Response to letter to the editor by videler et al.

We have read the valuable contribution of Videler et al. on signs of overwork weakness in patients with Charcot-Marie-Tooth (CMT). As in our study, overall, Videler et al. did not find a difference between the dominant and non-dominant hands in their CMT patients. This is in contrast with the study of Vinci et al., who, using manual muscle strength testing, found a stronger dominant hand in only 2 out of 212 muscles and a stronger non-dominant hand in 139 of these 212 muscles.
When selecting only the more severely affected patients, Videler et al. did find in this group of 22 patients a small, but significantly stronger, non-dominant hand for the tripod pinch. We agree with Videler that the latter finding may fit with the hypothesis of overwork weakness. However, it should be noted that the difference in strength between both hands for the tripod pinch is relatively small and that the non-dominant hand is also severely weakened. Therefore, it is unclear if this difference is clinically relevant. As suggested by Videler et al., larger prospective cohort studies or interventions studies, preferably using more specific measures of intrinsic hand muscle function would be needed to conclude on the presence of overwork weakness.
In summary, in the absence of a mechanism to explain overwork weakness in this population and in the absence of any data indicating that reducing activity would slow disease progression, we still feel that there is insufficient evidence to conclude that overwork weakness exists, and agree with Videler et al. that, at present, there are no grounds to advise patients to limit their activities.