Characterization of the nigroestriatal system in a sample of patients with amyotrophic lateral sclerosis.

Background: The coexistence of amyotrophic lateral sclerosis (ALS) with clinical forms of Parkinson disease (PD), although uncommon, is found to a greater degree than one would expect by chance. The pathological mechanisms of ALS and PD are still not fully understood, and the coexistence of these two diseases suggests that they could share mechanisms in common.

Objective: Here we present a sample of patients with clinically definitive or probable ALS who were evaluated with single-photon emission computed tomography SPECT/TRODAT and compared with non-ALS controls.

Methods: Patients with clinically definite or probable ALS were assessed with the amyotrophic lateral sclerosis functional rating scale (ALSFRS) to define severity and had their demographic data collected. The TRODAT results of patients with ALS were compared with those of patients with a diagnosis of PD with less than 10 years of duration, and with patients with a diagnosis of others movement disorders not associated with neurodegenerative diseases.

Results: A total of 75% of patients with ALS had TRODAT results below the levels considered normal; that was also true for 25% of the patients in the control group without neurodegenerative disease, and for 100% of the patients in the PD group. A statistically significant difference was found between patients with ALS and the control group without neurodegenerative disease in the TRODAT values < 0.05.

Conclusions: Our study fits with the neuropathological and functional evidence that demonstrates the existence of nigrostriatal dysfunction in patients with ALS. Further research to better understand the role of these changes in the pathophysiological process of ALS needs to be performed.