Quantification of walking mobility in neurological disorders

Difficulty in walking is a major feature of neurological disease, and loss of mobility is the activity of daily living on which patients place the most value.1 Consequently, how to measure and assess this is of importance to any member of the inter-disciplinary team. In clinical practice, the World Health Organization international classification of functioning (ICF)2 is often adopted as the underlying framework for the assessment of mobility, which is an individual's ability to move about effectively in their environment.2 The ICF also introduces the constructs of performance (what an individual does in his environment) and capacity (ability to execute a task or action). This has a clear impact on the current methodology for the assessment of mobility. Different pathologies and impairments culminate in abnormal or reduced walking. For instance, in multiple sclerosis (MS), impairments such as weakness and spasticity from pyramidal tract lesions, loss of proprioception and co-ordination from dorsal column and cerebellar lesions, vestibular and visual dysfunction, cognitive and mood disturbance and pain may all contribute (Figure 1). In primary muscle disease, mobility is determined by weakness but secondary factors such as weight gain, contractures, fatigue and breathlessness may have important impacts. The degree of impairment has a non-linear relationship with activity and participation. For example leg strength and walking speed are poorly correlated,3 while many personal and environmental factors may influence the impact of similar degrees of loss of walking on mobility. Figure 1. Framework of international classification of function (ICF) as illustrated by mobility in MS. Impaired walking can be a marker of both disability and disease progression, and is therefore an important outcome measure in the treatment and rehabilitation of diseases such as MS and Parkinson's disease (PD). In some cases, measurement of mobility may have a direct influence on access to treatment. … Address correspondence to Dr O.R. Pearson, Section of Neurology, University of Wales College of Medicine, Cardiff CF14 4XN. e-mail: pearsonor{at}cardiff.ac.uk