Single photon emission computed tomographic evaluation of brainstem release phenomenon and seizure in neonates

We report the ictal brain single photon emission computed tomographic (SPEC T) findings in two neonates. One neonate had hypoxic-ischemic encephalopath y, a disorganized discontinuous electroencephalogram (EEG) background, leth argy, seizures, and brainstem release phenomena. A brain SPECT was performe d during a brainstem release phenomenon characterized by a 34-second sustai ned tonic posture of the right arm and chewing. It did not reveal focal cer ebral hemisphere hyperfusion. The second neonate had hemimegalencephaly, lo w-voltage irregular EEG background, and seizures. A brain SPECT was perform ed during a seizure characterized by a 32-second sustained tonic posture of the right arm. It revealed focal hyperperfusion in the posterior region of the left hemisphere. The brain SPECT findings in these patients indicate t hat despite clinically similar events, brainstem release phenomena and seiz ures have different perfusion characteristics, and refute the theory that b rainstem release phenomena are due to epileptic foci in the cerebral hemisp heres undetectable by EEG.