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Sina Pourtaheri, Akshay Sharma, Jason Savage, Iain Kalfas, Thomas E. Mroz, Edward Benzel and Michael P. Steinmetz

OBJECTIVE

The flexed posture of the proximal (L1–3) or distal (L4–S1) lumbar spine increases the diameter of the spinal canal and neuroforamina and can relieve symptoms of neurogenic claudication. Distal lumbar flexion can result in pelvic retroversion; therefore, in cases of flexible sagittal imbalance, pelvic retroversion may be compensatory for lumbar stenosis and not solely compensatory for the sagittal imbalance as previously thought. The authors investigate underlying causes for pelvic retroversion in patients with flexible sagittal imbalance.

METHODS

One hundred thirty-eight patients with sagittal imbalance who underwent a total of 148 fusion procedures of the thoracolumbar spine were identified from a prospective clinical database. Radiographic parameters were obtained from images preoperatively, intraoperatively, and at 6-month and 2-year follow-up. A cohort of 24 patients with flexible sagittal imbalance was identified and individually matched with a control cohort of 23 patients with fixed deformities. Flexible deformities were defined as a 10° change in lumbar lordosis between weight-bearing and non–weight-bearing images. Pelvic retroversion was quantified as the ratio of pelvic tilt (PT) to pelvic incidence (PI).

RESULTS

The average difference between lumbar lordosis on supine MR images and standing radiographs was 15° in the flexible cohort. Sixty-eight percent of the patients in the flexible cohort were diagnosed preoperatively with lumbar stenosis compared with only 22% in the fixed sagittal imbalance cohort (p = 0.0032). There was no difference between the flexible and fixed cohorts with regard to C-2 sagittal vertical axis (SVA) (p = 0.95) or C-7 SVA (p = 0.43). When assessing for postural compensation by pelvic retroversion in the stenotic patients and nonstenotic patients, the PT/PI ratio was found to be significantly greater in the patients with stenosis (p = 0.019).

CONCLUSIONS

For flexible sagittal imbalance, preoperative attention should be given to the root cause of the sagittal misalignment, which could be compensation for lumbar stenosis. Pelvic retroversion can be compensatory for both the lumbar stenosis as well as for sagittal imbalance.

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Samuel T. Chao, Taisei Kobayashi, Edward Benzel, Chandana A. Reddy, Glen H. J. Stevens, Richard A. Prayson, Iain Kalfas, Richard Schlenk, Ajit Krishnaney, Michael P. Steinmetz, William Bingaman, Joseph Hahn and John H. Suh

Object

The goal in this study was to determine the role of radiation therapy (RT) in the treatment of spinal myxopapillary ependymomas (MPEs).

Methods

Thirty-seven patients with histologically verified spinal MPEs were reviewed. Kaplan-Meier analyses and Cox proportional hazard regression were used to determine what patient and treatment factors influenced overall survival (OS) and recurrence.

Results

At the time of initial diagnosis, the median age was 33 years and the Karnofsky Performance Scale score was 80. In 86.5% of cases, the most common presenting symptom was pain. All patients received surgery as their initial treatment. Nine patients also received RT along with surgery, with a median total dose of 50.2 Gy. The mean survival time was 12.2 years; however, only 4 of 37 patients had died at the time of this study. None of the patient or treatment parameters significantly correlated with OS. Sixteen patients (43.2%) were found to have a recurrence, with a median time to recurrence of 7.7 years. None of the patient or treatment parameters correlated with recurrence-free survival for an initial recurrence. The median time to the second recurrence (recurrence following therapy for initial recurrence) was 1.6 years. Use of RT as salvage therapy after initial recurrence significantly correlated with longer times to a second recurrence. The median recurrence-free survival time before the second recurrence was 9.6 years for those who received RT versus 1.1 years for those who did not receive RT (p = 0.0093). None of the other parameters significantly correlated with a second recurrence.

Conclusions

Radiation therapy may have a role as salvage therapy in delaying recurrences of spinal MPEs.

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Robert F. McLain, Iain Kalfas, Gordon R. Bell, John E. Tetzlaff, Helen J. Yoon and Maunak Rana

Object. Despite a history of safety and efficacy, spinal anesthesia is rarely used in lumbar surgery. Application of regional anesthetics is widely preferred for lower-extremity surgery, but general anesthesia is used almost exclusively in spine surgery, despite evidence that spinal anesthesia is as safe and may offer some advantages.

Methods. In this case-controlled study the authors analyzed outcomes obtained in 400 patients in whom either spinal anesthesia or general anesthesia was induced to perform a lumbar decompression. Patients were matched for anesthesia-related class, preoperative diagnosis, surgical procedure, and perioperative protocols. All aspects of surgery, recovery, postanesthesia care, and pain management were uniform irrespective of the anesthetic type. Case complexity was equivalent. An independent observer performed analysis of the data. Data from the intraoperative period through hospital discharge were collected and compared.

Two hundred consecutive patients meeting inclusion criteria were included in each group. Patients were treated for either lumbar stenosis or herniated nucleus pulposus. Demographically, both groups were well matched. Anesthetic and operative times were longer for patients receiving a general anesthetic (p < 0.05), in whom more nausea and greater requirements for antiemetics and pain medication were also present during recovery (p < 0.05). Overall complication rates and, specifically, the incidences of urinary retention were significantly lower in spinal anesthesia—induced patients (p < 0.05). There were no neural injuries in either group, and the incidence of spinal headache was lower in patients receiving a spinal anesthetic (1.5% compared with 3%).

Conclusions. Spinal anesthesia was as safe and effective as general anethesia for patients undergoing lumbar laminectomy. Potential advantages of spinal anesthsia include a shorter anesthesia duration, decreased nausea, antiemetic and analgesic requirements, and fewer complications. Successful surgery can be performed using either anesthesia type.