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

In 1980, Alan B Scott published the use of botulinum neurotoxin type A by injection into extraocular muscles for treatment of strabismus. Use in blepharospasm was published in 1985, and cervical dystonia in 1986, followed by hemifacial spasm and other dystonias, including spasmodic dysphonia, hand dystonia, and conditions such as limb spasticity.

Formulations of neurotoxin type A worldwide include: Botox/onabotulinumtoxinA, Dysport/abobotulinumtoxinA, Xeomin/incobotulinumtoxinA, and a Chinese product marketed under various brand names in Asia. Botulinum neurotoxin type B is marketed as Neurobloc/Myobloc, or rimabotulinumtoxinB. PrabotulinumtoxinA and daxibotuinumtoxinA-Ianm are type A toxins under development.

Botulinum toxin injection is a safe and effective procedure, with outcomes improved if selection and targeting of intended muscles is precisely executed. Individual differences in patient anatomy, and in muscle location or size, render the standard landmark-based, blind approach less effective. Also, adjacent structures such as blood vessels, nerves, the lung, or the thyroid gland, may be injured when hit by the cannula. Therefore, image-based guidance is recommended.

Ultrasound is a very safe imaging modality and is superior in image quality and more flexible during the procedure compared to other modalities (fluoroscopy, CT and MRI). Finally, the costs of acquisition and maintenance of a clinical ultrasound system are moderate, compared to other imaging modalities.

In this chapter, we performed selective ultrasound-guided injections using cadaver specimens to illustrate the muscles relevant in the treatment of cervical dystonia. With ultrasound, we advanced the needle using the in-plane technique to the center of each muscle, and performed a selective intramuscular injection using dilute India ink. The specific muscle was then exposed in a standard dissection and the extent of the staining was photo documented. In the last section we present panoramic still images of neck regions with a difficult muscle topology.

Cervical dystonia (CD) is an idiopathic focal dystonia characterized by abnormal head and neck posture caused by tonic involuntary contractions in a set of cervical muscles. Four subtypes, based on the principal direction of posture, consist of:

• - Torticollis: Rotation of the head left or right in the transverse plane.

• - Lateralcollis: Head tilt toward left or right shoulder, in the coronal plane.

• - Anterocollis: Head tilt forward, with neck flexion in the sagittal plane.

• - Retrocollis: Head tilt backward, with neck extension, in the sagittal plane.

The clinical spectrum of CD is extremely variable: the 54 muscles involved in head and neck posture may show complex mixtures of involvement, unilateral or bilateral, with contractions of tonic, tremulous or myoclonic character. Currently, the most effective, and now first-line treatment of CD, has become intramuscular injection of botulinum toxin.

This chapter enumerates the different muscles involved in major subtypes of CD, grouped by anatomical location, and their principal direction of action. Sets of muscles involved in different head postures are presented in tabular format for easy selection and targeting. Dose ranges for individual muscles are tabulated for each of the four commonly used botulinum neurotoxin preparations.