**1. Introduction**

Cerebral Palsy (CP) is a combined disorder of movement, posture, and motor function often complicated or associated with various sensory, neurological, musculoskeletal complications, and behavioral problems. Nowadays, spastic CP is the most common type (more than 2/3rd cases) followed by dyskinetic, hypotonic, and ataxic. In spastic CP, diplegia is the most common (>50%), followed by quadriplegia, hemiplegia, and monoplegia [1]. Spasticity is commonly managed by stepped-up management protocol beginning with the more conservative options (exercises, physical modalities, occupation therapy, and orthoses) followed by oral medications (like baclofen, tizanidine, dantrolene, and tolperisone) and various surgical options for relatively older children at last resort, where stiffness and progressive deformities continue to hamper rehabilitative treatment. Chemodenervation by botulinum toxinA (BTx-A) decreases spasticity by denervating the muscle by inhibiting acetylcholine release from the neuromuscular junction [2]. It has a relatively focal, reversible effect with a wide safety margin. This BTx-A denervation temporarily reduces muscle tone and provides an opportunity to effect changes in motor learning and cortical motor organization [3].

BTx-A injection in the lower limb muscles may help in reducing spasticity, increase in range of motion, and improvement in gait pattern [4, 5]. BTx-A injection in the upper limb may also have favorable effects on decreasing the spasticity or resistance to passive movement of the spastic wrist and fingers and on self-care as an adjunct to other basic conservative means described above [6, 7].

In this chapter, we will be discussing surface anatomical or landmark-guided injection techniques in children with spastic cerebral palsy.

Most of the spastic upper and lower limb muscles can be injected by surface or anatomical landmark-guided technique. However, in the case of obese children or distorted anatomy, multiple times botulinum toxin injection ultrasound (US) guidance may be useful nowadays.

For surface anatomy or landmark-guided BTx-A injections, a common spastic pattern affecting the muscle and dynamic function is identified. In upper limb spasticity, the child has usually various combinations of isolated adducted and internally rotated shoulder, flexed elbow, forearm pronation, flexed wrist and finger, and thumb in palm posturing. Muscle injected commonly are pectoralis major, subscapularis, biceps, brachialis, brachioradialis, pronator teres & pronator quadratus, flexor carpi radialis & ulnaris, flexor pollicis longus, flexor digitorum superficialis, and profundus, adductor pollicis, opponents pollicis, and flexor pollicis Brevis. Whereas in the lower limb, any combination of hip in flexion, adduction, knee in flexion, ankle in equinus/ equinovarus, flexed toes, and stiff knee on dynamic or static assessment.

For practical purposes, the injection site in the center of maximum muscle bulk usually lies in the midpoint of muscle or some cases between proximal one-third to the midpoint of muscle bulk. So, surface anatomical landmarks are midpoint or at maximum bulk and if another injection point is required, then a few centimeters proximal to this point depending upon the age and muscle involved.

#### **1.1 Theory pearls**

At muscle bulk there lies the end plate zone. Many past animal research has shown that injections close to these motor end plates are more efficacious [8] and in some muscles, it is also scattered throughout (sartorius, gracilis) [9]. As we cannot localize end plates by surface anatomy or clinical palpation. It is easy and practical to use surface/landmark-guided injection.

So, our target should be to identify surface landmarks, insert the needle in the belly (preferably midpoint and mid-thickness) of the muscle, and then gently stretch passively, needle movement is best appreciated if it is in the desired muscle. One should also ensure nil or minimal movement of the needle, while stretching other nearby/ overlapping muscles or muscle slips.

In a few situations, we may have to use US guidance or US visualization for muscle identification and depth, then surface anatomical guidance may become more easier and precise. This is particularly required for deep muscles and relatively smaller muscles.

Otherwise, it might inject into undesired or neighboring muscles. As for any injection technique, we must ensure needle tips should not be in blood vessels or injure neural tissues.

*Anatomical Surface Guided Techniques for Botulinum Toxin Injection in Spastic Cerebral… DOI: http://dx.doi.org/10.5772/intechopen.107200*

Here, only commonly done lower limb and upper limb muscle is described in this chapter from proximal to distal joints/muscle and ease of doing the injection, which are as follows-.
