Shape Analysis of the Subcortical Nuclei in Amyotrophic Lateral Sclerosis without Cognitive Impairment

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that mainly affects the pyramidal motor system. However, recent studies have suggested that degeneration of the extramotor system plays a role in the disability experienced by patients with ALS. We investigated the local shape changes and mean volumes of the subcortical nuclei in sporadic ALS patients with preserved cognition.

The participants comprised 32 patients with ALS and 43 age- and sex-matched healthy controls. Three-dimensional T1-weighted structural images were acquired. Surface-based vertex analysis was performed with fully automated segmentation of both amygdalae, hippocampi, caudate nuclei, nuclei accumbens, putamina, pallida, and thalami, and the brainstem. The scalar distances from the mean surfaces of the individual subcortical nuclei were compared between groups, and correlations of the local shape distances with initial Amyotrophic Lateral Sclerosis Functional Rating Scale Revised (ALS-FRS-R) scores and the delta FRS-R and with the disease duration were analyzed.

ALS patients showed regional shape contractions on the lateral surfaces of both pallida, the lateroposterior surface of the right putamen, and the anterior basal surface of the right accumbens. Delta FRS-R scores were negatively correlated with local shape distances in the right hippocampus and the putamina. However, the initial ALS-FRS-R score and disease duration were not correlated with local shape distances.

Subcortical gray-matter structures are involved in the neurodegenerative process of ALS before cognitive impairment becomes evident.