Electroencephalogram abnormality and high-dose busulfan in conditioning regimens for stem cell transplantation.

High-dose busulfan (BU) is widely used in combined chemotherapy before allogeneic or autologous bone marrow transplantation. Convulsions are reported as a side-effect of high-dose BU. We recorded electroencephalograms (EEGs) before and on the third day of BU administration in 22 patients. Abnormal EEGs were observed on the third day in 13 cases (59%). These patients were older (P < 0.05) and had had larger doses of BU (P < 0.025) than the nine patients with normal EEGs. Convulsions occurred in two of the 22 patients, one of whom was receiving prophylaxis with phenytoin. Gamma aminobutyric acid (GABA), a natural mediator of defense against epileptic activity, concentrations in cerebrospinal fluid measured before and after administration of BU showed no definite changes.