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Tuesday, December 2, 2014

Causes, Symptoms and Treatment of Ischemic Stroke

What is an ischemic stroke?

Ischemic stroke or cerebral infarction, or "white" Stroke is the most common form of stroke. Cause is called ischemia sudden hypoperfusion of the brain and thus a reduced supply of oxygen and glucose needed for energy. The reduced blood flow is usually caused by a narrowing or occlusions of arteries supplying the brain. Ischemia can be reversible or lead to the death of nerve and other brain cells. Then a stroke.

The different regions of the brain perform different functions. These regions are supplied by blood vessels that vary between individuals within narrow limits. This leads to a circulatory disorder in a given blood vessel can be associated with a specific symptoms usually that can be explained by the failure of the dependent vascular area of the brain.

Heart attack is a medical emergency and heard in the industrialized countries of the leading causes of death and disability. The treatment is preferably carried out in a narrow time window prospect of success and in specialized departments. In the follow-up care occupational therapy, physiotherapy and speech therapy have a high priority.

Occurrence and frequency

Stroke is in Germany after myocardial infarction and malignant neoplasms (cancer), 15 percent of all deaths the third leading cause of death. Among the strokes form the ischemic strokes with about 80 percent of the largest group. In addition, the stroke is the most common cause of acquired disability in adults. Studies on the epidemiology of stroke type for Germany an incidence of 182 / 100,000 (Lit .: Kolominsky-Raba 2004). Absolutely, these are 150,000 new cases of stroke recurrence and around 15,000 cases per year. The prevalence is around 600 / 100,000 inhabitants. Stroke is the leading cause of long-term care in old age.

Causes of ischemic stroke

As microangiopathy general changes of large vessels are called. A common cause of ischemic stroke is the macroangiopathy of the great arteries supplying the brain, which is usually caused by atherosclerotic plaques. Through various mechanisms such as increased blood pressure and infections can lead to a rupture of plaques (rupture), and it can supports blood clots. These local arterial thrombosis can on the one hand lead to a narrowing of the vessel, so that cerebral blood flow is reduced behind the narrow and may be insufficient for the supply of the brain tissue (see the section thrombosis). On the other hand, the local thrombi can be carried away by the blood stream and thus cause an embolism. The embolus may be a more distant blood vessel seal (see the section embolism).

TOAST classification
Accessible, but controversial is the differentiation according to TOAST (Lit .: Adams 1993), figures for Germany:

-Cardiac embolism: In the heart clots that are washed into the cerebral arteries and block form (incidence: 30.2 / 100,000)
-Closure of small arteries (25.8 / 100,000)
-Atherosclerosis of large arteries (15.3 / 100,000)
-Other cause (2.1 / 1,000,000)
-Undetermined cause (39.3 / 100,000) (Lit .: Kolominsky-Raba 2001)

Ischemic stroke symptoms

In ischemic stroke occurs typically in a sudden appearance of several symptoms. The symptoms can fluctuate or gradually increase. The symptoms but does not allow differentiation of the causes of stroke.

-Clouding of consciousness: These can range from mild drowsiness of fatigue (somnolence, stupor) to unconsciousness or deep coma. At worst, a stroke lead within minutes to death by respiratory failure. The disturbance of consciousness is one of the keynotes at infarcts in the posterior (vertebrobasilar) basin.
-Nausea, vomiting

Others Keynotes, which are typical of ischemic stroke:

-Hemiplegia (hemiparesis) or paralysis of a limb (rarely paralysis of all extremities)
-Pathological reflexes of the Babinski group
-Involvement of cranial nerves (swallowing disorder, kloßige language)
-Neuropsychological deficits (aphasia, alexia, apraxia, neglect, cognitive dysphrasia)
-Head or turning of (stove views)
-Visual field defects (hemianopia)
-Memory loss (amnesia)

Strokes in front basin
For an overview of the blood supply to the brain see there.
The following symptoms may in unilateral infarcts of the internal carotid artery (ICA) (50% of all insults), middle cerebral artery (ACM) (25% of cases) and infarction of vessels that occur from such leave (Part infarcts). In infarcts on both sides of the same symptoms, expanded found on both sides of the body:

-Unilateral varying degrees of paralysis of the extremities (hemiplegia, hemiparesis). By crossing of nerve fibers in the pyramidal decussation the left side of the body is affected and vice versa for an infarct in the right hemisphere.
-The face may also be paralyzed on one side (eg. As hanging mouth by facial palsy).
-With hemiplegia may be lost the sense of heat, cold, pressure and position of the affected side (often temporary). This is also reflected in discomfort or numbness of the affected side of the body (feeling disorder, sensory disturbance).
-Perception disorder (neglect - can see, hear, feel and relate to the motor) Half body and the environment on the affected side. In this disorder the affected side of the patient does not exist. The patient does not realize that his perception is disturbed, so he can not even detect a possibly concurrent hemiparesis.
-Blurred vision, is in both eyes, one half (or quarter) of the visual field no longer perceived (hemianopia or Quadrantenanopsie); Disturbance of the processing image information in the brain.
-Use of both eyes toward the affected side of the brain: Déviation conjuguée ("herd glance")
-Language disorder or difficulty understanding speech (aphasia) when the spoke dominant hemisphere (usually the left) is affected.
-Swallowing disorders (disorders of the cranial nerves IX, X and XII).
-Apraxia, ie inability to perform certain actions: buttons buttoned, phone calls and much more
-Disturbance of general brain functions such as concentration, memory, flexible response to demands of the environment ...

Stroke in the posterior circulation territory
The back part of the cerebrum and brain stem, cerebellum and bridge are vertebral arteries from the supplied which combine basilar artery for unpaired. From this springs on both sides of the posterior cerebral artery (so-called. Posterior cerebral circulation), which is infarcted approximately 10%.

In an infarct in the area of posterior cerebral circulation may occur:

-Sudden onset of vertigo with nystagmus
-Gait instability, insecurity when grasping objects by excessive arm and hand movements (ataxia)
-Shaking (tremor)
-Double images by disorders of eye movement (cranial nerve III)
-View paresis (gaze palsy), ie, the view is possible only in certain directions
-Pain in the back of the head
-Sparse blink

Ischemic stroke treatment

Admission to a stroke unit
Even for the initial treatment of stroke admitted to hospital on a special ward for stroke patients, called a stroke unit (stroke unit) should be done if possible. The first goal here is to give the patient a rapid and optimal diagnostics to offer to set the optimal therapy. The further treatment is based on an intensive continuous monitoring of the patient. Continuously the basic parameters of blood pressure, pulse, temperature, blood sugar and breathing are monitored. The close cooperation of various medical disciplines such as neurologists, internists, neurosurgeons and radiologists is another advantage of the stroke unit as well as the early initiation of a longer term rehabilitation (physical therapy, occupational therapy, physiotherapy, speech therapy, aids and equipment).

Thrombolytic therapy (thrombolysis)
There are no contraindications such as advanced age, severe pre-existing conditions mentioned above, however, and by means of computed tomography been ruled a brain hemorrhage (meta-analysis of ECASS I-III and ATLANTIS studies) can be attempted within 4.5 hours after latest study results, the blood clot (thrombus ) dissolve (lysis therapy) to perfuse the brain supplied less area again and reduce the long-term consequences. The sooner treatment can begin, the better ("time is brain"). It is between a systemic thrombolytic therapy (medication is available in the entire circulatory distributed) distinction and a locally applied thrombolysis. The greatest danger in the context of thrombolysis are secondary bleeding. This can occur because the blood coagulation is inhibited for hours. This can lead to both bleeding in the brain with further deterioration in neurological status and the blood loss over other existing wounds. Risk factors for bleeding are relevant to old age, large infarct and predamage the smallest cerebral vessels (microangiopathy of the brain, especially the white matter). In an American and European studies (eg European Cooperative Acute Stroke Study -. ECASS), the positive effects of systemic thrombolytic therapy in patients with ischemic stroke were shown. Whether patients from thrombolysis after six hours still benefit or whether the risks of side effects predominate, has not yet been clarified. Currently, the thrombolysis in Germany is performed normally only in the period of up to three hours after the onset of symptoms; in certain rare subtypes of stroke, this time window can, however, extend to six or even twelve hours (Lit .: 2002 guidelines). In September 2008, was shown in the third European study for the treatment of stroke thrombolysis with that up to 4.5 hours after the onset of deficiency symptoms can be treated. Currently in the professional world is vividly discussed individualization of thrombolytic therapy concept. For example, by the use of magnetic resonance imaging (MRI) after the 4.5-hour window (or with unexplained symptom onset, eg when waking from sleep (wake-up stroke)) lysis be useful if the size of the actual tissue damage and the scale of the circulatory disorder differ from each other (so-called. Perfusionswichtungs diffusion mismatch). An MRI scan, which is at least as sensitive just like a CAT scan, but should not result in a significant delay of initiation of therapy, because the sooner a thrombolytic therapy begins, the more effective it is. The selection of patients for thrombolytic therapy is currently available on the test, ie, it is considered to subject patients with very severe or very slight loss symptoms such therapy since the mid-term earnings (ie after 90 days) seems to be better than without lysis. In addition, new drugs for the extension of the time period tested. The expectations of the derived blood-sucking bats with the inhibitor drug Desmoteplase, which is to be used up to 9 hours after onset of symptoms, however, could not be met (DIAS-2 study).

It should be noted a sufficient oxygenation of the blood. Secured data from prospective studies are currently not available. In patients not intubationspflichtigen the DGN recommends the administration of oxygen only in severe symptoms and a dose 2-4 liters / minute via nasal tube. The general administration of oxygen is currently controversial.

Blood pressure
According to the established doctrine of the blood pressure should not be too far and too fast reduced, particularly in patients with pre-existing hypertension. It should thus be trying to maintain elevated blood pressure blood flow in the penumbra, as the autoregulation of blood pressure is disturbed in this area and therefore the blood flow from the systemic arterial blood pressure depends. Due to inappropriate lowering blood pressure can lead to a worsening of symptoms. As a guideline, should be engaged only medication in the acute phase, when blood pressure exceeds 220/120 mmHg. Conversely, it may also be necessary to raise the blood pressure medication to high normal values. After about three days, blood pressure should be treated for 180/100 mmHg in patients with high blood pressure 180/105 mmHg values. However, the study location is not sufficient. Neither the benefits of the use of pressor nor of antihypertensive agents is adequately secured (Lit .: Blood pressure 2000). Currently, a large study (CHHIPS) is carried out on this subject (Lit .: Potter 2005).

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