Depletion of neutralising antibodies resensitises a secondary non-responder to botulinum A neurotoxin

The objective was to evaluate whether removal of neutralising antibodies potentially resensitises a secondary nonresponder to botulinum neurotoxin A (BoNT/A). Neutralising antibodies directed against BoNTIA are produced during long term treatment with BoNT/A-hemagglutinin complex in up to 10% of patients with cervical dystonia. These patients become secondary nonresponders. Other serotypes of BoNT are not yet generally available and may also bear the risk of inducing antibody formation. Plasma exchange (PE) (one treatment cycle) and immunoadsorption on a protein A column (IA-PA; three treatment cycles) was employed over 15 months to remove neutralising antibodies from a severely disabled secondary nonresponder with cervical dystonia. After plasma exchange or IA-PA, BoNTIA was reinjected. Antibodies were measured with a sensitive functional toxin neutralising test. Repeated use of plasma exchange and IA-PA depleted neutralising antibodies to below the detection limit and subsequently allowed successful BoNTIA injection into dystonic muscles. No serious side effects were found related to the depletion of IgG. In conclusion PE or IA-PA performed before BoNTIA readministration may provide an alternative strategy in treating selected secondary non-responders who are severely disabled.