Predictability in Achieving Target Intervertebral Lordosis Using Personalized Interbody Implants.

BACKGROUND: Lumbar lordosis distribution has become a pivotal factor in re-establishing the foundational alignment of the lumbar spine. This can directly influence overall sagittal alignment, leading to improved long-term outcomes for patients. Despite the wide availability of hyperlordotic stock cages intended to achieve optimal postoperative alignment, there is a lack of correlation between the lordotic shape of a cage and the resultant intervertebral alignment. Recently, personalized spine surgery has witnessed significant advancements, including 3D-printed personalized interbody implants, which are customized to the surgeon's treatment and alignment goals. This study evaluates the reliability of 3D-printed patient-specific interbody implants to achieve the planned postoperative intervertebral alignment. METHODS: This is a retrospective study of 217 patients with spinal deformity or degenerative conditions. Patients were included if they received 3D-printed personalized interbody implants. The desired intervertebral lordosis (IVL) angle was prescribed into the device design for each personalized interbody (IVL goal). Standing postoperative radiographs were measured, and the IVL offset was calculated as IVL achieved minus IVL goal. RESULTS: In this patient population, 365 personalized interbodies were implanted, including 145 anterior lumbar interbody fusions (ALIFs), 99 lateral lumbar interbody fusions (LLIFs), and 121 transforaminal lumbar interbody fusions. Among the 365 treated levels, IVL offset was 1.1° ± 4.4° (mean ± SD). IVL was achieved within 5° of the plan in 299 levels (81.9%). IVL offset depended on the approach of the lumbar interbody fusion and was achieved within 5° for 85.9% of LLIF, 82.6% of transforaminal lumbar interbody fusions and 78.6% of ALIFs. Ten levels (2.7%) missed the planned IVL by >10°. ALIF and LLIF levels in which the plan was missed by more than 5° tended to be overcorrected. CONCLUSIONS: This study supports the use of 3D-printed personalized interbody implants to achieve planned sagittal intervertebral alignment. CLINICAL RELEVANCE: Personalized interbody implants can consistently achieve IVL goals and potentially impact foundational lumbar alignment.

Melanoma metastasis to the femoral nerve: a novel case of melanoma masquerading as mononeuropathy. Illustrative case.

BACKGROUND: Metastatic cancer may involve the central and peripheral nervous system, usually in the late stages of disease. At this point, most patients have been diagnosed and treated for widespread systemic disease. Rarely is the involvement of the peripheral nervous system the presenting manifestation of malignancy. One reason for this is a proposed "blood-nerve barrier" that renders the nerve sheath a relatively privileged site for metastases. OBSERVATIONS: The authors presented a novel case of metastatic melanoma presenting as intractable leg pain and numbness. Further workup revealed concurrent disease in the brain and breast, prompting urgent treatment with radiation and targeted immunotherapy. LESSONS: This case highlights the rare presentation of metastatic melanoma as a mononeuropathy. Although neurological complications of metastases tend to occur in later stages of disease after initial diagnosis and treatment, one must remember to consider malignancy in the initial differential diagnosis of mononeuropathy.

Fractured Lumbar Drain Catheter Retrieval Using an Endoscopic Transforaminal Approach to the Lumbar Spine.

BACKGROUND AND IMPORTANCE: Lumbar drain placement is a common neurosurgical procedure, with several surgical and medical indications extending even beyond the specialty. One complication of placement is a fractured catheter fragment. In some circumstances, catheter retrieval is necessary which is classically performed through an open approach. Here, we present the only reported case of a retained lumbar drain catheter which was retrieved using a transforaminal endoscopic approach to the lumbar spine. CLINICAL PRESENTATION: This is a 39 year-old woman who underwent an elective craniotomy with planned perioperative lumbar drain placement for cerebrospinal fluid diversion using a 14-gauge Tuohy needle. Placement was noted to be technically challenging, and during the final attempt on removal of the system, it was noted that the distal end of the catheter had been sheared and retained in the thecal sac. Postoperatively a computed tomography scan of the lumbar spine was obtained showing the catheter fragment which entered the thecal sac dorsally at the L3-4 level but penetrated the ventral dura traveling in the epidural space caudally and terminating in the left lateral recess of L4-5. Given its presumed epidural location near the left L4-5 lateral recess and foramen, the decision was made to attempt a left transforaminal endoscopic approach for catheter retrieval before resorting to a standard open surgery. CONCLUSION: As minimally invasive spine techniques for spine surgery continue to evolve, we have highlighted the versatility of the endoscope in spine surgery as it was implemented in our case, allowing for reduced perioperative morbidity associated with retained spinal catheter retrieval.

The First Pilot Study of an Interactive, 360° Augmented Reality Visualization Platform for Neurosurgical Patient Education: A Case Series.

BACKGROUND: Interactive technologies are increasingly being used for patient education. Augmented reality (AR) is the technology of superimposing digital content on the reality that the user observes. OBJECTIVE: To evaluate a brand new, commercial prototype of a 360° AR visualization platform (360 ARVP) to enhance patient education for neurosurgical patients. METHODS: This pilot study was a single-center, single-provider study that took place in the clinic setting of the senior author. Patients were given the opportunity to use the 360 ARVP (Surgical Theater) concurrently with the neurosurgeon. All patients completed a survey on their experience with the 360 ARVP immediately after use. RESULTS: A total of 24 patients participated in the study. All patients (19 [79.2%] strongly agreed and 5 [20.8%] agreed) reported that using the 360 ARVP system helped improve understanding of their medical condition. The total percentage of patients who either agreed or strongly agreed that experiencing the 360 ARVP helped improve their comfort levels and that they felt included in decisions about their treatment was 95.8%. When asked to rate their level of understanding of their treatment plans on a 0 to 10 scale, the difference in means for the patients' ratings before and after the use of 360 ARVP was statistically significant (P < .0017). CONCLUSION: This pilot study demonstrates that AR can be used as an adjunctive tool for patient education. Patients found that the 360 ARVP increased their understanding of their medical conditions and improved their comfort level with the proposed treatments.

Alterations to the gut microbiome after sport-related concussion in a collegiate football players cohort: A pilot study.

Concussions, both single and repetitive, cause brain and body alterations in athletes during contact sports. The role of the brain-gut connection and changes in the microbiota have not been well established after sports-related concussions or repetitive subconcussive impacts. We recruited 33 Division I Collegiate football players and collected blood, stool, and saliva samples at three time points throughout the athletic season: mid-season, following the last competitive game (post-season), and after a resting period in the off-season. Additional samples were collected from four athletes that suffered from a concussion. 16S rRNA sequencing of the gut microbiome revealed a decrease in abundance for two bacterial species, Eubacterium rectale, and Anaerostipes hadrus, after a diagnosed concussion. No significant differences were found regarding the salivary microbiome. Serum biomarker analysis shows an increase in GFAP blood levels in athletes during the competitive season. Additionally, S100ß and SAA blood levels were positively correlated with the abundance of Eubacterium rectale species among the group of athletes that did not suffer a diagnosed concussion during the sports season. These findings provide initial evidence that detecting changes in the gut microbiome may help to improve concussion diagnosis following head injury.

The Role of Instrumentation in the Surgical Treatment of Spondylodiscitis and Spinal Epidural Abscess: A Single-Center Retrospective Cohort Study.

BACKGROUND: Despite the high incidence of spinal infections that require an operation, there is no consensus on the most appropriate initial surgical management for these patients regarding decompression with vs without instrumented fusion. In this study, we investigated the differences in clinical outcomes, complication rates, and reoperation rates between patients with spinal epidural abscess who underwent decompression alone vs decompression with instrumented fusion. METHODS: Records of patients undergoing operative intervention for spondylodiscitis with spinal epidural abscess at the authors' institution between 2011 and 2018 were reviewed. Two cohorts were observed: patients who underwent decompression alone and patients who underwent decompression with instrumented fusion as the initial operation. Patient demographics and primary outcomes were analyzed and compared. RESULTS: Medical records of 74 patients with spinal infection were reviewed, and 47 patients met the inclusion criteria. There were 27 (57.4%) patients who underwent decompression alone and 20 (42.6%) patients who underwent decompression and fusion. There were no significant differences in the comorbidities, level, and/or extent of infectious involvement between the decompression alone cohort and the decompression with fusion cohort. Although no significant differences were seen between groups with regard to complication rates and neurological outcomes, the reoperation rate was significantly higher in the patients who underwent decompression alone (51.9% vs 10%, P = 0.004). CONCLUSIONS: Decompression with instrumented fusion delivers neurological outcomes and complication rates similar to those seen with decompression alone in patients with spondylodiscitis. However, there was a significantly higher reoperation rate in the decompression only cohort compared to the decompression and fusion cohort.

The utility of intraoperative neuromonitoring on simple posterior lumbar fusions-analysis of the National Inpatient Sample.

BACKGROUND: Several studies have demonstrated the utility of intraoperative neuromonitoring (IOM) including somatosensory evoked potentials (SSEPs), motor-evoked potentials (MEPs), and electromyography (EMG), in decreasing the risk of neurologic injury in spinal deformity procedures. However, there is limited evidence supporting the routine use of IOM in elective posterolateral lumbar fusion (PLF). METHODS: The National Inpatient Sample (NIS) was analyzed for the years 2012-2015 to identify patients undergoing elective PLF with (n=22,404) or without (n=111,168) IOM use. Statistical analyses were conducted to assess the impact of IOM on length of stay, total charges, and development of neurologic complications. These analyses controlled for age, gender, race, income percentile, primary expected payer, number of reported comorbidities, hospital teaching status, and hospital size. RESULTS: The overall use of IOM in elective PLFs was found to have increased from 14.6% in the year 2012 to 19.3% in 2015. The total charge in hospitalization cost for all patients who received IOM increased from $129,384.72 in 2012 to $146,427.79 in 2015. Overall, the total charge of hospitalization was 11% greater in the IOM group when compared to those patients that did not have IOM (P<0.001). IOM did not have a statistically significant impact on the likelihood of developing a neurological complication. CONCLUSIONS: While there may conceivably be benefits to the use of this technology in complex revision fusions or pathologies, we found no meaningful benefit of its application to single-level index PLF for degenerative spine disease.

The utility of routine post-hospitalization CT imaging in patients with non-operative mild to moderate traumatic brain injury.

Primary Objective: The purpose of this study was to determine the utility of CT imaging in patients with non-operative mild-moderate TBI with respect to changes in management.Methods: We conducted a retrospective analysis for 191 patients over a 5-year interval to examine whether follow-up CT initiated a change in management. We created a logistic regression model to incorporate different variables contributing to change in management.Results: Of 191 patients, 31 (16.2%) underwent a change in management. Change in management was associated with older age (65 yo vs. 55 yo, p = .011), diagnosis of subdural hematoma (p = .041), antiplatelet/anticoagulant therapy (p = .009), imaging performed (p = .16), and increased blood products on CT (p = <0.0001). For patients on antiplatelet/anticoagulant therapy, only those with worsening findings on CT required a change in management (p = .0002, 0.039). Surgical intervention was indicated in two patients.Conclusions: Limited clinical value exists in repeat CT scans for patients with mild TBI. Most patients with traumatic SAH, contusions, or asymptomatic patients should not have repeat imaging, as our study revealed only 2% of patients with positive CT finding and 0.6% requiring surgical intervention.

Hybrid Anterior Column Realignment-Pedicle Subtraction Osteotomy for Severe Rigid Sagittal Deformity.

OBJECTIVE: Recently, a hybrid anterior column realignment-pedicle subtraction osteotomy (ACR-PSO) approach has been conceived for patients with severe rigid sagittal deformity, the clinical and radiographic outcomes of which require further investigation compared with ACR only. METHODS: A single-center, retrospective chart review identified patients undergoing a combination of hyperlordotic lateral lumbar interbody grafting (ACR) and concurrent Schwab grade 3 three-column osteotomy and propensity-matched patients undergoing ACR only in the same time frame. Anterior longitudinal ligament was directly released or partially sectioned in all patients. Chart data included demographics, Oswestry Disability Index scores, ACR and osteotomy locations, cage dimensions, fusion length, and complications. Radiographic measurements included lumbar lordosis, sagittal vertical axis, pelvic tilt (PT), and proximal junctional kyphosis. RESULTS: Fourteen patients were enrolled in the ACR + PSO group and 36 in the ACR-only group. Mean ages were 68.5 and 63.9 years, 64% and 67% were female, average body mass index was 27.9 and 29.2, and cardiopulmonary comorbidities were 21% and 17%, respectively. There was no difference in complications (P = 0.347). The average follow-up for the ACR + PSO and ACR-only groups were 22 and 18 months, respectively. Excluding 2 mortalities, fusion occurred in all patients. Average change in lumbar lordosis measured -40.8 ± 9.2 degrees and -19.1 ± 15.7 degrees (P = 0.0006), and PT correction measured 10.5 ± 3.4 degrees and 27.3 ± 1.6 degrees (P < 0.0001), respectively. CONCLUSIONS: For patients with severe rigid sagittal deformity, the hybrid ACR-PSO approach offers significant restoration of lumbar lordosis compared with ACR only, with similar complications but reduced PT correction.

Chordoma-Current Understanding and Modern Treatment Paradigms.

Chordoma is a low-grade notochordal tumor of the skull base, mobile spine and sacrum which behaves malignantly and confers a poor prognosis despite indolent growth patterns. These tumors often present late in the disease course, tend to encapsulate adjacent neurovascular anatomy, seed resection cavities, recur locally and respond poorly to radiotherapy and conventional chemotherapy, all of which make chordomas challenging to treat. Extent of surgical resection and adequacy of surgical margins are the most important prognostic factors and thus patients with chordoma should be cared for by a highly experienced, multi-disciplinary surgical team in a quaternary center. Ongoing research into the molecular pathophysiology of chordoma has led to the discovery of several pathways that may serve as potential targets for molecular therapy, including a multitude of receptor tyrosine kinases (e.g., platelet-derived growth factor receptor [PDGFR], epidermal growth factor receptor [EGFR]), downstream cascades (e.g., phosphoinositide 3-kinase [PI3K]/protein kinase B [Akt]/mechanistic target of rapamycin [mTOR]), brachyury-a transcription factor expressed ubiquitously in chordoma but not in other tissues-and the fibroblast growth factor [FGF]/mitogen-activated protein kinase kinase [MEK]/extracellular signal-regulated kinase [ERK] pathway. In this review article, the pathophysiology, diagnosis and modern treatment paradigms of chordoma will be discussed with an emphasis on the ongoing research and advances in the field that may lead to improved outcomes for patients with this challenging disease.

Patient-Reported Outcomes: Quality of Care on a Neurosurgical Ward.

BACKGROUND AND OBJECTIVES: Patient experience has become a quality measure in hospitals across the United States. To improve our understanding of our neurosurgical patient population's satisfaction needs, we undertook a detailed survey to identify areas of needed improvement. METHODS: Upon institutional review board approval, a detailed survey adopted from the Swedish quality-of-care patient questionnaire was distributed to all patients being discharged from the neurosurgical ward over a month period. From June 2014 to July 2014, all patients admitted to the neurosurgery service through the emergency department, clinic, or other facilities were enrolled. There were no specific inclusion criteria except for age older than 18 years, intact cognition to complete the survey, and return of a completed survey. Data were collected in 6 major categories, including information availability, patient accessibility, treatment received, caring perception, hospital environment, and overall satisfaction. Patients were evaluated by age, gender, surgery, and admission type. RESULTS: Our analysis demonstrated an improved overall satisfaction in those patients being admitted electively from the clinic as compared with emergency department admissions or hospital transfers. In addition, patients admitted on an emergent basis reported a lower satisfaction pertaining to receiving information, specifically test results. CONCLUSIONS: Emergent admissions represent a subpopulation that may require additional strategies to improve patient satisfaction survey scores.

Is Flow Diversion the Death of Simple Coiling or Stent-assisted Coiling? A Single-center Experience.

BACKGROUND: Since the introduction of endovascular methods to treat cerebral aneurysms, several technical advances have allowed a greater number of aneurysms to be treated endovascularly as opposed to open surgical clipping. These include flow diverting stents, which do not utilize coils and instead treat aneurysms by acting as an "internal bypass." We sought to investigate whether flow diversion is replacing coiling at our institution. METHODS: A retrospective chart review on five years of data was conducted to investigate the possible increasing use of flow diversion devices compared to traditional simple or stent-assisted coiling. RESULTS: Over five years, the population revealed a trend toward an increased proportion of female patients, increased frequency of basilar tip and internal carotid artery (ICA) aneurysm location, increased hospital volume, and increased volume of patients treated by dual-trained neurosurgeons over interventional radiologists. Patients were stratified by aneurysm location and statistically significant differences were observed. Flow diversion devices were used with increasing frequency when treating aneurysms arising from the proximal internal carotid artery (Odds ratio (OR)=1.24, 95% CI: 1.02-1.50; p = 0.03), and middle cerebral artery (OR=2.60, 95% CI: 1.38-4.88; p = 0.003). Distal internal carotid artery aneurysm location came close to achieving statistical significance (OR=1.3, 95% CI: 0.99-1.72; p = 0.063). CONCLUSION: In our single center experience at Houston Methodist Hospital, flow diversion devices are being used more frequently for aneurysms arising from the proximal ICA, MCA, and likely distal ICA (though this third location barely failed to achieve statistical significance.

Complications associated with L4-5 anterior retroperitoneal trans-psoas interbody fusion: a single institution series.

BACKGROUND: Lateral lumbar interbody fusion (LLIF), first described in the literature in 2006 by Ozgur et al., involves direct access to the lateral disc space via a retroperitoneal trans-psoas tubular approach. Neuromonitoring is vital during this approach since the surgical corridor traverses the psoas muscle where the lumbar plexus lies, risking injury to the lumbosacral plexus that could result in sensory or motor deficits. The risk of neurologic injury is especially higher at L4-5 due to the anatomy of the plexus at this level. Here we report our single-center clinical experience with L4-5 LLIF. METHODS: A retrospective chart review of all patients who underwent an L4-5 LLIF between May 2016 and March 2019 was performed. Baseline demographics and clinical characteristics, such as body mass index (BMI), medical comorbidities, surgical history, tobacco status, operative time and blood loss, length of stay (LOS), and post-op complications were recorded. RESULTS: A total of 220 (58% female and 42% male) cases were reviewed. The most common presenting pathology was spondylolisthesis. The average age, BMI, operative time, blood loss, and LOS were 64.6 years, 29 kg/m2, 214 min, 75 cc, and 2.5 days respectively. A review of post-operative neurologic deficits revealed 31.4% transient hip flexor weakness and 4.5% quadricep weakness on the approach side. At 3-week follow-up, 9.1% of patients experienced mild hip flexor weakness (4 or 4+/5), 0.9% reported mild quadricep weakness, and 9.5% reported anterior thigh dysesthesias; 93.2% of patients were discharged home and 2.3% were readmitted within the first 30 days post discharge. Female sex, higher BMI and longer operative time were associated with hip flexor weakness. CONCLUSIONS: LLIF at L4-5 is a safe, feasible, and versatile approach to the lumbar spine with an acceptable approach-related sensory and motor neurologic complication rates.

Utility of Patient-Specific Rod Instrumentation in Deformity Correction: Single Institution Experience.

INTRODUCTION: Patient-specific instrumentation is an emerging technology with the promise of a better fit to patient anatomy. With the advent of deformity correction planning software, prefabricated rods can mitigate the need to bend rods in the operating room. Prefabricated rods allow the surgeon to provide a deformity correction closely in line with the surgical plan. METHODS: A retrospective chart review was completed, and all patients with Medicrea UNiD rod were included. A minimum of 3 week follow up upright 36-inch lateral radiograph was necessary for analysis. Overall 21 patients had Medicrea UNiD rods placed; four were excluded (one for cervicothoracic fusion, three for incomplete follow up). Pelvic parameters were documented from the preoperative, surgical plan, and postoperative radiographs using Surgimap (Nemaris Inc, NY). The parameters for the rods were based on the surgical plan. Paired t-tests were used to compare the preoperative, surgical plan, and postoperative pelvic parameters. RESULTS: Average lumbar lordosis, pelvic tilt, sacral slope, and sagittal vertical axis in preoperative radiographs were 35.12°, 24.82°, 28.65°, and 65.65 mm, respectively. In postoperative imaging, lumbar lordosis, pelvic tilt, sacral slope, and sagittal vertical axis were 57.00°, 18.00°, 35.71°, and 21.59 mm, respectively. There was a statistically significant difference in pelvic tilt, sacral slope, lumbar lordosis, and sagittal vertical axis between the preoperative film and surgical plan (p < 0.001), whereas no statistically significant difference was found between the surgical plan and postoperative pelvic parameters (p > 0.05). CONCLUSIONS: Cases in which prefabricated rods were utilized demonstrated improved spinopelvic alignment. Additionally, there was no statistical difference between the surgical plan and postoperative imaging in terms of pelvic parameters. Future studies are needed to investigate the possible benefits of prefabricated rods.

The use of robotics in minimally invasive spine surgery.

The field of spine surgery has changed significantly over the past few decades as once technological fantasy has become reality. The advent of stereotaxis, intra-operative navigation, endoscopy, and percutaneous instrumentation have altered the landscape of spine surgery. The concept of minimally invasive spine (MIS) surgery has blossomed over the past ten years and now robot-assisted spine surgery is being championed by some as another potential paradigm altering technological advancement. The application of robotics in other surgical specialties has been shown to be a safe and feasible alternative to the traditional, open approach. In 2004 the Mazor Spine Assist robot was approved by FDA to assist with placement of pedicle screws and since then, more advanced robots with promising clinical outcomes have been introduced. Currently, robotic platforms are limited to pedicle screw placement. However, there are centers investigating the role of robotics in decompression, dural closure, and pre-planned osteotomies. Robot-assisted spine surgery has been shown to increase the accuracy of pedicle screw placement and decrease radiation exposure to surgeons. However, modern robotic technology also has certain disadvantages including a high introductory cost, steep learning curve, and inherent technological glitches. Currently, robotic spine surgery is in its infancy and most of the objective evidence available regarding its benefits draws from the use of robots in a shared-control model to assist with the placement of pedicle screws. As artificial intelligence software and feedback sensor design become more sophisticated, robots could facilitate other, more complex surgical tasks such as bony decompression or dural closure. The accuracy and precision afforded by the current robots available for use in spinal surgery potentially allow for even less tissue destructive and more meticulous MIS surgery. This article aims to provide a contemporary review of the use of robotics in MIS surgery.

Contemporary Management of Increased Intraoperative Intracranial Pressure: Evidence-Based Anesthetic and Surgical Review.

Increased intracranial pressure (ICP) is frequently encountered in the neurosurgical setting. A multitude of tactics exists to reduce ICP, ranging from patient position and medications to cerebrospinal fluid diversion and surgical decompression. A vast amount of literature has been published regarding ICP management in the critical care setting, but studies specifically tailored toward the management of intraoperative acute increases in ICP or brain bulk are lacking. Compartmentalizing the intracranial space into blood, brain tissue, and cerebrospinal fluid and understanding the numerous techniques available to affect these individual compartments can guide the surgical team to quickly identify increased brain bulk and respond appropriately. Rapidly instituting measures for brain relaxation in the operating room is essential in optimizing patient outcomes. Knowledge of the efficacy, rapidity, feasibility, and risks of the various available interventions can aid the team to properly tailor their approach to each individual patient. In this article, we present the first evidence-based review of intraoperative management of ICP and brain bulk.

Minimally Invasive Tubular Tethered Cord Release in the Pediatric Population.

BACKGROUND: Tethered cord syndrome (TCS) refers to a clinical constellation of signs and symptoms associated with tension in the spinal cord and associated with pathologies related to abnormally low-lying conus medullaris. As minimally invasive spinal operations have become more prevalent in the past decade, we applied expanding indications to selected intradural procedures, such as tethered cord release (TCR). We present the first series of minimally invasive muscle-sparing TCR in the pediatric population. METHODS: A retrospective review of the Texas Children's Hospital, Houston, neurosurgical database was conducted for patients who underwent TCR between 2010 and 2017. Charts were reviewed to determine the source of TCS and whether surgery was conducted in a minimally invasive fashion. To establish a cohort of control population, age-matched cases of open TCR were selected in the same. Exclusion criterion was non-fatty filum sources of TCS. The length of stay, operative time, estimated blood loss, and postoperative complications were recorded. RESULTS: Eleven patients underwent minimally invasive TCR. Mean age of the patients was 10.1 years. All patients underwent L4-5 tubular laminotomy and cord detethering by 2 pediatric neurosurgeons at Texas Children's Hospital. The average length of stay in the hospital was 2.6 days. The average operative time was 167 minutes and average estimated blood loss was 8.2 mL. Ten patients reported clinical improvement and 1 patient was lost to follow-up. CONCLUSIONS: Minimally invasive TCR is a safe and represents a viable alternative to the open approach with advantages such as minimal estimated blood loss, shortened length of stay, and postoperative pain control.

Combinatorial Anatomic and Functional Neural Tract Mapping for Stereotactic Radiosurgery Planning.

Introduction Stereotactic radiosurgery (SRS) is effective and safe for the treatment of the vast majority of brain metastases (BMs). SRS is increasingly used for the simultaneous treatment of multiple lesions, retreatment of recurrence, or subsequent treatment of new lesions. Although radiation injury is relatively uncommon, with the increased utilization of SRS, it is imperative to develop approaches to assess and mitigate radiation-induced neurologic toxicity. Multiple factors influence the development of radiation injury, including patient age, genomic variations, prior treatment, dose and volume treated, and anatomic location. Functional neural structure proximity to SRS targets is a critical factor in developing a systematic integrated risk assessment for SRS patients. Methods We developed an approach for risk assessment based on the combinatorial application of i) the anatomic localization of target lesions using a reference neuroanatomical/functional imaging atlas merged with patient-specific imaging and ii) validation with functional MRI (fMRI) and diffusion tensor imaging MRI (DTI-MRI) to identify neural tracts. Results In the case of a thalamic/midbrain junction breast carcinoma metastasis, the reference image analysis revealed proximity to the corticospinal tract (CST), which was validated by functional DTI-MRI. Dose-volume exposure of the CST could be estimated and considered in the development of a final treatment plan. Conclusion Merging pretreatment MR imaging with neuroanatomical/functional reference MRIs and subsequent validation with fMRI or DTI-MRI may prove to be a valuable approach to screen for neural risks in individual SRS patients. Incorporating this approach in larger studies could further our understanding of dose tolerances in a broad range of neural structures.

Patent Foramen Ovale in Cryptogenic Stroke and Migraine with Aura: Does Size Matter?

INTRODUCTION: There is an association between cryptogenic strokes and patent foramen ovale (PFO), as well as between migraines with aura and PFO. The purpose of the current study was to compare shunt characteristics in the stroke and migraine populations. METHODS: We retrospectively evaluated the degree of the shunt in 68 consecutive patients with cryptogenic stroke (n=33) or migraines with aura (n=35) evaluated in a single transcranial Doppler laboratory. All patients underwent an intravenous injection of agitated saline, followed by the insonation of the middle cerebral artery to determine the degree of the right-to-left shunt. We graded the shunt size according to the number of emboli: Grade I, none; Grade II, 1-10; Grade III, 11-100; and Grade IV, >100. Grades I and II were considered low-grade shunts, and Grades III and IV were considered high-grade. RESULTS: In the 14-month study period, we found 31 high-grade shunts and 37 low-grade shunts. Among migraines with aura patients, 27 (77%) had high-grade shunts, whereas only 4 patients (12%) with cryptogenic stroke had high-grade shunts. These percentages were significantly different between groups (Fisher's exact test, p<0.0001). CONCLUSIONS: In a standardized laboratory using uniform methods, we found a significant difference in shunt size associated with PFO between cryptogenic stroke and migraine with aura patients. We hypothesize that in migraines with aura, venous admixture with arterial blood is the main mechanism by which PFO contributes to the condition. In contrast, cryptogenic strokes associated with PFO are more likely to arise from an atrial septal clot within the PFO space.