Difficulties with differentiating botulinum toxin treatment effects in essential blepharospasm

Blepharospasm is a focal dystonia in which the extraocular muscles contract repetitively, leading to excessive blinking and forced eyelid closure. Botulinum toxin type A (BoNTA) is the primary symptomatic treatment for blepharospasm and its effects have been evaluated using numerous rating scales. The main scales in use today were initially used to determine whether BoNTA treatment was superior to placebo, and most controlled trials have confirmed this. More recently, these scales have been used to determine whether there are efficacy differences between different BoNTs in blepharospasm. However, although the scales used in these trials are able to differentiate the effects of BoNT from placebo, they may not be sensitive enough to differentiate between BoNTs. Most of the scales include only four possible points for each item, which would necessitate a 25% greater improvement in one group than the other to detect any differences. Current scales are also relatively insensitive to patients with mild disability who may experience mainly psychosocial problems related to their blepharospasm. Clinical trials comparing BoNTs that include substantial numbers of mildly affected patients may be unlikely to find differences because the scales do not adequately measure mild symptoms. Additional challenges with evaluating blepharospasm include the lack of precision and objectivity of current measures, symptom variability, the need to evaluate aspects of the disorder that are most important to patients, and the different types of blepharospasm. Although no single scale may be able to capture all relevant aspects of blepharospasm, more sensitive and patient-centered scales are needed

Ultra-Long-Term Therapy of Benign Essential Blepharospasm with Botulinumtoxin A—30 Years of Experience in a Tertiary Care Center

Aim of this study was to investigate the long-term results of botulinum toxin A (BoNT-A) injections for the treatment of benign essential blepharospasm (BEB) and to report our experience with (ultra-)long-term treatment with onabotulinumtoxin-A. We conducted a retrospective cross-sectional analysis at a university hospital. Patients with BEB and BoNT-A treatment were assigned to the Total Blepharospasm Group, patients with ≥21 onabotulinumtoxin-A injections to the Ona Long-Term Group. The Total Blepharospasm Group (n = 1940) included 33,933 BoNT-A injections. The age of patients at symptom onset was (mean ± SD) 58.0 ± 13.1 years, and 70.4% were female. The Ona long-term group (n = 234) included 10,632 onabotulinumtoxin-A injections. In this group, patients received 45.4 ± 22.9 injections with a mean dose of 22.2 IU ± 0.5. The duration of treatment was 12.6 ± 5.4 years, ranging from 2.9 to 30.0 years. The effect–duration–dose quotient did not change during long-term treatment. The observed side effects were comparable in type and frequency to other studies, even with the (ultra-)long treatment with onabotulinumtoxin-A. Our results, based on one of the largest patient populations and a treatment duration of up to 30 years, impressively demonstrate that onabotulinumtoxin-A is a safe and effective therapy for essential blepharospasm, even in the ultra-long term