Manual needle placement: accuracy of botulinum toxin A injections

Abstract

Introduction: Electrophysiological or ultrasound guidance can facilitate botulinum toxin A (BoNt-A) injection accuracy, but clinical landmarks and palpation are often used for superficial muscles. We evaluated the accuracy of manual needle placement in the gastrocnemius muscles (GC) guided only by anatomical landmarks and palpation.

Methods: Bilateral limbs from 30 cadavers were used to evaluate ink injection into the GC. One anatomist and one orthopedic surgeon verified the accuracy of manual needle placement postinjection by calf muscle dissection. Injection was considered a failure if the ink was not located in the head of the target GC.

Results: One hundred twenty-one practitioners were evaluated. Fifty-two injections were successful (43%), and 69 failed (57%). This result was unrelated to injector experience (P = 0.097).

Conclusions: Our findings show a poor success rate, regardless of injector experience. Therefore, muscle palpation and anatomical landmarks are insufficient to ensure the accuracy of BoNt-A injections, even for large, superficial muscles.