CRANIAL COMPUTERIZED TOMOGRAPHY IN PHENYLKETONURIA1

Abstract

To our knowledge there have been no previous studies on children with phenylketonuria using cranial computerized tomography. Besides microscopic changes in the form of status spongiosus and signs of demyelinization, neuropathological studies have also shown macroscopic changes in the brain of PKU patients. The changes observed in adults and untreated PKU patients were microcephaly, a disproportion within the cerebral regions, a tendency to pachygyra and focal demyelinization in the subcortical white matter. Pneumencephalographic and sonoencephalographic studies on children with phenylketonuria reported signs of cerebral atrophy, in particular in patients who were treated at a late stage. In order to understand the present morphological changes, cranial computerized tomography was carried out on 8 mentally retarded PKU patients who manifested neurological and pathological EEG changes. As a control group, 5 patients with classical PKU who had been treated at an early stage and a child with hyperphenylalaninemia were examined. Indications of a myelinization defect were found in only one mentally retarded patient in the form of hypodensic areas in the region of the white matter, accompanied by cortical atrophy. This patients was known to have had an extremely abnormal postnatal course with generalised cyanosis in the first week of life. Advanced cortical atrophy was found in a patient diagnosed at a very late stage who had suffered from pneumococcus meningitis during infancy. Computerized tomography showed a slight enlargement of the cysterna interhemisphaerica of the cerebellum in a severely retarded female patient who had been diagnosed very late. Thus, we were able to find pathological results in the form of advanced cerebral atrophy in only two patients, with indications of hypoxy or meningitis, while computerized tomography produced normal results from two children who were seriously retarded and had been diagnosed very late. This suggests that the described pathological changes are probably not due to PKU. No significant deviation in density values for white or gray matter was found between the retarded patients and the children who developed normally and were treated early (apart from 3 late treated cases with relative higher values for white matter, possibly due to motion artifacts).