Nigrostriatal dysfunction in patients with amyotrophic lateral sclerosis and parkinsonism

The pathomechanism of amyotrophic lateral sclerosis (ALS) with parkinsonism (ALS-P) has not been clarified. We report two patients with ALS-P who showed dysfunction of the nigrostriatal system. The first patient showed tremor dominant, asymmetric parkinsonism which was more severe on the right side, while the second patient exhibited predominant freezing of gait. Both patients showed reduced uptake of [¹⁸F] N-(3-fluoropropyl)-2ß-carbon ethoxy-3ß-(4-iodophenyl) nortropane (¹⁸F-FP-CIT) in the posterior parts of bilateral putamina on positron emission tomography (PET). Based on our PET findings, we suggest that presynaptic nigrostriatal dysfunction may be involved in the pathomechanism of parkinsonism combined with ALS.