title: EEG suppression and increased blood-brain barrier permeability following intracarotid injection of iothalamate meglumine (Conray) in dogs.
abstract: Over a 2-year period we observed three cases of unilateral suppression of the electroencephalogram (EEG) lasting from 45 s to 4 min following intracarotid injection of 60% iothalamate meglumine (Conray) for intraoperative carotid angiography postendarterectomy. As a result of these cases we undertook studies in 11 dogs anesthetized with isoflurane to examine causes of EEG suppression following intracarotid contrast medium injection. In group 1 (n = 6) cerebral blood flow (CBF), the cerebral metabolic rate for oxygen (CMRO2), EEG activity, and permeability of the blood-brain barrier (BBB) were determined. In group 2 (n = 5) cerebrospinal fluid (CSF) pressure, EEG activity, and BBB permeability were determined. Intracarotid injection of 5 ml of 60% Conray was associated with unilateral EEG suppression and increased BBB permeability in 1 of 11 dogs. Injection of contrast material caused no change in CBF or CMRO2 and caused a statistically significant but physiologically unimportant increase of CSF pressure (from 12 +/- 1 to 16 +/- 1 cm H2O, mean +/- SEM). It is concluded that EEG suppression following intracarotid injection of Conray is a rare event. It seems unlikely that EEG suppression resulted from cerebral ischemia or hypoxia, but rather was associated with increased BBB permeability. Increased BBB permeability likely was caused by the osmotic effect of Conray and not by hypoxic-ischemic microvascular injury or loss of autoregulation of CBF.
authors.affiliation: Department of Anesthesiology, University of Washington School of Medicine, Seattle, Washington, USA.
authors.forename: A A
authors.initials: AA
authors.lastname: Artru
authors.forename: D
authors.initials: D
authors.lastname: Stout
authors.forename: R A
authors.initials: RA
authors.lastname: Katz
authors.forename: P R
authors.initials: PR
authors.lastname: Freund