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 >= 12800). 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.