Faculty Bibliography

BACKGROUND:Neuroimmune activation in the spinal dorsal horn plays an important role in the pathogenesis of chronic pain after peripheral nerve injury. OBJECTIVE:The aim of this study was to examine the role of neuroimmune activation in below-level neuropathic pain after traumatic spinal cord injury (SCI). METHODS:Right hemilateral SCI was created in male Sprague-Dawley rats by controlled blunt impact through a T12 laminectomy. Pain-related behaviors were assessed using both evoked reflex responses and an operant conflict-avoidance test. Neuroimmune activation was blocked by the anti-inflammatory cytokine interleukin-10 (IL-10) delivered by a nonreplicating herpes simplex virus (HSV)-based gene transfer vector (vIL10). Markers of neuroimmune activation were assessed using immunohistochemistry and Western blot. RESULTS:One week after SCI, injured animals demonstrated mechanical allodynia, thermal hyperalgesia, and mechanical hyperalgesia in the hind limbs below the level of injury. Animals inoculated with vIL10 had a statistically significant reduction in all of these measures compared to injured rats or injured rats inoculated with control vector. Conflict-avoidance behavior of injured rats inoculated with vIL10 was consistent with significantly reduced pain compared with injured rats injected with control vector. These behavioral results correlated with a significant decrease in spinal tumor necrosis factor α (mTNFα) expression assessed by Western blot and astrocyte activation assessed by glial fibrillary acidic protein immunohistochemistry. CONCLUSION/CONCLUSIONS:Below-level pain after SCI is characterized by neuroimmune activation (increase mTNFα and astrocyte activation). Blunting of the neuroimmune response by HSV-mediated delivery of IL-10 reduced pain-related behaviors, and may represent a potential novel therapeutic agent.

OBJECT/OBJECTIVE:Surgery for spinal metastasis is considered palliative, and postoperative survival is often less than a year. Recurrence of metastatic lesions is quite common, and it remains unclear whether repeat surgery is effective. In this study, the authors assessed independent predictors for survival at 6 months, 1 year, and 2 years after surgery, and examined whether repeat surgery for recurrence of spinal metastasis influenced survival rates. METHODS:Retrospective review of the electronic medical records was performed to identify a consecutive population of adult patients who underwent surgery for spinal metastasis during the period 2005-2011. Utilizing a Cox proportional hazard regression model, the authors assessed independent predictors and risk factors for survival at 6 months, 1 year, and 2 years after surgery. In addition, the impact of repeat surgery on survival was specifically assessed via multivariable analysis. RESULTS:A total of 99 patients were included in the final analysis. The overall mean postoperative duration of survival was 9.6 months. In addition to previously identified predictors of survival (preoperative ambulation, Karnofsky Performance Status [KPS], radiotherapy, primary cancer type, presence of extraspinal metastasis, and number of spinal segments with metastasis), pain on presentation and body mass index (BMI) of 25-30 were both independently associated with survival. Patients with recurrence who underwent repeat surgery had longer mean survival times than patients with recurrence who did not undergo repeat surgery (19.6 months vs 12.8 months, respectively). Repeat surgery was also independently associated with higher survival rates on multivariate analysis. Follow-up KPS was significantly higher in patients who underwent repeat surgery as well. CONCLUSIONS:In addition to confirming previously identified predictors of survival following surgery for spinal metastasis, the authors identified BMI and pain on presentation as independent predictors of survival. They also found that repeat surgery may be a viable option in patients with metastatic recurrence and may offer prolonged survival, likely due to improved functionality, mitigating complications associated with immobility.

OBJECT/OBJECTIVE:Leiomyosarcoma is a smooth-muscle sarcoma that rarely metastasizes to the spine. Its clinical course is variable, although patients with metastatic leiomyosarcoma can experience prolonged survival as compared with patients with more aggressive metastatic tumors. The authors report their single-institution experience in the surgical treatment of patients with leiomyosarcoma metastatic to the spine. METHODS:A retrospective review of the electronic medical records was performed to obtain details on clinical management and outcomes for patients who had undergone surgical intervention for metastatic leiomyosarcoma of the spine. The few articles available in the current literature on this topic were also analyzed. RESULTS:Eight patients with metastatic leiomyosarcoma of the spine underwent surgical management between 2005 and 2011. Six patients (75%) had improvement in their Nurick grade. Patients who had presented with pain as a primary symptom experienced significant relief. Five patients (63%) had lesion recurrence, and 4 underwent repeat surgery at a mean of 10.2 months after their initial surgery. The mean duration of survival was 11.7 months (range 3.3-23.0 months). CONCLUSIONS:Leiomyosarcoma rarely metastasizes to the spine. However, surgical intervention can relieve pain and improve neurological function. Given the potential for prolonged survival, aggressive management should be considered in well-selected patients.

INTRODUCTION/BACKGROUND:In patients who require additional surgery for velopharyngeal insufficiency (VPI), a higher incidence of obstructive sleep apnea (OSA) may be incurred. Although this phenomenon has been demonstrated with the posterior pharyngeal flap, the effect of dynamic sphincter pharyngoplasty (DSP) on OSA is less clear. The purposes of this case series were to (1) determine the incidence of OSA after DSP, (2) assess the changes in polysomnography after DSP, and (3) identify risk factors for the development of OSA after DSP. Our global hypothesis is that OSA and VPI exist on a continuum and that speech outcomes should not be considered in isolation. METHODS:For a 13-year period, 146 patients with idiopathic VPI, submucous cleft palate, cleft palate only, or cleft lip and palate underwent DSP for VPI. The diagnosis of OSA was defined as the prescription of continuous positive airway pressure therapy by a pediatric sleep medicine physician. The incidence of OSA preoperatively and postoperatively was compared using Fisher exact test. When available, preoperative and postoperative apnea-hypopnea indices (AHIs) were compared using the pairwise, 2-tailed, Student's t-test. Patient factors, such as obesity (body mass index ≥ 95th percentile), the presence of a craniofacial syndrome, surgical history, and a preexisting OSA diagnosis, were noted. A multiple logistic regression was performed to elucidate risk factors for the development of OSA. RESULTS:The average age at surgery was 9.2 years (range, 4-40 y), and the mean follow-up time was 4.5 years (range, 1 mo to 12 y). The incidence of OSA increased after DSP, from 2 to 33 patients (1.4%-22%, respectively; P = 0.05). In 23 patients (16%), both preoperative and postoperative AHIs were available. There was a significant increase in AHI after DSP, from 3.1 to 8.4 episodes per hour of sleep (P = 0.001). Previous tonsillectomy/adenoidectomy was predictive of OSA after DSP (relative risk = 2.4; P = 0.04). CONCLUSIONS:We report an increased incidence of OSA and higher-than-average AHIs postoperatively after DSP. Preoperative tonsillectomy/adenoidectomy predicted the development of OSA after DSP. A high index of suspicion for development of OSA must be maintained in patients who undergo secondary speech operations for VPI. Clinical screening for OSA should be used in this population, with a low threshold for polysomnographic evaluation. The surgeon must be wary that improvements in speech after DSP may change airway dynamics and increase the risk of OSA.

OBJECT/OBJECTIVE:Identifying risk factors for surgical morbidity and mortality might improve the safety and efficacy of neurosurgical intervention. Cigarette smoking is a relatively common practice and is associated with several adverse health outcomes. The authors examined the relationship between smoking and intraoperative blood loss, postoperative outcomes, and survival following craniotomy for tumor resection. METHODS:A consecutive population of patients undergoing craniotomy for tumor resection between 2006 and 2009 was identified. Using multivariable models and Cox proportional hazard regression analysis, the authors assessed the relation between smoking and operative outcomes including blood loss, complication rates, hospital length of stay, 30-day mortality, and 1-year survival among patients who underwent craniotomy for tumor resection. RESULTS:A total of 453 patients were included in this study: 237 patients never smoked, 54 quit smoking for at least 1 year, and 162 were current smokers. Current smoking status was an independent risk factor for higher intraoperative blood loss, complication risk, and lower 1-year survival following intervention relative to patients who never smoked. Patients who quit smoking had significantly higher mean blood loss, but did not carry a higher risk for other outcomes such as postoperative complications and 1-year mortality compared with patients who never smoked. CONCLUSIONS:Current cigarette smoking is associated with poor surgical outcome and lower 1-year survival after undergoing craniotomy for tumor resection. However, quitting smoking and implementing strict smoking cessation programs may help mitigate these risks. Future research might investigate mechanisms underlying these associations.

OBJECT/OBJECTIVE:The extent of resection (EOR) is a known prognostic factor in patients with glioblastoma. However, gross-total resection (GTR) is not always achieved. Understanding the factors that prevent GTR is helpful in surgical planning and when counseling patients. The goal of this study was to identify demographic, tumor-related, and technical factors that influence EOR and to define the relationship between the surgeon's impression of EOR and radiographically determined EOR. METHODS:The authors performed a retrospective review of the electronic medical records to identify all patients who underwent craniotomy for glioblastoma resection between 2006 and 2009 and who had both preoperative and postoperative MRI studies. Forty-six patients were identified and were included in the study. Image analysis software (FIJI) was used to perform volumetric analysis of tumor size and EOR based on preoperative and postoperative MRI. Using multivariate analysis, the authors assessed factors associated with EOR and residual tumor volume. Perception of resectability was described using bivariate statistics, and survival was described using the log-rank test and Kaplan-Meier curves. RESULTS:The EOR was less for tumors in eloquent areas (p = 0.014) and those touching ventricles (p = 0.031). Left parietal tumors had significantly greater residual volume (p = 0.042). The average EOR was 91.0% in this series. There was MRI-demonstrable residual tumor in 69.6% of cases (16 of 23) in which GTR was perceived by the surgeon. Expert reviewers agreed that GTR could be safely achieved in 37.0% of patients (17 of 46) in this series. Among patients with safely resectable tumors, radiographically complete resection was achieved in 23.5% of patients (4 of 17). An EOR greater than 90% was associated with a significantly greater 1-year survival (76.5%) than an EOR less than 90% (p = 0.005). CONCLUSIONS:The authors' findings confirm that tumor location affects EOR and suggest that EOR may also be influenced by the surgeon's ability to judge the presence of residual tumor during surgery. The surgeon's ability to judge completeness of resection during surgery is commonly inaccurate. The authors' study confirms the impact of EOR on 1-year survival.

BACKGROUND:Incidence and predictors of neurosurgical interventions following nonsevere traumatic brain injury (TBI) with mildly abnormal head computed tomographic (CT) findings are poorly defined. Despite this, neurosurgical consultation is routinely requested in this patient population. Our objective was to determine incidence of neurosurgical intervention in this patient population and identify clinical and radiographic features predicting the subsequent need for these interventions. METHODS:We identified all consecutive adult patients with nonsevere TBI admitted from January 1, 2001, through December 31, 2010. The definitions of "mildly abnormal initial head CT findings" and "neurosurgical interventions" were determined a priori by author consensus. Cumulative incidence of neurosurgical interventions was determined, and multivariate logistic regression was used to identify independent predictors of neurosurgical intervention. RESULTS:Of 677 patients, 51 underwent neurosurgical intervention for a cumulative incidence of 7.5%. Only 1.6% required an intracranial procedure. In adjusted analysis, presence of coagulopathy (odds ratio [OR], 2.21; 95% confidence interval [CI], 1.13-4.3; p = 0.02), suspected cerebrospinal fluid leak (OR, 11.36; 95% CI, 2.83-45.58; p = 0.001), any basal cistern or sylvian fissure subarachnoid hemorrhage (OR, 2.94; 95% CI, 1.56-5.57; p = 0.001), depressed skull fracture (OR, 2.84; 95% CI, 1.29-6.28; p = 0.01), or unstable repeated head CT findings (OR, 2.81; 95% CI, 1.52-5.2; p = 0.001) remained an independent predictor of the need for subsequent neurosurgical intervention. CONCLUSION/CONCLUSIONS:Among patients with nonsevere TBI and mildly abnormal head imaging findings in which routine neurosurgical consultation is obtained, there is a low incidence of neurosurgical interventions. Our findings suggest that routine early neurosurgical consultation in this patient population may not be necessary; however, this should be tested in a prospective, comparative study. LEVEL OF EVIDENCE/METHODS:Prognostic study, level III; therapeutic study, level IV.

BACKGROUND CONTEXT/BACKGROUND:Intracranial hypotension typically occurs spontaneously. Acquired or secondary intracranial hypotension is less common but has been reported after spinal procedures, such as lumbar puncture. Cranial nerve (CN) III palsy is a rare sequela of intracranial hypotension. There are currently no established or standard interventions to treat intracranial hypotension. PURPOSE/OBJECTIVE:To describe a case of delayed CN III palsy resulting from intracranial hypotension because of a spinal cerebrospinal fluid (CSF) leak occurring during resection of a paraspinous tumor. STUDY DESIGN/METHODS:Case report. METHODS:A 41-year-old woman underwent resection of a large thoracic schwannoma complicated by dural tear. Postoperatively, the patient was neurologically normal. She subsequently became acutely unresponsive and required reintubation. She awakened with intermittent headaches and was noted to have a right ptosis, which progressed to a complete right CN III palsy. RESULTS:Initial head computed tomography showed evidence of a small, right-sided subdural hematoma. Magnetic resonance imaging (MRI) of the brain showed diffuse leptomeningeal enhancement and crowding of the foramen magnum consistent with intracranial hypotension. The patient's symptoms were treated successfully with flat bed rest. She fully recovered by time of discharge and at 6-month follow-up was neurologically normal. CONCLUSIONS:Spinal surgery complicated by CSF leak is a potential cause of intracranial hypotension. Although most commonly associated with positional headaches, intracranial hypotension can cause uncommon symptoms, including acute mental status changes and CN deficits. Symptoms highly suspicious for intracranial hypotension accompanied by MRI of the brain are important for establishing a diagnosis of intracranial hypotension. Conservative treatment should be considered before attempting invasive intervention. As in the case presented, simple bed rest was a successful treatment option.

Before the advent of minimally invasive spine surgery (MIS), open transforaminal lumbar interbody fusion (TLIF) was performed to treat spondylosis, spondylolisthesis, and spondylolysis. Minimally invasive TLIF has recently become more popular based upon the premise that a smaller, less traumatic incision should afford better recovery and outcomes. However, the learning curve associated with this technique must be considered. To analyze the perioperative factors associated with the learning curve in patients who underwent MIS TLIF versus open TLIF, we identified 22 patients who underwent TLIF from 2005 to 2008 within levels L4-S1 by the senior author (D.C.). Patients were subdivided into two groups according to whether they underwent: (i) MIS TLIF (10 patients, the first MIS TLIF procedures performed by D.C.); or (ii) open TLIF (12 patients). Preoperative, perioperative and postoperative factors were evaluated. Patients who underwent MIS TLIF had a statistically significant lower intraoperative transfusion rate, and rate of required postoperative surgical drains; and shorter periods of required drainage, and time to ambulation. However, the MIS TLIF group tended to have a higher rate of complications, which might have been associated with the learning curve. Both groups had a minimum of 1-year follow-up.

BACKGROUND:Anterior approaches for thoracolumbar corpectomies can have significant morbidity. Spine surgeons have historically performed their own anterior approaches, but recently access surgeons are being used more frequently. OBJECTIVE:To evaluate the morbidity rates of approaches performed by an access surgeon and by an approach-trained spinal neurosurgeon. METHODS:From 2004 to 2008, 46 patients undergoing anterior thoracolumbar corpectomies (levels T2-L5) by the senior author (D.C.) were identified and subdivided into 2 groups based on whether an access surgeon was involved. Nine patients were excluded, leaving 37 patients in the final analysis. Blood loss, operative times, length of hospital stay, complications, and neurological outcomes were evaluated. RESULTS:Eighteen patients had anterior spinal access by an approach-trained spinal neurosurgeon, and 19 patients underwent the approach by an access surgeon. Surgeries performed by the spinal neurosurgeon alone were comparable to those performed by an access surgeon with respect to operative time, days spent in the hospital, blood loss, complication rates, and improvement in neurological function. CONCLUSION/CONCLUSIONS:There appears to be no increased morbidity of anterior approaches performed by an approach-trained spinal neurosurgeon compared with approaches performed by an access surgeon in terms of operative time, complication rate, and improvement in neurological function.