CLINICAL PROGRESSIVE SUPRANUCLEAR PALSY - DIFFERENTIAL-DIAGNOSIS BY IBZM-SPECT AND MRI

In order to in vivo identify subgroups in eight patients with the clin ical diagnosis of progressive supranuclear palsy (PSP), we have perfor med I-123-iodobenzamide single photon emission computed tomography (IB ZM-SPECT), a nuclear medicine technique, to visualize dopamine D2 rece ptors in vivo, and high resolution (TE/TR 2900/20-90) magnetic resonan ce imgaging (MRI) to evaluate morphological CNS changes. All patients exhibited similar clinical features including supranuclear vertical ga ze palsy, especially of downward gaze, predominantly axial rigidity es pecially in the neck, bradykinesia, instability of balance with easy f alls, and poor response to dopaminergic drugs. Specific striatal dopam ine D2 receptor binding in IBZM-SPECT, as calculated by a basal gangli a to frontal cortex ratio (BG/FC) was reduced in 5 patients, but norma l in 3 patients. In MRI, these 3 patients exhibited multiple hyperinte nse white matter lesions; 2 of them had no midbrain atrophy. In contra st, all 5 patients with reduced IBZM binding lacked multiple white mat ter lesions in MRI, but 4 of them showed marked midbrain atrophy. This pilot study with IBZM-SPECT for in vivo, imaging of striatal dopamine D2 receptors and T2-weighted MRI supports published neuropathological findings that clinical signs of PSP appeared to be due to heterogeneo us neuropathology.