Anti-MAG/SGPG associated neuropathy does not commonly cause distal nerve temporal dispersion

Patients with anti-myelin associated glycoprotein (anti-MAG) neuropathy have uniform slowing without temporal dispersion, but do usually have disproportionately distal slowing. We evaluated distal compound muscle action potential (CMAP) dispersion in 29 patients with anti-MAG/sulphated glucuronyl paragloboside (SGPG) neuropathy (titres > or = 12,800). Among 138 motor responses, 15% (tibial), 7.3% (peroneal), 10.7% (median) and 13.8% (ulnar) had distal CMAP duration > 9 ms. Disproportionate distal slowing with normal distal CMAP duration in the arms may be useful to differentiate chronic inflammatory demyelinating polyneuropathy from anti-MAG/SGPG associated neuropathy.