Technetium-99m HM-PAO Brain SPECT in Epileptic Patients Before and During Unilateral Hemispheric Anesthesia (Wada Test): Report of Three Cases

The lipophilic brain SPECT agent ["Tcjhexamethyl propylene amine oxime (HM-PAO) was used in three cases before and during unilateral anesthesia of one hemisphere for lateralization of speech dominance (Wada test). This procedure led to a decrease of regional cerebral blood flow (rCBF) in each of the hemispheres to 55 and 90%, respectively. Diminution of rCBF was significantly more pronounced in the dominant hemisphere. A second phenomenon observed during the Wada test was crossed cerebellar diaschisis. These findings support the assumption that HM-PAO allows monitoring of brain perfusion, as rapid changes of rCBF due to decreased neuronal activity cause respective alterations of cerebral and cerebellar uptake of this new brain agent. J NucÃ-Med 28:1763-1767,1987 kJingle photon emission computed tomography (SPECT) of the brain with iodine- 123-labeled amphet amine derivatives has become a routine diagnostic pro cedure for the lateralization and localization of epileptic foci (1-4). However, since 1985 a lipophilic eliciate o