Are electrophysiological features related to disability in patients with anti-MAG neuropathy?
OBJECTIVE
To explore clinical-neurophysiological correlations in anti-myelin-associated glycoprotein (anti-MAG) neuropathy.


METHODS
Clinical and electrophysiological data of 42 patients with anti-MAG neuropathy were retrospectively analysed. Disability was evaluated using the Overall Neuropathy Limitation Scale (ONLS), motor impairment through MRC sum score and sensory deficiency through INCAT sensory score. Compound motor action potential (CMAP) sum score was calculated adding the distal CMAP amplitude of the median, ulnar, tibial and fibular nerves of both sides.


RESULTS
In multivariate analysis, motor impairment was associated with CMAP sum score (r=0.35, P=0.047) and distal motor latency in the median nerves (r=-0.45 P=0.012), sensory deficiency was related to motor conduction velocity in the median nerve (r=-0.65. P=0.02). Disability was correlated with CMAP sum score (r=-0.37, P=0.022).


CONCLUSIONS
Electrophysiological features are associated with clinical involvement in anti-MAG neuropathy. Reduction of CMAP amplitudes reflects distal motor latency delay and is mainly due to axonal loss. Since it is related to muscle weakness and disability, CMAP sum score may be a good marker in the evaluation of patients with anti-MAG neuropathy.
Referral centre for ALS and Neuromuscular diseases, La Timone Hospital, Aix-Marseille University, 264, rue Saint-Pierre, 13005 Marseille, France; Neurology Department, centre hospitalier intercommunal Toulon La-Seyne, 83000 Toulon, France.
Aude
A
Gesquière-Dando
Referral centre for ALS and Neuromuscular diseases, La Timone Hospital, Aix-Marseille University, 264, rue Saint-Pierre, 13005 Marseille, France; CNR2M, CNRS UMR 7286, Medicine Faculty, Aix-Marseille University, 13015 Marseille, France. Electronic address: emilien.delmont@ap-hm.fr.
Emilien
E
Delmont
Service d'explorations fonctionnelles du système nerveux, pôle des neurosciences cliniques, hôpital Pasteur 2, CHU de Nice, 06000 Nice, France.
Mael
M
Launay
CNR2M, CNRS UMR 7286, Medicine Faculty, Aix-Marseille University, 13015 Marseille, France.
Jose
J
Boucraut
Referral centre for ALS and Neuromuscular diseases, La Timone Hospital, Aix-Marseille University, 264, rue Saint-Pierre, 13005 Marseille, France; Inserm UMR S 910, Medical Genetics and Functional Genomics, Aix-Marseille université, 13005 Marseille, France.
Sharham
S
Attarian
D000200:Action Potentials; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology; D018992:Myelin-Associated Glycoprotein / Q000276:immunology*; D009431:Neural Conduction; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis* / Q000276:immunology / Q000503:physiopathology*; D012189:Retrospective Studies; D012720:Severity of Illness Index
D018992:Myelin-Associated Glycoprotein
Anti-MAG neuropathy; CMAP sum score; Disability; Incapacité fonctionnelle; Indice de latence distale; Myelin-associated glycoprotein (MAG); Neuropathie à anticorps anti-MAG; Overall Neuropathy Limitation Scale (ONLS); Somme des amplitudes motrices; Terminal latency index