Occipital artery to vertebral artery bypass for treatment of bilateral vertebral artery occlusion with QMRA as an adjunct to diagnostic assessment.

PURPOSE: Stroke, the second leading cause of death globally, often involves ischemia in the vertebrobasilar territory. This condition is underexplored, despite significant morbidity and mortality risks. The purpose of this study is to present a case of occipital artery to V3 segment vertebral artery bypass, emphasizing the role of quantitative magnetic resonance angiography (qMRA) in assessing flow and guiding surgical intervention. METHODS: A 66-year-old man with bilateral vertebral artery occlusion presented acute symptoms. qMRA was employed to evaluate flow dynamics and determine the feasibility of a flow augmentation bypass surgery. The occipital artery to left vertebral artery bypass (OA-to-VA) was performed, utilizing an inverted hockey-stick incision and an antegrade inside-out technique. The patency of the bypass was confirmed using both Doppler probe and Indocyanine green. RESULTS: Postoperative assessments, including computed tomography angiography (CTA) and qMRA, demonstrated the patency of the bypass with improved flow in the basilar artery and left vertebral artery. The patient's condition remained stable postoperatively, with residual peripheral palsy of the left facial nerve. CONCLUSION: In conclusion, the presented case illustrates the efficacy of the OA-to-VA bypass in addressing symptomatic bilateral vertebral artery occlusion. The study underscores the pivotal role of qMRA in pre- and postoperative assessments, providing noninvasive flow quantification for diagnostic considerations and long-term follow-up in patients with vertebrobasilar insufficiency.

Characterization of T-/natural killer cell lymphoproliferative neoplasms associated with systemic, chronic, active Epstein-Barr virus in adults: A report of 5 cases in a Western population.

OBJECTIVES: Because of its low frequency in adult populations and clinical and laboratory overlap with hemophagocytic lymphohistiocytosis and other T-cell lymphomas, T-cell/natural killer (NK) cell systemic, chronic, active Epstein-Barr virus (EBV) (T/NK sCAEBV) infection remains underdiagnosed, preventing critical, prompt therapeutic interventions. METHODS: We report a 5-case series that included 2 adult patients with T/NK sCAEBV and 3 additional adult patients with T/NK lymphomas with concomitant systemic EBV infection to review these entities' overlapping diagnostic and clinical features. RESULTS: Approximately 95% of the world population has been infected with EBV during their lifetime, and infection is usually asymptomatic, with symptomatic cases eventually resolving spontaneously. A small subset of immunocompetent patients develops CAEBV, a life-threatening complication resulting from EBV-infected T-cell or NK cell neoplastic lymphocytes. The sites of end-organ damage in T/NK sCAEBV demonstrate pathologic findings such as reactive lymphoid proliferations, making the diagnosis difficult to establish, with the only curative option being an allogeneic hematopoietic stem cell transplant. CONCLUSIONS: This diagnosis is most prevalent in Asia, with few cases reported in Western countries. Adult age is an independent risk factor for poor outcomes, and most cases are diagnosed in pediatric populations.

Surgical Outcomes in Octogenarians with Central Cord Syndrome: A Propensity-Score Matched Analysis.

OBJECTIVE: Central cord syndrome (CCS) is a traumatic cervical spine injury that is treated with surgical decompression. In octogenarians (80-89), surgeons often opt for conservative management instead due to fears of postoperative complications and prolonged recovery times. This study aims to assess the in-hospital complications and outcomes in octogenarians undergoing surgery compared to those undergoing nonsurgical management for CCS. METHODS: The National Trauma Data Bank was queried from 2017 to 2019 for octogenarians with CCS. Patients who received surgical fusion or decompression were divided into the surgery group and the remaining into the nonsurgical group. The surgery group was sampled and propensity score matched with the non-surgery group. Student t tests and Pearson χ2 tests were used to test for group differences. RESULTS: A total of 759 octogenarians with CCS were identified. Following sampling and propensity score matching, 225 patients were identified in each group. The surgery group experienced longer intensive care unit (6.8 days vs. 3.21 days, P < 0.001) and hospital (13.79 days vs. 7.8 days, P < 0.001) lengths of stay and higher rates of deep vein thrombosis (4.89% vs. 0.44%, P = 0.02) and ventilator-associated pneumonia (4% vs. 0%, P = 0.02). Patients did not otherwise differ in mortality rate, other hospital complications, and discharge disposition. CONCLUSIONS: Octogenarians undergoing surgery for CCS experience longer length of stay and complications consistent with prolonged hospitalization but otherwise have similar mortality, hospital complications, and discharge disposition compared to non-surgical treatment. Given the relative lack of short-term drawbacks, surgery should be considered first-line management when the long-term benefits are substantive.

Racial disparities in incidence, treatment, and survival in adult brain metastases: a 10-year national database analysis.

OBJECTIVE: The aim of this study was to assess demographic and racial disparities in incidence, treatment, and survival of adults with metastatic malignancy to the brain. METHODS: Using the Surveillance, Epidemiology, and End Results (SEER) Program database, the authors identified adults with nonprimary brain metastases between 2010 and 2019. Incidence was calculated for all 10 years while data from 2010 to 2014 were used for survival analysis. The primary outcome measure was all-cause mortality within 5 years, assessed by 6-month, 1-year, 2-year, and 5-year survival rates. Chi-square tests of independence and one-way ANOVA were used to compare categorical and continuous measures, respectively, between non-Hispanic White (NHW), Hispanic White (HW), Black, and Asian/Pacific Islander (API) patients. A multivariable Cox proportional hazards model was developed to evaluate the risk of death within 5 years. RESULTS: A total of 64,690 patient records were identified and analyzed following exclusion based on age (patients > 84 years or < 18 years were excluded), missing race data, and missing survival data. Incidences are reported per 100,000 adults. The incidence of brain metastases increased from 2.59 in 2010 to 2.78 in 2019, with an average 10-year incidence of 2.72. API patients had the highest population-adjusted incidence (3.52), followed by NHW (2.99), Black (2.32), and HW (1.59) patients. Black patients were the most likely to have low income and single status, while API patients were the most likely to have high income and married status. Subsequently, Black patients had the shortest survival time (9.05 months vs 9.19 months for NHW vs 12.93 months for HW vs 15.89 months for API patients, p < 0.001). After controlling for the effect of socioeconomic factors on survival, the multivariable analysis showed that Black (HR 0.91, 95% CI 0.88-0.94), HW (HR 0.73, 95% CI 0.69-0.76), and API (HR 0.69, 95% CI 0.66-0.73) patients all had a survival advantage compared with NHW patients. Surgery also conferred a strong survival advantage (HR 0.47, 95% CI 0.44-0.49). CONCLUSIONS: The incidence of brain metastases has increased slightly between 2010 and 2019, with the highest rate in API patients. Black patients had the lowest survival, potentially due to poor socioeconomic status and lower rates of surgery and chemotherapy. Black patients were the most likely to not be recommended surgery, suggesting a discrepancy in services offered to these patients. More research is warranted to understand the underlying causes of these disparities.

Effect of perioperative anticoagulant prophylaxis in patients with traumatic subdural hematoma and a history of anticoagulant use: a propensity-matched National Trauma Data Bank analysis.

OBJECTIVE: The use of anticoagulation to prevent venous thromboembolism (VTE) is controversial in the setting of neurosurgical decompression for traumatic subdural hematoma (SDH). In these patients, there is concern that anticoagulation may cause secondary hemorrhage, increasing the risk of death and other complications. Patients with a history of anticoagulant use are at further risk of VTE, but the effect of VTE prophylaxis (VTEP) following neurosurgery for SDH has not been thoroughly investigated in this population. This study aims to investigate the differences in in-hospital outcomes in patients with SDH and preexisting anticoagulant use who received VTEP following neurosurgical intervention compared with those who did not. METHODS: The National Trauma Data Bank was queried from 2017 to 2019 for all patients with preexisting anticoagulant use presenting with an SDH who subsequently underwent neurosurgical intervention. Patients who received VTEP were propensity score matched with patients who did not based on demographics, insurance type, injury severity, and comorbidities. Paired Student t-tests, Pearson's chi-square tests, and Benjamini-Hochberg multiple comparisons correction were used to compare differences in in-hospital complications, length of stay (LOS), and mortality rate between the two groups. A logistic regression model was developed to identify risk factors for in-hospital mortality. RESULTS: Two thousand seven hundred ninety-four patients matching the inclusion criteria were identified, of whom 950 received VTEP. Following one-to-one matching and multiple comparisons correction, the VTEP group had a lower mortality rate (18.53% vs 34.53%, p < 0.001) but longer LOS (14.09 vs 8.57 days, p < 0.001) and higher rates of pressure ulcers (2.11% vs 0.53%, p = 0.01), unplanned intensive care unit admission (9.05% vs 3.47%, p < 0.001), and unplanned intubation (9.47% vs 6.11%, p = 0.021). The multivariable logistic regression showed that use of unfractionated heparin (UH; OR 0.36, p < 0.001) and low-molecular-weight heparin (LMWH; OR 0.3, p < 0.001) were associated with lower odds of in-hospital mortality. CONCLUSIONS: In patients with traumatic SDH and a history of anticoagulant use, perioperative VTEP was associated with increased LOS but provided a mortality benefit. LMWH and UH use were the strongest predictors of survival.

Characteristics of work-related spine injury in the USA: a National Trauma Data Bank analysis.

PURPOSE: Workplace injury is a commonplace occurrence in the USA. Spine injuries are especially devastating as they can cause chronic pain and limit mobility which prevents patients from returning to work. Gaining a better understanding of the patients, mechanisms, and treatments associated with these injuries can aid in improving outcomes. The purpose of this study is to characterize the nature of work-related spine injuries. METHODS: The National Trauma Data Bank was queried from 2017 to 2019 for all diagnoses involving the cervical, thoracic, lumbar, and sacral spine. Patient demographics, comorbidities, injury characteristics, spinal diagnoses, and procedures were identified for each occupation. Occupational industries, patient demographics, mechanisms of injury, diagnoses, and spinal procedures were characterized. RESULTS: A total of 100,842 work-related injuries were identified between 2017 and 2019. Of those, 19,002 (19%) were spine injuries, and subsequently, 3963 (21%) required spinal surgery. Eight thousand twenty-nine (42%) cases were seen among construction workers, which had the highest proportion of Hispanic patients (36%). Smoking was prevalent in labor-intensive occupations with high rates of spine injury such as building and grounds maintenance. The most common mechanism of injury was a fall from a roof. The most common injury diagnoses were L1, L2, and L3 fractures, and the most common procedures were T12-L1 fusion, multilevel thoracic fusion, and multilevel lumbar fusion. CONCLUSION: Spine injuries represent a significant portion of work-related injuries in the USA and a considerable portion require neurosurgical intervention. Initial efforts should focus on the prevention and management of lumbar spine injuries in the construction industry.

Transmandibular Cervical Corpectomy for Persistent Spinal Cord Compression in a Patient With Klippel-Feil Syndrome: A Technical Note and Systematic Review.

BACKGROUND: Few studies have described a transmandibular approach for decompression in a patient with Klippel-Feil syndrome (KFS) for cervical myelopathy. OBJECTIVE: To describe the transmandibular approach in a KFS patient with cervical myelopathy and to perform a systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. METHODS: A systematic review was performed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Embase and PubMed databases were searched from January 2002 to November 2022 for articles examining patients with KFS undergoing cervical decompression and/or fusion for cervical myelopathy and/or radiculopathy were included. Articles describing compression due to nonbony causes, lumbar/sacral surgery, nonhuman studies, or symptoms only from basilar invagination/impression were excluded. Data collected were sex, median age, Samartzis type, surgical approach, and postoperative complications. RESULTS: A total of 27 studies were included, with 80 total patients. Thirty-three patients were female, and the median age ranged from 9 to 75 years. Forty-nine patients, 16 patients, and 13 patients were classified as Samartzis Types I, II, and III, respectively. Forty-five patients, 21 patients, and 6 patients underwent an anterior, posterior, and combined approach, respectively. Five postoperative complications were reported. One article reported a transmandibular approach for access to the cervical spine. CONCLUSION: Patients with KFS are at risk of developing cervical myelopathy. Although KFS manifests heterogeneously and may be treated through a variety of approaches, some manifestations of KFS may preclude traditional approaches for decompression. Surgical exposure through the anterior mandible may prove an option for cervical decompression in patients with KFS.

Acute Subdural Hematoma Associated with Aneurysmal Rupture: A Case Series and Review of Literature.

BACKGROUND: Ruptured cerebral aneurysms represent a neurosurgical emergency with characteristic clinical presentation and imaging findings. However, atypical presentations may occur in association with acute subdural hematomas (SDHs). METHODS: A retrospective review was conducted at our institution between 2013 and 2021 to identify patients with aneurysmal rupture presenting with SDH. Cases were reviewed for clinical presentation, imaging findings, management, and outcome. RESULTS: A total of 8 patients were included in this review with an average age of 48.5 years. Six patients were women. The average Glasgow coma scale upon arrival was 6.3, and the Hunt-Hess average grade was 4.6. Aneurysm locations included posterior communicating artery (n = 3), anterior communicating artery (n = 2), middle cerebral artery (n = 2), and internal carotid artery terminus (n = 1). The size of aneurysm varied between 3 and 11 mm. Seven patients required surgical intervention, either craniotomy or craniectomy for hematoma evacuation, and aneurysms were treated by coiling (n = 2) or clipping (n = 6). CONCLUSIONS: Ruptured aneurysms may present with SDH with or without significant subarachnoid hemorrhage. This illustrative case series highlights this challenging presentation and the importance of early recognition and appropriate management.

Clinical and radiographic benefits of skipping C7 instrumentation in posterior cervicothoracic fusion: a retrospective analysis.

Background: C7 instrumentation during posterior cervicothoracic fusion can be challenging because it requires additional work of either placing side connectors to a single rod or placing two rods. Our clinical observations suggested that skipping instrumentation at C7 in a multi-level posterior cervicothoracic fusion will result in minimal intraoperative complications and decreased blood-loss while still maintaining sagittal balance parameters of cervical fusion. The objective of this study is to determine the clinical and radiographic outcomes of skipping C7 instrumentation compared to instrumenting the C7 vertebra in posterior cervicothoracic fusion. Methods: This is a retrospective chart review of 314 consecutive patients who underwent multilevel posterior cervical fusion (PCF) at our institution. Out of 314 patients, 19 were instrumented at C7 serving as the control group, while the remaining 295 patients were not. Evaluation of efficacy was based on intraoperative complications, operative time, estimated blood loss (EBL), significant long-term complications, and radiographic evidence of fusion. Results: Skipping the C7 level resulted in a significant reduction in EBL (488±576 vs. 822±1,137; P=0.007); however, operative time was similar between groups (174±95 vs. 184±86 minutes; P=0.844). Complications were minimal in both groups and not statistically significant. Radiographic analysis revealed C7 bridge patients had a significantly increased postoperative sagittal vertical axis (SVA) (29.3±13.1 vs. 20.2±3.1 mm; P=0.008); however, there was no significant difference between groups in SVA correction (-0.3±16.2 vs. -16.1±16.0 mm; P=0.867), T1 slope correction (3.4°±9.9° vs. 3.2°±5.5°; P=0.127), or cervical cobb angle correction (-5.7°±14.2° vs. -7.0°±12.2°; P=0.519). There were no significant long-term complications in either group. Conclusions: Skipping instrumentation at C7 in a multilevel posterior cervicothoracic fusion is associated with significantly reduced operative blood loss without loss of radiographic correction. This study demonstrates the clinical benefits of skipping C7 instrumentation in posterior cervicothoracic fusion with maintenance of radiographic correction parameters.

Severe High Cervical Cord Compression Due to Large Bilateral Neurofibromas in a Patient With Neurofibromatosis Type 1: A Case Report and Review of Literature.

Spinal neurofibromas are rare benign lesions associated with neurofibromatosis Type 1. They can often cause compression on nerve roots and the spinal cord. In this rare case, there are bilateral large neurofibromas with severe cord compression presenting as progressive myelopathy. We illustrate the surgical management as well as post-operative care along with a detailed literature review of similar cases. To our knowledge, this is the first report, in English literature, of spinal neurofibroma with large size, bilateral high cervical cord compression.

Safety and efficacy of balloon-mounted stent in the treatment of symptomatic intracranial atherosclerotic disease: a multicenter experience.

BACKGROUND: Randomized clinical trials have failed to prove that the safety and efficacy of endovascular treatment for symptomatic intracranial atherosclerotic disease (ICAD) is better than that of medical management. A recent study using a self-expandable stent showed acceptable lower rates of periprocedural complications. OBJECTIVE: To study the safety and efficacy of a balloon-mounted stent (BMS) in the treatment of symptomatic ICAD. METHODS: Prospectively maintained databases from 15 neuroendovascular centers between 2010 and 2020 were reviewed. Patients were included if they had severe symptomatic intracranial stenosis in the target artery, medical management had failed, and they underwent intracranial stenting with BMS after 24 hours of the qualifying event. The primary outcome was the occurrence of stroke and mortality within 72 hours after the procedure. Secondary outcomes were the occurrence of stroke, transient ischemic attacks (TIAs), and mortality on long-term follow-up. RESULTS: A total of 232 patients were eligible for the analysis (mean age 62.8 years, 34.1% female). The intracranial stenotic lesions were located in the anterior circulation in 135 (58.2%) cases. Recurrent stroke was the qualifying event in 165 (71.1%) while recurrent TIA was identified in 67 (28.9%) cases. The median (IQR) time from the qualifying event to stenting was 5 (2-20.75) days. Strokes were reported in 13 (5.6%) patients within 72 hours of the procedure; 9 (3.9%) ischemic and 4 (1.7%) hemorrhagic, and mortality in 2 (0.9%) cases. Among 189 patients with median follow-up time 6 (3-14.5) months, 12 (6.3%) had TIA and 7 (3.7%) had strokes. Three patients (1.6%) died from causes not related to stroke. CONCLUSION: Our study has shown that BMS may be a safe and effective treatment for medically refractory symptomatic ICAD. Additional prospective randomized clinical trials are warranted.

Risk Factors for Hyponatremia and Perioperative Complications With Malignant Intracranial Tumor Resection in Adults: An Analysis of the Nationwide Inpatient Sample from 2012 to 2015.

BACKGROUND: The present study aims to study the incidence and risk factors for developing hyponatremia and associated perioperative outcomes in adult patients admitted for malignant brain tumor resection. METHODS: The 2012-2015 Nationwide Inpatient Sample was queried for all patients undergoing surgical resection of malignant brain tumors. These patients were then grouped by the presence of concurrent diagnosis of hyponatremia, and compared with respect to various clinical features, perioperative and postoperative complications, all-cause mortality, discharge disposition, length of stay, and hospitalization costs. Propensity score matching was utilized to control for appropriate baseline confounders and the influence of other endpoint variables. RESULTS: The search criteria identified 12,480 adult patients admitted for malignant brain tumor resection, of whom 1162 (9.3%) developed hyponatremia in the perioperative period. Patients with obstructive hydrocephalus (risk ratio [RR] = 1.23, P < 0.001), diabetes (RR = 1.14, P = 0.014), hypertension (RR = 1.15, P < 0.001), and depression (RR = 1.24, P < 0.002) were more likely to develop hyponatremia. Tumor location was not associated with risk of developing hyponatremia. Patients with hyponatremia were more likely to require ventriculostomy (RR = 1.23, P < 0.001), ventriculoperitoneal shunt (RR = 1.34, P < 0.001), and lumbar puncture (RR = 1.25, P < 0.001), and were also more likely to be discharged to short-term hospital (RR = 1.25, P < 0.001) or rehabilitation (RR = 1.21, P < 0.001), as well as have longer hospital stay (P < 0.001) and increased hospital charges (P < 0.001). CONCLUSIONS: Patients with obstructive hydrocephalus, diabetes, hypertension, and depression were more likely to develop perioperative hyponatremia. Hyponatremia was associated with increased morbidity following malignant brain tumor resection.

Spatiotemporal transformations for gaze control.

Sensorimotor transformations require spatiotemporal coordination of signals, that is, through both time and space. For example, the gaze control system employs signals that are time-locked to various sensorimotor events, but the spatial content of these signals is difficult to assess during ordinary gaze shifts. In this review, we describe the various models and methods that have been devised to test this question, and their limitations. We then describe a new method that can (a) simultaneously test between all of these models during natural, head-unrestrained conditions, and (b) track the evolving spatial continuum from target (T) to future gaze coding (G, including errors) through time. We then summarize some applications of this technique, comparing spatiotemporal coding in the primate frontal eye field (FEF) and superior colliculus (SC). The results confirm that these areas preferentially encode eye-centered, effector-independent parameters, and show-for the first time in ordinary gaze shifts-a spatial transformation between visual and motor responses from T to G coding. We introduce a new set of spatial models (T-G continuum) that revealed task-dependent timing of this transformation: progressive during a memory delay between vision and action, and almost immediate without such a delay. We synthesize the results from our studies and supplement it with previous knowledge of anatomy and physiology to propose a conceptual model where cumulative transformation noise is realized as inaccuracies in gaze behavior. We conclude that the spatiotemporal transformation for gaze is both local (observed within and across neurons in a given area) and distributed (with common signals shared across remote but interconnected structures).

Intracranial Leiomyoma Associated with Epstein-Barr Virus: A Cerebellopontine Angle Mass Presenting with Trigeminal Neuralgia.

BACKGROUND: Primary intracranial leiomyoma is a rare smooth muscle tumor often associated with Epstein-Barr virus (EBV), with <30 cases reported worldwide. These tumors commonly occur in patients with immunocompromised status, especially those with human immunodeficiency virus. In the present report, we have described the case of an EBV-associated leiomyoma at the cerebellopontine angle. The patient had presented with trigeminal neuralgia, which, to the best of our knowledge, is the first reported anatomical location and presentation for this tumor type. CASE DESCRIPTION: A 41-year-old male patient had presented with right-sided facial pain in the V1 and V2 dermatomes and previous workup and imaging studies. The patient had undergone treatment of a presumed right-side cerebellopontine angle meningioma as determined by the magnetic resonance imaging characteristics (no biopsy). The patient subsequently underwent right-sided retrosigmoid craniotomy and gross total resection of the tumor. The postoperative period was uneventful with resolution of the trigeminal neuralgia. Histopathologic examination revealed spindle cell neoplasm with histopathologic and immunohistochemical features consistent with leiomyoma. The tumor cells were positive for smooth muscle actin and desmin and were negative for S100, SOX-10, epithelial membrane antigen, glial fibrillary acidic protein, progesterone receptor, CD31, CD34, and E-cadherin. CONCLUSIONS: Primary intracranial leiomyomas are rare tumors associated with EBV infection that occur in immunocompromised patients. These lesions should be considered in the differential diagnosis for patients with known immunocompromised status (e.g., human immunodeficiency virus), and tissue biopsy should be considered.

Timing Determines Tuning: A Rapid Spatial Transformation in Superior Colliculus Neurons during Reactive Gaze Shifts.

Gaze saccades, rapid shifts of the eyes and head toward a goal, have provided fundamental insights into the neural control of movement. For example, it has been shown that the superior colliculus (SC) transforms a visual target (T) code to future gaze (G) location commands after a memory delay. However, this transformation has not been observed in "reactive" saccades made directly to a stimulus, so its contribution to normal gaze behavior is unclear. Here, we tested this using a quantitative measure of the intermediate codes between T and G, based on variable errors in gaze endpoints. We demonstrate that a rapid spatial transformation occurs within the primate's SC (Macaca mulatta) during reactive saccades, involving a shift in coding from T, through intermediate codes, to G. This spatial shift progressed continuously both across and within cell populations [visual, visuomotor (VM), motor], rather than relaying discretely between populations with fixed spatial codes. These results suggest that the SC produces a rapid, noisy, and distributed transformation that contributes to variable errors in reactive gaze shifts.

The Influence of a Memory Delay on Spatial Coding in the Superior Colliculus: Is Visual Always Visual and Motor Always Motor?

The memory-delay saccade task is often used to separate visual and motor responses in oculomotor structures such as the superior colliculus (SC), with the assumption that these same responses would sum with a short delay during immediate "reactive" saccades to visual stimuli. However, it is also possible that additional signals (suppression, delay) alter visual and/or motor response in the memory delay task. Here, we compared the spatiotemporal properties of visual and motor responses of the same SC neurons recorded during both the reactive and memory-delay tasks in two head-unrestrained monkeys. Comparing tasks, visual (aligned with target onset) and motor (aligned on saccade onset) responses were highly correlated across neurons, but the peak response of visual neurons and peak motor responses (of both visuomotor (VM) and motor neurons) were significantly higher in the reactive task. Receptive field organization was generally similar in both tasks. Spatial coding (along a Target-Gaze (TG) continuum) was also similar, with the exception that pure motor cells showed a stronger tendency to code future gaze location in the memory delay task, suggesting a more complete transformation. These results suggest that the introduction of a trained memory delay alters both the vigor and spatial coding of SC visual and motor responses, likely due to a combination of saccade suppression signals and greater signal noise accumulation during the delay in the memory delay task.

Preoperative steroids do not improve outcomes for intramedullary spinal tumors: a NSQIP analysis of 30-day reoperation and readmission rates.

BACKGROUND: Intramedullary spinal cord tumors (IMSCTs) account for 8-10% of all spinal cord tumors and affect patients of all ages. Although uncommon, IMSCTs carry risk of neurological morbidity and mortality, with 5-year survival rates ranging from 50% to 80%. In this study, we utilize the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database to determine the effect of steroid administration on 30-day outcomes following surgery for IMSCTs. METHODS: ACS-NSQIP data for patients undergoing surgery for intramedullary tumors from 2005 to 2015 was reviewed. Patients were selected based on current procedural terminology (CPT) codes 63285 (Laminectomy, intradural, intramedullary, cervical), 63286 (Laminectomy, intradural, intramedullary, thoracic), and 63287 (Laminectomy, intradural, intramedullary, thoracolumbar). ICD-9 and ICD-10 codes were chosen based on the diagnosis of a tumor. The 30-day clinical outcome data, including reoperations and readmission rates, were collected and compared. RESULTS: A total of 259 patients were reviewed. One hundred eighty-one patients had benign intramedullary tumors and 78 had malignant intramedullary tumors. The majority of IMSCTs were at the thoracic level (n=100), followed by the cervical (n=99), and thoracolumbar (n=39) levels. Thirty-one patients were on corticosteroid therapy prior to surgery. Patients with preoperative steroid administration had no significant difference in reoperation and readmission rates. No significant differences were noted between steroid vs. non-steroid therapy for discharge destination, length of hospital stay, or other postoperative complications. CONCLUSIONS: Contrary to previous reports, corticosteroid use prior to surgery for IMSCTs does not have a significant impact on 30-day risk of readmission, reoperation, and risk of postoperative complications.

Transition from Target to Gaze Coding in Primate Frontal Eye Field during Memory Delay and Memory-Motor Transformation.

The frontal eye fields (FEFs) participate in both working memory and sensorimotor transformations for saccades, but their role in integrating these functions through time remains unclear. Here, we tracked FEF spatial codes through time using a novel analytic method applied to the classic memory-delay saccade task. Three-dimensional recordings of head-unrestrained gaze shifts were made in two monkeys trained to make gaze shifts toward briefly flashed targets after a variable delay (450-1500 ms). A preliminary analysis of visual and motor response fields in 74 FEF neurons eliminated most potential models for spatial coding at the neuron population level, as in our previous study (Sajad et al., 2015). We then focused on the spatiotemporal transition from an eye-centered target code (T; preferred in the visual response) to an eye-centered intended gaze position code (G; preferred in the movement response) during the memory delay interval. We treated neural population codes as a continuous spatiotemporal variable by dividing the space spanning T and G into intermediate T-G models and dividing the task into discrete steps through time. We found that FEF delay activity, especially in visuomovement cells, progressively transitions from T through intermediate T-G codes that approach, but do not reach, G. This was followed by a final discrete transition from these intermediate T-G delay codes to a "pure" G code in movement cells without delay activity. These results demonstrate that FEF activity undergoes a series of sensory-memory-motor transformations, including a dynamically evolving spatial memory signal and an imperfect memory-to-motor transformation.

Spatial transformations between superior colliculus visual and motor response fields during head-unrestrained gaze shifts.

We previously reported that visuomotor activity in the superior colliculus (SC)--a key midbrain structure for the generation of rapid eye movements--preferentially encodes target position relative to the eye (Te) during low-latency head-unrestrained gaze shifts (DeSouza et al., 2011). Here, we trained two monkeys to perform head-unrestrained gaze shifts after a variable post-stimulus delay (400-700 ms), to test whether temporally separated SC visual and motor responses show different spatial codes. Target positions, final gaze positions and various frames of reference (eye, head, and space) were dissociated through natural (untrained) trial-to-trial variations in behaviour. 3D eye and head orientations were recorded, and 2D response field data were fitted against multiple models by use of a statistical method reported previously (Keith et al., 2009). Of 60 neurons, 17 showed a visual response, 12 showed a motor response, and 31 showed both visual and motor responses. The combined visual response field population (n = 48) showed a significant preference for Te, which was also preferred in each visual subpopulation. In contrast, the motor response field population (n = 43) showed a preference for final (relative to initial) gaze position models, and the Te model was statistically eliminated in the motor-only population. There was also a significant shift of coding from the visual to motor response within visuomotor neurons. These data confirm that SC response fields are gaze-centred, and show a target-to-gaze transformation between visual and motor responses. Thus, visuomotor transformations can occur between, and even within, neurons within a single frame of reference and brain structure.

Visual-Motor Transformations Within Frontal Eye Fields During Head-Unrestrained Gaze Shifts in the Monkey.

A fundamental question in sensorimotor control concerns the transformation of spatial signals from the retina into eye and head motor commands required for accurate gaze shifts. Here, we investigated these transformations by identifying the spatial codes embedded in visually evoked and movement-related responses in the frontal eye fields (FEFs) during head-unrestrained gaze shifts. Monkeys made delayed gaze shifts to the remembered location of briefly presented visual stimuli, with delay serving to dissociate visual and movement responses. A statistical analysis of nonparametric model fits to response field data from 57 neurons (38 with visual and 49 with movement activities) eliminated most effector-specific, head-fixed, and space-fixed models, but confirmed the dominance of eye-centered codes observed in head-restrained studies. More importantly, the visual response encoded target location, whereas the movement response mainly encoded the final position of the imminent gaze shift (including gaze errors). This spatiotemporal distinction between target and gaze coding was present not only at the population level, but even at the single-cell level. We propose that an imperfect visual-motor transformation occurs during the brief memory interval between perception and action, and further transformations from the FEF's eye-centered gaze motor code to effector-specific codes in motor frames occur downstream in the subcortical areas.