Trends in Hospital-to-Hospital Transfers for Aneurysmal Subarachnoid Hemorrhage: A Single-Institution Experience from 2006 to 2017

BACKGROUND

Despite evidence to support that aneurysmal subarachnoid hemorrhage (aSAH) is best treated at high-volume centers, it is unknown whether clinical practice reflects these findings.

METHODS

We analyzed patients transferred to our high-volume center for aSAH between 2006 and 2017. Data collection included number of transfers, demographic data, Hunt and Hess score, Fisher score, comorbid conditions, length of stay (LOS), discharge disposition, in-hospital mortality rates, insurance status, and hospital charges. Comparisons were made across 3 time periods (2006-2009, 2010-2013, and 2014-2017) and included subgroup analyses by treatment modality (endovascular vs. microsurgical).

RESULTS

aSAH transfers declined from 213 in 2006-2009 to 160 in 2014-2017. While there was no change in presenting Hunt and Hess scores, the percentage of modified Fisher scores of 4 increased from 2006-2009 to 2014-2017. Transferred patients had a greater comorbidity index and decreased predicted 10-year survival. Despite this, the average LOS decreased. In-hospital mortality decreased from 2006-2009 to 2014-2017, especially in the endovascular cohort. The proportions of patients who were either self-pay or Medicaid did not change. Overall inflation-adjusted hospital charges decreased from $76,975 in 2006-2009 to $59,870 in 2014-2017.

CONCLUSIONS

Between 2006 and 2017, transfers to our center for aSAH declined. However, transferred patients had greater levels of complexity, more comorbidities, and were at greater risk for vasospasm based on their presenting Fisher score. Nonetheless, average LOS, in-hospital mortality, and cost declined. These changing referral patterns have implications for outcome data, quality reporting, resident education, and developing systems of care to optimize outcomes.

Cigarette smoking and risk of intracranial aneurysms in middle-aged women

BACKGROUND AND PURPOSE

We previously reported a single-centre study demonstrating that smoking confers a six-fold increased risk for having an unruptured intracranial aneurysm (UIA) in women aged between 30 and 60 years and this risk was higher if the patient had chronic hypertension. There are no data with greater generalisability evaluating this association. We aimed to validate our previous findings in women from a multicentre study.

METHODS

A multicentre case-control study on women aged between 30 and 60 years, that had magnetic resonance angiography (MRA) during the period 2016-2018. Cases were those with an incidental UIA, and these were matched to controls based on age and ethnicity. A multivariable conditional logistic regression was conducted to evaluate smoking status and hypertension differences between cases and controls.

RESULTS

From 545 eligible patients, 113 aneurysm patients were matched to 113 controls. The most common reason for imaging was due to chronic headaches in 62.5% of cases and 44.3% of controls. A positive smoking history was encountered in 57.5% of cases and in 37.2% of controls. A multivariable analysis demonstrated a significant association between positive smoking history (OR 3.7, 95%CI 1.61 to 8.50), hypertension (OR 3.16, 95% CI 1.17 to 8.52) and both factors combined with a diagnosis of an incidental UIA (OR 6.9, 95% CI 2.49 to 19.24).

CONCLUSIONS

Women aged between 30 and 60 years with a positive smoking history have a four-fold increased risk for having an UIA, and a seven-fold increased risk if they have underlying chronic hypertension. These findings indicate that women aged between 30 and 60 years with a positive smoking history might benefit from a screening recommendation.

Off-Label Utilization of Syphontrak Catheter for Mechanical Thrombectomy in Acute Stroke

BACKGROUND

It is not known whether aspiration-specific catheters are necessary for successful mechanical thrombectomy, but if not, off-label use of more versatile catheters could offer significant cost savings over specialized aspiration catheters. The Syphontrak (Depuy Synthes, Raynham, MA, USA) support catheter is designed for introduction of devices into distal neurovasculature but is not specifically indicated for use in mechanical thrombectomy. We sought to compare our experience using this catheter to historical controls to show the non-inferiority of aspiration achieved.

METHODS

Data were collected retrospectively on patients who underwent mechanical thrombectomy using the Syphontrak catheter for aspiration at our institution. Patient demographics, procedure characteristics, and outcome information was recorded. Results were compared to five landmark studies on mechanical thrombectomy: MR CLEAN, ESCAPE, REVASCAT, SWIFT PRIME, and EXTEND-IA.

RESULTS

There were 63 patients who underwent mechanical thrombectomy for anterior circulation ischemic stroke. Despite significantly older patients and greater time from symptom onset to groin puncture, Thrombolysis in Cerebral Infarction grade 2B or 3 reperfusion was achieved in significantly more patients than in MR CLEAN, ESCAPE, and REVASCAT. Development of symptomatic intracranial hemorrhage occurred in 6.4% of patients, which was not significantly different from MR CLEAN, ESCAPE, REVASCAT, and EXTEND-IA. Mortality was 19.1%, which was not significantly different from any of the trials.

CONCLUSIONS

These data support the off-label use of distal intracranial support catheters for this mechanical thrombectomy, which may result in significant cost savings over aspiration-specific catheters, especially in low-volume centers.

Delayed presentation of acute ischemic strokes during the COVID-19 crisis

BACKGROUND

The COVID-19 pandemic has disrupted established care paths worldwide. Patient awareness of the pandemic and executive limitations imposed on public life have changed the perception of when to seek care for acute conditions in some cases. We sought to study whether there is a delay in presentation for acute ischemic stroke patients in the first month of the pandemic in the US.

METHODS

The interval between last-known-well (LKW) time and presentation of 710 consecutive patients presenting with acute ischemic strokes to 12 stroke centers across the US were extracted from a prospectively maintained quality database. We analyzed the timing and severity of the presentation in the baseline period from February to March 2019 and compared results with the timeframe of February and March 2020.

RESULTS

There were 320 patients in the 2-month baseline period in 2019, there was a marked decrease in patients from February to March of 2020 (227 patients in February, and 163 patients in March). There was no difference in the severity of the presentation between groups and no difference in age between the baseline and the COVID period. The mean interval from LKW to the presentation was significantly longer in the COVID period (603±1035 min) compared with the baseline period (442±435 min, P<0.02).

CONCLUSION

We present data supporting an association between public awareness and limitations imposed on public life during the COVID-19 pandemic in the US and a delay in presentation for acute ischemic stroke patients to a stroke center.

Investigation of the "Superior Facet Rule" Using 3D-Printed Thoracic Vertebrae With Simulated Corticocancellous Interface

BACKGROUND

Pedicle screw placement is the most common method of fixation in the thoracic spine. Use of the "superior facet rule" allows the operator to locate the borders of the pedicle reliably using posterior landmarks alone. This study investigated the ability of 3-dimensionally (3D)-printed thoracic vertebrae, made from combined thermoplastic polymers, to demonstrate pedicle screw cannulation accurately using the superior facet as a reliable landmark.

METHODS

An anonymized computed tomography scan of the thoracic spine was obtained. The T1-T12 thoracic vertebrae were anatomically segmented and 3D-printed. The pedicle diameters and distance from the midpoint of the superior facet to the ventral lamina were recorded. A total of 120 thoracic pedicles in 60 thoracic vertebral models were instrumented using a freehand technique based only on posterior landmarks. The vertebral models were then coronally cut and examined for medial or lateral violations of the pedicle after screw placement.

RESULTS

A total of 120 pedicle screws were placed successfully within the 3D-printed thoracic vertebral models. Average measurements fell within 1 standard deviation of previous population studies. There were no pedicle wall violations using standard posterior element landmarks for instrumentation. There were 3 lateral violations of the vertebral body wall during screw placement, all attributable to the insertion technique.

CONCLUSIONS

3D-printed thoracic vertebral models using combined thermoplastic polymers can accurately demonstrate the anatomical ultrastructure and posterior element relationships of the superior facet rule for safe thoracic pedicle screw placement. This method of vertebral model prototyping could prove useful for surgical education and demonstrating spinal anatomy.

Thrombectomy Technique Predicts Outcome in Posterior Circulation Stroke—Insights from the STAR Collaboration

BACKGROUND

Randomized controlled trials evaluating mechanical thrombectomy (MT) for acute ischemic stroke predominantly studied anterior circulation patients. Both procedural and clinical predictors of outcome in posterior circulation patients have not been evaluated in large cohort studies.

OBJECTIVE

To investigate technical and clinical predictors of functional independence after posterior circulation MT while comparing different frontline thrombectomy techniques.

METHODS

In a retrospective multicenter international study of 3045 patients undergoing MT for stroke between 06/2014 and 12/2018, 345 patients had posterior circulation strokes. MT was performed using aspiration, stent retriever, or combined approach. Functional outcomes were assessed using the 90-d modified Rankin score dichotomized into good (0-2) and poor outcomes (3-6).

RESULTS

We included 2700 patients with anterior circulation and 345 patients with posterior circulation strokes. Posterior patients (age: 60 ± 14, 46% females) presented with mainly basilar occlusion (80%) and were treated using contact aspiration or ADAPT (39%), stent retriever (31%) or combined approach (19%). Compared to anterior strokes, posterior strokes had delayed treatment (500 vs 340 min, P &lt; .001), higher national institute of health stroke scale (NIHSS) (17.1 vs 15.7, P &lt; .01) and lower rates of good outcomes (31% vs 43%, P &lt; .01). In posterior MT, diabetes (OR = 0.28, 95%CI: 0.12-0.65), admission NIHSS (OR = 0.9, 95%CI: 0.86-0.94), and use of stent retriever (OR = 0.26, 95%CI: 0.11-0.62) or combined approach (OR = 0.35, 95%CI: 0.12-1.01) vs ADAPT were associated with lower odds of good outcome. Stent retriever use was associated with lower odds of good outcomes compared to ADAPT even when including patients with only basilar occlusion or with successful recanalization only.

CONCLUSION

Despite similar safety profiles, use of ADAPT is associated with higher rates of functional independence after posterior circulation thrombectomy compared to stent retriever or combined approach in large “real-world” retrospective study.

Laboratory assessments of therapeutic platelet inhibition in endovascular neurosurgery: complication prediction using the VerifyNow P2Y12 assay and thromboelastography with platelet mapping

OBJECTIVE

Inhibition of platelet aggregation is universally used to prevent thromboembolic complications related to stent placement in endovascular neurosurgery, but excessive inhibition potentiates hemorrhagic complications. Previously, the authors demonstrated that two different commercially available measures of adenosine diphosphate (ADP)-dependent platelet inhibition-the VerifyNow P2Y12 clopidogrel assay (measured in platelet reactivity units [PRU]) and maximal amplitude (MA) attributable to ADP activity (MA-ADP) derived from thromboelastography (TEG) with platelet mapping (PM)-yielded wildly different results. This study sought to analyze observed complications to quantify the ideal therapeutic windows for both tests.

METHODS

Ninety-one patients with simultaneous or near-simultaneous PRU and TEG-PM results who underwent craniocervical endovascular stenting at the authors' institution between September 2015 and November 2017 were identified and retrospectively enrolled. From November 2017 until June 2019, 109 additional patients were prospectively enrolled. For this study, in-hospital thrombotic and hemorrhagic complications (both CNS and non-CNS) were tabulated, and receiver operating characteristic (ROC) curve analysis was used to identify threshold values of the PRU and MA-ADP for predicting each type of complication.

RESULTS

Of the 200 patients enrolled, 7 were excluded because of anemia or thrombocytopenia outside of the test manufacturer's specified ranges and 1 was excluded because they did not have a TEG-PM result. Including complications of all severities, there were a total of 15 CNS thrombotic complications, 1 access-site thrombotic complication, 3 CNS hemorrhages, 8 access-site hemorrhagic complications, and 3 hemorrhagic complications not affecting either the CNS or the access site. ROC curve analysis yielded therapeutic threshold values of 118-144 PRU. The results demonstrated PRU has a significant dose-dependent effect on the rates of thrombosis and hemorrhage. Logistic regression models did not demonstrate statistically significant relationships between the MA-ADP and either thrombosis or hemorrhage. ROC analysis based on these models is of little value and did not identify significant threshold values for MA-ADP.

CONCLUSIONS

There continues to be poor correlation between the results of TEG-PM and PRU. PRU accurately predicted complications, with a relatively narrow ideal value range of 118-144. The MA-ADP alone does not appear able to accurately predict either hemorrhagic or thrombotic complications in this group.

Abstract 125: Observation versus Treatment for Low-Grade Intracranial Dural Arteriovenous Fistulas: A Multicenter Matched Cohort Study

Background and Purpose: Given the benign natural history of intracranial low-grade dural arteriovenous fistulas (dAVFs), their routine treatment remains controversial. The aim of this study is to compare the outcomes of low-grade dAVF treatment to conservative management.

Methods: We performed a retrospective review of dAVF patients derived from 12 institutions participating in the Consortium for Dural Arteriovenous Fistula Outcomes Research (CONDOR). Patients with low-grade (Borden I) dAVFs were included and categorized into treatment and observation cohorts. Primary outcome was defined as modified Rankin Scale (mRS) score at final follow-up. Secondary outcomes were rates of excellent (mRS 0-1) and good (mRS 0-2) functional outcomes, symptomatic improvement, mortality, and obliteration at final follow-up.

Results: The treatment and observation cohorts comprised 230 and 112 patients, respectively. At last follow up, no difference in primary or secondary outcomes was observed between the two cohorts, with the exception of obliteration, which was higher in the treatment cohort (79.3% vs. 28.2%, p<0.001; Table 1). The two cohorts were then matched in a 1:1 ratio, resulting in 64 patients in each matched cohort. No difference in primary or secondary outcomes was observed between the matched cohorts, with the exception of obliteration, which was higher in the matched treatment cohort (75.4% vs. 28.6%, p<0.001; Table 2). Subgroup analysis of symptomatic patients demonstrated higher obliteration rate in the treatment cohort, but no difference in primary or other secondary outcomes were found.

Conclusions: Low-grade dAVF treatment was not associated with increased functional disability compared to conservative management. Although higher obliteration rates were achieved in the treatment cohort, rates of symptomatic improvement were similar between the two cohorts. This study did not provide evidence to support the routine treatment of low-grade dAVFs.

Direct enhancement of readiness for wartime critical specialties by civilian-military partnerships for neurosurgical care: residency training and beyond

Military neurosurgery has played an integral role in the development and innovation of neurosurgery and neurocritical care in treating battlefield injuries. It is of paramount importance to continue to train and prepare the next generation of military neurosurgeons. For the Army, this is currently primarily achieved through the military neurosurgery residency at the National Capital Consortium and through full-time out-service positions at the Veterans Affairs-Department of Defense partnerships with the University of Florida, the University of Texas-San Antonio, and Baylor University. The authors describe the application process for military neurosurgery residency and highlight the training imparted to residents in a busy academic and level I trauma center at the University of Florida, with a focus on how case variety and volume at this particular civilian-partnered institution produces neurosurgeons who are prepared for the complexities of the battlefield. Further emphasis is also placed on collaboration for research as well as continuing education to maintain the skills of nondeployed neurosurgeons. With ongoing uncertainty regarding future conflict, it is critical to preserve and expand these civilian-military partnerships to maintain a standard level of readiness in order to face the unknown with the confidence befitting a military neurosurgeon.

Laboratory assessments of therapeutic platelet inhibition in endovascular neurosurgery: comparing results of the VerifyNow P2Y12 assay to thromboelastography with platelet mapping

OBJECTIVEInhibition of platelet aggregation is vital to preventing thromboembolic complications related to stent placement in endovascular neurosurgery, but excessive inhibition potentiates hemorrhagic complications. Recent evidence suggests an ideal inhibition range of 70-150 P2Y12 response units (PRU) as measured on the VerifyNow assay, which relies on photometric measurements of platelet aggregation. Thromboelastography (TEG) with platelet mapping (PM) is an alternative assay that directly measures clot formation and mechanical strength. This study compares the results of PRU to TEG-PM.METHODSPatients with simultaneous or near-simultaneous PRU and TEG-PM results who underwent cervical carotid artery stenting, intracranial stent-assisted aneurysm coiling, or flow diversion at the authors' institution between August 2015 and November 2016 were identified. PRU results were compared with the TEG maximal amplitude (MA) attributable to adenosine diphosphate (ADP) activity (MA-ADP) as measured by TEG-PM. Platelet inhibition was considered therapeutic for MA-ADP values < 50 mm or PRU < 194. The Pearson correlation coefficient was calculated, and the sensitivity and specificity of PRU were calculated assuming that the results of TEG-PM reflected the true degree of platelet inhibition.RESULTSTwenty-three patients were identified with a total of 37 matched sets of TEG-PM and PRU. Three of these pairs were excluded due to anemia outside of the PRU manufacturer's recommended range. The Pearson correlation coefficient for these values was 0.50 (p = 0.0026). The prevalence of clopidogrel nonresponders determined by TEG-PM (9%) matched reported rates (5%-12%); PRU demonstrated much higher prevalence (39%). For detecting a therapeutic level of platelet inhibition, PRU demonstrated a sensitivity of 0.59, specificity of 0.50, positive predictive value of 0.95, and negative predictive value of 0.07. Ideal inhibition was concordant in only 25% of observations in which at least one of the results was ideal.CONCLUSIONSAgreement between TEG-PM and PRU regarding the degree of platelet inhibition is poor. PRU likely overestimates clopidogrel resistance, as 93% of patients with PRU > 194 demonstrate a therapeutic level of platelet inhibition on TEG.

Cervical Spine Deformity Correction Techniques

Cervical kyphotic deformity can be a debilitating condition with symptoms ranging from mechanical neck pain, radiculopathy, and myelopathy to impaired swallowing and horizontal gaze. Surgical correction of cervical kyphosis has the potential to halt progression of neurological and clinical deterioration and even restore function. There are various operative approaches and deformity correction techniques. Choosing the optimal strategy is predicated on a fundamental understanding of spine biomechanics. Preoperative characterization of cervical malalignment, assessment of deformity rigidity, and defining postoperative clinical and radiographic objectives are paramount to formulating a surgical plan that balances clinical benefit with morbidity. This review of cervical deformity treatment provides an overview of the biomechanics of cervical kyphosis, radiographic classification, algorithm-based management, surgical techniques, and current surgical outcome studies.

Does Ossification of the Posterior Longitudinal Ligament Progress After Fusion?

Starting in the 1960s, ossification of the posterior longitudinal ligament (OPLL) became more commonly diagnosed in Japan. The disease is characterized by a gradual increase in calcification of the posterior longitudinal ligament with the eventual sequelae of cervical canal stenosis and myelopathy. Surgical interventions to relieve stenosis and neurologic symptoms are performed to decompress the cervical canal. Studies demonstrate continued ossification of the OPLL in both nonsurgical and surgically treated patients. In this review, the authors evaluate the epidemiology, pathophysiology, and literature regarding disease progression in OPLL after cervical fusion.

A Comparison of the Existing Wellness Programs in Neurosurgery and Institution Champion's Perspectives

Once the accepted norm during Harvey Cushing's time, the mantra of work to the exclusion of family and lifestyle is now recognized as deleterious to overall well-being. A number of neurosurgical residency training programs have implemented wellness programs to enhance the physical, mental, and emotional well-being of trainees and faculty. This manuscript highlights existing organized wellness education within neurosurgery residency programs in order to describe the motivations behind development, structure, and potential implementation strategies, cost of implementation, and identify successes and barriers in the integration process. This manuscript is designed to serve as a “how-to” guide for other programs who may identify a need in their own trainees and begins the discussion of how to develop wellness, leadership, grit, and resiliency within our future generation of neurosurgeons.

The Patient Size Setting: A Novel Dose Reduction Strategy in Cerebral Endovascular Neurosurgery Using Biplane Fluoroscopy

BACKGROUND

In some fluoroscopy machines, the dose-rate output of the fluoroscope is tied to a selectable patient size. Although patient size may play a significant role in visceral or cardiac procedures, head morphology is less variable, and high dose outputs may not be necessary even in very obese patients. We hypothesized that very small patient size setting can be used to reduce dose for cerebral angiography without compromising image quality.

METHODS

Patients who underwent endovascular neurosurgical procedures during the 2015-2016 academic year were identified, and estimated procedural air kerma (AK) was tabulated retrospectively. Technologists were instructed to begin using the very small patient size setting for all procedures performed using our Philips Allura Xper FD20 biplane fluoroscopy system beginning in March 2016. No changes were made in a second procedure room using a Toshiba Infinix system. Student t tests and logistic regression models were used to compare radiation exposure before and after March 1, 2016, for both machines.

RESULTS

For diagnostic cerebral angiograms performed on the Philips system (n = 302), AK was reduced by approximately 17% (1277 vs. 1061 mGy; P = 0.0006.) Changes in table height, total fluoroscopy time, patient weight, and body mass index did not contribute to this difference. No significant change was seen in total AK using the Toshiba system (n = 237). Blinded review by a neuroradiologist did not demonstrate any change in image quality.

CONCLUSIONS

Using the very small patient size reduces fluoroscopy dose by 17% for cerebral angiography without impacting image quality.

Spinal Stabilization Using Orthopedic Extremity Instrumentation Sets During Operation Enduring Freedom-Afghanistan

BACKGROUND

The Role III, Multinational Medical Unit at Kandahar Air Field, Afghanistan, was established to provide combat casualty care in theater for International Security Assistance Forces, Afghanistan National Security Forces, and local nationals during Operation Enduring Freedom-Afghanistan. The authors describe their experience of treating unstable lumbar spine fractures with orthopedic extremity instrumentation sets from January 2007 to January 2008 and November 2010 to May 2011.

METHODS

During the study periods, 15 patients comprising Afghanistan National Security Forces and local nationals presented to the medical facility for treatment of unstable lumbar spine fractures. The patients underwent surgery for either anterior corpectomy and instrumented fusion (n = 5) or posterior instrumented fusion (n = 10). Because of periodic scarcity of spinal instrumentation sets, orthopedic extremity instrumentation sets were used (Synthes Large Fragment LCP Instrument and Implant Set) for spinal stabilization.

RESULTS

Immediate postoperative standing and sitting plain radiographs demonstrated no evidence of fracture progression or immediate hardware failure. One patient was seen in follow-up at 4 weeks and demonstrated construct stability on follow-up radiographs.

CONCLUSIONS

In the combat environment with sparse resources, unstable spine fractures may potentially be treated using instrumentation not specifically designed for spinal implantation. This is an off-label use, and the authors do not recommend the use of these techniques as standard treatment in most medical environments.

Contemporary imaging of mild TBI: the journey toward diffusion tensor imaging to assess neuronal damage

OBJECTIVES

To follow the progression of neuroimaging as a means of non-invasive evaluation of mild traumatic brain injury (mTBI) in order to provide recommendations based on reproducible, defined imaging findings.

METHODS

A comprehensive literature review and analysis of contemporary published articles was performed to study the progression of neuroimaging findings as a non-invasive 'biomarker' for mTBI.

RESULTS

Multiple imaging modalities exist to support the evaluation of patients with mTBI, including ultrasound (US), computed tomography (CT), single photon emission computed tomography (SPECT), positron emission tomography (PET), and magnetic resonance imaging (MRI). These techniques continue to evolve with the development of fractional anisotropy (FA), fiber tractography (FT), and diffusion tensor imaging (DTI).

DISCUSSION

Modern imaging techniques, when applied in the appropriate clinical setting, may serve as a valuable tool for diagnosis and management of patients with mTBI. An understanding of modern neuroanatomical imaging will enhance our ability to analyse injury and recognize the manifestations of mTBI.

Osmotic diuresis paradoxically worsens brain shift after subdural grid placement

OBJECTIVE

The purpose of this study was to assess for peri-operative factors associated with brain shift following craniotomy for subdural grid electrode placement.

METHODS

A retrospective analysis of cases operated at a single institution was undertaken, examining 63 consecutive patients undergoing craniotomy for subdural grid placement for seizure monitoring between 2001 and 2007. Peri-operative records were reviewed in order to assess for intraoperative employment of osmotic duiresis. Postoperative MRI scans were analyzed for shift of the midline and brain displacement.

RESULTS

One patient was excluded due to gross hemispheric atrophy confounding the midline, and four patients were excluded due to lack of available imaging. Hence 58 patients were radiographically reviewed. The employment of osmotic diuresis during grid placement appeared to be the most significant peri-operative factor influencing brain shift. Osmotic diuresis was administered in only 14 patients. Midline shift of the third ventricle was greater in the osmotic diuresis group (2.3 ± 0.3 mm vs. 1.5 ± 0.2 mm, p = 0.037). Moreover, the volume of shifted brain was significantly higher in the osmotic diuresis group (7.9 ± 0.5 cm(3) vs. 4.7 ± 0.5 cm(3), p = 0.003). There was no significant difference in the rates of neurological complications between patients who received osmotic diuresis and those who did not.

CONCLUSION

Employment of osmotic diuresis during grid placement appears to be associated with a paradoxical increase in the volume of shifted brain. This may be due to a combination of the resultant "sagging" of the brain and the pressure exerted by the grid, suggesting that osmotic diuresis might not improve mass effect as intended when employed within this context.

Intraoperative acquisition of three-dimensional imaging for frameless stereotactic guidance during transsphenoidal pituitary surgery using the Arcadis Orbic System

Object

Intraoperative fluoroscopy has long been used for anatomical localization in transsphenoidal pituitary surgery. More recently, frameless stereotaxy has been used to supplement 2D sagittal radiographs with 3D multiplanar reconstructions. Use of Arcadis Orbic allows both conventional fluoroscopic views and multiplanar reconstructions to be acquired intraoperatively without need for preoperative planning studies. The authors report their initial experience using Arcadis Orbic during transsphenoidal pituitary surgery.

Methods

To test the system, the authors placed a dehydrated human skull in a radiolucent head holder, and obtained standard 2D fluoroscopic images of the skull base and sella turcica. Arcadis Orbic was then used with frameless stereotaxy to register 3D multiplanar reconstructed images of skull base anatomy. The authors then used Arcadis Orbic in 26 transsphenoidal pituitary tumor resections and compared image quality, accuracy, and ease-of-use to standard techniques.

Results

Arcadis Orbic 2D fluoroscopic images matched or exceeded the quality of images acquired by standard C-arm machines. Arcadis Orbic multiplanar reconstructions provided excellent images of the skull base when compared with preoperative Stealth computed tomography (CT) studies. Intraoperative frameless stereotactic navigation using Arcadis Orbic was highly accurate and more reliable than registering preoperative CT images.

Conclusions

Arcadis Orbic provides excellent quality 2- and 3D images during transsphenoidal pituitary surgery, and intraoperative frameless navigation using these images is highly accurate. Arcadis Orbic is easy to use, even in patients with large body habitus, and image acquisition takes no longer than registration during a frameless stereotactic case. Based upon our preliminary experience, Arcadis Orbic precludes the need for preoperative CT studies in patients with pituitary lesions requiring frameless stereotactic navigation.