NEUROBEHAVIORAL EFFECTS OF PHENYTOIN AND CARBAMAZEPINE IN PATIENTS RECOVERING FROM BRAIN TRAUMA - A COMPARATIVE-STUDY

Objective: To compare the effects of prophylactic anticonvulsant use o f phenytoin and carbamazepine on the cognitive and emotional status of the patient after brain injury. Design: Double-blind, placebo-control led study with assessments before and after withdrawal from drug treat ment. Setting: Patients had been initially treated by neurosurgeons at a university hospital and were followed up during the study on an out patient basis. Patients: Forty of 64 patients receiving phenytoin and 42 of 127 patients receiving carbamazepine from 6 to 44 months for sei zure prophylaxis after brain injury met study criteria and were assign ed to continue or discontinue treatment. Groups were balanced for age, sex, race, weight, intelligence, type of injury, duration of therapy, and drug plasma concentration at screening. Intervention: A battery o f neuropsychological tests was administered twice during a dr-week bas eline period, at the end of a 4- to 5-week period of continued drug tr eatment or placebo, and after 4 weeks of not receiving medication. Mai n Outcome Measures: Attention and concentration, psychomotor speed, me mory, verbal fluency, and emotional state. Results: No significant dif ferences were found in the performance of patients in medication and p lacebo groups for either drug at the end of the placebo phase. Patient s in the combined groups showed significant improvement (P<.01) on sev eral measures of motor and speeded performance following cessation of drug treatment. Multivariate analyses showed additional differences be tween phenytoin and carbamazepine and also suggested a significant pra ctice effect on some measures used. Conclusions: Both phenytoin and ca rbamazepine seem to have negative effects on cognitive performance, pa rticularly on tasks with significant motor and speed components. Pract ice effects were noted and may account for much of the improvement whe n patients stopped taking the drugs. Overall effects of the drugs were small and of limited clinical significance, but differences among sub jects were noted that may affect selection of a particular drug for th e individual patient.