MR imaging of putamenal iron predicts response to dopaminergic therapy in parkinsonian patients

Summary

We have previously demonstrated abnormal signal attenuation in the putamen consistent with increased iron on high field strength (1.5 Tesla) MR scans in patients with Parkinson Plus syndromes. We now describe 31 therapeutically naive parkinsonian patients who underwent MR imaging prior to entering a prospective randomized blinded study comparing bromocriptine to Sinemet as primary treatment. Patients were followed for a mean of 35 months at which time the MR scans were reviewed by a blinded radiologist and compared to the clinical scores recorded by blinded observers. Ten patients were considered to have abnormal scans due to increased signal attenuation in the putamen. Total Parkinson score in these patients deteriorated from baseline by 38.8% while those with normal MR scans improved by 33% (p < 0.0001). 60% of patients with abnormal MR scans had a poor response while 75% of those with normal MR scan had a good response to drug treatment. Eight patients were suspected by the blinded observers of having evolved into a Parkinson Plus syndrome and seven of these had abnormal signal attenuation in the putamen on the initial MR scan. We propose that signal attenuation in the putamen consistent with increased iron reflects striatal damage, predicts a poor response to dopaminergic therapy and can be identified early in the course of the illness.