Spasticity is part of the upper motor neuron syndrome produced by conditions such as stroke, multiple sclerosis, traumatic brain injury, spinal cord injury or cerebral palsy that affect upper motor neurons or their efferent pathways in the brain or spinal cord. It is characterized by increased muscle tone, exaggerated tendon reflexes, repetitive stretch reflex discharges (clonus) and abnormal spastic posturing. Late sequelae may include contracture, pain, fibrosis and muscle atrophy. The most common pattern of spasticity in the upper limb involves flexion of the fingers, wrist and elbow, adduction with internal rotation at the shoulder and sometimes thumb curling across the palm or fist. The most common pattern of spasticity in the lower limb involves extension at the knee, plantarflexion at the ankle and sometimes inversion of the foot.

Chemodenervation by intramuscular injection of botulinum toxin can reduce spastic muscle tone, normalize limb posture, ameliorate pain, modestly improve motor function and prevent contractures. This chapter uses anatomical illustrations to depict the muscles involved in common patterns of spastic posturing, using a “clinician’s eye” view to demonstrate approaches to injection points, discusses guidance techniques such as electromyography and tabulates dose ranges of the common toxin preparations for specific muscles.

Idiopathic cervical dystonia (CD) is characterized by sustained muscle contraction leading to abnormal postures and twisting movements of the head and neck. BoNT is the gold standard for treatment of the abnormal postures and movements associated with CD. It provides a long duration of symptomatic relief of the pain or postures associated with CD with minimal side effects.

The complex regional anatomy in the craniocervical region increases the potential risks of injections in this area. Ultrasound guidance provides useful information about the depth and thickness of the target muscles, structures to be avoided when inserting/advancing a needle, a safe path to the target and the location of the injectate within the muscle. When treating patients with CD, ultrasound is frequently combined with EMG guidance which provides additional information about muscle activity and potential contribution to a posture. This chapter provides a review of ultrasound guidance for injections for craniocervical dystonia