Quantitative PET findings in patients with posttraumatic anosmia

Objective: To investigate quantitative positron emission tomography (PET) f indings, particularly from orbitofrontal cortex. in patients with posttraum atic anosmia. Setting: Neuropsychology outpatient clinic and university bra in imaging center. Subjects: Eleven patients with head injury resulting in severe anosmia and 11 controls matched for age. All 11 head-injured patient s had their head injuries at least 2 years before involvement in the study Measures: Regional cerebral glucose metabolism was measured with PET. Resul ts: Quantitative evaluation of PET findings fur anosmic patients as a group showed orbitofrontal hypometabolism compared with controls. Decreased acti vity was also noted in mesial temporal lobe. Activity in subcortical white matter was essentially identical between groups. Conclusions: Findings stro ngly suggest that posttraumatic anosmia is closely associated with hypometa bolism in the orbitofrontal cortex and the medial prefrontal cortex. The re sults also underscore the importance of posttraumatic anosmia as a clinical sign of orbitofrontal damage, as has been shown previously with neuroSPECT (single photon emission computed tomography).