Certain coincident (and modifiable) pathologic perturbations have been associated with worse outcomes in AIS. These include fever, hyperglycemia, and hypertension. The American Heart Association (AHA) has issued Class I recommendations that these conditions be evaluated and treated in the stroke patient.

Fever is defined as a core body temperature greater than 37.5° to 38° C. The AHA recommends that fever in stroke should be treated (though without further specific guidelines). The data to treat fever in AIS are based on observations about the effect of fever on infarct size and worse neurological outcome.^15,16,17,18 More formal studies are needed to determine exactly how and when to treat fever in AIS, but it is reasonable to use 1 g of acetaminophen for a temperature greater than 38° C.¹⁹ Fever should also prompt the clinician to consider endocarditis or CNS infection as etiologies of the focal neurological deficit.

Hyperglycemia is defined as blood glucose greater than 140 mg/dL. In both diabetic and nondiabetic patients, it has been associated with more severe stroke and worse neurologic outcome.^20,21 The reasons for this are not entirely clear, but they may involve both metabolic effects of hyperglycemia and the effect of elevated glucose on the development of brain edema.²² MRI studies of hyperglycemic stroke patients have shown that elevated blood glucose promotes production of lactate in the brain and facilitates conversion of “at risk” tissue at the penumbra of the stroke into actual infarction.²³ The emergency physician should therefore initiate insulin therapy if the blood glucose is above 185 mg/dL with the goal of achieving normoglycemia.²⁴

The issue of hypertension in acute stroke is a complex one. It certainly has been demonstrated that arterial hypertension is associated with worse prognosis in AIS.^25,26,27 However, even without pharmacologic intervention, the blood pressure of these patients often will tend to lower spontaneously,^28,29 and it is clear that precipitous falls in blood pressure can lead to worse neurological outcomes.^30,31 Because of these complexities, the AHA guidelines for when to treat hypertension in stroke are set at relatively high blood pressures. In the patient who is a candidate for thrombolysis, blood pressure should not be treated unless greater than 185/110 mmHg. In this case, pharmacologic options for lowering blood pressure are included in the box on page 14. If one of these therapies does not lower the blood pressure appropriately, the patient should no longer be considered a candidate for rTPA. Patients who are not candidates for thrombolysis should not have blood pressure treated unless greater than 220/120 mmHg.