Steele‐Richardson‐Olszewski‐Syndrome: Reduction of dopamine D ₂ receptor binding relates to the severity of midbrain atrophy in vivo: ¹²³ IBZM SPECT and MRI study

Abstract

Patients with the clinical diagnosis of progressive supranuclear palsy (PSP) show heterogeneous neuropathological findings. In neuropathologically proven cases with numerous neurofibrillary tangles of neuropil threads, the brainstem and striatum are always affected. We compared (123)I-iodobenzamide single photon emission computed tomography (IBZM-SPECT) for imaging of striatal dopamine D(2) receptors in vivo with high-resolution magnetic resonance imaging (MRI) in 13 patients with possible or probable PSP. Clinically, all patients exhibited similar signs including supranuclear vertical-down-gaze palsy, axial rigidity especially involving the neck, bradykinesia, instability of balance with easy falls, and a poor response to dopaminergic drugs. Specific striatal dopamine D(2) receptor binding in IBZM-SPECT was reduced in 10 patients but was normal in three patients. Mean midbrain diameter was 23.7 mm. The reduction of IBZM-binding was statistically significantly correlated to midbrain atrophy (P = 0.010) either in all 13 patients or in those without striatal or white matter lesions (P = 0.015). We suggest that technical investigations, mainly MRI, are able to corroborate the in vivo diagnosis, if PSP is clinically suspected.