Botulinum toxin is used with remarkable success to treat various muscle and exocrine gland hyperactivity syndromes. Rarely, treatment failure due to formation of botulinum toxin antibodies (ABF) occurs.^1,2 To reduce the risk of ABF, a new formulation of Botox (in the following referred to as “current Botox”; Allergan, Irvine, California, USA) with increased specific biological potency was introduced. Although ABF could not be detected with current Botox in a large prospective study, it has been reported recently in a patient with special immunoreactive predisposition.^3,4 We are now reporting ABF after current Botox in an immunologically unremarkable patient.

A 50-year-old woman had substantial idiopathic tonic–clonic cervical dystonia for the past 7 months. Her score on the Toronto Western Torticollis Rating Scale (TWSTRS) was 25 (Torticollis Severity Scale), 22 (Disability Scale) and 17.5 (Pain Scale).⁵ Treatment was initiated with current Botox (100 MU/1.0 ml, 0.9% NaCl/H₂O) (table 1). Two weeks after injection series …