Brace modification improves aerobic performance in Charcot-Marie-Tooth disease - A single-subject design

Objective: Ankle-foot orthoses (AFOs) can lower energy expenditure in patie nts with hemiplegia by 10%-13%. Review of the lower motor injury literature reveals insufficient physiologic evidence supporting the use or modificati on of AFOs in patients with lower motor neuron injury and, specifically, pr ogressive conditions such as Charcot-Marie-Tooth disease. We sought to test the hypothesis that optimal AFOs would improve submaximal aerobic performa nce and submaximal perceived exertion, while producing no change in maximal aerobic capacity. Design: In an individual with Charcot-Marie-Tooth disease, a single-subject design study was used. An A-B-A design was used, with "A" corresponding to use of the patient's old AFOs and "B" corresponding to the newly prescribe d AFOs. The subject underwent treadmill exercise tolerance testing using a modified Balke protocol. Indirect calorimetry was used to measure oxygen co nsumption per unit time ((V) over dot (2)), and the Borg scale was used to measure perceived exertion. Results: At the same submaximal exercise intensities, (V) over dot (2), rat e-pressure product, and perceived exertion were all reduced when using the modified AFOs. Additionally, these conditions allowed the subject to conduc t the treadmill exercise test 20% longer. Maximal (V) over dot (2) remained constant under all conditions. Conclusion: Optimizing the AFO prescription in a patient with Charcot-Marie -Tooth disease can enhance physiologic performance and perceived exertion a t submaximal activity levels. Larger controlled trials are necessary to fur ther demonstrate such benefits in patients with progressive neuropathy and other causes of lower motor neuron injury.