What drives the increasing utilisation of hemicraniectomy in acute ischaemic stroke?

BACKGROUND

Survival after malignant middle cerebral artery infarcts is dismal. In 2007, a pooled analysis of randomised trials in Europe demonstrated a substantial survival benefit from decompressive hemicraniectomy, with a number needed to treat of 2 for survival. Our objective was to review factors driving the nationwide utilisation of this potentially lifesaving procedure in the USA.

METHODS

Data from the Nationwide Inpatient Sample for 2001-2009 were reviewed. Hospitalisations with a discharge diagnosis of an acute ischaemic stroke were included. Hemicraniectomy utilisation was determined within this subset. Nationwide estimates of utilisation were calculated for each year. Trends across the years were estimated for various subgroups.

RESULTS

From 2001 to 2009, there were an estimated 4 909 519 acute ischaemic stroke discharges. The estimated frequency of hemicraniectomy increased from 118 (0.02% of stroke discharges in 2001) to 804 (0.15% of stroke discharges in 2009) (trend p<0.001). The increased utilisation was greatest for younger subjects (age<45 years; trend p<0.001) and men (trend p<0.001). Urban teaching hospitals were responsible for the greatest increase in hemicraniectomy utilisation: from 0.05% of stroke discharges in 2001 to 0.28% in 2009. The increase was steady and sustained over the decade. In comparison, rural and urban non-teaching hospitals showed a much smaller improvement in utilisation.

CONCLUSION

Utilisation of hemicraniectomy in the USA has increased significantly, in line with compelling results from European clinical trials. Early transfer of patients with malignant infarctions to urban teaching centres could potentially extend the survival benefit to a larger population.

A Strategic Application of Fast Fourier Transform as a Novel Tool to Evaluate the Extent of Neuronal Insult in Rat Model of Focal Cerebral Ischemia

The present work envisages mathematical modeling of induced focal cerebral ischemia in animal model using EEG data with the help of Fast Fourier Transformation method. Amongst several analysis methods, spectral analysis methods are important because it detects the frequencies and characteristics changes of brain waveforms depending on the brain function affected from disorders and physiological state. There are many applications of FFT, and the most important being that it is one of the basic conventional spectral analysis methods. However, it has some limitations, for instance, it adds contributions in the low frequency region which are not present in the original signal, and necessitates the use of windowing for decreasing the error rate. The present analysis was undertaken to ensure actual correlation of the different mathematical paradigms. EEG data were obtained from different regions of rat brain and were processed by FFT modeling in MATLAB platform. The assessment of long lasting functional outcome and to prevalent classical approach to study stroke was necessitated and therefore highly recommended to evaluate the efficacy of therapeutic strategies in relation to EEG in animal model of brain stroke. This mathematical modeling specifically Power Spectrum Density analysis was done to correlate the different prevalent condition of rat brain function. DOI: http://dx.doi.org/10.3329/bjmp.v5i1.14666 Bangladesh Journal of Medical Physics Vol.5 No.1 2012 29-36

Early access to a neurologist reduces the rate of missed diagnosis in young strokes

BACKGROUND

We hypothesized that the presence of an in-house neurologist or a neurology or emergency medicine (EM) residency is associated with a lower rate of missed stroke diagnosis and a greater use of thrombolytic therapy.

METHODS

The outpatient Young Stroke registry from our academic medical center was reviewed. Patients 16 to 50 years of age who presented with ischemic stroke were included. Information on presentation, acute therapy, and missed diagnosis was obtained. The presence of an EM or neurology residency at the presenting hospital was recorded. We also assessed whether hospital teaching status in these fields affected missed diagnosis rates, the use of thrombolysis, or stroke intervention.

RESULTS

Ninety-three patients were included. Thirteen patients were misdiagnosed. In hospitals with and without a neurology residency, the missed diagnosis rate was 6.3% versus 18.0%, respectively (P=.21). Two patients were misdiagnosed in hospitals with a neurology residency, but neither had neurology consultations in the emergency department. If these cases are removed from our analysis, the rate of missed diagnosis with and without a neurology residency is 0% versus 20.6%, respectively (P=.008). Acute stroke therapy was administered in 17.9% of patients seen with an EM residency, compared to 2.7% without an EM residency (P=.046). With and without a neurology residency, acute stroke therapy was administered in 25% versus 8.2% of cases, respectively (P=.055).

CONCLUSIONS

Young adults with ischemic stroke seen at hospitals with a neurology residency had a lower missed diagnosis rate. The presence of an EM resident or a neurology teaching program was associated with a greater use of acute stroke therapies. These results support initiatives to triage young adults with suspected acute stroke to hospitals with access to neurologic expertise in the emergency department.

Teleneurology applications: Report of the Telemedicine Work Group of the American Academy of Neurology

OBJECTIVE

To review current literature on neurology telemedicine and to discuss its application to patient care, neurology practice, military medicine, and current federal policy.

METHODS

Review of practice models and published literature on primary studies of the efficacy of neurology telemedicine.

RESULTS

Teleneurology is of greatest benefit to populations with restricted access to general and subspecialty neurologic care in rural areas, those with limited mobility, and those deployed by the military. Through the use of real-time audio-visual interaction, imaging, and store-and-forward systems, a greater proportion of neurologists are able to meet the demand for specialty care in underserved communities, decrease the response time for acute stroke assessment, and expand the collaboration between primary care physicians, neurologists, and other disciplines. The American Stroke Association has developed a defined policy on teleneurology, and the American Academy of Neurology and federal health care policy are beginning to follow suit.

CONCLUSIONS

Teleneurology is an effective tool for the rapid evaluation of patients in remote locations requiring neurologic care. These underserved locations include geographically isolated rural areas as well as urban cores with insufficient available neurology specialists. With this technology, neurologists will be better able to meet the burgeoning demand for access to neurologic care in an era of declining availability. An increase in physician awareness and support at the federal and state level is necessary to facilitate expansion of telemedicine into further areas of neurology.

Abstract TP400: Racial Differences in the Recovery from Ischemic Stroke after tPA

Racial minorities are at a disadvantage with regards access to acute stroke therapies. We tested the hypothesis that differences between races would result in disparate recovery from ischemic stroke in patients who receive tPA. Data from the Nationwide Inpatient Sample (NIS) for the years 2001 through 2009 were analyzed. The data represents a 20% sample of all inpatient hospitalizations in the United States. Patients discharged with a diagnosis of Ischemic stroke were identified using ICD-9 codes. The code 99.10 was used to identify patients who received tPA. Patients with self reported races: white, black and hispanic who received tPA for ischemic stroke were included. Outcomes of hospitalization including death and discharge destination were assessed. Racial subgroups by age and gender were also analyzed. In the NIS, 15,279 patients received tPA for ischemic stroke between 2001 and 2009. This included 75.3% white, 12.8% black and 6.3% hispanic. In-hospital death rates were not significantly different: 12.8% for white, 10.9% for black and 6.9% for Hispanic; p=0.07. Death rates remained similar even after adjustments for age. In-hospital death was also analyzed in racial subgroups of men, women, young(≤45), middle age (46-70) and elderly(>70); and there was no difference between races. Discharge destination was used as a surrogate for recovery. Blacks and hispanics had about 25% greater odds of being discharged home. However, when adjusted for age, there was no true difference between the races. Considering a home discharge or discharge to a short term rehabilitation facility as a good outcome, blacks were at a significant disadvantage compared to whites; age adjusted OR 0.88(0.80-0.98). This disparity was noted among black men only, and not in black women. As a minority, Hispanic patients had similar rates of home or rehabilitation discharge as whites. In conclusion, in-hospital death rates and the likelihood of home discharge were similar among races. The mechanisms driving disparate access to acute rehabilitation services among black men are probably biological and social. Reasons for differential access to tPA should be explored and addressed, as minorities receiving tPA have similar survival potential and likelihood for home discharge.

Abstract WP51: Racial Differences in Salvageable Ischemic Penumbra

Objective: African Americans (AA) have a higher incidence of intracranial atherosclerosis than Caucasians. Resulting chronic ischemia may lead to the formation of collateral circulation. Our hypothesis was that AA will have a greater sustainability of their ischemic penumbra from collateral circulation after an acute stroke.

Methods: Ischemic stroke patients that underwent perfusion computed tomography (PCT) at admission from August 2011 to March 2012 were reviewed. PCT included 4 supratentorial slices, 8 mm thick. Images were processed using Vitrea® to obtain cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT). Areas of increased MTT were traced and marked as ischemic area. Corresponding area of preserved CBV was labeled as penumbra area. The mean CBF, MTT or CBV for the total ischemic area (or penumbra) was estimated by multiplying each ischemic area (or penumbra) by the corresponding CBF (MTT or CBV), adding the value of four slices and dividing by total area. The ischemic and penumbra areas in four slices were added and multiplied by slice thickness (0.8 cm) to give ischemic volume (IV) and penumbra volume (PV) respectively.

Results: Perfusion abnormalities were found in 43 (65.1 % AA vs. 30.2 % Caucasian) patients. The mean ischemic volume was less in AA as compared to Caucasians (63.64 ±36.7 cm 3 vs. 89.57 ±52.6 cm 3 ) as was mean penumbra volume (42.77±28.9 cm 3 vs. 64.36 ± 43.8 cm 3 ). Within the penumbra in AA, CBF was increased (28 ±12.2 ml/100 gm/sec vs. 23.11 ±12.5 ml/100 gm/sec) as was CBV (3.46 ±1.4 ml/100gm vs. 2.98 ±1.1 ml/100gm). The penumbra MTT was faster in AA (8.59 ±2.2 sec vs. 9.46 ±2.72 sec). The trends in CBF, CBV and MTT did not reach statistical significance due to the small sample size. A CBF less than 20 ml/100 gm/sec is conventionally defined as vulnerable ischemic tissue. In the area of ischemia, only 36% of AA had CBF less than 20 ml/100 gm/min as opposed to 61.5% in Caucasians (p=0.17).

Conclusion This exploratory analysis showed that AA have a somewhat greater CBF and CBV with faster MTT in the region of penumbra as compared to Caucasians indicating the presence of biological mechanisms to preserve the area at risk. Further analysis to assess collateral cerebral blood flow as a protective mechanism in AA is warranted.

Abstract TMP105: High Utilization Of CAS Procedures Among The Elderly In The Post Crest Era

Background: An important interaction of age with outcome was revealed in Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST) where elderly patients ≥70 years had worse outcomes with Carotid stenting (CAS) than with Endarterectomy (CEA). Our hypothesis was that following the CREST study, the proportion of CAS procedures in the elderly would decrease.

Methods: We performed a retrospective review of carotid revascularization procedures between June 2009 and April 2012 at a large volume urban medical center. Demographics, indications, surgical high-risk criteria and outcomes of in-hospital stroke/death/MI were collected. Data analysis was performed in subjects over 70 years. Time trends were examined in the post-CREST period.

Results: A total of 701 procedures (CEA 36%, CAS 64%) were performed during the study period, of which 360 (51.4%) were in patients ≥70 years (CEA 33%, CAS 67%). A significant proportion (22.1%) was in those ≥80 years. The choice of procedure did not change following CREST. The majority of CAS procedures in elderly (90.8%) were performed by cardiologists. Asymptomatic patients (47.3%) and patients with non-specific symptoms (18.7%) comprised a large proportion of this subgroup. A third of elderly patients with asymptomatic and nonspecific symptoms did not have any surgical high-risk criterion. The proportion of elderly patients receiving CAS for non-specific symptoms increased progressively over time post CREST (27.9% in the most recent months). A similar rise in non-specific indications was noted in the subgroup of patient ≥80 years receiving CAS. About half of this subgroup did not have any surgical high-risk criterion.

Conclusion: Two years after CREST results, CAS continues to be performed among the elderly, often for non-specific symptoms or in asymptomatic patients. The lack of a decrease in CAS procedures in the elderly raises questions about whether evidence-based carotid revascularization occurs in the real world.

Abstract WP444: Older Age, Hypertension and Diabetes Influence the Proportion of Salvageable Ischemic Tissue Following Stroke

Objective: Increasing age, hypertension (HTN), diabetes (DM), hyperlipidemia, smoking and chronic kidney disease are implicated in endothelial dysfunction. Our hypothesis was that endothelial dysfunction would decrease the amount of salvageable ischemic tissue (penumbra) in patients with acute ischemic stroke.

Methods: Patients with ischemic stroke that underwent perfusion computed tomography (PCT) at admission from August 2011 to March 2012 were reviewed. Demographics and risk factors were abstracted. PCT protocol included 4 supratentorial slices, 8 mm thick. Areas of increased mean transit time were traced and marked as ischemic area. Corresponding area of preserved cerebral blood volume was labeled as penumbra area. The ischemic and penumbra areas in four slices were added and multiplied by the slice thickness (0.8 cm) to give ischemic volume (IV) and penumbra volume (PV) respectively. The proportion of penumbra (penumbra/ischemia volume) was calculated and compared across the different risk factors.

Results: Of the 47 patients that underwent PCT, 43 (22 males; mean age 61.6 ±12.6 years) had perfusion abnormalities. Subjects younger than 45 years had significantly higher median IV (118.8 cm 3 vs. 58.4 cm 3 ; p=0.01) and median PV (97.9 cm 3 vs. 38.7 cm 3 ; p<0.01). The median proportion of penumbra, was significantly lower in subjects older than 45 years (72.2% vs. 82.0%; p=0.04). Other factors that demonstrated trends toward a decrease in proportion of penumbra, but did not reach statistical significance due to small numbers: HTN (72.8% vs. 80.0% ; p=0.20) and DM (67.5% vs. 75.7%; p=0.56). In our subset, smoking, hyperlipidemia and kidney disease did not affect the penumbra proportion.

Conclusion: Older patients and those with HTN or DM are less likely to have a large proportion of salvageable penumbra. While endothelial dysfunction may be a common denominator to these risk factors, the biological mechanisms underlying this phenomenon need to be elucidated.

Abstract WMP106: Increased Carotid Stenting For Nonspecific Symptoms In The Post-crest Era

Background: Nonspecific symptoms such as dizziness and syncope may prompt evaluation of the carotid circulation and detection of carotid stenosis. The Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST) demonstrated equivalent outcomes from Endarterectomy (CEA) and Stenting (CAS) in asymptomatic stenosis. We reviewed the trends in selection and outcomes from revascularization procedures for nonspecific symptoms in the light of CREST results.

Methods: We performed a retrospective review of carotid revascularization procedures at a large volume urban medical center, between June 2009 (8 months pre-CREST) and April 2012. Demographics, surgical risk features and in-hospital outcomes of stroke/death/MI were reviewed. Patients were labeled as having nonspecific symptoms when they presented with posterior circulation symptoms or with non-focal symptoms i.e. Dizziness, syncope, etc. To evaluate the effect of CREST, we compared pre CREST (up to Jan 2010) and post CREST cases (Feb 2010 to Apr 2012).

Results: 701 procedures (36.1% CEA, 63.9% CAS) were performed and mean age was 70 ±10 years. Non-specific indications accounted for 13% of CEA and 15.9% of CAS. Procedures for nonspecific symptoms did not increase post CREST in the CEA group (12.1% VS 13.3%). They increased significantly in the CAS group (6.3% pre and 18.5% post CREST). Among CAS, the rise was insignificant in the first 8 months (Feb 2010-Sep 2010) post CREST: 7.5%. This rose to 21.2% from Oct 2010 to May 2011: p=0.0017; and 23.8% from June 2011 to April 2012: p=0.0004. The rise in CAS was noted among elderly patients (>70 years), a group in which CREST demonstrated higher complication rates. The rise was noted among both men and women and they did not have surgical high-risk criteria. In-hospital complication rates of stroke/death/MI were 5.6% in this group. Most complications occurred in patients >70 years.

Conclusion: CAS for nonspecific symptoms has increased following CREST, and the complication rates associated with these procedures is significant. This raises concern about the value of this procedure. Primary care physicians evaluating non-specific symptoms should obtain neurological expertise prior to revascularization procedures, to allow appropriate patient selection.

Self-assembled hierarchical nanostructures composed of novel chalcopyrite nanosheets for photovoltaic properties

Self-assembled nanostructures of CulnGaSe2 (CIGS) comprising of nanosheets with sheet thickness of 20 nm have been developed via one-step electrochemically alloying technique. These self-assembled nanoplates exhibit highly intersecting behavior and transform from CuSe to CIGS as the reduction potential was varied. The morphological analysis indicated that the process resulted in a progression of crystallites to a series of heavy dense intersecting nanoplates. Further analyses revealed that the nanostructures keep their integrity on heat treatment. The structure confirms the inclusion of Indium and Gallium at higher reduction potentials and its transition from pseudoamorphous to polycrystalline structure. A strong correlation between reduction potential, and the composition was established. The spectroscopic and optical spectra clearly prove that the direct band gap for the as-grown and annealed thin films, and appropriate for solar cell applications. These self-assembled dense interweaved nanoplates structure have not been observed previously in CIGS semiconductor system and have potential implications forenergy applications.

Early use of MRI improves diagnostic accuracy in young adults with stroke

OBJECTIVES

The misdiagnosis of acute ischemic stroke in young adults is a significant problem since patients may have many decades of potential disability. Also, proven therapies for acute stroke may not be administered if there is an initial misdiagnosis. We assessed the hypothesis that early use of MRI, arrival by ambulance, and presentation to a Primary Stroke Center (PSC) would be associated with a reduced rate of misdiagnosis.

METHODS

A prospective database of young adults (ages 16-49 years) with ischemic stroke (final diagnosis provided by vascular neurologists) was reviewed. We collected information on several variables, including age, race, arrival by ambulance, whether brain MRI was performed within 48 h, and initial presentation to a PSC. Variables were tested against emergency department (ED) misdiagnosis using univariate and multivariate methods.

RESULTS

77 patients with a mean age of 37.9 years were reviewed. 48.3% of patients arrived by ambulance, 53.2% had a brain MRI within 48 h, and 23.4% initially presented to a PSC. The overall rate of ED misdiagnosis was 14.5%. In multivariate testing, performance of MRI within 48 h (p=0.023) was associated with a lower rate of misdiagnosis and age <35 years was linked with greater likelihood of misdiagnosis (p=0.047).

CONCLUSIONS

Early performance of MRI leads to greater accuracy of stroke diagnosis in young adults presenting to the ED. Patients less than age 35 years have a greater risk of misdiagnosis. ED physicians and neurologists should consider early use of MRI in young adults with stroke-like deficits and diagnostic uncertainty.

Safety considerations in the epilepsy monitoring unit for psychogenic nonepileptic seizures

Injury occurs in epilepsy monitoring units (EMUs) to patients with epileptic seizures (ES); however, there are limited data regarding the safety concerns of patients with psychogenic nonepileptic seizures (PNES) being monitored in EMUs. We reviewed EMU records from 116 PNES and compared them to 170 ES. Three falls (2.6%) occurred in PNES without injury compared to 6 falls (3.5%) in ES with 1 injury, a facial hematoma. Of the 9 total falls, 8 patients were ambulatory during their events. Several adverse incidents occurred for both groups. Of the PNES without staff response, 30 of 39 were due to PNES being less than 60s in duration, and 16 of 39 involved lack of push-button activation to alert the staff. For the ES group, 57 of 101 were due to electrographic seizures without seizure detection software or push-button activation. Similar safety protocols should be administered while monitoring these patients regardless of seizure type.

Poly(3-methylthiophene)/graphene composite: in-situ synthesis and its electrochemical characterization

Poly(3-methylthiophene)/Graphene composites (G-PMT) and poly(3-methylthiophene) (PMT) were synthesized by in-situ chemical oxidative polymerization and investigated as electrode material for supercapacitors. The interaction between graphene and polymer chains was characterized by Fourier Transform Infrared (FTIR) spectroscopy. The morphology of the nanocomposites was characterized by Scanning Electron Microscopy (SEM) and High Resolution Transmission Electron Microscopy (TEM). The thermal stability of the composite and the polymer was studied by Thermogravimetric Analysis (TGA) which shows G-PMT has higher thermal stability than PMT. The electrochemical properties were investigated by Cyclic Voltammetry (CV), Cyclic Charging-discharging tests (CC) and Electrochemical Impedance Spectroscopy (EIS) in a three-electrode system. G-PMT resulted in higher specific capacitance of 240 F/g. The specific capacitance retention after 500 cycles on G-PMT was also higher compared with PMT. These results indicate that G-PMT has good electrochemical performance than PMT hence it is useful for the making of electrode in supercapacitor application.

Particulate matter characterization by gray level co-occurrence matrix based support vector machines

An efficient and highly reliable automatic selection of optimal segmentation algorithm for characterizing particulate matter is presented in this paper. Support vector machines (SVMs) are used as a new self-regulating classifier trained by gray level co-occurrence matrix (GLCM) of the image. This matrix is calculated at various angles and the texture features are evaluated for classifying the images. Results show that the performance of GLCM-based SVMs is drastically improved over the previous histogram-based SVMs. Our proposed GLCM-based approach of training SVM predicts a robust and more accurate segmentation algorithm than the standard histogram technique, as additional information based on the spatial relationship between pixels is incorporated for image classification. Further, the GLCM-based SVM classifiers were more accurate and required less training data when compared to the artificial neural network (ANN) classifiers.

Role of non-high-density lipoprotein cholesterol in predicting cerebrovascular events in patients following myocardial infarction

Although there appears to be a role for statins in reducing cerebrovascular events, the exact role of different lipid fractions in the etiopathogenesis of cerebrovascular disease (CVD) is not well understood. A secondary analysis of data collected for the placebo arm (n = 2,078) of the Cholesterol and Recurrent Events (CARE) trial was performed. The CARE trial was a placebo-controlled trial aimed at testing the effect of pravastatin on patients after myocardial infarction. Patients with histories of CVD were excluded from the study. A Cox proportional-hazards model was used to evaluate the association between plausible risk factors (including lipid fractions) and risk for first incident CVD in patients after myocardial infarction. At the end of 5 years, 123 patients (6%) had incident CVD after myocardial infarction (76 with stroke and 47 with transient ischemic attack). Baseline non-high-density lipoprotein (HDL) cholesterol level emerged as the only significant lipid risk factor that predicted CVD; low-density lipoprotein cholesterol and HDL cholesterol were not significant. The adjusted hazard ratios (adjusted for age, gender, hypertension, diabetes mellitus, and smoking) for CVD were 1.28 (95% confidence interval [CI] 1.06 to 1.53) for non-HDL cholesterol, 1.14 (95% CI 0.96 to 1.37) for low-density lipoprotein cholesterol, and 0.90 (95% CI 0.75 to 1.09) for HDL cholesterol (per unit SD change of lipid fractions). This relation held true regardless of the level of triglycerides. After adjustment for age and gender, the hazard ratio for the highest natural quartile of non-HDL was 1.76 (95% CI 1.05 to 2.54), compared to 1.36 (95% CI 0.89 to 1.90) for low-density lipoprotein cholesterol. In conclusion, non-HDL cholesterol is the strongest predictor among the lipid risk factors of incident CVD in patients with established coronary heart disease.