A Comparative Study of the Cognitive Effects of Phenytoin and Carbamazepine in Patients with Blunt Head Injury

Studies of cognitive function have suggested that patients on carbamazepine perform better on neuropsychological testing than patients on phenytoin. Most of these studies involved patients with idiopathic epilepsy and normal controls. It is not known whether these medications have a differential effect on the cognitive functioning of patients with traumatic encephalopathies. In a retrospective study, forty-three patients were identified with blunt head injury. Fifteen patients were on carbamazepine and twenty-eight were on phenytoin (prophylactically or therapeutically), and all participated in formal neuropsychological testing within one year post-injury. A series of one-way Analyses of Variance did not reveal any differences between groups on measures of nonverbal abstract problem solving, verbal skills, visuospatial/visuomotor abilities, speed of mentation, cognitive flexibility, or overall memory functioning. Furthermore, no differences were noted on functional measures from a locally devised rating scale. These findings suggest that there may be no significant advantage to the use of carbamazepine over phenytoin when considering the cognitive functioning of patients with blunt head injury.