Introduction

One important factor influencing the effectiveness of botulinum neurotoxin (BoNT) injection in the treatment of upper and lower limb spasticity is the accuracy of administration into the target muscle. Indeed, incorrect needle placement can result in complete failure of treatment. Neurotoxin diffusion outside of target muscles can cause weakness or paresis, particularly for small muscles of the hand and forearm. The use of various guidance techniques may improve both effectiveness and safety, decreasing the occurrence of side effects.

A wide range of injection techniques has been described, such as manual needle placement using surface anatomy landmarks or palpation, electromyographic guidance, electrical stimulation of the muscle and ultrasound guidance (Childers 2003; Berweck et al., 2004). Generally, manual needle placement is considered to be an acceptable technique for delivering the BoNT to large, superficial muscles, but not for small, slender, deep muscles. Therefore, guidance is recommended where the goal of treatment is the modulation of muscle hypertonicity to improve the dexterity of spastic muscles (particularly for hand spasticity), as well as for deep and small muscles of the limbs, whereas it is considered optional for larger easily palpated muscles.