Integrated Ecosystem Assessment: Lake Ontario Water Management

BACKGROUND: Ecosystem management requires organizing, synthesizing, and projecting information at a large scale while simultaneously addressing public interests, dynamic ecological properties, and a continuum of physicochemical conditions. We compared the impacts of seven water level management plans for Lake Ontario on a set of environmental attributes of public relevance. METHODOLOGY AND FINDINGS: Our assessment method was developed with a set of established impact assessment tools (checklists, classifications, matrices, simulations, representative taxa, and performance relations) and the concept of archetypal geomorphic shoreline classes. We considered each environmental attribute and shoreline class in its typical and essential form and predicted how water level change would interact with defining properties. The analysis indicated that about half the shoreline of Lake Ontario is potentially sensitive to water level change with a small portion being highly sensitive. The current water management plan may be best for maintaining the environmental resources. In contrast, a natural water regime plan designed for greatest environmental benefits most often had adverse impacts, impacted most shoreline classes, and the largest portion of the lake coast. Plans that balanced multiple objectives and avoided hydrologic extremes were found to be similar relative to the environment, low on adverse impacts, and had many minor impacts across many shoreline classes. SIGNIFICANCE: The Lake Ontario ecosystem assessment provided information that can inform decisions about water management and the environment. No approach and set of methods will perfectly and unarguably accomplish integrated ecosystem assessment. For managing water levels in Lake Ontario, we found that there are no uniformly good and bad options for environmental conservation. The scientific challenge was selecting a set of tools and practices to present broad, relevant, unbiased, and accessible information to guide decision-making on a set of management options

Thunderclap headache and reversible segmental cerebral vasoconstriction associated with use of oxymetazoline nasal spray

OXYMETAZOLINE IS A SYMPATHOMIMETIC amine found in over-the-counter nasal decongestants. We report a case of chronic use of nasal oxymetazoline associated with thunderclap headache due to reversible segmental intracranial vasoconstriction

The hyperdense sylvian fissure MCA ”dot“ sign: a marker of acute CT ischemia

P40 Background: The hyperdense appearance of the middle cerebral artery is now a familiar early warning of large cerebral infarction, brain oedema and poor prognosis. Less well described, however, is the hyperdensity associated with embolic occlusion of branches of the middle cerebral artery seen in the sylvian fissure (MCA ”dot“ sign). The aim of this study was to define this sign, and to determine the incidence, its diagnostic value, and reliability. Methods: Computed tomographic (CT) scans performed on patients with acute ischemic stroke within 3 hours of symptom onset were analysed for signs of thromboembolic stroke and evidence of early CT ischemia. Two neuroradiologists and two stroke neurologists initially blinded to all clinical information, and then with knowledge of the affected hemisphere evaluated scans for the presence of a hyperdense MCA sign (HMCA), a hyperdense sylvian fissure MCA ”dot“ sign, and for early MCA territory ischemic changes. Results: Of 100 consecutive patients presenting within 3 hours of symptom onset early CT ischemia was seen in 74 % of the baseline CT scans. The HMCA sign was seen in 5% of CT scans whereas the MCA ”dot“ sign was seen in 16% of which 2 were associated with a HMCA sign. The presence of a HMCA sign was associated with a greater probability of dependence or death than when a MCA ”dot“ sign was observed or no hyperdensity was seen (P&lt;0.05). All 5 patients with a HMCA sign, including 2 with an associated MCA ”dot“ sign were either dead or dependent at 3 months. Patients with a dot sign alone had independent outcomes in 64% of cases (P&lt;0.8). Balanced kappa statistics for both signs were in the moderate to good range when the side of stroke was known. Conclusions: The hyperdense sylvian fissure MCA ”dot“ sign is an early marker of thromboembolic occlusion of the distal MCA and of its branches. </jats:p

A stroke neurologist/nurse operated acute stroke TCD service can reliably identify MCA occlusion when compared to MRA.

P39 Background: Hyperacute neurovascular imaging has great potential to help clinicians better tailor stroke therapy. Future decisions to use intravenous and/or intra-arterial lytics may depend on site of MCA occlusion. TCD has not been seriously considered as such a technique because of the misconception TCD is too operator dependent and not reliable. We evaluated if our acute stroke TCD service could accurately and reliably identify MCA occlusion. Methods: A series of acute stroke patients underwent TCD examination by 1 of 3 stroke physicians or 1 stroke nurse. MRA was also performed at a time closely corresponding to TCD exam. Blind to MRA findings and patient info except symptom side, all 4 sonographers independently interpreted the TCD exam for presence of MCA occlusion using previously established TCD criteria and evaluated TIBI flow grades (5 normal waveform, 4 stenotic, 3 dampened, 2 blunted, 1 minimal, 0 absent) at 65, 55, 45 mm MCA depths. This result was compared to blinded neuroradiologists MRA interpretation for M1-MCA and distal MCA occlusion. Results: 37 cases compared. Mean age 67, median baseline NIHSS 8. Median symptom onset to TCD 5.9 hours and MRA 6.3 hours. Median time between TCD and MRA 1.3 hours. TPA treatment preceded or occurred during TCD or MRA imaging in 27% of cases. MRA identified 19 MCA occlusion (12 M1-MCA, 7 distal MCA) and 18 no MCA occlusion. Comparing all sonographer TCD interpretations (n=148) with MRA the sensitivity, specificity, PPV, NPV for MCA occlusion was: 82%, 81%, 82%, 81% respectively. Intraclass correlation coefficent for TIBI flow grades at prox, mid, distal MCA depths was : 0.73,0.84,0.83. Median TIBI scores at these 3 MCA depths respectively were: 5,5,5 when no MCA occlusion on MRA, 3,3,3 if distal MCA occlusion and 2,2,2 if M1-MCA occlusion. Conclusion: TCD showed good accuracy at identifying MCA occlusion compared to MRA when TCD was performed and interpreted by a stroke clinician/nurse. TIBI flow grades were reliably identified and appear potentially useful to discriminate between normal MCA, and proximal or distal MCA occlusion. TCD is a useful bedside tool that could aid future stroke treatment. </jats:p

Impact of neuroradiologist second opinion on staging and management of head and neck cancer

Article deposited according to agreement with BMC, December 2, 2010 and according to publisher policies: http://www.biomedcentral.com/about/copyright [July 23, 2013].YesFunding provided by the Open Access Authors Fund

A comparison of CT versus MR imaging in acute stroke using ASPECTS: Will the “new” replace the “old” as the preferred imaging modality?

49 Background: CT is considered less sensitive and reliable than MRI for the detection of ischemia in hyperacute stroke. This study compares these two modalities. Methods: We included all ischemic stroke patients who had both CT &lt; 6 hours and MRI &lt; 7 hours from onset. A quantitative scoring system (ASPECTS) was applied to CT, MR FLAIR and DWI at baseline and at follow-up (&lt;36h) by five independent observers (2 neuroradiologists and 3 stroke neurologists) with only knowledge of stroke symptom side. CT was also assessed for hyperdense MCA and sylvian fissure MCA “dot” signs. The analysis was derived from consensus agreement among individual observers. MRA was the “gold standard” for vascular occlusion. Results: 52 patients had CT and MRI acutely. The median NIHSS was 9. The mean onset to CT was 125 minutes and to MRI 241 minutes (P&lt; 0.001). Baseline CT and DWI ASPECTS were highly correlated (r 0.75 P&lt;0.001). Median baseline CT, FLAIR and DWI scores using ASPECTS were 9, 10, and 8.5 respectively. At baseline DWI ASPECTS was 0.5 points lower than CT, but CT ASPECTS was a significant 1 point lower than FLAIR (P&lt;0.03 and &lt;0.001 respectively, Wilcoxon signed rank). However there was no difference between baseline CT and DWI at predicting follow-up DWI ASPECTS (P=0.12 Wilcoxon signed rank). Intraclass correlation coefficients to assess agreement among observer scores at baseline were moderate to excellent for CT and DWI (0.72 95% CI 0.62–0.81 and 0.71 95% CI 0.62–0.81 respectively) but was poor for FLAIR (0.43 95% CI 0.29–0.57). Hyperdense MCA and MCA “dot” signs had sensitivity 0.57 and specificity 0.96, using MRA as the “gold standard” for MCA occlusion (χ 2 P&lt;0.001). Interobserver agreement for hyperdense signs was in the moderate to good range (kappa 0.50–0.67). Conclusion: CT appears as good as DWI for assessing ischemic tissue in hyperacute stroke when evaluated by experienced CT readers using ASPECTS. We speculate this surprising finding could be explained by excessive DWI basal ganglia hypointensity, MR susceptibility artifact at skull base, and less conspicuous DWI abnormality than previously recognised in the first hours of ischemia. </jats:p