Measurement of upper limb function in ALS: a structured review of current methods and future directions

Abstract

Measurement of upper limb function is critical for tracking clinical severity in amyotrophic lateral sclerosis (ALS). The Amyotrophic Lateral Sclerosis Rating Scale-revised (ALSFRS-r) is the primary outcome measure utilised in clinical trials and research in ALS. This scale is limited by floor and ceiling effects within subscales, such that clinically meaningful changes for subjects are often missed, impacting upon the evaluation of new drugs and treatments. Technology has the potential to provide sensitive, objective outcome measurement. This paper is a structured review of current methods and future trends in the measurement of upper limb function with a particular focus on ALS. Technologies that have the potential to radically change the upper limb measurement field and explore the limitations of current technological sensors and solutions in terms of costs and user suitability are discussed. The field is expanding but there remains an unmet need for simple, sensitive and clinically meaningful tests of upper limb function in ALS along with identifying consensus on the direction technology must take to meet this need.

Upper limb movements as digital biomarkers in people with ALS

“…Monitoring of arm function with digital quantitative tools, such as accelerometers, has been challenging because arm movements are substantially affected by physiological and habitual differences between individuals and differences in individuals’ built environment. 33 As a result, upper limb activity monitoring has occurred predominantly in controlled settings with individuals performing a predefined set of activities. Under these conditions, researchers have proposed methods to recognize basic functional primitives (e.g., reaching, retrieving, idling) using heuristics (e.g., sequence of sensor orientations 34 ) or machine learning techniques (e.g., k- mean clustering 35 ).…”

“…Also, compared to the published multi-device and multi-sensor approaches and analyses, 42 , 43 the method recognizes upper limb movements from a single wrist-worn device which limits patient burden and may improve wear compliance in a free-living environment. 33 , 44 As a result, our approach could allow for comparison of metrics across other ALS studies, deeper understanding of upper limb functioning across various health conditions, and establishment of upper limb movement baselines.…”

Biomarkatzaile molekularrak Alboko Esklerosi Amiotrofikoaren diagnostikoan

“…Gaur egun, zeinuetan oinarritutako diagnostikoa azterketa elektrofisiologikoetan (elektromiografia eta nerbio-kondukzioa) oinarritzen da gehienbat [21] eta, neurri txikiago batean neuroirudi tekniketan [22,23], likido zefalorrakideoaren (LZR) analisia eta nerbio edo muskuluetako biopsiak oso gutxitan erabiltzen diren bitartean [14,24]. Dena den, oraindik ere endekapen-zeinu eta sintometan oinarritutako El Escorial irizpideak [9] eta ALSFRS-R (ALS Functional Rating System-Revised) izeneko eskala [25] dira diagnostikorako gehien erabiltzen direnak.…”