CHARCOT-MARIE-TOOTH DISEASE

Abstract

Charcot-Marie-Tooth (CMT) disease is the most commonly inherited peripheral sensorimotor neuropathy and affects 1:2500. Most CMT patients are Type Ia and exhibit slowed nerve conduction velocities and distal muscle weakness. There is no known treatment for the disease and patients are not traditionally referred to exercise programs. Since CMT is characterized by peripheral weakness, we hypothesized that this muscle weakness would make these patients less likely to engage in exercise and may contribute to obesity. In addition, little is known about the functional capacity or the magnitude of the increase in the time needed to perform activities of daily living (ADLs) in these patients compared to age-matched controls. PURPOSE: To determine the body composition and functional capacity of patients with CMT and quantify the increase in the time required to perform ADLs compared to age-matched controls. METHODS: Sixteen CMT patients, 8 men and 8 women, mean age 44 years, volunteered for the study. Control subjects included 6 men and 4 women, mean age 49 years. Body composition was determined in CMT by air plethysmography. Functional capacity was measured in patients by bicycle graded-exercise test (GXT) starting at 50 watts and increasing 25 watts every two minutes to volitional fatigue. Heart rate (HR) and VO2 were monitored continuously. ADLs included timed chair-rise, supine-to-sitting position, 8-step stair-climb, and lift-and-reach with 2, 3, 5, and 8 lb weights (mean of three attempts for each). RESULTS: CMT patients had 40% body fat with a Body Mass Index (BMI) of 30 versus control BMI of 25 (p < .05). Resting blood pressure (BP) was 121/78 with a resting HR of 91 bpm in CMT and peak BP was 164/87 with a max HR of 143 bpm. Mean time of GXT was 8.36 minutes, mean VO2 was 21 ml/kg/min; patients achieved 81% of age-predicted max HR and 77% of predicted VO2. Mean chair-rise time was 50% longer for CMT (1.34s vs. 0.67s), supine-rise 47% slower for CMT (2.1s vs. 0.98s), stair-climb was 68% slower in CMT (14.4s vs. 4.6s), and lift-and-reach took 30% longer in CMT (20.2s vs. 14.4s) (p < .05). CONCLUSIONS: CMT patients are obese and have poor exercise tolerance with VO2 in the poor category. This may increase their risk for CAD. ADLs require 30–68% more time to complete and reflect the severity of their impairment. Whether an exercise intervention can improve functional capacity, body composition and/or time to complete ADLs is unknown.