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BACKGROUND Uterine leiomyosarcoma is a rare, extremely aggressive tumor with a high rate of metastasis. Five-year survival for individuals with metastatic disease is only 10%–15%. Metastases to the brain are exceptionally rare and are associated with poor survival. OBSERVATIONS The authors report a case of uterine leiomyosarcoma that metastasized to the brain in a 51-year-old woman. A single lesion on magnetic resonance imaging was discovered in the right posterior temporo-occipital region 44 months after resection of the primary uterine tumor. The patient underwent a right occipital craniotomy with gross-total resection of the tumor and is receiving adjuvant stereotactic radiosurgery and chemotherapy with gemcitabine and docetaxel. At 8 months postresection, the patient remains alive and asymptomatic with no sign of recurrence. A literature review of prior reported cases was conducted to analyze patterns of approach to patient treatment and survival. LESSONS The authors found an apparent survival benefit in patients receiving adjuvant radiation therapy.

OBJECTIVE The aim of this study was to investigate cerebral reorganization, both structurally and functionally, occurring in patients with degenerative cervical myelopathy (DCM) after surgical decompression. METHODS In the current observational study of 19 patients, high-resolution T1-weighted structural MRI and resting-state functional MRI scans were obtained pre- and postoperatively in patients with DCM and healthy controls (HCs). The resting-state functional MRI data were utilized to perform region-of-interest (ROI)–to-ROI and ROI-to-voxel functional connectivity (FC) analysis and were similarly compared between and within cohorts. Macroscopic structural plasticity was evaluated by assessing for changes in cortical thickness within the DCM cohort after decompression surgery. RESULTS Prior to surgery, FC patterns were significantly different between DCM patients and HCs in cerebral areas responsible for postural control, motor regulation, and perception and integration of sensory information. Significantly stronger FC between the cerebellum and frontal lobes was identified in DCM patients postoperatively compared with DCM patients preoperatively. Additionally, increased FC between the cerebellum and primary sensorimotor areas was found to be positively associated with neurological improvement in patients with DCM. No macroscopic structural changes were observed in the DCM patients after surgery. CONCLUSIONS These results support the authors’ hypothesis that functional changes within the brain are associated with effective postoperative recovery, particularly in regions associated with motor regulation and with perception and integration of sensory information. In particular, increased FC between the cerebellum and the primary sensorimotor after surgery appears to be associated with neurological improvement. Macroscopic morphological changes may be too subtle to be detected within 3 months after surgery.

OBJECTIVESumatriptan, a serotonin receptor agonist, has been used in the management of primary headache disorders and has been shown to affect trigeminal dural afferents. There is limited literature on the safety and efficacy of sumatriptan for postcraniotomy pain management. This study aimed to identify whether subcutaneous sumatriptan is a safe and efficacious pain management strategy after elective craniotomy.METHODSThe authors retrospectively reviewed patients who underwent supratentorial or suboccipital craniotomy between 2016 and 2019 that was performed by a single provider at a single institution to identify patients given subcutaneous sumatriptan in the postoperative period. Pain scores and intravenous and oral opioid use were compared in patients with (n = 15) and without (n = 45) sumatriptan administration.RESULTSPatients with and without sumatriptan administration had no significant differences in baseline characteristics or surgery type. There were no sumatriptan-related complications. The average pain score decreased from 3.9 to 1.3 within 1 hour after sumatriptan administration (p = 0.014). In both adult and pediatric patients there was decreased postoperative pain (adults: pain score of 1.1 vs 7.1, p < 0.001; pediatric: 1.1 vs 3.9, p = 0.007) within the first 48 hours. There were decreases in intravenous opioid use, length of intravenous opioid use, maximum dose of intravenous opioid used, oral opioid use, length of oral opioid use, and maximum dose of oral opioid used in both adult and pediatric patients.CONCLUSIONSThe authors identified subcutaneous sumatriptan as a safe and efficacious tool for postoperative pain management after craniotomy. Large multicenter randomized controlled studies are needed to further evaluate the specific role of sumatriptan in postoperative pain management after craniotomy.

BackgroundBest practice guidelines for treating lumbar stenosis include a multidisciplinary approach, ranging from conservative management with physical therapy, medication, and epidural steroid injections to surgical decompression with or without instrumentation. Marketed as an outpatient alternative to a traditional lumbar decompression, interspinous process devices (IPDs) have gained popularity as a minimally invasive stabilization procedure. IPDs have been embraced by non-surgical providers, including physiatrists and anesthesia interventional pain specialists. In the interest of patient safety, it is imperative to formally profile its safety and identify its role in the treatment paradigm for lumbar stenosis.Case DescriptionWe carried out a retrospective review at our institution of neurosurgical consultations for patients with hardware complications following the interspinous device placement procedure. Eight cases within a 3-year period were identified, and patient characteristics and management are illustrated. The series describes the migration of hardware, spinous process fracture, and worsening post-procedural back pain.ConclusionsIPD placement carries procedural risk and requires a careful pre-operative evaluation of patient imaging and surgical candidacy. We recommend neurosurgical consultation and supervision for higher-risk IPD cases.

Degenerative cervical myelopathy (DCM) is the most common cause of spinal cord impairment in adults. Previous supraspinal investigations have primarily focused on cortical changes in this patient population. As the nexus between the brain and the spinal cord, the brainstem has been understudied in patients with DCM. The current study examined the structural and functional connectivity between the brainstem and cortex in DCM patients using probabilistic tractography and resting-state functional MRI. A total of 26 study patients and 32 neurologically intact, healthy volunteers (HCs) participated in this prospective analysis. The study cohort included DCM patients (n=18), as well as neurologically asymptomatic patients with evidence of cervical spine degenerative changes and spinal cord compression (n=8). Results of the study demonstrated significant differences in fiber density (FD), fiber cross-section (FDC), and the functional connectivity (FC) between the study cohort and HCs. Through seeding the brainstem, the study cohort showed reductions in FD and FDC along the corticospinal tract, including regions extending through the corona radiata and internal capsule. By correlating FD and FDC with the Neck Disability Index (NDI), and the modified Japanese Orthopaedic Association (mJOA), we identified increasing total volume of projections to the thalamus, basal ganglia, and internal capsule, and increased functional connectivity to visual network and the posterior parietal cortices. These results support our hypothesis that DCM patients tend to have long-term FC reorganization not only localized to sensorimotor regions, but also to regulatory and visual processing regions, designed to ultimately preserve neurological function.

Background The referral process for consultation with a spine surgeon remains inefficient, given a substantial proportion of referrals to spine surgeons are nonoperative. Objective To develop a machine-learning-based algorithm which accurately identifies patients as candidates for consultation with a spine surgeon, using only magnetic resonance imaging (MRI). Methods We trained a deep U-Net machine learning model to delineate spinal canals on axial slices of 100 normal lumbar MRI scans which were previously delineated by expert radiologists and neurosurgeons. We then tested the model against lumbar MRI scans for 140 patients who had undergone lumbar spine MRI at our institution (60 of whom ultimately underwent surgery, and 80 of whom did not). The model generated automated segmentations of the lumbar spinal canals and calculated a maximum degree of spinal stenosis for each patient, which served as our biomarker for surgical pathology warranting expert consultation. Results The machine learning model correctly predicted surgical candidacy (ie, whether patients ultimately underwent lumbar spinal decompression) with high accuracy (area under the curve = 0.88), using only imaging data from lumbar MRI scans. Conclusion Automated interpretation of lumbar MRI scans was sufficient to correctly determine surgical candidacy in nearly 90% of cases. Given that a significant proportion of referrals placed for spine surgery evaluation fail to meet criteria for surgical intervention, our model could serve as a valuable tool for patient triage and thereby address some of the inefficiencies within the outpatient surgical referral process.

Manual delineation of anatomy on existing images is the basis of developing deep learning algorithms for medical image segmentation. However, manual segmentation is tedious. It is also expensive because clinician effort is necessary to ensure correctness of delineation. Consequently most algorithm development is based on a tiny fraction of the vast amount of imaging data collected at a medical center. Thus, selection of a subset of images from hospital databases for manual delineation - so that algorithms trained on such data are accurate and tolerant to variation, becomes an important challenge. We address this challenge using a novel algorithm. The proposed algorithm named 'Eigenrank by Committee' (EBC) first computes the degree of disagreement between segmentations generated by each DL model in a committee. Then, it iteratively adds to the committee, a DL model trained on cases where the disagreement is maximal. The disagreement between segmentations is quantified by the maximum eigenvalue of a Dice coefficient disagreement matrix a measure closely related to the Von Neumann entropy. We use EBC for selecting data subsets for manual labeling from a larger database of spinal canal segmentations as well as intervertebral disk segmentations. U-Nets trained on these subsets are used to generate segmentations on the remaining data. Similar sized data subsets are also randomly sampled from the respective databases, and U-Nets are trained on these random subsets as well. We found that U-Nets trained using data subsets selected by EBC, generate segmentations with higher average Dice coefficients on the rest of the database than U-Nets trained using random sampling (p 0.05 using t-tests comparing averages). Furthermore, U-Nets trained using data subsets selected by EBC generate segmentations with a distribution of Dice coefficients that demonstrate significantly (p 0.05 using Bartlett's test) lower variance in comparison to U-Nets trained using random sampling for all datasets. We believe that this lower variance indicates that U-Nets trained with EBC are more robust than U-Nets trained with random sampling.

Cerebral acidosis is a consequence of secondary injury mechanisms following traumatic brain injury (TBI), including excitotoxicity and ischemia, with potentially significant clinical implications. However, there remains an unmet clinical need for technology for non-invasive, high resolution pH imaging of human TBI for studying metabolic changes following injury. The current study examined 17 patients with TBI and 20 healthy controls using amine chemical exchange saturation transfer echoplanar imaging (CEST EPI), a novel pH-weighted molecular MR imaging technique, on a clinical 3T MR scanner. Results showed significantly elevated pH-weighted image contrast (MTRasym at 3 ppm) in areas of T2 hyperintensity or edema (P, Highlights • Cerebral acidosis is a consequence of traumatic brain injury (TBI) with significant clinical implications. • Amine CEST EPI is a novel pH-weighted molecular MR imaging technique for clinical 3T MR scanners. • Results showed significantly elevated pH-weighted image contrast (MTRasym at 3 ppm) in T2 hyperintense lesions. • This pH-weighted MR contrast correlated with Glasgow Coma Scale (GCS), 6 month clinical outcome, and time from initial injury to MRI exam.

Objective: To evaluate the hypothesis that circulating pro and antiangiogenic profiles predict the degree of angiographic neovascularization in patients undergoing EDAS for the treatment of symptomatic ICAS. Methods: This is a prospective observational study of circulating angiogenic factors in patients with arterial stenosis greater than 70% due to ICAS. All patients received intensive medical management. Patients with persistent symptoms underwent in addition EDAS revascularization. Twenty-one angiogenic factors were analyzed in serum samples collected at baseline, before surgery, using multiplex ELISA. All samples were run in duplicate and accepted as valid if the intersample variability was less than 20%. Patients have angiographic follow up 6 months after EDAS and a Neovascularization Index (NI) based on Perren grades and ASITN collaterals were calculated. Angiogenic profiles (APs) were defined using Principal Component Analysis (PCA). Seven profiles were selected for each time-point (Eigenvalue greater than 1.0). A regression model was built for the outcome variable NI using as predictor variables age, smoking history diabetes, and the 7 APs. Forward stepwise modeling with minimum BIC stopping rule was used to select the best fitted model. Results: Fifteen patients were enrolled. Mean age was 62.1 ± 12.3, 75% were females. The regression model demonstrated significant associations of age, diabetes and the AP 1-6 with the NI. Whole model P=0.023, Rsquare=0.93. The solution of the regression formula for the significant AP components revealed a strong negative association of the antiangiogenic factors endostatin and angiostatin (regression parameters -1.8 and -4.5, respectively, p=0.02). At 6 months follow up no patients had suffer strokes. Conclusion: In this prospective study of angiogenic factors in patients with ICAS undergoing EDAS revascularization, we have found that baseline levels of the antiangiogenic factors endostatin and angiostatin are significantly negatively associated to the degree of postoperative revascularization at 6 months. This finding supports the concept that neutralization of antiangiogenic factors may serve as a new pharmacological target to treat cerebral ischemia in patients with ICAS.

Objective: VEGFA isoforms 165a and 165b are pro and antiangiogenic, respectively. We aimed to evaluate the effects of IMM and EDAS in the VEGFA165a/b ratio in patients with ICAS. Methods: This is a prospective observational study of VEGFA165a and b in patients with stenosis greater than 70% due to ICAS. All patients received IMM. Patients with persistent symptoms underwent EDAS while maintaining IMM. Serum samples were collected at baseline, 1 week, 1, 3, and 6 months. VEGFA isoforms were quantified using multiplex sandwich ELISA. All samples were run in duplicate and accepted as valid if the intersample variability was less than 20%. A mixed model was built for the outcome variable VEGFA165a/b ratio using the predictor variables timepoint, treatment, and the interaction of time and treatment. The restricted maximum likelihood method was used to fit the model with random effects to account for the repeated measurements and intersubject variability. Results: A total of 72 patients were enrolled, of which 58 had IMM alone and 14 had EDAS. Mean age was 61.8 ± 12.3, 53% were females. The regression model demonstrated that there were no significant differences in the VEGFA165a/b ratio at baseline and 1 month after enrollment. Significant differences in VEGFA165a/b ratio were found at one week with higher levels in the surgical group (EDAS: 0.46 ± 0.22, IMM: 0.24 ± 0.07, p=0.03) and at 3 and 6 months with higher levels in the IMM group (3m: EDAS: 0.29 ± 0.14, IMM: 0.45 ± 0.20, p=0.03, 6m: EDAS:0.19 ± 0.11, IMM 0.37 ± 0.19 p=0.01). Conclusion: While the surgical event may well explain the early elevation of the VEGFA165a/b ratio one week after surgery, the elevation of a proangiogenic profile by the 3rd and 6th month in the IMM group is relevant. None of the patients in the IMM or EDAS groups had strokes at the last 6 months follow-up, and the peak (early for EDAS and at 3 and 6 months for IMM) of the VEGFA165a/b ratio may indicate a protective effect, averting stroke.

Objective: To evaluate the levels of circulating angiogenic factors in patients with moyamoya disease (MMD), intracranial atherosclerosis (ICAS), and controls, and the effects of EDAS in their levels. Methods: Prospective longitudinal study of angiogenic factors in 22 patients with MMD, ICAS, and controls. Patients with MMD and ICAS underwent EDAS surgery. Control cases had cranial surgery for non-vascular or tumor pathology. Angiogenic factors were measured at baseline and 7 days after surgery. Log-corrected levels were compared between groups. Multivariate analysis of variance (MANOVA) was used to examine differences within pairs and between groups. Regression mixed models were built to account for intrasubject correlation and evaluate the association of angiogenic levels with group and treatment. Results: Mean age was 41 ± 11 in MMD, 65 ± 16 in ICAS, and 51 ± 19 in controls. There were 83% females in the MMD group, 44% in ICAS, and 43% in controls. Patients with MMD had significantly higher levels of PDGFAA (568.8 pg/ml), vs ICAS (165.9pg/mL), and controls (38.4 pg/mL) p=0.007; PDGFBB (1449.7 pg/mL), vs. ICAS (141.2 pg/mL), and controls (65.2 pg/mL) p=0.03; TGFB1 (24.5 ng/mL), vs. ICAS (13.8 ng/mL), and controls (6.2 ng/mL) p=0.006; TSP1 (128.5 ng/mL), vs. ICAS (91.7 ng/mL), and controls (9 ng/mL) p=0.0007. After surgery (EDAS for MMD and ICAS vs. cranial surgery for controls) levels of PDGFAA, PDGFBB, and TGFB1 increased on the ICAS and control groups eliminating the baseline differences. EDAS, independently from etiology, affected the levels of pro-angiogenic TGFB2 (EDAS: 290 pg/mL, controls: 161 pg/mL), and BMP2 (EDAS: 153 pg/mL, controls: 109 pg/mL) p Conclusion: Patients with MMD have baseline higher levels of pro-angiogenic factors PDGFAA, PDGFBB, and TGFB1, involved in vessel maturation. EDAS, independent from etiology, affected the levels of TGFB2, BMP2 and TSP2, cytokines involved in vessel maturation, increased vascular permeability, and modulation of cell migration, respectively.

Objective: In order to study the mechanisms associated with neovascularization after indirect bypass (EDAS), we have developed a mice model of synangiosis and cerebral ischemia. Method: Healthy 12-24 week old male C57/BL6J mice were used. The temporalis muscle served as donor for the external carotid artery vessels through a window in the temporalis bone. The distal MCA was ligated after opening the dura. The temporalis muscle was reattached in direct apposition to the ischemic brain surface. Animals were sacrificed at one month and their heads were prepared in block. Brain slices were stained with CD31 (endothelial cell marker), Ki67 (proliferation maker), and DAPI (nuclear marker) antibodies. Confocal laser microscopy was used for immunofluorescent imaging. Standardized relative quantification of immunofluorescence staining was performed using ImageJ following the Arqués protocol. Inferential comparisons among groups were performed with a generalized linear model. Data was nested in the model by animal to account for intrasubject correlation. Results: A total of 12 mice were operated. One subject died after surgery (attrition rate 8%). All other subjects displayed no deficits. The number of DAPI+ cells/image was no different between the synangiosis and the control side. The index CD31/DAPI was significantly higher in the synangiosis side (mean 0.90 ± 1.13 vs. controls: 0.60 ± 0.65, p Conclusions: Our model of synangiosis in mice was well tolerated and produced quantifiable neovascularization in the brain as indicated by the neovascularization indexes observed in confocal microscopy. This model of synangiosis is a promising tool for future studies of neovascularization and collateral formation in individuals with ischemia.

Introduction: Recent work in cancer biology has identified splice variants of human VEGF-A that inhibit angiogenesis. These isoforms arise from differential splicing of exon 8: a proangiogenic VEGF-A165a and the antiangiogenic VEGF-A165b. The purpose of this study was to compare circulating VEGF-A165a / VEGF-A165b ratios in patients with ICAS to those of patients with moyamoya and controls with no vascular or tumoral disease. Identifying a potential target to facilitate the generation of spontaneous collaterals could open novel treatment avenues for ICAS patients. Methods: This is a prospective observational study of circulating VEGF-A165a and VEGF-A165b. Serum samples were collected at baseline, 1 week, 1 month, 3 months, and 6 months after enrollment. Levels of VEGFA-165a and VEGFA-165b were determined by a multiplex sandwich ELISA. All samples were run in duplicate with an acceptance threshold for intersample variability of less than 20%. A mixed model regression model was built to predict square root transformed VEGF-A165a / VEGF-A165b ratio using age and etiology as the predictor variables. A repeated autoregressive 1 structure was used to account for repeated measures and subject random effects were used to account for intersubject variability. Results: The study population consisted of 72 individuals with ICAS (age = 61.7±12.0), 8 with moyamoya (age = 42.7±12.6), and 7 controls (age = 44.3±13.9). A total of 230 samples were collected (ICAS: 188, moyamoya: 21, control: 21). One outlier was excluded due to an exorbitantly high VEGFA-165a concentration. VEGFA-165a/VEGFA-165b ratios were as follows for each etiology: ICAS (0.15±0.17), moyamoya (0.38±0.52), and control (0.10±0.12). Mixed model regression analysis found a significant independent positive association of moyamoya to elevated VEGF-A165a/ VEGF-A165b ratio (p=0.03). Conclusion: In this prospective analysis of VEGF-A165a/ VEGF-A165b ratio, moyamoya patients had elevated ratios compared to ICAS and controls. This finding supports the concept that VEGF-A165b could serve as a new pharmacological target to treat cerebral ischemia in patients with ICAS as its neutralization may augment the activities of proangiogenic growth factors in developing collaterals.

Encephaloduroarteriosynangiosis has been shown to generate collateral vessels from the extracranial-to-intracranial circulation in patients with Moyamoya disease and intracranial arterial steno-occlusive disease. The mechanisms involved are not well-understood. We hypothesized that angiogenesis is the leading mechanism forming collaterals after encephaloduroarteriosynangiosis because there are no pre-existing connections. Angiogenesis-generated collaterals should exhibit higher architectural complexity compared with innate collaterals.Pre- and postoperative digital subtraction angiograms were analyzed in patients enrolled in a prospective trial of encephaloduroarteriosynangiosis surgery. Branching angioscore, tortuosity index, and local connected fractal dimension were compared between innate and postoperative collaterals.One hundred one angiograms (50 preoperative, 51 postoperative) were analyzed from 44 patients (22 with intracranial atherosclerosis and 22 with Moyamoya disease). There was a significantly higher median branching angioscore (13 versus 4, P.001) and a lower median tortuosity index (1.08 versus 1.76, P.001) in the encephaloduroarteriosynangiosis collaterals compared with innate collaterals. Higher mean local fractal dimension peaks (1.28 ± 0.1 versus 1.16 ± 0.11, P.001) were observed in the encephaloduroarteriosynangiosis collaterals compared with innate collaterals for both intracranial atherosclerosis (P.001) and Moyamoya disease (P.001) groups. The observed increase in high connectivity was greater in the intracranial atherosclerosis group compared with patients with Moyamoya disease (P = .01).The higher median branching angioscore and local connected fractal dimension, along with the lower median tortuosity index of encephaloduroarteriosynangiosis collaterals, are consistent with the greater complexity observed in the process of sprouting and splitting associated with angiogenesis.

Remote ischemic conditioning (RIC) is a powerful innate response to transient subcritical ischemia that protects against severe ischemic insults at distant sites. We have previously shown the safety and feasibility of limb RIC in aneurysmal subarachnoid hemorrhage (aSAH) patients, along with changes in neurovascular and cerebral metabolism. In this study, we aim to detect the potential effect of an established lower-limb conditioning protocol on clinical outcomes of aSAH patients. Neurologic outcome (modified Rankin Scale (mRS)) of patients enrolled in a prospective trial (RIPC-SAH) was measured. A matching algorithm was applied to identify control patients with aSAH from an institutional departmental database. RIC patients underwent four lower-limb conditioning sessions, consisting of four 5-min cycles per session over nonconsecutive days. Good functional outcome was defined as mRS of 0 to 2. The study population consisted of 21 RIC patients and 61 matched controls. There was no significant intergroup difference in age, gender, aneurysm location, clipping vs coiling, Fisher grades, Hunt and Hess grades, or vasospasm. RIC was independently associated with good outcome (OR 5.17; 95% confidence interval (CI) 1.21-25.02). RIC also showed a trend toward lower incidence of stroke (28.6 vs. 47.5%) and death (4.8 vs. 19.7%). Lower-limb RIC following aSAH appears to have a positive effect in the functional outcomes of patients with aSAH. While this effect is consistent with prior preclinical studies, future trials are necessary to conclusively evaluate the effects of RIC for aSAH.

Objectives Reducing variability is integral in quality management. As part of the ongoing Encephaloduroarteriosynangiosis Revascularisation for Symptomatic Intracranial Arterial Stenosis (ERSIAS) trial, we developed a strict anaesthesia protocol to minimise fluctuations in patient parameters affecting cerebral perfusion. We hypothesise that this protocol reduces the intraoperative variability of targeted monitored parameters compared to standard management. Design Prospective cohort study of patients undergoing encephaloduroarteriosynangiosis surgery versus standard neurovascular interventions. Patients with ERSIAS had strict perioperative management that included normocapnia and intentional hypertension. Control patients received regular anaesthetic standard of care. Minute-by-minute intraoperative vitals were electronically collected. Heterogeneity of variance tests were used to compare variance across groups. Mixed-model regression analysis was performed to establish the effects of treatment group on the monitored parameters. Setting Tertiary care centre. Participants 24 participants: 12 cases (53.8 years±16.7 years; 10 females) and 12 controls (51.3 years±15.2 years; 10 females). Adults aged 30–80 years, with transient ischaemic attack or non-disabling stroke (modified Rankin Scale

BACKGROUND: Double-injection models of subarachnoid hemorrhage (SAH) in rats are the most effective in producing vasospasm, delayed neurological deficits and infarctions. However, they require two large surgeries to expose the femoral artery and the atlanto-occipital membrane. We have developed a minimally-invasive modification that prevents confounding effects of surgical procedures, leakage of blood from the subarachnoid space and minimizes risk of infection. METHODS: Rats are anesthetized and the ventral tail artery is exposed through a small (5 mm), midline incision, 0.2 mL of blood is taken from the artery and gentle pressure is applied for hemostasis. The rat is flipped prone, and with the head flexed to 90 degrees in a stereotactic frame, a 27G angiocath is advanced in a vertical trajectory, level with the external auditory canals. Upon puncturing the atlanto-occipital membrane, the needle is slowly advanced and observed for cerebrospinal fluid (CSF). A syringe withdraws 0.1 mL of CSF and the blood is injected into the subarachnoid space. The procedure is repeated 24 hours later by re-opening the tail incision. At 8 days, the rats are euthanized and their brains harvested, sectioned, and incubated with triphenyltetrazolium chloride (TTC). RESULTS: Rats develop neurological deficits consistent with vasospasm and infarction as previously described in double-injection models. Cortical and deep infarctions were demonstrated by TTC staining and on histopathology. CONCLUSIONS: A minimally invasive, double-injection rat model of SAH and vasospasm is feasible and produces neurological deficits and infarction. This model can be used to study neuroprotective treatments for vasospasm and delayed neurological deficits following SAH, reducing the confounding effects of surgical interventions.

BACKGROUND AND PURPOSE: Indirect cerebral revascularization has been successfully used for treatment in Moyamoya disease and symptomatic intracranial atherosclerosis. While angiographic neovascularization has been demonstrated after surgery, measurements of local tissue perfusion are scarce and may not reflect the reported successful clinical outcomes. We investigated probabilistic independent component analysis and conventional perfusion parameters from DSC-MR imaging to measure postsurgical changes in tissue perfusion. MATERIALS AND METHODS: In this prospective study, 13 patients underwent unilateral indirect cerebral revascularization and DSC-MR imaging before and after surgery. Conventional perfusion parameters (relative cerebral blood volume, relative cerebral blood flow, and TTP) and probabilistic independent components that reflect the relative contributions of DSC signals consistent with arterial, capillary, and venous hemodynamics were calculated and examined for significant changes after surgery. Results were compared with postsurgical DSA studies to determine whether changes in tissue perfusion were due to postsurgical neovascularization. RESULTS: Before surgery, tissue within the affected hemisphere demonstrated a high probability for hemodynamics consistent with venous flow and a low probability for hemodynamics consistent with arterial flow, whereas the contralateral control hemisphere demonstrated the reverse. Consistent with symptomatic improvement, the probability for venous hemodynamics within the affected hemisphere decreased with time after surgery (P = .002). No other perfusion parameters demonstrated this association. Postsurgical DSA revealed an association between an increased preoperative venous probability in the symptomatic hemisphere and neovascularization after surgery. CONCLUSIONS: Probabilistic independent component analysis yielded sensitive measurements of changes in local tissue perfusion that may be associated with newly formed vasculature after indirect cerebral revascularization surgery.