Stephen E. Sullivan

Comparison of the accuracy of ventricular catheter placement using freehand placement, ultrasonic guidance, and stereotactic neuronavigation.

OBJECT The objective of this study was to compare the accuracy of 3 methods of ventricular catheter placement during CSF shunt operations: the freehand technique using surface anatomy, ultrasonic guidance, and stereotactic neuronavigation. METHODS This retrospective cohort study included all patients from a single institution who underwent a ventricular CSF shunting procedure in which a new ventricular catheter was placed between January 2005 and March 2010. Data abstracted for each patient included age, sex, diagnosis, method of ventricular catheter placement, site and side of ventricular catheter placement, Evans ratio, and bifrontal ventricular span. Postoperative radiographic studies were reviewed for accuracy of ventricular catheter placement. Medical records were also reviewed for evidence of shunt failure requiring revision through December 2011. Statistical analysis was then performed comparing the 3 methods of ventricular catheter placement and to determine risk factors for inaccurate placement. RESULTS There were 249 patients included in the study; 170 ventricular catheters were freehand passed, 51 were placed using stereotactic neuronavigation, and 28 were placed under intraoperative ultrasonic guidance. There was a statistically significant difference between freehand catheters and stereotactic-guided catheters (p<0.001), as well as between freehand catheters and ultrasound-guided catheters (p<0.001). The only risk factor for inaccurate placement identified in this study was use of the freehand technique. The use of stereotactic neuronavigation and ultrasonic guidance reduced proximal shunt failure rates (p<0.05) in comparison with a freehand technique. CONCLUSIONS Stereotactic- and ultrasound-guided ventricular catheter placements are significantly more accurate than freehand placement, and the use of these intraoperative guidance techniques reduced proximal shunt failure in this study.

Dysphagia due to anterior cervical hyperosteophytosis.

BACKGROUND Anterior cervical hyperosteophytosis describes the excessive formation of osteophytes along the ventral spine. Dysphagia due to ACH is considered an uncommon entity described mainly in case reports. Symptomatic ACH has been attributed to multiple etiologies including DISH, trauma, postlaminectomy syndromes, and cervical spondylosis. We report one of the largest series of patients with ACH-induced dysphagia requiring surgery. METHODS After IRB approval, a retrospective chart review was completed. From 2001 to 2006, 9 patients presented with dysphagia due to ACH requiring surgical treatment. RESULTS Eight patients were male, and the mean age was 65.1 years. Cervical spine x-rays and CT clearly demonstrated ACH in each case. Esophagram or a video fluoroscopic swallowing study was used to verify that dysphagia was caused by osteophytic overgrowth in all instances but one. In 2 patients, a focal osteophyte had formed adjacent to a previously fused segment. Of the remaining 7 patients, osteophytic formation was attributed to cervical spondylosis in 2 patients and DISH in 5 patients. All patients underwent osteophytectomy without spinal fusion. Average follow-up was 9.8 months. Although all 9 patients experienced resolution of dysphagia, improvement was delayed in 2 patients. CONCLUSIONS Diffuse idiopathic skeletal hyperostosis and spondylosis are the most common etiologies accounting for ACH-induced dysphagia. Adjacent segment disease may also be a potential cause of symptomatic ACH and has not been previously reported. Regardless of etiology, surgical resection is highly successful if conservative measures fail.

Sinonasal undifferentiated carcinoma: a 13-year experience at a single institution.

We present our experience with sinonasal undifferentiated carcinoma at the University of Michigan over 13 years and review prior published data. We conducted a retrospective review of 19 patients who presented to a tertiary care academic center multidisciplinary skull base clinic with sinonasal undifferentiated carcinoma between 1995 and 2008. Overall survival was 22% at 5 years, and the estimated 5-year distant metastasis-free survival was 35%. At 2 years, local control was 83%, regional control was 50%, and distant control was 83%. Local control was best in those patients treated nonsurgically, as was median survival, though this was not statistically significant. Nodal disease in the neck, either at presentation or at recurrence, was noted in 26% of patients. Survival for sinonasal undifferentiated carcinoma remains poor. It is possible that up-front radiation or chemoradiation will lead to better local control rates, though surgery remains a mainstay of treatment. In all cases, the cervical nodes should be addressed with primary treatment.

Evaluating the use and utility of noninvasive angiography in diagnosing traumatic blunt cerebrovascular injury.

BACKGROUND Digital subtraction angiography (DSA) is the gold standard for radiographic diagnosis of blunt cerebrovascular injury (BCVI), but use of computed tomography angiography (CTA) and magnetic resonance angiography (MRA) has increased dramatically in BCVI screening. This study explores the utility, effectiveness, and cost of noninvasive CTA and MRA screening for BCVI. METHODS Medical records of 2,025 consecutive adults evaluated for acute blunt neck trauma and BCVI were reviewed retrospectively. The incidence of BCVI, level(s) of cervical injury, involvement of foramina transversaria and internal carotid canals, presence of bony dislocation or subluxation, and subsequent treatment received were assessed. Asymptomatic patients were analyzed based on fracture and injury patterns. The cost effectiveness of CTA compared with DSA and the effects of CTA sensitivity and screening yield were determined. RESULTS Of reviewed patients, 196 received CTA or MRA. Thirty-eight patients (19.4%) were diagnosed with BCVI. Screening yield in patients symptomatic at presentation was 48.8%. Large-vessel internal carotid, vertebral, anterior spinal, and basilar artery occlusion were associated with a positive screen, as were concurrent stroke and spinal cord injury (p < 0.01). Of patients with injuries found with noninvasive imaging, 50.0% of BCVI involved C1-3 fracture, 34.2% involved subluxation, and 65.8% involved foramina transversaria. In both symptomatic and asymptomatic patients, CTA screening was more cost effective than DSA. CONCLUSION Noninvasive imaging is a safe, accurate, and cost-effective tool for BCVI screening. Symptomatic presentation was the best predictor of BCVI. Significant cost savings were realized using CTA rather than DSA, with similar effectiveness and patient outcomes. LEVEL OF EVIDENCE Diagnostic study, level III; economic analysis, level IV.

Postoperative outcomes following closed head injury and craniotomy for evacuation of hematoma in patients older than 80 years

OBJECT Advances in the management of trauma-induced intracranial hematomas and hemorrhage (epidural, subdural, and intraparenchymal hemorrhage) have improved survival in these conditions over the last several decades. However, there is a paucity of research investigating the relation between patient age and outcomes of surgical treatment for these conditions. In this study, the authors examined the relation between patient age over 80 years and postoperative outcomes following closed head injury and craniotomy for intracranial hemorrhage. METHODS A consecutive population of patients undergoing emergent craniotomy for evacuation of intracranial hematoma following closed head trauma between 2006 and 2009 was identified. Using multivariable logistic regression models, the authors assessed the relation between age (> 80 vs ≤ 80 years) and postoperative complications, intensive care unit stay, hospital stay, morbidity, and mortality. RESULTS Of 103 patients, 27 were older than 80 years and 76 patients were 80 years of age or younger. Older age was associated with longer length of hospital stay (p = 0.014), a higher rate of complications (OR 5.74, 95% CI 1.29-25.34), and a higher likelihood of requiring rehabilitation (OR 3.28, 95% CI 1.13-9.74). However, there were no statistically significant differences between the age groups in 30-day mortality or ability to recover to functional baseline status. CONCLUSIONS The findings suggest that in comparison with younger patients, patients over 80 years of age may be similarly able to return to preinjury functional baselines but may require increased postoperative medical attention in the forms of rehabilitation and longer hospital stays. Prospective studies concerned with the relation between older age, perioperative parameters, and postoperative outcomes following craniotomy for intracranial hemorrhage are needed. Nonetheless, the findings of this study may allow for more informed decisions with respect to the care of elderly patients with intracranial hemorrhage.

Insurance Status and Inequalities in Outcomes After Neurosurgery

OBJECTIVE Little is known about socioeconomic differences in postoperative outcomes after neurosurgery. We assessed the relation between insurance status and postoperative complication risk, neurosurgical intensive care unit stay, and hospital stay after neurosurgery. METHODS We collected data on 918 consecutive craniotomy or spine-related neurosurgical cases in patients at least 18 years of age at the University of Michigan Hospitals after April 2006. Bivariate χ(2) tests and analysis of variance were used to assess bivariate relations, and multivariable logistic regression models and analysis of covariance were used to adjust for potential confounders. RESULTS A total of 11.2% of privately insured patients, 23.6% of Medicare patients, 25.8% of Medicaid patients, and 27.3% of uninsured patients suffered complications within 30 days of surgery (P < 0.001). In adjusted models, odds of postoperative complications among Medicare (odds ratio [OR] = 2.1, 95% confidence interval [CI] 1.3-3.3), Medicaid (OR = 3.1, 95% CI 1.5-6.1), and uninsured patients (OR = 3.6. 95% CI 1.3-10.3) were higher than among privately insured patients. By analysis of covariance, only Medicaid patients had significantly longer intensive care unit (P = 0.040) and hospital stays (P = 0.028) than privately insured patients. CONCLUSIONS Our findings suggest important socioeconomic disparities in outcomes after neurosurgical intervention. Access to postoperative outpatient care may mediate our findings.

Thermal model to investigate the temperature in bone grinding for skull base neurosurgery

This study develops a thermal model utilizing the inverse heat transfer method (IHTM) to investigate the bone grinding temperature created by a spherical diamond tool used for skull base neurosurgery. Bone grinding is a critical procedure in the expanded endonasal approach to remove the cranial bone and access to the skull base tumor via nasal corridor. The heat is generated during grinding and could damage the nerve or coagulate the blood in the carotid artery adjacent to the bone. The finite element analysis is adopted to investigate the grinding-induced bone temperature rise. The heat source distribution is defined by the thermal model, and the temperature distribution is solved using the IHTM with experimental inputs. Grinding experiments were conducted on a bovine cortical bone with embedded thermocouples. Results show significant temperature rise in bone grinding. Using 50°C as the threshold, the thermal injury can propagate about 3mm in the traverse direction, and 3mm below the ground surface under the dry grinding condition. The presented methodology demonstrated the capability of being a thermal analysis tool for bone grinding study.

Iatrogenic Creutzfeldt-Jakob disease via surgical instruments

Creutzfeldt-Jakob disease (CJD) is a neurodegenerative prion disease that can spread via contaminated neurosurgical instruments previously used on an infected patient. We examine current guidelines on how to recognize, handle, and prevent instrument-related iatrogenic CJD. Despite only four reported patients worldwide implicating contaminated neurosurgical instruments, and none in the past 30 years, the public health consequences of potential instrument-related iatrogenic CJD can be far-reaching. Conventional sterilization and disinfection methods are inadequate in reducing prion infectivity of contaminated instruments, and World Health Organization recommendations for disinfection using bleach or sodium hydroxide are often impractical for routine decontamination. Recently, possible CJD exposure via infected surgical instruments was suspected at a large teaching hospital. Although CJD was later disproven, the intervening investigation exposed the difficulty in tracking infected surgical instruments and in protecting subsequent surgical patients from prion infection. To identify patients at risk for iatrogenic CJD, infectivity of instruments after this index patient is estimated using simple scenario modeling, assuming a certain log reduction of infectivity for each cleansing cycle. Scenario modeling predicts that after six cycles of instrument use with conventional cleansing following an index patient, other patients are highly unlikely to be at risk for iatrogenic CJD. Despite its rarity, the threat of iatrogenic CJD transmission via contaminated instruments poses tremendous challenges to neurosurgeons. Basic prevention strategies should be employed for patients with suspected CJD, including use of disposable instruments where possible and quarantining non-disposable instruments until the diagnosis is ascertained, or using special instrument reprocessing methods if CJD is suspected.

Dural closure using the U-clip in minimally invasive spinal tumor resection.

Study Design Technical case report. Objective To report an alternative to suture for dual closure in minimally invasive spinal surgery. Summary of Background Data Dural closure in minimally invasive spinal intradural tumor resection can be technically challenging. The U-clip is a novel self-closing device that was originally designed to facilitate coronary arterial anastomosis by obviating the need for suture management and knot tying. Given its ability to achieve tissue approximation without knot tying, the U-clip is ideal for dural closure in the narrow surgical corridors provided by the retractors used in minimally invasive procedures. Methods We report the results of 2 cases in which the U-clip device was used for dural closure after minimally invasive spinal resection of an intradural mass. Results Two patients presented with spinal intradural tumors. Patient 1 presented with severe upper back pain and was found to have an intradural extramedullary mass at T2 causing severe spinal cord compression. Patient 2 was incidentally found to have an intradural mass causing significant compression of the cauda equina at L2-3. Both patients underwent minimally invasive tumor resection using an expandable tubular retraction system. Dural closure was accomplished using the U-clip device in conjunction with Tisseal. Postoperatively, both patients were mobilized early and neither developed symptoms related to cerebrospinal fluid leakage. Conclusions Successful dural closure can be achieved using the U-clip device, thereby eliminating the difficulty associated with suture management and knot tying during minimally invasive spinal procedures.

A physical simulator for endoscopic endonasal drilling techniques: technical note.

In this paper, the authors present a physical model developed to teach surgeons the requisite drilling techniques when using an endoscopic endonasal approach (EEA) to the skull base. EEA is increasingly used for treating pathologies of the ventral and ventrolateral cranial base. Endonasal drilling is a unique skill in terms of the instruments used, the long reach required, and the restricted angulation, and gaining competency requires much practice. Based on the successful experience in creating custom simulators, the authors used 3D printing to build an EEA training model from post-processed thin-cut head CT scans, formulating the materials to provide realistic haptic feedback and endoscope handling. They performed a preliminary assessment at 2 institutions to evaluate content validity of the simulator as the first step of the validation process. Overall results were positive, particularly in terms of bony landmarks and haptic response, though minor refinements were suggested prior to use as a training device.