Orofacial pain disorder or trigeminal autonomic cephalalgia? Insights into pathophysiology and implications in medicine and dentistry

Objective

This narrative review highlights the importance of orofacial pain considerations in the differential diagnosis of trigeminal autonomic cephalalgias (TACs)/trigeminal autonomic orofacial pains (TAOPs). In addition, we provide novel insights into the pathophysiology of the presentation of TACs in the maxillary (V2) and mandibular (V3) trigeminal distributions (TAOPs).

Background

TACs are lifelong disorders characterized by severe unilateral head pain accompanied by cranial autonomic phenomena. However, the head pain experienced may refer to the face, be present solely in the orofacial region as TAOPs, or even be experienced as a toothache. These presentations, involving V2/V3, may resemble disorders of diverse etiology and pathophysiology that may share some similarities with TACs, confusing the patient while relating symptoms, and creating a diagnostic dilemma for the clinician potentially leading to misdiagnosis. Moreover, TACs pathophysiology has not been discussed in relation to V2/V3 presentations (TAOPs).

Methods

A literature search was performed on PubMed/Scopus to find relevant literature about TACs and TAOPs, and case reports of orofacial presentations. Deep reanalysis of several of our published articles on preclinical models of TACs was conducted to assess potential of V2‐V3 components.

Results

TACs orofacial presentations are not as common but if present can lead to misdiagnosis with significant consequences. Patients presenting TACs involving the midface as TAOPs experience an important delay for a correct diagnosis including multiple and diverse health provider visits, with a risk of having well‐intended but misguided procedures. Differential diagnosis considerations need to include dental/odontogenic causes, sinusitis, temporomandibular disorders, Eagle syndrome, trigeminal neuralgia, and migraine (orofacial migraine, neurovascular orofacial pain). A reanalysis of preclinical data provides novel insights into this orofacial involvement. In two TAC‐specific preclinical neuronal populations, recording either trigeminal or superior salivatory nucleus neurons, it was observed that ~20% and 37.5% of neurons, respectively, had cutaneous receptive fields that included or were exclusively within the V2‐V3 trigeminal division. Whereas the numbers are not large, these demonstrate that even in rodent models in neuronal populations that could be considered TAC‐like, they can extend to, or exclusively involve, the facial region, similar to TAOPs.

Conclusion

The potential presence of TACs in the orofacial region can be observed from preclinical models to the clinical setting. The International Classification of Headache Disorders (ICHD) needs to recognize this additional localization, as well as the intraoral one, including dental structures. Education about TACs/TAOPs in the medical and dental setting is vital. Evidence has shown that dentists are one of the first providers that are seen by this patient population due to similarities with dental pain. The dentist specialized in orofacial pain is a key ally in the identification of TACs/TAOPs. The medical/neurology and dental/orofacial pain settings have a great opportunity and responsibility to work together to stop years of pain in this patient population.

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