Insights into the Functional Anatomy Behind the PREEMPT Injection Paradigm: Guidance on Achieving Optimal Outcomes

Abstract

Objective: To provide clinically relevant insights on the identification of the muscles and techniques involved in the safe and effective use of onabotulinumtoxinA for chronic migraine prophylaxis.

Background: Although guidance on the use of onabotulinumtoxinA for chronic migraine is available, based on the Phase III Research Evaluating Migraine Prophylaxis Therapy (PREEMPT) clinical program, clinical experience has shown that insufficient understanding of the anatomy and function of the head and neck muscles may lead to undesirable outcomes and suboptimal efficacy.

Design/methods: Each muscle involved in the standardized PREEMPT injection paradigm is reviewed with a thorough description of each muscle's anatomy (ie, muscle description and location, innervation, vascular supply) and function. Key insights based on clinical experience are also provided to help improve outcomes.

Results: The identification of the muscles in the PREEMPT injection paradigm should be based on each patient's unique anatomy and injections should be administered using the advised techniques. A thorough examination of the patient prior to treatment is also critical to determine if any preexisting conditions may increase the risk for unwanted outcomes and appropriate expectations should be communicated.

Conclusions: Thorough knowledge of the functional anatomy of the muscles involved in the standardized PREEMPT injection paradigm is critical to achieve the efficacy and safety observed in clinical trials. In addition, it is important to assess a patient's baseline condition to anticipate the risk for unwanted outcomes that may result from treatment.

Keywords: chronic migraine; clinical; injection technique; onabotulinumtoxinA.

Figure 1

Distribution of peripheral nerves. (a) Anterior and lateral view of the trigeminal (CN V) and occipital (C2, C3) sensory nerves. (b) Cervical sensory nerves (C2, C3). Reproduced with permission.16

Figure 2

Various depictions of ptosis. (a) No ptosis. (b) Lid ptosis with compensatory frontal overactivity. (c) Pseudo ptosis. (d) Brow ptosis. (e) Medial brow ptosis with compensatory lateral brow elevation.

Figure 3

Fixed‐site, fixed‐dose PREEMPT injection site locations. (a) Corrugator, as depicted by purple dots; procerus, as depicted by the red dot; frontalis, as depicted by orange dots. (b) Occipitalis area, as depicted by purple dots; cervical paraspinal area, as depicted by orange dots; trapezius, as depicted by red dots. (c) Temporalis, as depicted by purple dots.