Cervical and Lumbar Spinal Arthroplasty: Clinical Review

In contrast to cervical and lumbar fusion procedures, the principal aim of disk arthroplasty is to recapitulate the normal kinematics and biomechanics of the spinal segment affected. Following decompression of the neural elements, disk arthroplasty allows restoration of disk height and maintenance of spinal alignment. Based on clinical observations and biomechanical testing, the anticipated advantage of arthroplasty over standard arthrodesis techniques has been a proposed reduction in the development of symptomatic ALD. In this review of cervical and lumbar disk arthroplasty, we highlight the clinical results and experience with standard fusion techniques, incidence of ALD in the population of patients with surgical fusion, and indications for arthroplasty, as well as the biomechanical and clinical outcomes following arthroplasty. In addition, we introduce the devices currently available and provide a critical appraisal of the clinical evidence regarding arthroplasty procedures

Survival and Functional Outcome After Surgical Resection of Intramedullary Spinal Cord Metastases

Objective: Intramedullary spinal cord metastasis (ISCM) is a rare manifestation of systemic cancer and data about the optimal management of these lesions are lacking. To clarify the role of surgery, we investigated survival and neurological outcomes after surgical resection of ISCMs. Methods: Between 2003 and 2010, we surgically treated 10 ISCMs in 9 patients. For each patient, we retrospectively collected the following data: demographic variables, history of prior cancer, site of primary cancer, extent of cancer on presentation, degree of resection, preoperative and postoperative spinal cord impairment (American Spinal Injury Association [ASIA] grade), and postoperative survival. We investigated the relationship between these variables, overall survival, and preservation of function. Results: Eight ISCMs were treated with gross total resection and two were treated with subtotal resection. Overall postoperative survival was 6.4 ± 9.4 months (mean ± standard deviation), with one patient still alive at last follow-up. Patients with a diagnosis of melanoma had higher mean survival than those with nonmelanoma histology (20.5 ± 13.4 vs. 2.4 ± 1.7 months, P \u3c 0.01). Degree of resection, number of organ systems affected, ambulatory status, and ASIA grade pre operatively or postoperatively, were not significantly associated with survival. Of the nine patients, seven (78%) demonstrated no change in ASIA grade postoperatively, one (11%) improved, and one patient (11%) deteriorated. All patients who were ambulatory preoperatively remained ambulatory postoperatively and at last follow-up. Conclusions: Although ISCM is associated with poor prognosis, survival appears to be greater in patients with melanoma. Surgical resection does not appear to significantly lengthen survival but may be indicated to preserve ambulatory status in symptomatic patients. © 2012 Elsevier Inc

Comparative analysis of isocentric 3-dimensional C-arm fluoroscopy and biplanar fluoroscopy for anterior screw fixation in odontoid fractures

STUDY DESIGN: Retrospective clinical study. OBJECTIVE: To compare long-term radiographic and clinical outcomes of patients undergoing anterior odontoid screw placement using traditional biplanar fluoroscopy or isocentric 3-dimensional C-arm (iso-C) fluoroscopy-assisted techniques. SUMMARY OF BACKGROUND DATA: Anterior screw fixation of odontoid fractures preserves motion at the C1-C2 joint, but accurate screw positioning is essential for successful outcomes. Biplanar fluoroscopy image guidance is most often used; however, iso-C imaging improves the ease and accuracy of screw placement with less radiation exposure. METHODS: Fifty-one patients underwent anterior odontoid screw fixation for type II (48 patients) and rostral type III fractures (3 patients). Procedures were guided by biplanar fluoroscopy in 25 (49%) patients, and with iso-C assistance in 26 (51%). Length of surgery, complications, and clinical outcomes based on the Smiley-Webster score were evaluated. Computed tomography confirmed adequate screw placement. Follow-up ranged from 3 to 9 months. RESULTS: At 3-month follow-up, screw position and fusion across the fracture were evident in 87% of the cases treated with biplanar fluoroscopy and in 100% treated by iso-C. The average outcome score in the iso-C group was superior to that of the biplanar group (1.08 vs. 1.33, respectively), although not statistically significant. At last follow-up, the rate of successful fusion was 88% in the biplanar group and 95% in the iso-C group. Length of surgery was significantly lower in the iso-C group compared with the biplanar group (P=0.05). The significantly longer preparation time in the iso-C group (P=0.04) accounted for no overall difference in total operating room occupancy time between the 2 groups. CONCLUSIONS: Iso-C significantly decreased surgical time. At last follow-up iso-C assistance was associated with improved rates of radiographic fusion with comparable outcome and complication profiles. This series represents the largest cohort of patients treated with intraoperative real-time navigation assistance for odontoid fractures

Multimodality Treatment of Conus Medullaris Arteriovenous Malformations: 2 Decades of Experience With Combined Endovascular and Microsurgical Treatments

BACKGROUND: Conus medullaris arteriovenous malformations (AVMs) are rare, challenging spinal vascular lesions that cause progressive debilitating myeloradiculopathy. Only sporadic reports of conus AVMs have been published. OBJECTIVE: To better define the presentation, prognosis, and optimal treatment of these lesions, we present the first case series of conus AVMs, reflecting over 2 decades of experience with a multimodality endovascular and surgical approach. METHODS: We retrospectively reviewed the charts of 16 patients with a conus AVM evaluated at our institution from 1989 to 2010. For each patient, the following clinical data were collected: age, sex, symptoms, angiographic findings, type of treatment, complications, degree of angiographic obliteration, recurrence at follow-up, and need for re-treatment. Ambulatory status, Frankel Grade, motor function, and bladder/bowel function were assessed before treatment, at discharge, and at last follow-up. RESULTS: All 16 patients were treated. Eight (50%) patients underwent embolization followed by microsurgical resection, and 8 (50%) underwent microsurgical resection only. The rate of complete angiographic obliteration was 88%. At last follow-up (mean, 70 months), 43% of patients neurologically improved, 43% were stable, and 14% worsened in comparison with before treatment. During follow-up, 3 recurrences were detected, including the only 2 instances of long-term neurological decline. In the absence of recurrence, all patients ambulatory before treatment remained ambulatory at follow-up, whereas 75% of the initially nonambulatory patients regained the ability to walk. CONCLUSION: Although conus AVMs are challenging to treat, excellent long-term outcomes are possible with a multimodality approach. Recurrence is associated with long-term neurological decline and calls for close follow-up. Copyright © 2012 by the Congress of Neurological Surgeons

A Simple and Quantitative Method to Predict Symptomatic Vasospasm After Subarachnoid Hemorrhage Based on Computed Tomography: Beyond the Fisher Scale

BACKGROUND: Although the Fisher scale is commonly used to grade vasospasm risk in aneurysmal subarachnoid hemorrhage (aSAH) patients, it fails to account for increasing subarachnoid hemorrhage (SAH) thickness. OBJECTIVE: We developed a simple quantitative scale based on maximal SAH thickness and compared its reproducibility and ability to predict symptomatic vasospasm against the Fisher scale. METHODS: The incidence of radiographic and symptomatic vasospasm among 250 aSAH patients treated at our institution was investigated. Admission head computed tomography scans were graded according to the Fisher scale and the proposed scale, which assigns a score from 1 to 5 based on a single measurement of maximum SAH thickness. We calculated vasospasm risk per grade for the Fisher scale and the proposed scale, and compared inter-and intraobserver variability for both scales. RESULTS: Forty-five patients (20.6%) developed symptomatic vasospasm. On the proposed scale, grade 5 patients were at highest risk, with an odds ratio for symptomatic vasospasm of 11 (95% confidence interval [CI] 2.27-53.37). Odds ratios for proposed grades 4 and 3 were 4.63 (95% CI 1.10-19.59) and 3.04 (95% CI 0.85-10.90), respectively. The odds ratio for Fisher grade 3 was 3.3 (0.96-11.30). Mean inter-and intraobserver agreement was greater for the proposed scale in comparison with the Fisher scale (κ0.65 and κ0.81 vs κ0.51 and κ0.35, respectively). CONCLUSION: The new scale accounted for increasing SAH thickness and was superior to the Fisher scale in inter-and intraobserver agreement and in predicting symptomatic vasospasm, particularly among the highest-risk patients. Copyright © 2012 by the Congress of Neurological Surgeons

2002 Research Honors Program Abstracts

Faculty in the College of Agriculture and Life Sciences at Cornell University mentor and guide undergraduate students who have chosen to pursue a research project and graduate with honors. These abstracts reflect the depth of their scholarship and intellectual ability. The research projects encompass work in animal science, biological science, entomology, natural resources, physical science, plant science, and social science