Neutralizing antibodies in dystonic patients who still respond well to botulinum toxin type A.
BACKGROUND
Complete secondary therapy failure due to antibodies against botulinum toxin A (BoNT/A-ABs) may raise extensive treatment difficulties. We tested whether neutralizing BoNT/A-ABs can be detected in dystonic patients with good clinical responses to botulinum toxin A (BoNT/A) treatment.


METHODS
We used the ninhydrin sweat test (NST) and the mouse diaphragm test (MDT) in 28 subjects. Of 119 dystonic patients who responded well to BoNT/A, we randomly selected 14 and compared the results of the NST and MDT with 14 healthy controls.


RESULTS
Higher BoNT/A-AB titers correlated significantly with smaller anhidrotic areas. We found seven patients with borderline antibody (AB) values (MDT 0.4 to 0.8 mU/mL) with significantly smaller anhidrotic areas (NST) compared with healthy controls and AB-negative patients. Risk factors for smaller anhidrotic areas were short injection intervals but not prolonged exposure to BoNT/A or high injection doses.


CONCLUSIONS
These data demonstrate that >40% of dystonic patients who respond well to botulinum toxin A (BoNT/A) show partial nonresponsiveness on the ninhydrin sweat test and have low titers of neutralizing BoNT/A antibodies.
Kranz
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G
Department of Neurology, Medical University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria. gottfried.kranz@meduniwien.ac.at
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Voller
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Schnider
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D000328:Adult; D000368:Aged; D000906:Antibodies / Q000032:analysis* / Q000097:blood / Q000494:pharmacology; D019274:Botulinum Toxins, Type A / Q000276:immunology* / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004421:Dystonia / Q000188:drug therapy* / Q000276:immunology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000276:immunology* / Q000627:therapeutic use*; D009555:Ninhydrin / Q000737:chemistry; D018709:Statistics, Nonparametric; D013542:Sweat / Q000737:chemistry / Q000276:immunology
D000906:Antibodies; D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A; D009555:Ninhydrin