Ajit A. Krishnaney

Outcome after the Treatment of Spinal Dural Arteriovenous Fistulae: A Contemporary Single-institution Series and Meta-analysis

OBJECTIVE:Spinal dural arteriovenous fistulae (Type I spinal AVMs) are the most common type of spinal vascular malformations. The optimal treatment strategy has yet to be defined, and endovascular embolization is being offered with increasing frequency. A 7-year single-institution retrospective review of outcome with surgical management of Type I spinal AVMs is presented along with a meta-analysis of existing literature. METHODS:For the institutional analysis, a retrospective review of all patients who underwent treatment at our institution for Type I spinal AVMs was performed. Between 1995 and the present (the time frame during which endovascular treatments were available), 19 consecutive patients were treated. Follow-up was performed by clinical examination or telephone interview, and functional status was measured by use of the Aminoff-Logue score. For the meta-analysis, a MEDLINE search between 1966 and the present was performed for surgical, endovascular, or combined treatment of spinal dural arteriovenous fistula. These series were included in a meta-analysis to evaluate success and failure rates, complications, and functional outcome. Specifically, embolization and microsurgery were compared. RESULTS:For the institutional analysis, 18 of 19 patients were available for long-term follow-up after surgery. There were no surgical failures, but one complication was seen. Patients demonstrated a statistically significant improvement in gait and bladder function after surgery. For the meta-analysis, 98% of those patients treated with microsurgery had their dural arteriovenous fistulae successfully obliterated after the initial treatment, compared with only 46% with embolization, as judged by radiographic or clinical follow-up. 89% percent of patients demonstrated improvement or stabilization in neurological symptoms after surgical treatment. Few complications were demonstrated with either surgery or embolization. CONCLUSION:At this point, surgery seems to be superior to embolization for the management of spinal dural arteriovenous fistula. The fistula is usually obliterated after the initial treatment, with few clinical or radiographic recurrences. The majority of patients either improve or stabilize after treatment. Few worsen, and the morbidity is minimal. It is reasonable to attempt initial embolization, especially at the time of the initial diagnostic spinal angiogram. The treating physicians and patients should be aware of the high chance of recurrence, and patients may ultimately require surgery or repeat embolization. After endovascular therapy, patients are committed to repeat angiography and probably embolization. For these reasons, it is the authors’ opinion that surgery should be used as the first-line therapy for spinal dural arteriovenous fistulae.

World Health Organization Grades II and III meningiomas are rare in the cranial base and spine.

OBJECTIVEThis study was undertaken to assess a possible relationship between the tumor location and the incidence of World Health Organization (WHO) Grades II and III meningiomas. METHODSA retrospective review of 794 consecutive patients who underwent meningioma resection between January 1991 and March 2004 was conducted. Among these, 47 patients (5.9%) with WHO Grade II meningiomas and 16 patients (2%) with Grade III meningiomas were further analyzed. Tumor location was assessed using preoperative magnetic resonance imaging scans and/or operative reports. Histological grading was done according to the WHO 2000 Classification scheme. RESULTSWHO Grade II tumors were found in eight out of 289 (2.8%) cranial base meningiomas and in zero spinal meningiomas, compared with 39 out of 429 (9.1%) non-cranial base meningiomas. Grade III histology was encountered in two (0.7%) cranial base tumors and in one out of 76 (1.3%) spinal tumors, compared with 13 (3%) non-cranial base tumors. The combined incidence of Grades II and III meningiomas was significantly lower in the cranial base (3.5%) and spinal (1.3%) locations compared with non-cranial base locations (12.1%) (P < 0.001). CONCLUSIONWHO Grades II and III meningiomas occur far less frequently in the cranial base and spinal locations. Tumors arising from these locations may have different mechanisms of tumorigenesis and/or progression compared with meningiomas arising from other (non-cranial base) regions.

Radiation Exposure to the Surgeon During Open Lumbar Microdiscectomy and Minimally Invasive Microdiscectomy : A Prospective, Controlled Trial

Study Design. This is a prospective in vivo study comparing radiation exposure to the surgeon during 10 minimally invasive lumbar microdiscectomy cases with 10 traditional open discectomy cases as a control. Objective. Radiation exposure to the eye, chest, and hand of the operating surgeon during minimally invasive surgery (MIS) and open lumbar microdiscectomy were measured. The Occupational Exposure Guidelines were used to calculate the allowable number of cases per year from the mean values at each of the 3 sites. Summary of Background Data. Fluoroscopy is a source of ionizing radiation and as such, is a potential health hazard with continued exposure during surgery. Presently, radiation exposure to the surgeon during MIS lumbar microdiscectomy is unknown. Methods. Radiation exposure to the surgeon (millirads [mR]) per case was measured by digital dosimeters placed at the level of the thyroid/eye, chest, and dominant forearm. Other data collected included operative side and level, side of the surgeon, side of the x-ray source, total fluoroscopy time, and energy output. Results. The average radiation exposure to the surgeon during open cases was thyroid/eye 0.16 ± 0.22 mR, chest 0.21 ± 0.23 mR, and hand 0.20 ± 0.14 mR. During minimally invasive cases exposure to the thyroid/eye was 1.72 ± 1.52 mR, the chest was 3.08 ± 2.93 mR, and the hand was 4.45 ± 3.75 mR. The difference between thyroid/ eye, chest, and hand exposure during open and minimally invasive cases was statistically significant (P = 0.010, P = 0.013, and P = 0.006, respectively). Surgeons standing in an adjacent substerile room during open cases were exposed to 0.2 mR per case. Conclusion. MIS lumbar microdiscectomy cases expose the surgeon to significantly more radiation than open microdiscectomy. One would need to perform 1623 MIS microdiscectomies to exceed the exposure limit for whole-body radiation, 8720 cases for the lens of the eye, and 11,235 cases for the hand. Standing in a substerile room during x-ray localization in open cases is not fully protective.

Comparative Effectiveness of Ventral vs Dorsal Surgery for Cervical Spondylotic Myelopathy

BACKGROUND:Cervical spondylotic myelopathy (CSM) is the most common cause of spinal cord dysfunction. OBJECTIVE:To determine the feasibility of a randomized clinical trial comparing the clinical effectiveness and costs of ventral vs dorsal decompression with fusion surgery for treating CSM. METHODS:A nonrandomized, prospective, clinical pilot trial was conducted. Patients ages 40 to 85 years with degenerative CSM were enrolled at 7 sites over 2 years (2007-2009). Outcome assessments were obtained preoperatively and at 3 months, 6 months, and 1 year postoperatively. A hospital-based economic analysis used costs derived from hospital charges and Medicare cost-to-charge ratios. RESULTS:The pilot study enrolled 50 patients. Twenty-eight were treated with ventral fusion surgery and 22 with dorsal fusion surgery. The average age was 61.6 years. Baseline demographics and health-related quality of life (HR-QOL) scores were comparable between groups; however, dorsal surgery patients had significantly more severe myelopathy (P < .01). Comprehensive 1-year follow-up was obtained in 46 of 50 patients (92%). Greater HR-QOL improvement (Short-Form 36 Physical Component Summary) was observed after ventral surgery (P = .05). The complication rate (16.6% overall) was comparable between groups. Significant improvement in the modified Japanese Orthopedic Association scale score was observed in both groups (P < .01). Dorsal fusion surgery had significantly greater mean hospital costs (

POSTOPERATIVE COMPLICATIONS ASSOCIATED WITH DURAL SUBSTITUTES IN SUBOCCIPITAL CRANIOTOMIES

29 465 vs

Postoperative cervical sagittal imbalance negatively affects outcomes after surgery for cervical spondylotic myelopathy.

19 245; P < .01) and longer average length of hospital stay (4.0 vs 2.6 days; P < .01) compared with ventral fusion surgery. CONCLUSION:Surgery for treating CSM was followed by significant improvement in disease-specific symptoms and in HR-QOL. Greater improvement in HR-QOL was observed after ventral surgery. Dorsal fusion surgery was associated with longer length of hospital stay and higher hospital costs. The pilot study demonstrated feasibility for a larger randomized clinical trial.

Is It Safe to Use Recombinant Human Bone Morphogenetic Protein in Posterior Cervical Fusion

OBJECTIVE Dural replacements are used in cranial surgery when primary closure of native dura is not possible. The goal is to recreate a watertight barrier to prevent cerebrospinal fluid leakage with few associated complications. We reviewed a single-institution experience with a variety of dural substitutes in posterior fossa neurosurgery, for which higher complication rates are well described. METHODS Patients were screened for suboccipital posterior fossa neurosurgery between November 2005 and April 2007. Surgical logs were reviewed for diagnosis, procedure, and use of dural replacement. Clinical courses were reviewed for hydrodynamic complications, including delayed hydrocephalus, clinically significant pseudomeningocele, aseptic meningitis, and persistent cerebrospinal leakage. RESULTS One hundred twenty-eight patients were included, and a dural replacement was used in 106. Overall, the complication rate was 21.9% (28 patients). Complications were seen for acellular human dermis in 33.3%, for collagen matrix in the original formulation in 18.2%, for the reformulation in 16.9%, for the suturable formulation in 50%, for nonautologous materials in 24%, and for no dural replacement in 16.7%. Univariate and multivariate analysis demonstrated that hydrodynamic complications were associated with use of the suturable collagen matrix (odds ratio, 10.8; 95% confidence interval, 2.5–46.1; P = 0.0014) and trended with use of acellular human dermis (odds ratio, 4.6; 95% confidence interval, 0.9–23.1; P = 0.06). CONCLUSION The increased risk of hydrodynamic complications associated with suboccipital neurosurgery is modified by choice of dural replacement. Similar complication rates were seen for most materials with a variety of primary abnormalities, with the exception of suturable bovine collagen matrix, with hydrodynamic complications in 50% of patients.

The role of adjuvant radiation therapy in the treatment of spinal myxopapillary ependymomas

Study Design. Prospective observational cohort study. Objective. To determine if postoperative cervical sagittal balance is an independent predictor of health-related quality of life outcome after surgery for cervical spondylotic myelopathy. Summary of Background Data. Both ventral and dorsal fusion procedures for CSM are effective at reducing the symptoms of myelopathy. The importance of cervical sagittal balance in predicting overall health-related quality of life outcome after ventral versus dorsal surgery for CSM has not been previously explored. Methods. A prospective, nonrandomized cohort of 49 patients undergoing dorsal and ventral fusion surgery for CSM was examined. Preoperative and postoperative C2–C7 sagittal vertical axis was measured on standing lateral cervical spine radiographs. Outcome was assessed with 2 disease-specific measures—the modified Japanese Orthopedic Association scale and the Oswestry Neck Disability Index and 2 generalized outcome measures—the Short-Form 36 physical component summary (SF-36 PCS) and Euro-QOL-5D. Assessments were performed preoperatively, and at 3 months, 6 months, and 1 year postoperatively. Statistical analyses were performed using SAS version 9.3 (SAS Institute). Results. Most patients experienced improvement in all outcome measures regardless of approach. Both preoperative and postoperative C2–C7 sagittal vertical axis measurements were independent predictors of clinically significant improvement in SF-36 PCS scores (P = 0.03 and P = 0.02). The majority of patients with C2–C7 sagittal vertical axis values greater than 40 mm did not improve from an overall health-related quality of life perspective (SF-36 PCS) despite improvement in myelopathy. The postoperative sagittal balance value was inversely correlated with a clinically significant improvement of SF-36 PCS scores in patients undergoing dorsal surgery but not ventral surgery (P = 0.03 vs. P = 0.93). Conclusion. Preoperative and postoperative sagittal balance measurements independently predict clinical outcomes after surgery for CSM. Level of Evidence: 2

Complications and Outcomes for Surgical Approaches to Cervical Kyphosis.

Study Design. A retrospective chart review of all patients who underwent posterior cervical fusion during a 1-year time period. Objective. To analyze the safety profile of recombinant human bone morphogenetic protein (rhBMP)-2 in posterior cervical fusion. Summary of Background Data. Use of rhBMP-2 in anterior cervical spine surgery has been associated with complications including postoperative edema, dysphagia, and hematoma formation. No literature exists regarding the safety of rhBMP-2 use for posterior cervical fusion. Methods. We reviewed all posterior cervical fusions performed during 1 year at our hospital following institutional review board permission. Results. A total of 83 patients underwent posterior cervical fusion. Sixty-seven (81%) did not receive rhBMP (control group), whereas 16 (19%) underwent fusion with rhBMP. The most common reason for the use of rhBMP was a failure of an anterior cervical fusion resulting in persistent neck pain, myelopathy, or radiculopathy. The average dose of rhBMP used was 1.3 mL per level. Immediate postoperative medical complications occurred in 5 (7%) in the control group and 2 (13%) in the rhBMP group. A new neurologic deficit after surgery was found in 3 (4%) in the control group and 1 (6%) in the rhBMP group. Wound infection requiring further surgery occurred in 8 (12%) in the control group, and in none in the rhBMP group. One (6%) patient in the rhBMP group had significant postoperative neck swelling, but improved with steroid treatment over 1 week, and without any compromise of vital neck structures. No postoperative hematomas were seen in either group. &khgr;2 analysis revealed that no complication variable reached significance (P < 0.05) when the 2 groups were compared. Conclusion. rhBMP can safely be used in patients undergoing posterior cervical fusion, as it does not produce complications at the rate previously seen with its use in the anterior cervical spine.

Spine instrumentation failure after spine tumor resection and radiation: Comparing conventional radiotherapy with stereotactic radiosurgery outcomes

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.