Neural Substrates of Mobility and Postural Impairments in People with Multiple Sclerosis

Abstract

Background & Purpose Damage to the central nervous system is a primary corollary of multiple sclerosis (MS) and commonly results in mobility and balance impairments, placing people with MS at greater risk for experiencing a fall, thereby decreasing independence and quality of life. To date, research has largely focused on the role of the corticospinal tract in mobility and balance impairments seen in people with MS. However, evidence from lesion studies in animals suggests that the reticulospinal tract (RST), a bilateral motor neuron pathway originating in the brainstem, is critical for gross motor movements such as posture and locomotion. Methods We collected behavioral data in the form of the Mini-Balance Evaluation Systems Test from 25 MS and 25 neurotypical participants to assess gait and mobility. We then used transcranial magnetic stimulation and electromyography recordings from the tibialis anterior on both legs to assess neural communication via the RST. Lastly, we used diffusion tensor imaging as an anatomic measure of neural structure to determine if there are white matter differences in the RST. Results To date our analysis has only been performed on the behavioral data, showing that people with MS score lower on all sections of the Mini-Balance Evaluation Systems Test. By the time of this conference, we will have preliminary evidence from both of our other measures to share. Discussion Recent literature suggests that acute neural adaptations to resistance training may be mediated by the RST. Several studies have found that resistance training in people with MS increases muscle strength and functional capacity. However, the underlying neural adaptions have yet to be fully determined. Our results will highlight the RST as a key contributor to mobility deficits in people with MS and suggest that stimulation of the RST such as with resistance training could promote better balance and mobility. Damage to the central nervous system is a primary corollary of multiple sclerosis (MS) and commonly results in mobility and balance impairments, placing people with MS at greater risk for experiencing a fall, thereby decreasing independence and quality of life. To date, research has largely focused on the role of the corticospinal tract in mobility and balance impairments seen in people with MS. However, evidence from lesion studies in animals suggests that the reticulospinal tract (RST), a bilateral motor neuron pathway originating in the brainstem, is critical for gross motor movements such as posture and locomotion. We collected behavioral data in the form of the Mini-Balance Evaluation Systems Test from 25 MS and 25 neurotypical participants to assess gait and mobility. We then used transcranial magnetic stimulation and electromyography recordings from the tibialis anterior on both legs to assess neural communication via the RST. Lastly, we used diffusion tensor imaging as an anatomic measure of neural structure to determine if there are white matter differences in the RST. To date our analysis has only been performed on the behavioral data, showing that people with MS score lower on all sections of the Mini-Balance Evaluation Systems Test. By the time of this conference, we will have preliminary evidence from both of our other measures to share. Recent literature suggests that acute neural adaptations to resistance training may be mediated by the RST. Several studies have found that resistance training in people with MS increases muscle strength and functional capacity. However, the underlying neural adaptions have yet to be fully determined. Our results will highlight the RST as a key contributor to mobility deficits in people with MS and suggest that stimulation of the RST such as with resistance training could promote better balance and mobility.