Magnetic resonance volumetry of the cerebellum in epileptic patients after phenytoin overdosages.

The aim of this study was to evaluate the relationship between phenytoin medication and cerebellar atrophy in patients who had experienced clinical intoxication. Five females and 6 males, 21-59 years of age, were examined with a 1.5-T whole-body system using a circular polarized head coil. Conventional spin echo images were acquired in the sagittal and transverse orientation. In addition, we performed a high-resolution 3D gradient echo, T1-weighted sequences at a 1-mm slice thickness. The images were subsequently processed to obtain volumetric data for the cerebellum. Cerebellar volume for the patient group ranged between 67.66 and 131.08 ml (mean 108.9 ml). In addition 3D gradient echo data sets from 10 healthy male and 10 healthy female age-matched volunteers were used to compare cerebellar volumes. Using linear regression we found that no correlation exists between seizure duration, elevation of phenytoin serum levels and cerebellar volume. However, multiple regression for the daily dosage, duration of phenytoin treatment and cerebellar volume revealed a correlation of these parameters. We conclude that phenytoin overdosage does not necessarily result in cerebellar atrophy and it is unlikely that phenytoin medication was the only cause of cerebellar atrophy in the remaining patients. Quantitative morphometric studies of the cerebellum provide valuable insights into the pathogenesis of cerebellar disorders.