Neuromotor and functional assessment of the non-progressive to progressive transition in multiple sclerosis: a multiple case study

Abstract

Background The search for sensitive outcome measures that discriminate among subtypes of multiple sclerosis (MS) is important for targeting appropriate treatment and assessing the efficacy of intervention. Even more elusive are measures that can identify and track disease progression. Longitudinal studies targeted at assessing functional and neuromotor measures over time may enable us to characterize the natural history of the transition from non-progressive to progressive forms. Methods In this multiple case study, we examined functional and neuromotor measures from three individuals who were part of a large-scale longitudinal study (N=93), and for whom we captured the transition to progressive MS. All participants were tested at 3 timepoints (approximately every 12 months) across 5 domains: patient-reported (Fatigue Severity Score, Visual Analog Fatigue Scale, Activities Balance Confidence Scale, Godin Leisure Time Questionnaire), mobility function (Timed 25 Foot Walk, Timed Up and Go), sensation (vibration sensitivity thresholds of foot and hand), proprioception (ankle- and elbow- position matching, and a multi-joint finger matching task) and motor (rapid foot and hand tapping). Only descriptive data will be reported. Results One participant transitioned between the first and second visits, while two transitioned between the second and third. Across most outcome measures there was rarely a linear change identified. Particularly for the participants for which transition occurred between visits 2 and 3, the second visit (just prior to their diagnosis of progressive MS) often demonstrated an inflection point of either worsening or improvement of neuromotor measures followed by a reversal towards their baseline levels. Foot vibration sensitivity demonstrated worsening that appeared to mirror means of the larger cohort, although there was a ceiling effect. Discussion These data underscore the need for robust longitudinal studies with frequent assessments to characterize how neuromotor and functional measures change prior to, during and following the transition from non-progressive to progressive MS. The search for sensitive outcome measures that discriminate among subtypes of multiple sclerosis (MS) is important for targeting appropriate treatment and assessing the efficacy of intervention. Even more elusive are measures that can identify and track disease progression. Longitudinal studies targeted at assessing functional and neuromotor measures over time may enable us to characterize the natural history of the transition from non-progressive to progressive forms. In this multiple case study, we examined functional and neuromotor measures from three individuals who were part of a large-scale longitudinal study (N=93), and for whom we captured the transition to progressive MS. All participants were tested at 3 timepoints (approximately every 12 months) across 5 domains: patient-reported (Fatigue Severity Score, Visual Analog Fatigue Scale, Activities Balance Confidence Scale, Godin Leisure Time Questionnaire), mobility function (Timed 25 Foot Walk, Timed Up and Go), sensation (vibration sensitivity thresholds of foot and hand), proprioception (ankle- and elbow- position matching, and a multi-joint finger matching task) and motor (rapid foot and hand tapping). Only descriptive data will be reported. One participant transitioned between the first and second visits, while two transitioned between the second and third. Across most outcome measures there was rarely a linear change identified. Particularly for the participants for which transition occurred between visits 2 and 3, the second visit (just prior to their diagnosis of progressive MS) often demonstrated an inflection point of either worsening or improvement of neuromotor measures followed by a reversal towards their baseline levels. Foot vibration sensitivity demonstrated worsening that appeared to mirror means of the larger cohort, although there was a ceiling effect. These data underscore the need for robust longitudinal studies with frequent assessments to characterize how neuromotor and functional measures change prior to, during and following the transition from non-progressive to progressive MS.