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cerebrovascular event, a full bladder, nausea, pain, preexisting hypertension, a physiological response to hypoxia, or a response to increased intracranial pressure.241,242 In a study that correlated acute blood pressure values with other findings in the setting of acute stroke, Vemmos et al243 found that among patients with most subtypes of ischemic stroke, elevated blood pressure was correlated with a past history of hypertension or severity of neurological impairments. The same investigators found a U-shaped relationship between death and admission blood pressure; both elevated and low admission levels were associated with high rates of early and late death.243 They also correlated death due to brain injury and brain edema with high initial blood pressure levels. Castillo et al240 have reported similar findings. Using the data from the Glycine Antagonist in Neuroprotection (GAIN) study, Aslanyan et al244 found that an elevated baseline mean arterial blood pressure was not independently associated with an unfavorable outcome after stroke. However, elevations in mean blood pressure during the first days after stroke had an unfavorable effect on outcomes. The same investigators showed that an elevated pulse pressure (the difference between systolic and diastolic blood pressure values) was independently associated with poor outcomes 3 months after stroke.245 Theoretical reasons for lowering blood pressure include reducing the formation of brain edema, lessening the risk of hemorrhagic transformation of the infarction, preventing further vascular damage, and forestalling early recurrent stroke. In addition, urgent antihypertensive therapy may be needed to treat patients with stroke who also have hypertensive encephalopathy, aortic dissection, acute renal failure, acute pulmonary edema, or acute myocardial infarction.242,246 Conversely, aggressive treatment of blood pressure may lead to neurological worsening by reducing perfusion pressure to ischemic areas of the brain.242,247,248 In a majority of patients, a decline in blood pressure occurs within the first hours after stroke even without any specific medical treatment.241 The blood pressure often falls spontaneously when the patient is moved to a quiet room, the patient is allowed to rest, the bladder is emptied, or the pain is controlled. In addition, treatment of increased intracranial pressure may result in a decline in arterial blood pressure. There are several questions about the management of arterial hypertension in the setting of acute stroke.249–251 Should patients previously taking antihypertensive medications continue taking them during the first hours after stroke? Are some of these medications contraindicated or indicated? Should new antihypertensive agents be started? What level of blood pressure would mandate initiation of new antihypertensive treatment? Which medication should be administered in this situation? Unfortunately, definite answers to these questions are not available. Since the publication of the last guidelines, several clinical studies have provided additional information. A randomized trial testing nimodipine found that unfavorable outcomes among patients treated with the medication were associated with lowering of the blood pressure.252,253 Reanalyzing some of the data from the studies of nimodipine, Fogelholm et al254 noted that favorable outcomes were associated with higher levels of blood pressure among patients with mild to moderate strokes receiving nimodipine. The converse was true among patients with severe strokes. In a study that involved 115 patients admitted within 24 hours of stroke, Oliveira-Filho et al255 noted that systolic blood pressure dropped by ≈28% during the first day whether or not medications were prescribed. They noted an adverse effect on outcomes with lowering of the blood pressure, with an association found with degree in decline. Each 10% decline was associated with an increased odds ratio of 1.89 in unfavorable outcomes. The impact was similar to the effects of age or NIHSS scores. Castillo et al240 noted that drops in either systolic or diastolic blood pressure of >20 mm Hg were associated with early neurological
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