ROLE OF IMPAIRED CO2 REACTIVITY IN THE DIAGNOSIS OF CEREBRAL LOW-FLOWINFARCTS

Previous studies on CO2 reactivity in cerebral low flow infarcts (LFIs ) included patients with lesions in the frontoparasagittal area, supra ganglionic white matter, and temporoparieto-occipital zone. Supragangl ionic white matter LFIs are, however, difficult to separate from non-l ow flow induced infarcts of the lacunar type, and temporoparieto-occip ital LFIs from infarcts in the territory of the inferior stem of the m iddle cerebral artery. The CO2 reactivity of the middle cerebral arter y was studied in 56 patients with high grade stenoses and occlusions o f the internal carotid artery and LFIs (n = 9) in the frontoparasagitt al border zone, territorial infarcts (n = 26), no infarcts (n = 21), a nd normal subjects (n = 25) by means of transcranial Doppler sonograph y. The aim was to investigate whether patients with LFIs have signific antly lower CO2 reactivity than patients with territorial infarcts, no infarcts, and normal subjects. Patients with LFIs had the most severe ly reduced CO2 reactivity on the symptomatic side and CO2 reactivity w as significantly lower than on the asymptomatic side. It was also lowe r than in patients with unilateral and bilateral internal carotid arte ry obstructions and territorial infarcts, asymptomatic patients, and h ealthy volunteers. It is concluded that LFIs are associated with signi ficantly reduced CO2 reactivity.