ALS Assessments Should Include Comprehensive Sensory Testing, Researchers Advise

Neuroimaging of patients with amyotrophic lateral sclerosis (ALS) showed degeneration of anatomical structures involved in somatosensory, visual, and auditory processing, researchers reported in the Journal of Integrative Neuroscience.

“Key subcortical hubs, white matter tracts, and cortical components of the somatosensory system are affected in ALS,” wrote a research team from Trinity College in Dublin, Ireland. “ALS should no longer be regarded as a condition exclusively involving motor and frontotemporal regions.”

The prospective neuroimaging study included 22 patients with ALS who were C9orf72 positive (C9+ ALS), 138 patients with ALS who were C9orf72 negative (C9- ALS), and 127 healthy controls. Researchers focused on cerebral gray and white matter structures involved in processing, relaying, and mediation of sensory information.

Quiz: Which of these proteins may serve as a biomarker for ALS?

Compared with healthy control subjects, C9+ ALS patients showed widespread cortical alterations in primary as well as secondary somatosensory regions, according to the study. C9- ALS patients demonstrated reduced cortical thickness in the postcentral gyrus, and volume reductions in thalamic nuclei relaying somatosensory information and in medial and lateral geniculate nuclei. C9- ALS patients also exhibited posterior thalamic radiation pathology and a trend of left medial lemniscus degeneration.

“Our radiology data confirm the degeneration of somatosensory, visual, and auditory pathways in ALS,” researchers indicated, “which is more marked in GGGGCC hexanucleotide repeat expansion carriers.”

The authors suspect the involvement of somatosensory, auditory, and visual pathways may have important clinical ramifications easily missed in the context of unremitting motor decline.

“Subtle sensory deficits may exacerbate mobility, contribute to fall risk, impair dexterity, and worsen bulbar dysfunction,” they wrote, “therefore comprehensive sensory testing should also be performed as part of the clinical assessments in ALS.”

Reference

Chipika RH, Mulkerrin G, Murad A, Lope J, Hardiman O, Bede P. Alterations in somatosensory, visual and auditory pathways in amyotrophic lateral sclerosis: an under-recognised facet of ALS. J Integr Neurosci. 2022;21(3):88. doi: 10.31083/j.jin2103088