Stroke patients, cerebral blood

Mehta, N., et al. Prediction of final infarct size in acute stroke using cerebral blood flow/cerebral blood volume mismatch added value of quantitative first pass CT perfusion imaging in successfully treated versus unsuccessfully treated/untreated patients, in Proceedings of the 41st Annual Meeting of the American Society of Neuroradiology. 

Wintermark M, Reichhart M, Thiran JP, Maeder P, Chalaron M, Schnyder P, Bogous-slavsky J, MeuU R. Prognostic accuracy of cerebral blood flow measurement by perfusion computed tomography, at the time of emergency room admission, in acute stroke patients. Ann Neurol 2002 51 417-432. 

Depending upon the location and severity of the stroke at admission, patients may have cardiac and/or respiratory instability at the time of presentation to the emergency department (ED). They may need to be stabilized hemodynamically or intubated for airway protection or respiratory distress. Blood pressure management is often a crucial management issue, and the use of vasopressor or antihypertensive medications is common. In stroke patients at risk for malignant cerebral... 

Nimodipine, a member of the dihydropyridine group of calcium channel blockers, has a high affinity for cerebral blood vessels and appears to reduce morbidity after a subarachnoid hemorrhage. Nimodipine was approved for use in patients who have had a hemorrhagic stroke, but it has recently been withdrawn. Nicardipine has similar effects and is used by intravenous and intracerebral arterial infusion to prevent cerebral vasospasm associated with stroke. Verapamil as well, despite its lack of vasoselectivity, is used by the intra-arterial route in stroke. Some evidence suggests that calcium channel blockers may also reduce cerebral damage after thromboembolic stroke. 

Lin W, Lee JM, Lee YZ, Vo KD, Pilgram T, Hsu CY (2003) Temporal relationship between apparent diffusion coefficient and absolute measurements of cerebral blood flow in acute stroke patients. Stroke 34 64-70... 

Fiehler J, von Bezold M, Kucinski T et al (2002) Cerebral blood flow predicts lesion growth in acute stroke patients. Stroke 33 2421-2425... 

Fig. 7.2. Relationship between relative (rADC) and cerebral blood flow (CBF). ADC drops to below normal at CBF values around 15-24 ml/min/100 g, as shown in a pixel-wise comparison between diffusion and perfusion imaging in acute stroke patients. A lower threshold (15 ml/min/100 g) was found for patients imaged earlier (up to 4 h ) compared to the value (24 ml/min/100 g) of those patients imaged between 4.5 and 6.5 h ( ).The data show that the ADC threshold increases with time. [Reproduced with permission from Lin et al. (2003)]...

The longer the neurological deficit lasts and the later in the course of the stroke symptoms CT or DWI are performed, the higher the likelihood of a positive finding. Moderate decreases of cerebral perfusion as defined by increased relative mean transit times (rMTT), decreased relative cerebral blood flow (rCBF) but normal relative cerebral blood volume (rCBV) are typically found in DWI negative TIA or stroke patients (Ay et al. 1999b). 

A significant reduction of the ICP was seen, which was similar to the results of Marion and Shiozaki, who used hypothermic therapy in traumatic brain injuries (37,38). With an unaffected mean arterial blood pressure (MABP) and increased cerebral perfusion pressure (CPP), hypothermic therapy appeared to benefit stroke patients, as uncontrolled intracranial hypertension is the main cause of death in the first week after stroke. However, rewarming the patients consistently led to a secondary rise of ICP, which required additional ICP therapy with mannitol. In some cases it even exaggerated the initial ICP levels (Fig. 3). 

Q1 A stroke involves significant reduction in blood flow to a part of the brain. It can be caused either (i) by an embolus or by intravascular clotting, which blocks blood flow to an area (approximately 85% of strokes), or (ii) by haemorrhage from a ruptured blood vessel, which compresses the brain tissue (approximately 15% of strokes). Patients with extensive atherosclerosis are at risk of intravascular coagulation and blockage of cerebral blood flow, but a vessel can be blocked by a thrombus originating in another part of the circulation. This cause of stroke is common in elderly patients >60 years of age. Aneurysms which rupture suddenly are a more common cause of stroke in younger patients. 

Knowledge of the anatomy of the blood supply of the brain is often helpful in understanding the etiology and mechanisms of TIA and stroke, which enable accurate targeting of acute treatment and secondary prevention. An awareness of the mechanisms underpinning the regulation of cerebral blood flow allows the clinician to identify patients at risk of stroke and assess the possible effects of treatments. 

Moriwaki H, Uno H, Nagakane Y et al. (2004). Losartan, an angiotensin n (ATI) receptor antagonist, preserves cerebral blood flow in hypertensive patients with a history of stroke. Journal of Human Hypertension 18 693-699... 

Traon AP, Costes-Salon MC, Galinier M et al. (2002). Dynamics of cerebral blood flow autoregulation in hypertensive patients. Journal of Neurology Science 195 139-144 van der Grond J, Eikelboom BC, Mali WPThM (1996). Flow-related anaerobic metabolic changes in patients with severe stenosis of the internal carotid artery. Stroke 27 2026-2032... 

---