Cranial computed tomography in a patient with a variant form of maple syrup urine disease.

A male infant, who was suspected to be a case of variant form of maple syrup urine disease (MSUD) has been given dietary treatment since the age of 9 months. Prior to the treatment, computed tomography (CT) showed abnormally high lucidity in the cerebral white matter area with the marked narrowness in size of the frontal horn of lateral ventricles. As the treatment proceeded, clinical symptoms alleviated, and CT findings have gradually changed with the result of improved density of the white matter. 2 months after starting the treatment, however, the patient suddenly developed a hyperaminoacidemic crisis that lasted 4-5 days. Despite this hyperaminoacidemia, CT scan taken during the crisis have revealed unexpectedly normal lucidity of the white matter as well as the normal width of the frontal horn. From these findings it was concluded that markedly lucent area in CT findings prior to the treatment was not due to an acute change in serum aminoacid concentration, but rather to chronic brain edema which had insidiously and gradually developed.