Structural and Functional Neuroimaging in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal progressive disorder of the central nervous system affecting the upper and lower motor neurons. It is important to study the specific nature of the disease course and the character of neurodegenerative process expansion in ALS, since no effective methods of treatment for this disease have been developed yet. Despite the clear evidence of multisystem brain damage in ALS, there are no objective biomarkers of the upper motor neuron lesion and extramotor brain areas involvement. In recent years, structural and functional neuroimaging, such as MR-morphometry, diffusion-tensor magnetic resonance imaging, MR spectroscopy, functional MRI, positron emission tomography (PET), etc., have been playing a significant role in research on ALS. This review analyzes the results of neuroimaging methods in the context of their application for diagnostics, prediction, and monitoring the ALS course. The most sensitive and specific techniques to diagnose the disease are diffusion-tensor MRI, MR spectroscopy, PET, a combination of several neuroimaging methods, and neuroimaging with transcranial magnetic stimulation. Diffusion-tensor MRI and MR spectroscopy can be used to monitor and predict the disease course. The main limitations and weak points of the published studies on this topic, as well as the prospective for neuroimaging in ALS, are discussed.