[Cerebral circulation and metabolism in the patients with higher brain dysfunction caused by chronic minor traumatic brain injury: a study by the positron emission tomography in twenty subjects with normal MRI findings].
Many individuals are affected on their higher brain functions, such as intelligence, memory, and attention, even after minor traumatic brain injury (MTBI). Although higher brain dysfunction is based on impairment of the cerbral circulation and metabolism, the precise relationship between them remains unknown. This study was undertaken to investigate the relationship between the cerebral circulation or cerebral metabolism and higher brain dysfunction. Twenty subjects with higher brain dysfunction caused by chronic MTBI were studied. They had no abnormal MRI findings. The full-scale intelligence quotient (FIQ) were quantitatively evaluated by the Wechsler Adult Intelligence Scale-Revised (WAIS-R), and the subjects were classified into the normal group and the impaired group. Concurrent with the evaluation of FIQ, positron emission tomography (PET) was performed by the steady state method with 15O gases inhalation. Regional cerebral blood flow (rCBF), oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO2) were calculated in the bilateral frontal, parietal, temporal, and occipital lobe. First, of all twenty subjects, we investigated rCBF, OEF and CMRO2 in all regions. Then we compared rCBF, OEF, and CMRO2 between the normal group and the impaired group based on FIQ score. We also studied the change of FIQ score of 13 subjects 9.3 months after the first evaluation. In addition, we investigated the change of rCBF, OEF and CMRO2 along with the improvement of FIQ score. Although rCBF and OEF of all subjects were within the normal range in all regions, CMRO2 of more than half of subjects was under the lower normal limit in all regions except in the right occipital lobe, showing the presence of "relative luxury perfusion". Comparison of rCBF, OEF and CMRO2 between normal group and impaired group revealed that CMRO2 of the impaired group was significantly lower than that of the normal group in the bilateral frontal, temporal, and occipital lobe. After 9.3 months, FIQ scores of 13 subjects were significantly increased. CMRO2 was significantly increased in the bilateral frontal and temporal lobe, as well as in the right occipital lobe, along with the improvement of FIQ score. It was concluded that higher brain dysfunction caused by chronic MTBI was related to malfunction of neuronal networks based on the generalized decrease of brain oxygen metabolism in all brain regions. Damage to neuronal networks in the bilateral frontal and temporal lobe appeared to play the most important role in higher brain dysfunction.
Kabasawa
Hidehiro
H
Department of Rehabilitation, Nagoya City Rehabilitation and Sports Center, Mikanyama, Yatomi-cho, Mizuho-ku, Nagoya 467-8622, Japan.
Ogawa
Tetsuo
T
Iida
Akihiko
A
Matsubara
Michitaka
M
D000293:Adolescent; D000328:Adult; D001921:Brain / Q000378:metabolism*; D020208:Brain Injury, Chronic / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006613:Higher Nervous Activity / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged