Anterior circulation stroke

De Georgia et al. Stroke 2004 63 312-317 Prospective, randomized cooling vs. standard therapy for feasibility and safety 18 of40tx with hypothermia Hypothermia to 33°C with endovascular catheter on safety in pts with anterior circulation stroke and NIHSS >8 Similar clinical outcomes and lesion growth as measured on DWI MRI. Nonsignificant reduction in DWI volume in patients who cooled well. 

Aphasia is seen commonly in patients with anterior circulation strokes. 

Patients usually have multiple signs of neurologic dysfunction on physical examination. The specific deficits observed depend upon the area of the brain involved. Hemi- or monoparesis and hemisensory deficits are common. Patients with posterior circulation involvement may present with vertigo and diplopia. Anterior circulation strokes commonly result in aphasia. Patients may also experience dysarthria, visual field defects, and altered levels of consciousness. 

Headache is not uncommon around the time of stroke onset. It is more often severe in primary intracerebral hemorrhage than ischemic stroke, and more often severe with posterior than anterior circulation strokes. If the headache is localized at all, it tends to be over the site of the lesion. Headache is more common in cortical and posterior circulation than lacunar infarcts (Kumral et al. 1995). Severe unilateral neck, orbital or scalp pain suggests internal carotid artery dissection, particularly if there is an ipsilateral Horner s syndrome. Severe occipital headache can occur with vertebral artery dissection. Headache is also a particular feature of venous infarcts. Unusual headache in the days before stroke would suggest giant cell arteritis or perhaps a mass lesion rather than a stroke. 

L, Sorensen AG, Singhal AB. Stability of large diffusion/ perfusion mismatch in anterior circulation strokes for 4 or more hours. BMC Neurol. 2010 10 13... 

More recent studies have further refined the impact of core on cUnical outcome. Two studies have demonstrated that in anterior circulation strokes, an acute DWl lesion volume >70 mL has a high specificity for poor outcomes with or without therapy [223, 224], revising the earlier suggestion that 100 mL is the core volume cutoff for poor outcomes. In acute stroke patients treated with lAT between 3 and 6 h of stroke onset, core size was the best predictor of clinical outcome at three months [225]. In particular, any increment of 1 SD (13.2 mL) of the infarct core size increased the mRS score by about one point, whereas any increment of 1 SD (5.8 points) of admission NIHSS score raised the mRS by approximately 0.5 points. 

The largest study to date involving 109 patients with anterior circulation strokes was recently reported by Copen et al. [27]. All patients had diffusion/perfusion MRl within 24 h of stroke onset, and more than 50% had DWl/MTT mismatch volume of 160% or greater. This mismatch was most common among patients with proximal artery occlusions involving the distal internal carotid artery and/or the proximal middle cerebral artery identified by CTA or MRA. Of particular interest was the observation that there was no difference among patients who were scanned at different times after ictus 69% of patients who were scanned within 9 h had a 160% mismatch, which was very similar to the 68% of patients who were scanned after 9 h. The authors concluded that persistence of mismatch after 9 h is common and occurs most often in patients with proximal occlusions of the anterior circulation. 

The precise location of the occlusion provides further information regarding prognosis and response to therapy. In general, arterial occlusions that arise more proximally are associated with worse outcomes, with terminal ICA occlusions having the poorest outcomes among anterior circulation strokes [23, 32, 33]. A... 

Consider terminating infusion of thrombolytic by 8 h in anterior circulation stroke. Consider early angioplasty stenting for severe stenosis or occlusion of the extracranial carotid artery. 

Acute ischemic stroke s3miptoms with onset or last known well, clearly defined. Treatment within 6 h of established, nonfluctuating deficits due to Anterior Circulation (carotid/MCA) stroke, between 6 and 8 h mechanical treatment (e.g.. Concentric Retriever) should be considered. The window of opportunity for treatment is less well defined in posterior circulation (vertebral/basilar) ischemia, and patients may have fluctuating, reversible ischemic symptoms over many hours or even days and stiU be appropriate candidates for therapy. 

Using only a few neurological findings the Oxfordshire Community Stroke Project (OCSP) classification allocates strokes to four subgroups, locating them either in the territory of the anterior (total anterior circulation infarct, TACI partial anterior circulation infarct, PACI lacunar infarct, LACI) and the posterior circulation, (posterior circulation infarct, POCI) (Bamford et al. 1991). The OCSP is a clinical syndromic classification, which... 

Subcortical white matter infarcts may mimic a superficial MCA infarct causing a partial anterior circulation syndrome or present as a lacunar syndrome (pure motor, ataxic hemiparesis or sensori motor stroke). Superficial perforating artery infarcts (medullary branches) are often accompanied by cortical spotty lesions. Borderzone and white matter medullary branches infarctions are usually caused by hypoperfusion due lo large vessel occlusion or stenosis (Bogousslavsky 1993 Donnan and Yasaka 1998), but white matter medullary branches infarction can also be caused by cardioembolism (Lee et al. 2003). 

A study by Georgiadis et al. (31) induced hypothermia (target temperature 33°C) in 14 patients with an acute anterior circulation infarction involving at least two thirds of the left MCA territory. Patients received norepinephrine via continuous intravenous infusion and were mechanically ventilated. Hypothermia was initiated 26 h after onset of symptoms as a means to control intracranial hypertension and not for neuroprotection. In that study, static cerebral autoregulation did not appear impaired in the unaffected hemisphere with the use of alpha-stat for pH maintenance. However, the main concern in patients with acute stroke is the perfusion of the affected hemisphere, specifically of the penumbra (18). 

Mrs SL, aged 75, is admitted to hospital unable to speak, swallow or move her right arm and leg, having collapsed when out to dinner with her son. She has an urgent CT scan which reveals an ischaemic stroke of the partial anterior circulation (PAC) type. She had a transient ischaemic attack (TIA) two weeks ago and her son says she has had them infrequently for the last year. She has been treated for hypertension and high cholesterol for the past 2 years and has been taking aspirin. 

It may be difficult to distinguish between some partial anterior circulation syndromes and a lacunar stroke. 

Some overlap exists between the clinical classification (Bamford et al. 1991) and the etiological TOAST classification. In a large hospital-based series of patients with ischemic stroke, total and partial anterior circulation infarcts were most likely to be caused by large artery atherosclerosis, cardioembolism or both (Wardlaw et al. 1999). 

Total anterior circulation syndromes or brainstem strokes often cause some drowsiness, but in smaller lesions, consciousness is normal. Therefore if consciousness is impaired and yet the focal deficit is mild, it is important to ... 

So far predictive models only apply to a small proportion of patients and are not sufficiently accurate to inform treatment decisions in routine clinical practice. The various subtypes of ischemic stroke have very different outcomes patients with total anterior circulation infarction (TACI) have just as poor an outcome as those with primary intracerebral hemorrhage (Table 16.1). The best single predictor of early death is impaired consciousness, but many other predictors of survival have been identified (Table 16.2). Many of these variables are inter-related, but prognostic models based on independent variables do not provide much more information than an experienced clinician s estimate (Counsell and Dennis 2001 Counsell et al. 2002). 

Fig. 9.5 Stability of perfusion/diffusion mismatch for 4 h. Serial MRl scans that included diffusion and perfusion were acquired in 14 patients. Patients presented at an average of 7.1 h after stroke onset. All the 14 patients had anterior circulation proximal artery occlusion and were not eligible for thrombolytic...

Fig. 9.9 Prevalence of significant diffusion/perfusion abnormality up to 24 h after stroke onset. Data is from a study of consecutive patients presenting to the Emergency Department with acute ischemic stroke with demonstration of a proximal cerebral artery occlusion involving the anterior circulation identified by...

AIS is the third leading cause of death and the leading cause of severe disability in adults. There are 795,000 strokes annually in the U.S., of which 692,000 (87%) are ischemic [2], Proximal intracraiual artery occlusions (RAO) account for approximately 20-40% of ischemic strokes, but produce the preponderance of stroke-related morbidity and mortality (Figs. 12.1-12.3) [3-5]. The vast majority of these proximal occlusions occur in the anterior circulation [6-8] and this chapter is primarily focused on them. 

Parenchymal imaging to characterize the infarct core and the ischemic penumbra follows the identification of a treatable anterior circulation arterial occlusion in considering whether to proceed to endovascular recanalization. Even with endovascular therapy, greater than half (54-72%) of acute stroke patients with proximal artery occlusions have a poor outcome, and a significant fraction (16-44%) are dead at 90 days [47]. Certainly some of this morbidity and mortality are related to suboptimal or delayed reperfusion, but a significant proportion is likely secondary to infarcts that have already completed or are near completion before the initiation of therapy [47]. The major issue is the lack of appropriate patient selection. 

---