The effectiveness of O2 administration for transient ischemic attacks in moyamoya disease in children.

Moyamoya disease is a cerebrovascular obstructive disease of unknown etiology. The rebuild-up phenomenon, slowing of waves on electroencephalogram (EEG) seen after cessation of hyperventilation (HV), is one of the characteristic phenomena of the disease and is thought to be related to a development of its symptoms. Therefore, we investigated the mechanism involved in the rebuild-up phenomenon to clarify the mechanism of development of transient ischemic attack (TIA) in moyamoya disease. Ten patients with moyamoya disease were studied; they ranged in age from 7 to 17 years. The power spectra of the EEGs in the occipital region were obtained with a Berg Fourier EEG analyzer for quantitative analysis. Arterial blood gas change (pH, PaO2, PaCO2), respiratory pattern (abdominal and nasal), tidal volume and respiratory rate were analyzed simultaneously every 30 s-1 min before, during, and after HV. The slow wave power spectrum (rebuild-up) increased and symptoms of TIA developed as a result of the sharp decrease in PaO2 (PaO2 60.5 +/- 15.4 mmHg) after cessation of HV. Based on the fact that hypoxemia was playing a main role, 100% oxygen was administered at a rate of 0.5 l/min in 4 cases where the rebuild-up phenomenon was clear. The EEG power spectra and arterial blood gas were analyzed during rebuild-up with and without O2 administration. The effectiveness of O2 administration at the beginning of rebuild-up as measure to prevent the symptoms was checked by a recovery rate of slow wave power percentage, a recovery time of slow wave power percent and by clinical observation. The recovery rates were 11.8 +/- 4.2%/min and 5.5 +/- 4.0%/min with and without O2 inhalation, respectively (P < 0.001). Recovery times of slow wave power percentage were 4.3 +/- 1.8 min and 8.1 +/- 1.2 min with and without O2 inhalation, respectively (P < 0.01). Thus, oxygen administration soon after the cessation of HV was shown to be effective in eliminating the rebuild-up phenomenon and hence in abolishing its symptoms.