A Narrative Review of Therapeutic Peripheral Nerve Blocks for Chronic Orofacial Pain Conditions

To provide an analysis of the different therapeutic peripheral nerve blocks (PNBs), as well as their limitations and the related evidence base for their use in chronic orofacial pain (OFP) conditions, excluding migraine and other headache conditions. The evidence base for therapeutic PNBs for chronic OFP is poor and highlights the need for improved research in this area. The diagnostic criteria and interventional PNB definitions and techniques varied between studies. In addition, the placebo effect of a peripheral injection and its resultant bias was rarely considered. Most of the PNB interventions for temporomandibular disorders were for arthrogenous disorders (arthritis and disc entrapment with pain). However, there is emerging evidence for the use of onabotulinum toxin (BTX-A) in trigeminal neuralgia, with four prospective randomized controlled trials (pRCTs), and for postherpetic neuralgia. However, despite high-level evidence for BTX-A in posttraumatic neuropathic pain outside the trigeminal system, there is no evidence for its use for PTNP within the trigeminal system. There may be emerging evidence for treating trigeminal neuralgia with BTX-A injections; however, there is a need for future clinical studies of therapeutic PNBs in orofacial pain conditions.