[MRI findings in schizophrenic patient with frontal lobe atrophy]

Abstract

In schizophrenic patients, cognitive and behavioral deficits are often associated with frontal lobe dysfunction. By functional neuroimaging studies, abnormalities of the frontal lobe (especially the prefrontal lobe) have been detected in schizophrenic patients. As for morphological changes on neuroimaging, lateral lobe atrophy and enlargement of the lateral ventricles or third ventricle are often reported, but there is no consensus as to whether frontal lobe atrophy is seen more frequently in schizophrenic patients compared with normal controls. The reasons for this disagreement include variations in the precision of measurement on MRI, differences in the methods of MRI among studies, and biases in the subjects being evaluated. Here we present a patient with schizophrenia and frontal lobe atrophy, which was clearly recognized on MRI and showed no progress in the 2 years following its detection. The patient was a 26-year-old woman with a 4.5-year history of schizophrenia when she was referred to us for the treatment of persistent auditory hallucinations and delusions. She showed no neurological findings apart from her psychiatric symptoms. Head MRI showed mild atrophy of the frontal lobe, and the extent of atrophy did not change over the following two years. On resting SPECT 99mTc-HMPAO, hypoperfusion of the bilateral frontal regions was demonstrated. There were no significant findings in the temporal lobe on either MRI or SPECT. She achieved low scores in neuropsychological tests of intelligence, memory, and frontal lobe-associated functions, and showed almost the same degrees of impairment in all of the tests in 2 years of follow-up. The possibility of degenerative diseases, such as young-onset frontotemporal dementia, was ruled out. She had a low intelligence quotient in the WAIS-R and her answers showed the specific pattern which is commonly seen in schizophrenic patients. There is a possibility that hypoperfusion on resting SPECT reflected not only frontal lobe atrophy, but also frontal lobe dysfunction in this patient. Frontal lobe dysfunction in schizophrenics is generally considered to be a secondary effect of meso-limbic system pathology. In this patient, however, the dysfunction seemed to arise from an intrinsic disorder of the frontal lobe, because frontal lobe abnormalities were conspicuous, whereas the temporal lobe was almost normal on both MRI and SPECT.