Can electrophysiology differentiate polyneuropathy with anti-MAG/SGPG antibodies from chronic inflammatory demyelinating polyneuropathy?
OBJECTIVE
Patients with polyneuropathy and antibodies to myelin-associated glycoprotein (MAG) and sulphated glucuronyl paragloboside (SGPG) differ from chronic inflammatory demyelinating polyneuropathy (CIDP) because of a slower, progressive course, symmetrical and predominantly sensory involvement of legs, predominantly distal slowing of motor conductions, and poorer response to therapy. We studied whether a wide set of electrophysiologic parameters may differentiate these two neuropathies.


METHODS
We reviewed the electrophysiological studies of 10 patients with anti-MAG/SGPG antibodies and 22 with CIDP examining: (1) motor conduction velocity and distal compound muscle action potential amplitude; (2) conduction block (CB) and temporal dispersion; (3) distal motor latency and terminal latency index (TLI); (4) F wave and proximal conduction time; and (5) sensory conduction and occurrence of abnormal median with normal sural sensory potential.


RESULTS
Anti-MAG/SGPG neuropathies showed: (1) more severe involvement of peroneal nerves; (2) more frequent disproportionate distal slowing of motor conductions (TLI< or =0.25) and absent sural potential, and (3) no CB. However 3/22 CIDP patients also had at least two nerves with TLI< or =0.25 and no CB.


CONCLUSIONS
Electrophysiologic findings suggest in anti-MAG/SGPG neuropathy a length-dependent process with a likely centripetal evolution. A disproportionate slowing of conduction in distal segments of motor nerves suggests the diagnosis of anti-MAG/SGPG neuropathy, although it is not pathognomonic.
Capasso
Margherita
M
Center for Neuromuscular Diseases, University G. d'Annunzio, Chieti, Italy.
Torrieri
Filomena
F
Di Muzio
Antonio
A
De Angelis
Maria Vittoria
MV
Lugaresi
Alessandra
A
Uncini
Antonino
A
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001323:Autoantibodies / Q000097:blood; D003937:Diagnosis, Differential; D004558:Electric Stimulation; D004568:Electrodiagnosis / Q000379:methods*; D004594:Electrophysiology / Q000379:methods*; D005260:Female; D005915:Globosides / Q000276:immunology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018992:Myelin-Associated Glycoprotein / Q000276:immunology; D009431:Neural Conduction; D010543:Peroneal Nerve / Q000503:physiopathology; D011115:Polyneuropathies / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D020277:Polyradiculoneuropathy, Chronic Inflammatory Demyelinating / Q000175:diagnosis; D011237:Predictive Value of Tests; D011930:Reaction Time; D012189:Retrospective Studies; D013497:Sural Nerve / Q000503:physiopathology
D001323:Autoantibodies; D005915:Globosides; D018992:Myelin-Associated Glycoprotein; C051917:sulfate-3-glucuronyl paragloboside