Intramuscular Neural Distribution of Adductor Pollicis Muscle Spasticity in Cadaver Model Regarding Botulinum Neurotoxin Treatment

PURPOSE: The adductor pollicis muscle is frequently targeted for botulinum neurotoxin injective treatment for spasticity. However, there are no injective guidelines for delivering injection to the muscle. MATERIALS AND METHODS: A method known as the modified Sihler’s method was used to stain the adductor pollicis muscle in 16 specimens to reveal intramuscular neural distribution of the muscle. RESULTS: The most intramuscular neural distribution was located on 1/5 to 3/5 of the muscle regarding midline of 3rd metacarpal bone (0) to the base of the 1st proximal phalanx (5/5). The nerve entry point was mostly located on 0 to 1/5 of the muscle. CONCLUSION: The result suggests that botulinum neurotoxin should be delivered at the middle of second metacarpal bone via deep injection.