Ifosfamide encephalopathy: a reappraisal.

Eighteen consecutive cases of encephalopathy occurring after ifosfamide/mesna chemotherapy were prospectively assessed. No relationship was found with tumour type or chemotherapy response. Onset was from 12 to 146 (mean 46) h after the start of the infusion and median duration was 3 days (range 1-12). In two patients recovery was incomplete. A confusional state and agitation were the major clinical features. Plasma potassium fell from a mean of 4.12 mmol/l before chemotherapy to 2.94 mmol/l at the onset of encephalopathy (P less than 0.001) with plasma potassium less than 3.0 mmol/l in 10 patients. Duration of hypokalaemia was not related to duration of encephalopathy. Median survival following encephalopathy was 25 days. The incidence of encephalopathy in 82 patients treated on two protocols was 11% and the sensitivity of a published nomogram was 18%. It is concluded that ifosfamide/mesna encephalopathy is a serious complication which may be irreversible and remains difficult to predict.