deserves careful consideration and further detailed study because it may cause less stress on adjacent segments than rigid fixation while maintaining the benefits of the latter procedure.

Thoracolumbar extradural arachnoid cysts: a study of 14 consecutive cases.

BACKGROUND: To investigate characteristic clinical and radiological features of extradural arachnoid cysts (EDACs) in the thoracolumbar region, a retrospective review of medical records and imaging studies was performed. EDACs are well known but relatively rare lesions in the thoracolumbar spinal canal. The most common site is the lower thoracic spine, and it may cause neurological symptoms by compressing the spinal cord or nerve root. In this study, the pathogenesis, symptomatology, diagnostic approach, and surgical management of EDACs will be discussed. METHODS: We studied 14 consecutive patients who were surgically treated for EDACs in the thoracolumbar region at our institute between March 2000 and January 2011. The history, clinical presentations, image findings, operative findings, and surgical outcomes of these patients were retrospectively analyzed. The mean follow-up period was 28 months (range: 6-72 months). RESULTS: Progressive motor weakness was the predominant symptom in all patients. Nine patients had radicular leg pain and back pain in the thoracolumbar area. On MRI, the cyst compressed the dural sac and spinal cord posteriorly typically with bilateral foraminal extensions. On radiological study, a communication point with the subarachnoid was hardly observed. The surgical treatment of EDACs included complete resection of the walls and closing the communicating point with the subarachnoid space. All patients showed excellent outcomes according to Odom's criteria without recurrence. One CSF leakage and one postoperative hematoma were noted. CONCLUSIONS: Thoracolumbar EDAC patients presented paraparesis and leg pain. Complete excision and closing the communicating point with the subarachnoid space were the choices of treatment, and the outcomes were favorable.

The clinical features and surgical outcomes of patients with intramedullary spinal cord cavernous malformations.

BACKGROUND: Cavernous malformations (CMs) are not uncommon, but most of them are found to be located intracranially. Intramedullary CMs are rare, accounting for only 3-5% of identified total central nervous system lesions. The natural history of intramedullary CMs and their clinical features, including the risk of hemorrhage from a large series, still remains unclear and needs to be elucidated. We review our experience with surgically treated patients with intramedullary CMs and discuss the clinical features and surgical outcomes. METHODS: Between March 2004 and March 2010, a total of 21 patients with intramedullary spinal cord CMs were surgically treated in a single institution. Data from 21 patients were retrospectively analyzed. RESULTS: There were 13 females and 8 males ranging in age from 10 to 70 years (mean age 39.3 years). All patients harbored single symptomatic CM of the nervous system, and multiple lesions were not found. The annual retrospective hemorrhage rate was 2.18% per patient/year. All but one CM were completely resected, and the average follow-up period was 22.1 months (1-73 months). Ten of the 21 patients experienced an improvement in neurological state, 9 patients remained unchanged, and 2 patients experienced worsening of their conditions. CONCLUSIONS: Symptomatic intramedullary CMs should be surgically removed to avoid further neurological deterioration. Though there are some limitations due to the retrospective nature of this study and its small number of patients, the prognosis was found to be related to the preoperative neurological state and to the type of symptom presentation.

Intraoperative indocyanine green video-angiography: spinal dural arteriovenous fistula.

STUDY DESIGN: Technical note. OBJECTIVE: To describe the use of intraoperative indocyanine green (ICG) video-angiography for obliteration of a spinal dural arteriovenous fistula (DAVF) and to show a video clip. SUMMARY OF BACKGROUND DATA: ICG video-angiography is an emerging tool for delineating intraoperative vascular anatomy, and it has a significant potential in the treatment of vascular diseases in the spine. METHODS: The authors presented a case of a 73-year-old man with progressive and debilitating bilateral lower extremity weakness. The patient was diagnosed with a spinal DAVF of 10th thoracic spine based on the results of conventional spinal angiography. RESULTS: The patient underwent T9-10 laminotomy for microsurgical clip occlusion. Intraoperative ICG video-angiography was used before clip placement to identify the arterialized veins of the fistula and after clip placement to confirm obliteration of the fistulous connection and restoration of normal blood flow. CONCLUSION: Intraoperative ICG video-angiography serves an important role in the microsurgical treatment of DAVF. It is simple and provides real-time information about the precise location of spinal DAVF and result after obliteration of spinal DAVF.