Morphological Basis of Late Component Potentials in Duchenne Dystrophy

To the Editor.—  In their recent article (Arch Neurol 33:642, 1976) Desmedt and Borenstein claim that regeneration in Duchenne dystrophy involves collateral sprouting of motor axons. This is a sensible hypothesis since late component potentials were identified both in this disease and in partial denervation, in which collateral reinnervation is well documented. Unfortunately, Desmedt and Borenstein's statement is not supported by relevant morphological data as far as Duchenne dystrophy is concerned.Morphometric study of intramuscular nerve fibers and endings has clearly established that there was no increased collateral ramification of subterminal motor axons in this condition.¹ The mean value of terminal innervation ratio in our present series of 18 biopsies (1.12 ± 0.06) is not significantly different from that of controls (P >.2).Of course, this finding does not rule out the possibility of axonal sprouting occuring more proximally in intramuscular nerves or in nerve trunks, but there is