What is watershed pattern?
Watershed locations are those border-zone regions in the brain supplied by the major cerebral arteries where blood supply is decreased. Watershed strokes are a concern because they comprise approximately 10% of all ischemic stroke cases.
What is a watershed infarct?
WATERSHED INFARCTS are ischemic lesions which are situated along the border zones between the territories of two major arteries, for example the anteri- or and middle or the middle and posterior cerebral arteries (fig. 1).
What does an infarct look like on CT?
On CT or MR cortical infarct-like lesions are visible usually in the posterior temporal or occipito-temporal regions, often bilaterally and not strictly occupying a typical vascular territory. Cerebral venous thrombosis and infarction (A) pre- and (B) post-intravenous contrast.
What is territory infarct?
The PCA territory infarcts were characterized as cortical only or cortical and deep (thalamus or midbrain or both). The cortical distribution was defined according to arterial territories (calcarine, parieto-occipital, or temporal artery, the latter consisting of the anterior and posterior temporal arteries).
What are the characteristics of watershed?
Watersheds can be classified using any measurable characteristics in the area like- size, shape, location, ground water exploitation, and land use….The most common and important channel characteristics of the watersheds are:
- Channel Order.
- Channel Length.
- Channel Slope.
- Channel Profile.
- Drainage Density.
What are the characteristics of a healthy watershed?
A healthy watershed is one in which natural land cover supports:
- dynamic hydrologic. and geomorphologic.
- habitat of sufficient size and connectivity to support native aquatic and riparian.
- physical and chemical water quality conditions able to support healthy biological communities.
What does watershed blood supply mean?
Watershed area is the medical term referring to regions of the body, that receive dual blood supply from the most distal branches of two large arteries, such as the splenic flexure of the large intestine.
Why is watershed called watershed?
The area that drains into a single river is the watershed for that river. Watershed can also mean a ridge, like that formed by a chain of mountains, which sends water to two different rivers on either side. It’s from this meaning that watershed came to mean a turning point or dividing line in social life.
Can you see infarct on CT?
On CT 60% of infarcts are seen within 3-6 hrs and virtually all are seen in 24 hours. The overall sensitivity of CT to diagnose stroke is 64% and the specificity is 85%. In the table on the left the early CT-signs of cerebral infarction are listed.
What is the difference between infarct and ischemia?
The term ischemia means that blood flow to a tissue has decreased, which results in hypoxia, or insufficient oxygen in that tissue, whereas infarction goes one step further and means that blood flow has been completely cut off, resulting in necrosis, or cellular death.
What are 6 characteristics of a watershed?
Watershed characteristics such as size, slope, shape, drainage density, land use/land cover, geology and soils, and vegetation are important factors affecting various aspects of runoff.
What are the three key features to a watershed?
A watershed is dynamic and three-dimensional. It includes precipitation, the network of surface streams and the groundwater stored in underground aquifers.
What is an unhealthy watershed?
Unhealthy watersheds lack these essential qualities. Impervious surfaces (driveways, buildings, sidewalks, and parking lots) prevent rainwater from soaking into the ground. Storm sewers carry rainfall directly to streams.
What are the four characteristics of a watershed?
Watershed geomorphology refers to the physical characteristics of the watershed. Basin area, basin length, basin slope, and basin shape are the physical characteristics of watersheds, significantly affecting the characteristics of runoff and other hydrologic processes.
What are watershed characteristics?
What are watersheds made of?
The watershed consists of surface water–lakes, streams, reservoirs, and wetlands–and all the underlying groundwater. Larger watersheds contain many smaller watersheds. It all depends on the outflow point; all of the land that drains water to the outflow point is the watershed for that outflow location.
What does a stroke look like?
Sudden numbness or weakness in the face, arm, or leg, especially on one side of the body. Sudden confusion, trouble speaking, or difficulty understanding speech. Sudden trouble seeing in one or both eyes. Sudden trouble walking, dizziness, loss of balance, or lack of coordination.
Is MRI or CT better for stroke?
Results of the study show standard MRI is superior to standard CT in detecting acute stroke and particularly acute ischemic stroke. The four readers were unanimous in their agreement on the presence or absence of acute stroke in 80 percent of patients using MRI compared to 58 percent using non-contrast CT.
Why is circle of Willis important?
The circle of Willis plays an important role, as it allows for proper blood flow from the arteries to both the front and back hemispheres of the brain. The arteries that stem off from the circle of Willis supply much of the blood to the brain.
What does ischemia look like on an ECG?
The most common ECG sign of myocardial ischemia is flat or down-sloping ST-segment depression of 1.0 mm or greater. This report draws attention to other much less common, but possibly equally important, ECG manifestations of myocardial ischemia.
Which imaging findings are characteristic of watershed infarction?
Imaging of watershed infarction should also aim to determine the presence and severity of arterial stenosis and occlusion. These are usually wedge-shaped or gyriform: parallel parafalcine stripes in the subcortical white matter at the vertex – this type is seen with profound diffuse hypoperfusion
What is the difference between a stroke and watershed infarct?
You may already have guessed that Mr. Harrison is suffering from a stroke, but it’s actually impossible to differentiate between other types of strokes and watershed infarcts based on the clinical features, which is why this is a radiological diagnosis. But before we get into that, it becomes necessary to explain how they occur.
What are the neurologic signs of a PCA-MCA watershed infarct?
Specific neurologic signs depend on the region where the infarct occurred. A PCA-MCA watershed infarct will present with bilateral visual loss (we call this cortical blindness because the retina and visual pathways remain intact, but there is a problem at the visual cortex).
How do you rule out watershed infarcts?
ECG (to rule out cardiac pathologies, which are a common cause for watershed infarcts) and ideally a 24-hour ECG to exclude conditions like atrial fibrillation Carotid doppler – this is undertaken if we find an anterior circulation infarct, especially when a patient is fit for surgery.