THE FUNCTIONAL NEUROANATOMY OF TOURETTES-SYNDROME - AN FDG-PET STUDY .2. RELATIONSHIPS BETWEEN REGIONAL CEREBRAL METABOLISM AND ASSOCIATED BEHAVIORAL AND COGNITIVE FEATURES OF THE ILLNESS

We analyzed F-18 fluoro-deoxyglucose PET scans carried out in 18 drug- free patients with Tourette's syndrome (TS) in order to evaluate relat ionships between cerebral metabolism and complex cognitive and behavio ral features commonly associated with this disorder. These features (o bsessions and compulsions, impulsivity, coprolalia, self-injurious beh avior, echophenomena, depression, and measures of attentional and visu ospatial dysfunction) were associated with significant increases in me tabolic activity in the orbitofrontal cortices. Similar increases, alt hough less robust, were observed in the putamen and, in the case of at tentional and visuospatial measures, in the inferior portions of the i nsula. On the other hand, behavioral and cognitive features were not a ssociated with metabolic rates in other subcortical (midbrain, ventral striatum), paralimbic (parahippocampal gyrus), or sensorimotor region s (supplementary motor area, lateral premotor or Rolandic cortices), i n which metabolism had, in some cases more robustly, distinguished the se TS patients from controls (Braun et al., 1993). These results sugge st that a subset of regions in which metabolic activity appears to be associated with the diagnosis of TS per se, may be explicitly associat ed with the emergence of complex behavioral and cognitive features of the illness. This is most conspicuous in the orbitofrontal cortices, a nd if is consistent with the observation that these features resemble the elements of a behavioral syndrome typically seen in patients with lesions of the orbitofronfal cortex.