Toward Objective Quantification of Perfusion-weighted Computed Tomography in Subarachnoid Hemorrhage: Quantification of Symmetry and Automated Delineation of Vascular Territories

Rationale and Objectives: Perfusion-weighted computed tomography (CTP) is a relatively recent innovation that estimates a value for cerebral blood flow (CBF) using a series of axial head CT images tracking the time course of a signal from an intravenous contrast bolus. Materials and Methods: CTP images were obtained using a standard imaging protocol and were analyzed using commercially available software. A novel computer-based method was used for objective quantification of side-to-side asymmetries of CBF values calculated from CTP images. Results: Our method corrects for the inherent variability of the CTP methodology seen in the subarachnoid hemorrhage (SAH) patient population to potentially aid in the diagnosis of cerebral vasospasm (CVS). This method analyzes and quantifies side-to-side asymmetry of CBF and presents relative differences in a construct termed a Relative Difference Map (RDM). To further automate this process, we have developed a unique methodology that enables a computer to delineate vascular territories within a brain image, regardless of the size and shape of the brain. Conclusions: While both the quantification of image symmetry using RDMs and the automated assignment of vascular territories were initially designed for the analysis of CTP images, it is likely that they will be useful in a variety of applications

Intravenous Fluid Administration May Improve Post-Operative Course of Patients with Chronic Subdural Hematoma: A Retrospective Study

Background: The treatment of chronic subdural hematoma (cSDH) is still charged of significant risk of hematoma recurrence. Patient-related predictors and the surgical procedures themselves have been addressed in many studies. In contrast, postoperative management has infrequently been subjected to detailed analysis. Moreover variable intravenous fluid administration (IFA) was not reported in literature till now in the context of cSDH treatment. Methodology/Principal Findings: A total of 45 patients with cSDH were operated in our department via two burr hole craniostomy within one calendar year. Downward drainage was routinely left in hematoma cavity for a one day. Independent variables selected for the analysis were related to various aspects of patient management, including IFA. Two dependent variables were chosen as measure of clinical course: the rate of hematoma recurrence (RHR) and neurological status at discharge from hospital expressed in points of Glasgow Outcome Scale (GOS). Univariate and multivariate regression analyses were performed. Hematoma recurrence with subsequent evacuation occurred in 7 (15%) patients. Univariate regression analysis revealed that length of IFA after surgery influenced both dependent variables: RHR (p = 0.045) and GOS (p = 0.023). Multivariate regression performed by backward elimination method confirmed that IFA is a sole independent factor influencing RHR. Post hoc dichotomous division of patients revealed that those receiving at least 2000 ml/day over 3 day period revealed lower RHR than the group with less intensive IFA. (p = 0.031)

Electrical Stimulation to Conductive Scaffold Promotes Axonal Regeneration and Remyelination in a Rat Model of Large Nerve Defect

BACKGROUND: Electrical stimulation (ES) has been shown to promote nerve regeneration when it was applied to the proximal nerve stump. However, the possible beneficial effect of establishing a local electrical environment between a large nerve defect on nerve regeneration has not been reported in previous studies. The present study attempted to establish a local electrical environment between a large nerve defect, and examined its effect on nerve regeneration and functional recovery. METHODOLOGY/FINDINGS: In the present study, a conductive scaffold was constructed and used to bridge a 15 mm sciatic nerve defect in rats, and intermittent ES (3 V, 20 Hz) was applied to the conductive scaffold to establish an electrical environment at the site of nerve defect. Nerve regeneration and functional recovery were examined after nerve injury repair and ES. We found that axonal regeneration and remyelination of the regenerated axons were significantly enhanced by ES which was applied to conductive scaffold. In addition, both motor and sensory functional recovery was significantly improved and muscle atrophy was partially reversed by ES localized at the conductive scaffold. Further investigations showed that the expression of S-100, BDNF (brain-derived neurotrophic factor), P0 and Par-3 was significantly up-regulated by ES at the conductive scaffold. CONCLUSIONS/SIGNIFICANCE: Establishing an electrical environment with ES localized at the conductive scaffold is capable of accelerating nerve regeneration and promoting functional recovery in a 15 mm nerve defect in rats. The findings provide new directions for exploring regenerative approaches to achieve better functional recovery in the treatment of large nerve defect

Cervical spondylosis with spinal cord encroachment: should preventive surgery be recommended?

<p>Abstract</p> <p>Background</p> <p>It has been stated that individuals who have spondylotic encroachment on the cervical spinal cord without myelopathy are at increased risk of spinal cord injury if they experience minor trauma. Preventive decompression surgery has been recommended for these individuals. The purpose of this paper is to provide the non-surgical spine specialist with information upon which to base advice to patients. The evidence behind claims of increased risk is investigated as well as the evidence regarding the risk of decompression surgery.</p> <p>Methods</p> <p>A literature search was conducted on the risk of spinal cord injury in individuals with asymptomatic cord encroachment and the risk and benefit of preventive decompression surgery.</p> <p>Results</p> <p>Three studies on the risk of spinal cord injury in this population met the inclusion criteria. All reported increased risk. However, none were prospective cohort studies or case-control studies, so the designs did not allow firm conclusions to be drawn. A number of studies and reviews of the risks and benefits of decompression surgery in patients with cervical myelopathy were found, but no studies were found that addressed surgery in asymptomatic individuals thought to be at risk. The complications of decompression surgery range from transient hoarseness to spinal cord injury, with rates ranging from 0.3% to 60%.</p> <p>Conclusion</p> <p>There is insufficient evidence that individuals with spondylotic spinal cord encroachment are at increased risk of spinal cord injury from minor trauma. Prospective cohort or case-control studies are needed to assess this risk. There is no evidence that prophylactic decompression surgery is helpful in this patient population. Decompression surgery appears to be helpful in patients with cervical myelopathy, but the significant risks may outweigh the unknown benefit in asymptomatic individuals. Thus, broad recommendations for decompression surgery in suspected at-risk individuals cannot be made. Recommendations to individual patients must consider possible unique circumstances.</p

Evaluation of Ischemic Stroke Hybrid Segmentation in a Rat Model of Temporary Middle Cerebral Artery Occlusion using Ground Truth from Histologic and MR data

A segmentation method that quantifies cerebral infarct using rat data with ischemic stroke is evaluated using ground truth from histologic and MR data. To demonstrate alternative approach to rapid quantification of cerebral infarct volumes using histologic stained slices that requires scarifying animal life, a study with MR acquire volumetric rat data is proposed where ground truth is obtained by manual delineations by experts and automated segmentation is assessed for accuracy. A framework for evaluation of segmentation is used that provides more detailed accuracy measurements than mere cerebral infarct volume. Our preliminary experiment shows that ground truth derived from MRI data is at least as good as the one obtained from the histologic slices for evaluating segmentation algorithms for accuracy. Therefore we can develop and evaluate automated segmentation methods for rapid quantification of stroke without the necessitating animal sacrifice

Ground Truth for Evaluation of Ischemic Stroke Hybrid Segmentation in a Rat Model of Temporary Middle Cerebral Artery Occlusion

In vivo rodent models of focal cerebral ischemia have been developed to investigate stroke therapy. Typically these models require rapid quantification of cerebral infarct volumes using vital stains with tetrazolium salts to delineate the extent of neuronal death. To avoid animal sacrifice, we sought a study with MR acquired volumetric rata data where surrogate of ground truth is obtained by repeated manual delineation by experts, and an automated hybrid segmentation is evaluated for accuracy. We propose a rating system for the expert delineations that captures intra- and inter-expert discrepancy. Our preliminary results show that surrogate ground truth derived from MR data is at least as good as the one derived from histologic stained slices. Hence animal sacrifice is not necessary to evaluate ischemic stroke automated segmentation in a rat model of temporary middle cerebral artery occlusion

ICAR: endoscopic skull‐base surgery

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