• GUILLAIN-BARRE SYNDROME
• NEUROPHYSIOL, CLINICAL
• NEUROPHYSIOLOGY
• NEUROPATHY

We read the paper by Rajabally et al 1 with interest. Two major subtypes of Guillain-Barré syndrome (GBS), namely axonal (acute motor axonal neuropathy and acute motor-sensory axonal neuropathy) and demyelinating (acute inflammatory demyelinating polyneuropathy), are considered to have quite different pathophysiologies. However, electrodiagnostic classification is often difficult. Recent studies have revealed that in the early stage of the disease, axonal GBS can transiently present demyelinating-like features, such as prolonged distal motor latency (DML) or motor conduction block, which is called ‘reversible conduction failure’.2 Based on these new neurophysiological insights, the authors proposed new criteria. The proposed criteria include stricter criteria for demyelination. Motor conduction velocity (MCV) of 70% or less of the lower limit of normal (LLN) and DML of 150% or more of the upper limit of normal (ULN) is required for the consideration of demyelinating GBS. Conversely, mild conduction slowing became acceptable for the diagnosis of axonal GBS. Absence of F waves and motor conduction blocks are acceptable for both subtypes. We considered these modifications reasonable for the diagnosis of axonal GBS, but they increase the risk of underestimation of demyelinating GBS. We argue against their conclusion that a single electrophysiological study may suffice for the ‘ultimate’ diagnosis, because the presence of demyelinating-like features in axonal GBS depend, at least in part, on the number of …