Survey of practices employed by neurologists for the definition and management of secondary non-response to botulinum toxin in cervical dystonia.

Secondary non-response (SNR) to botulinum toxin (BoNT) in cervical dystonia (CD) lacks a universal definition. We conducted a retrospective survey to develop a definition based on clinicians' practice. Fifty-seven neurologists completed a 17-item questionnaire. In defining SNR, insufficiently improved posture was considered to be more relevant (98% of physicians) than insufficiently improved pain (86%). The most frequently used diagnostic test for SNR was the frontalis test (68%); antibody testing was performed by only 13% of physicians. Three consecutive unsuccessful injection cycles were considered the most appropriate indicator of SNR (55% of physicians). Physicians reported that 5.9% (median) of patients treated in 2008 became secondary non-responders to BoNT-A. The most common strategy for SNR was optimization of physiotherapy, considered by 98% of the physicians. On the basis of our findings, SNR can be defined as insufficiently improved posture after ≥3 unsuccessful injection cycles in CD patients previously achieving satisfactory results.