Related Experiment Video
Updated: Feb 9, 2026

ALS - Motor Neuron Disease: Mechanism and Development of New Therapies
Published on: July 29, 2007
Trajectory of Mobility Function Decline for People With Motor Neuron Disease
Trinh Sia1, Timothy P Sheehy1, Prue Morgan2
1Statewide Progressive Neurological Disease Service, Calvary Health Care Bethlehem, Melbourne, Victoria, Australia.
Objectives:
The primary aim of this study was to explore factors that may influence the rate of mobility function decline. A secondary aim was to identify the impact of neck weakness on mobility decline in people living with motor neuron disease (MND).
Design:
Retrospective, longitudinal observational study design.
Setting:
This study was conducted at a Statewide Progressive Neurological Disease Service (SPNDS) in inpatients, outpatients, and community-based services. The SPNDS clinic treats adults with MND from both metropolitan and rural settings.
Participants:
Adults with MND attending the SPNDS were recruited to participate in the study.
Interventions:
Not applicable.
Main Outcome Measures:
Categorical data relating to mobility function (walking endurance, gait aid used, and level of assistance required) were recorded. Neck weakness was measured as present or absent based on the participant's subjective report and/or objective observation of head position when upright.
Results:
Results from the 358 participants recruited showed that the median time to loss of independent gait was 30.5 months (range, 4-239; interquartile range [IQR], 26), full-time wheelchair use was 34 months (IQR, 35; range, 5-238), and median time to becoming housebound was 28 months from MND symptom onset (IQR, 24.5; range, 5-219 mo). A total of 141 (39.4%) participants had neck weakness. The presence of neck weakness resulted in earlier loss of independent gait and quicker to become housebound. There was no significant difference in time to full-time wheelchair use between participants with or without neck weakness.
Conclusions:
There was an effect of both phenotype and neck weakness on the trajectory of mobility function decline in people with MND. Overall, people with amyotrophic lateral sclerosis phenotype (bulbar, cervical, or lumbar onset) experienced a more rapid rate of decline in mobility function than those with flail limb and primary lateral sclerosis phenotypes. In addition, those demonstrating neck weakness were quicker to decline in mobility than those without neck weakness.
Related Concept Videos
Orthogonal Trajectories
Magnetic Declination
Conservation of Declining Populations
Effect of Hepatic Disease on Pharmacokinetics: Pathophysiologic Assessment and Liver Function Test
Motor Units
Motor Units
Motor units come in different sizes, with smaller units...

