Navigated TMS mapping using the grid-based algorithm to evaluate the reorganization of cortical muscle representation in amyotrophic lateral sclerosis

• Published in: Annaly kliničeskoj i èksperimentalʹnoj nevrologii (Online) Vol. 13; no. 3; pp. 55 - 62
• Main Authors: Ilya S. Bakulin, Dmitry O. Sinitsyn, Alexandra G. Poydasheva, Andrey Yu. Chernyavskiy, Natalia A. Suponeva, Maria N. Zakharova, Mikhail A. Piradov
• Format: Journal Article
• Language: English
• Published: Research Center of Neurology 01.09.2019
• Subjects: amyotrophic lateral sclerosis; biomarkers; cortical muscle representation; motor cortex excitability; motor cortex mapping; motor neurone disease; transcranial magnetic stimulation
• ISSN: 2075-5473; 2409-2533
• DOI: 10.25692/ACEN.2019.3.7

Introduction. Motor cortex mapping using navigated transcranial magnetic stimulation (TMS) is a promising method for assessing motor cortex reorganization in amyotrophic lateral sclerosis (ALS). The use of the grid-based algorithm allows the mapping protocol to be standardized and can help to reduce the variability of the assessed parameters. Study aim to analyse the reorganization features of the cortical representations of hand muscles in patients with classical ALS using navigated TMS mapping with a grid-based algorithm. Materials and methods. The study included 14 patients with classical ALS and 9 healthy volunteers. Navigated TMS mapping of the cortical representations of the right abductor pollicis brevis (APB) muscle was performed using a predetermined grid (77 square cells) centred around a hot spot. Five stimuli with an intensity of 110% of the individual resting motor threshold (RMT) were randomly applied to each cell. The RMT and area of cortical representation of the APB muscle were analysed, amplitude or probability weighted. Results. Patients with ALS showed a statistically significant decrease in the weighted amplitude of the area of cortical representations of the APB muscle compared with healthy volunteers. The RMT, area and weighted probability area of the cortical representations of the APB muscle did not differ significantly between the groups. A statistically significant correlation between RMT and severity of dysfunction and upper motor neuron damage was found in patients with ALS, based on the clinical data. There were no statistically significant correlations between cortical representation parameters and the clinical symptoms in patients with ALS. Conclusion. Navigated TMS mapping of the motor cortex with a grid-based algorithm in patients with ALS revealed a decrease in the weighted amplitude of the cortical representation area of the APB muscle. It is important to clarify the role of navigated TMS mapping with the proposed algorithm in the diagnosis, prognosis and monitoring of ALS.