Stevens-Johnson syndrome in patients on phenytoin and cranial radiotherapy

The use of phenytoin as a prophylactic anticonvulsant after brain surgery, particularly for brain tumors, is a common practice, regardless of whether the patient has a previous history of convulsions. This treatment policy as sumes that the benefits exceed the risks. Four cases are described of adver se reactions to phenytoin during the concomitant use of cranial radiotherap y. In one patient this proved fatal. There is increasing anecdotal support in the literature for a synergistic effect between phenytoin therapy and cr anial radiotherapy that can result in the life-threatening Stevens-Johnson syndrome. While the association is uncommon, Four cases within 24 months in one department suggest that the routine use of postoperative phenytoin as a prophylactic anticonvulsant in thr absence of a history of seizures may n ot be warranted, particularly if the patient is to receive cranial radiothe rapy.