Effects of prolonged walking on dual-task walking performance in persons with multiple sclerosis

Abstract

Objective: Motor impairment and fatigue perception may affect walking automaticity. We aimed to investigate the effect of prolonged walking administered by the 6-Minute Walk Test (6MWT) on motor-cognitive dual-task performance in persons with multiple sclerosis (pwMS) with different levels of disability compared to healthy controls (HC). Methods: A total of 50 pwMS [30 mildly disabled (EDSS<4.0), 20 moderately-severely disabled (EDSS 4.0 to 6.5)] and 29 age-and sex-matched HC were included. Spatiotemporal gait parameters during single (overground walking for 30 sec) and dual-task walking (overground walking for 30 sec with word list generation task) were assessed before and immediately after the 6MWT using three inertial gait sensors. The dual-task cost (DTC) of gait parameters was calculated as change (in percentage) between the dual-task to the single-task conditions. Perceived walking difficulties , fatigue, history of falls, fear of falling, and perceived dual-task difficulties were evaluated via self-report questionnaires. Results: PwMS with moderate-to-severe disability group had a significant deterioration in cadence, speed, double support, and asymmetry during dual-task walking after the 6MWT. However, there was no change in mildly disabled pwMS, and HC demonstrated better scores in cadence, speed, and gait variability after the 6MWT. As for the DTC, while mildly disabled pwMS (in speed and gait variability) and HC (in double support, cadence, and gait variability) showed improvements, no significant difference was found in moderate to severely disabled pwMS. Cognitive task performance incremented solely in HC following the 6MWT. Change in DTC was correlated to self-reported walking disability, fatigue, and perceived dual-task difficulties (r =-0.301 to-0.337) in pwMS. Conclusion: Prolonged walking affects severely disabled pwMS regardless of the cognitive task. This suggests that they focus more on walking than cognitive task performance. Mildly disabled pwMS and HC could maintain gait automatization and even reduce DTC after 6MWT, suggesting that 6MWT may not be sufficient to induce performance fatigability as measured by dual-task performance in mildly disabled pwMS and may even make gait more dynamic. Progressive multifocal encephalopathy (PML) is a potentially fatal opportunistic infection of the central nervous system by John Cuningham virus. We report on a multidisciplinary rehabilitation in a 45-year-old female suffering from PML after 20 natalizumab infusions. After natalizumab discontinuation immune reconstitution inflammatory syndrome (IRIS) developed leading to additional deterioration of the neurological disability of the patient. Initial right sided hemiparesis slowly progressed to hemiplegia, later left sided hemipa-resis appeared as well as motoric dysphasia so she became bedridden and completely dependent in activities of daily living (ADL). Physiotherapy treatment focused on deterioration of posture control , sensorimotor skills of the right-sided limbs and gait pattern. Exercises for postural stability and movement control were performed. Occupational therapy (OT) focused on maintaining ADL, underlying fatigue and sensory-motor impairment in right upper limb. After the deterioration of her health condition, physiotherapists implemented gradual verticalization and bed-wheelchair transfer. OT then focused on body positioning and impairments in both upper limbs, along with improving attitude to her current life situation. Clinical psychologist was included to provide psychological support and improve communication. We used basic cogni-tive behavioural model, relaxation techniques, normalisation, guided imagery for stress relief and regulation of mood. Speech language pathologist treatment was indicated when deviations in the quality and intelligibility of speech and communication appeared. Communication was maintained through closed-ended, dichotomous questions. With the progression of speech apraxia, the Augmentative and Alternative Communication board was introduced. Apraxia of speech persists at the forefront and significantly disables the patient in everyday communication. Multidisciplinary rehabilitation was essential in maintaining patient's functional level, preventing further decline as well as helping the neurologist monitor disease progression of her primary diagnosis as well as IRIS and in this way influence further diagnostic and therapeutic decisions.