Pallidoreticular lesion in carbon monoxide intoxication by gradient echo: report of a case with parkinsonism features and review of the literature.

PURPOSE Pallidoreticular damage was defined by lesions involving both the pallidum and the substantia nigra and was only reported in four cases after CO intoxication. CASE REPORT We report a patient with initial consciousness disturbances followed by parkinsonian features after carbon monoxide intoxication. The unique features in this patient included primary globus pallidus hemorrhage followed by delayed hemorrhage in pallidoreticular topography demonstrated by T1- and T2-weighted imaging. In the follow-up study 7 months later, the patient still presented with parkinsonism features and executive dysfunction while the pallidoreticular signal was only visible by gradient echo sequences but not the other MR conventional sequences. Hypometabolism in the frontal and basal ganglion regions were evident from 99mTc-TRODAT-1 study and partial responsiveness to levodopa in alleviating parkinsonian features was considered. CONCLUSION This case highlights the delayed development of pallidoreticular damages and its linkage in modulating prefrontal-subcortical neuronal circuits.