Pes cavus pathogenesis in Charcot-Marie-Tooth disease type 1A

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Sir, We thank Drs Burns and Ouvrier for their interest regarding our article; in their letter, they raise several concerns that we are going to address. But before doing so, we would like to emphasize the rationale of our study (Gallardo et al ., 2006). In previous longitudinal clinico-electrophysiological studies in 12 Charcot–Marie–Tooth disease type 1A duplication (CMT-1A) secondary patients (symptomatic or asymptomatic at-risk relatives affected upon clinico-electrophysiological examination), performed from infancy as the inclusion period (range: 1 month to 5 years; mean: 2 years) to the third decade of life (range: 6–23 years; mean: 13 years), we had found the following outstanding features (Garcia et al ., 1998; Berciano et al ., 2000, 2003): (i) abnormal post-natal nerve conduction maturation in every patient; (ii) all 12 children had normal milestones; (iii) during the inclusion period only two infants (17%) had already developed symptoms, whereas five (42%) were symptomatic at the end; (iv) number of abnormal examinations at the beginning was 6 (50%) and at conclusion was 10 (83%); (v) during the inclusion period, observed signs comprised lower limb areflexia, nerve enlargement, foot semeiology including pes cavus and shortening of Achilles' tendon, and difficulty in heel walking with no weakness or atrophy of peroneal musculature till the second decade of life; and (vi) progressive atrophy of extensor digitorum brevis (EDB) muscle correlated not with the degree of motor conduction velocity (MCV) slowing of peroneal nerve but with the degree of attenuation of compound muscle action potential (CMAP) of EDB. As pes cavus and intrinsic foot muscle atrophy may precede the appearance of peroneal muscle atrophy, we hypothesized that initial walking difficulties correlate with abnormal foot architecture owing to selective denervation …