Proceedings of the NASS 20th Annual Meeting / The Spine Journal 5 (2005) 1S–189S 177S DISCLOSURES: No disclosures. CONFLICT OF INTEREST: No conflicts. doi: 10.1016/j.spinee.2005.05.353 P139. Hyponatremia after acute cervical traumatic spinal cord injury: clinical, molecular and neuroanatomical evidence for disruption of descending renal sympathetic inhibitory pathways (DRSPs) Julio Furlan, MD, MBA, PhD, Michael Fehlings, MD, PhD, FRCS(C); Toronto Western Hospital, Toronto, Ontario, Canada BACKGROUND CONTEXT: Hyponatremia is frequent (30%) in the acute stage after spinal cord injury (SCI). While mild hyponatremia (serum sodium concentration [Na] from 130–135 mmol/L) is usually asymptomatic, moderate/severe hyponatremia ([Na]130) may cause agitation, confusion, seizures and coma. Animal studies indicate that loss of renal supraspinal control is associated with hyponatremia. We hypothesize that disruption of the human DRSPs would be associated with hyponatremia after acute cervical SCI. PURPOSE: To examine (1) the incidence of hyponatremia in early stage (2 weeks) after cervical traumatic SCI; (2) the association of hyponatremia with severity of SCI; (3) the localization of the DRSPs in humans; and (4) the effects of destruction of DRSPs on [Na]. STUDY DESIGN/SETTING: A retrospective cohort study and histopatho- logical, immunocytochemical examination of postmortem spinal cord tissue. PATIENT SAMPLE: We selected all consecutive cases of acute cervical spine trauma admitted to a university hospital from 1998–2000. Individuals with polytrauma or renal/chronic systemic diseases were excluded. Also, we examined postmortem spinal cord from 6 subjects with acute cervical SCI and 5 control cases without CNS trauma. OUTCOME MEASURES: Mean [Na], nadir of [Na] and fluid balance (IV intake– output) in the early stage after SCI. Area of degeneration and number of preserved axons within the descending vasomotor pathways (DVPs), 3mm-area, dorsal column (DC), and corticospinal tracts (CST) in sections caudal to the SCI site. METHODS: Postmortem spinal cord tissues from the study group were examined using staining for myelin preservation (LFB) and immunostaining for axonal preservation (NF200). Measurements and counts were carried out using Image-Pro software. RESULTS: There were 21 individuals (6F, 15M; ages 17–83 years, mean of 57) who mostly suffered mild SCI (ASIA 10C/4D) and 12 controls (4F, 8M; ages 18-90 years, mean of 46). Both groups were comparable for age, gender, fluid balance, and use of diuretics. Hyponatremia occurred in 85.7% in the SCI group and 25% in the control group (p.001). Moderate/severe hyponatremia was frequent in SCI individuals (28.6%) and controls (18.2%; p=.681). Methylprednisolone (MPSS) was more often used in the SCI group than controls (p.001), but there was no significant difference between individuals with SCI who received and who did not receive MPSS regarding the incidence of hyponatremia. The histopathological study included 5 controls (3M, 2F; ages 30–73 years, mean of 51) and 6 individuals (2F, 4M; ages 31–82 years, mean of 59) with severe SCI (ASIA 4A/2B) of whom 50% developed hyponatremia. Both groups were comparable for age and gender. Number of preserved axons within descending tracts was significantly reduced after SCI. Mean [Na] and nadir of [Na] at 2 weeks post- SCI were directly correlated with area of degeneration and were inversely correlated with number of preserved axons within 3mm-area (but not within the DVPs). Moreover, SCI individuals with normal [Na] showed more preserved axons within 3mm-area (but not within DVPs) than individuals who developed hyponatremia after acute cervical SCI. CONCLUSIONS: Hyponatremia is frequent and is associated with the severity of acute SCI. Our results, for the first time, suggest that the human DRSPs are likely located within the dorsolateral parts of the lateral funiculus at 3mm ventrolateral from the dorsolateral sulcus. The extent of destruction of DRSPs (3mm-area) is inversely correlated with hyponatremia post-SCI and this may reflect autonomic renal dysfunction. DISCLOSURES: No disclosures. CONFLICT OF INTEREST: Authors (JF, MF) Grant Research Support: Krembil Foundation and Canadian Syringomyelia Network. doi: 10.1016/j.spinee.2005.05.354 P140. Cervical reconstruction with a cage and plate Sara Myers, MS, Jeffrey Wingate, MD * ; Mt. Pleasant, SC, USA BACKGROUND CONTEXT: Achieving spinal stability and improving sagittal alignment are consistent goals for successful fusion in managing cer- vical spondylosis. Operative approaches using allograft or autograft bone often yield high nonunion rates for procedures greater than two levels. The Cervical Interbody Fusion System (Spine-tech) utilizes a BAK/C cage that collects bone in its chamber during insertion. Because the need for harvesting bone or using allografts is eliminated, potential graft complica- tions are avoided. The cage can be supplemented with an anterior plate for enhanced stability in cases involving multiple levels. PURPOSE: This study looks at the reliability of the BAK/C system in achieving high union rates and improving cervical lordosis. STUDY DESIGN/SETTING: This study is a retrospective, nonrandom- ized clinical trial of patients with cervical HNP and/or cervical spondylosis. The cases are consecutive with one operating surgeon. PATIENT SAMPLE: This cohort consists of 20 multi-level fusion patients who underwent two-, three-, and four-level fusion procedures. All patients are at least 12 months postoperative (ranging from 12 to 29 months). The mean age is 53.3 years old with a M:F ratio of 1:1.9. OUTCOME MEASURES: Plain radiographs and/or noncontrasted CT scans were used to assess fusion rate at all operative levels. Mean increases in lordotic angles were 6.6° (ranging from 3° to 12°), 5.5° (ranging from 2° to 9°) and 8° for two-, three-, and four-level fusions, respectively. METHODS: Plain X-rays were examined to identify fusion rate; CT scans were used to assess fusion in the presence of any subtle abnormality. Lordotic measurements were taken to determine the angle between the highest and lowest levels fused. Patients were evaluated clinically for pain and function using the SF-36 questionnaire. RESULTS: Radiographic results demonstrated a remarkable 100% fusion rate along with a significant increase in lordosis. All patients reported a decrease in axial neck pain as well as functional improvement. There were no major complications and no reports of pseudoarthrosis or cage subsidence/ migration. All patients employed preoperatively returned to their same occu- pations without limitation. Functional returns were greatest in patients 55 years of age and higher. CONCLUSIONS: The results demonstrate the safety and effectiveness of this procedure. While long-term patient follow-up will make this data more substantial, the study provides compelling evidence that the ACD+F procedure successfully restores alignment without compromising stability. Futhermore, the BAK/C system is readily available and requires a minimal learning curve compared with other current surgical techniques. DISCLOSURES: FDA device/drug: BAK/C cage. Status: Approved for this indication. CONFLICT OF INTEREST: No conflicts. doi: 10.1016/j.spinee.2005.05.355 P141. Instrumented extreme lateral interbody fusion (XLIF) through a single approach Neill Wright, MD; Washington University in St. Louis, St. Louis, MO, USA BACKGROUND CONTEXT: Anterior approaches to the lumbar spine allow placement of large interbody devices with restoration of disc space height and indirect decompression of the spinal canal and foramina, but can be complicated by injury to the abdominal contents, iliac vasculature, or sympathetic plexus. An access surgeon is often required and patient discharge is limited by postoperative ileus. Minimally invasive posterior