Acute motor conduction block neuropathy followed by axonal degeneration and poor recovery

To the Editor:

We read with interest the article by Rajabally et al.¹ describing a patient with an alleged acute motor conduction block neuropathy (AMCBN). The authors claim that conduction blocks (CBs) were not reversible in this patient, as we and others previously described,² but were followed by axonal degeneration and poor recovery. Interestingly, they argue that this case strengthens the idea that acute motor axonal neuropathy (AMAN) and AMCBN, both associated with Campylobacter jejuni infection and anti-GM1 antibodies, represent “electrophysiologic forms of the same disorder”.¹ We have some methodologic and conceptual remarks.

The authors found motor CBs 6 days after onset, but 8 weeks later CBs disappeared whereas amplitudes of distal and proximal compound motor action potentials (CMAPs) equalized.¹ These observations do not necessarily imply that CBs were followed by axonal degeneration but may merely reflect a length-dependent reduction of CMAP amplitude due to ongoing Wallerian degeneration.^3,4 At the first electrophysiologic examination, axonal degeneration and nerve inexcitability could not …