Terminal latency index in neuropathy with antibodies against myelin-associated glycoproteins.
Neuropathy with antibodies against myelin-associated glycoproteins (MAG/SGPG-N) and hereditary sensorimotor neuropathy type 1 (HMSN1) are characterized by chronic demyelination with little conduction block. Electrodiagnostic studies suggest that in HMSN1 conduction slowing occurs uniformly along the nerve, whereas in MAG/SGPG-N it is predominantly distal. Some but not all previous reports have shown that the terminal latency index (TLI) was useful to distinguish MAG/SGPG-N from chronic idiopathic demyelinating polyneuropathy. We compared median TLI from 21 patients with MAG/SGPG-N with those obtained from 26 patients with HMSN1, 20 with HMSN2, and 12 healthy volunteers. All patients with TLI <0.26 had MAG/SGPG-N, and all patients with TLI > or =0.32 had HMSN1. In the remaining patients with intermediate TLI values, ulnar distal motor latency (DML) aided in differentiation between MAG/SGPG-N and HMSN1 with an overall sensitivity of 100% and specificity of 98%. In conclusion, median TLI in combination with ulnar DML can further guide the demyelinating neuropathy evaluation toward hereditary or autoimmune causes.
Lupu
Vitalie D
VD
EMG Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA.
Mora
Carlos A
CA
Dambrosia
Jim
J
Meer
Jacob
J
Dalakas
Marinos
M
Floeter
Mary Kay
MK
D000200:Action Potentials / Q000502:physiology / Q000528:radiation effects; D000328:Adult; D000368:Aged; D000906:Antibodies / Q000097:blood*; D002607:Charcot-Marie-Tooth Disease / Q000503:physiopathology*; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology; D008875:Middle Aged; D018992:Myelin-Associated Glycoprotein / Q000276:immunology*; D009431:Neural Conduction / Q000502:physiology; D010523:Peripheral Nervous System Diseases / Q000276:immunology* / Q000503:physiopathology*; D011930:Reaction Time / Q000502:physiology*; D014459:Ulnar Nerve / Q000503:physiopathology
D000906:Antibodies; D018992:Myelin-Associated Glycoprotein