Twin Block in Myogenous Orofacial Pain: Applied Anatomy, Technique Update, and Safety

Abstract

The twin block, introduced in 2014, has proven to be more advantageous for the management of myogenous orofacial pain than the masseteric nerve block, which was introduced in 2009. The twin block is an extraoral nerve block injection which passes through the temporal fossa to anesthetize both the masseteric and the deep temporal nerves as they exit the infratemporal fossa at the infratemporal crest. Similar to the masseteric nerve block, the twin block has demonstrated efficacy with expeditious and sustained relief of myogenous face pain originating from the masseter muscle. Furthermore, in a 6-month prospective treatment study, that has been accepted for publication, the twin block has been demonstrated as comparable to trigger point injections in the management of chronic myofascial pain of masseteric origin. The twin block's ability to mitigate myogenous pain from both the masseter and temporalis muscles and its ease of administration are the key advantages over the masseteric nerve block. Since its inception, we have refined the technique for administering the twin block and our clinical experience corroborates its safety and efficacy. This review describes the refined technique and its safety in the context of the region's applied anatomy.

Keywords: Deep temporal nerve; Masseteric nerve; Myofascial pain; Myogenous face pain; Twin block.

© 2020 by the American Dental Society of Anesthesiology.

Figures

Figure 1

Temporal fossa (purple outline). (a) Sagittal view. (b) Supersagittal view. The figures display the superior (the temporal lines), medial (parietal, frontal, temporal bones and the greater wing of the sphenoid forming the pterion, bounded by the pericranium located deep to the temporalis muscle; also see Figure 2), lateral (temporal fascia), anterior (posterior border of the frontal process of the zygomatic bone, pericranium), and inferior (the infratemporal crest) borders of the temporal fossa. Note that the tip of the coronoid process is usually below the inferior border of the temporal fossa medial to the zygomatic arch (b).

Figure 2

Spatial relation of the facial nerve and the injection site. The relationship between the temporal branch of the facial nerve and twin block injection site. The landmark is for the twin block injection (solid red circle). This figure is modified from reference 5.

Figure 3

(a) Target site for the twin block. The puncture point (X) is 1 cm above the zygomatic arch and 1 cm behind the frontal process of the orbit. (b) Orientation of the needle. The needle is 35–45° away from the temporal bone and 90° to the zygomatic arch. (c) Full insertion of the needle.