Patient-centred evaluation of a reduced dose of botulinum toxin A in the management of myofascial pain

Abstract

In our previous service evaluation, we reported improvement in patients’ pain scores for masseteric pain and spasm, following injection of 50 units of botulinum toxin A (BtA), measured using visual analogue scales (VAS). We have recently introduced a lower dose BtA protocol, for appropriately selected patients, aimed to evaluate whether this is also effective at relieving symptoms of masseteric pain and spasm. The rationale was to reduce side-effects and costs.

VAS scores were measured before and after treatment for 48 patients who received treatment with the original BtA protocol (“Protocol A” - the historical cohort who received 50 units) and for 46 patients who receieved a modified BtA protocol (“Protocol B” - the current cohort who received 25 units).

Patients in both treatment groups reported severe symptoms prior to treatment. Patients who received protocol B reported, on average, a 5 unit improvement in VAS following treatment (95 % confidence interval 4.3 to 5.7 improvement in VAS). There was no evidence that protocol B was less effective, despite the lower dose.

We recommend a reduced dose of BtA, of 25 units, for injection for appropriately selected patients with masseteric pain and spasm. A lower dose of BtA reduces wastage, particularly for single muscles injection and may reduce the incidence of unwanted side-effects. Reducing the standard dose of BtA will reduce costs for healthcare providers and may therefore facilitate funding for provision of intramuscular injection of BtA, where justified.