Abstract and Introduction
Objective: This narrative review aims to update the reader on the new classification of trigeminal neuralgia (TN), clinical signs, pathophysiologic evidence, and their implications on management. This review is based on the authors' collective experience and knowledge of the literature in addition to a literature search.
Background: In recent years, the phenotype of TN has been intensively studied leading to discrete groups of patients. These include patients with TN with additional continuous pain, and patients with and without neurovascular compression of the trigeminal dorsal root entry zone. A number of associated clinical signs such as tearing and sensory changes need further research.
Methods: The literature on TN was searched in PubMed with the aims of providing evidence for the recently published third edition of the International Classification of Headache Disorders (ICHD) and update the clinical phenotype and management of the TN subcategories.
Results: The ICHD's new classification for TN is based on reliable clinical data, imaging, and neurophysiologic studies. The TN classification reflects current knowledge and has improved the possibility for clinicians to choose adequate management options. However, there is a lack of effective, safe drugs for the management of TN and sparse, robust data on neurosurgical options.
Conclusion: Research into all aspects of TN—diagnosis, pharmacotherapy, surgery, long-term management prognosis, and natural history—is needed. Research should adhere to the ICHD's schema for TN. Improved drugs are needed along with rigorous research into surgical options and their efficacy for different subtypes of TN.
Trigeminal neuralgia (TN) is a unilateral facial pain with pronounced physical signs and symptoms and a very typical clinical phenotype. The pain is excruciating, short-lasting, usually described as electrical or sharp and is "triggered" by light touch in the affected area. Often pain is accompanied by a characteristic spasm in the ipsilateral part of the face and explains its previous names "tic convulsif" or "tic douloureux." The disorder is debilitating and significantly affects the quality of life (QoL).[2,3]
Over the last decade or so we have recognized that TN does not exclusively present as described above. A large proportion of patients have continuous pain between attacks; attack duration may last for longer than 2 min; some patients have ipsilateral tearing; and mild sensory changes are quite common even in the absence of a space-occupying lesion or multiple sclerosis (MS). More recently, a large number of patients with TN have been shown to lack any significant neurovascular compression (NVC). The current schema for TN and its subtypes published by the International Headache Society (IHS) with the third edition of the International Classification of Headache Disorders, 3rd edition (ICHD-3) is the result of intense collaboration between the IHS and the International Association for the Study of Pain (Table 1).
During the last decade, new "faces" of TN have been described with different phenotypes, variably including continuous pain, tearing, and longer attack duration, which are now also partly reflected in ICHD-3. This raises some important questions: Are the different clinical phenotypes a spectrum of the same disorder? Or are we seeing the emergence of clearly different subtypes with related but distinct pathophysiologies and possibly treatment protocols? These are the emerging faces of TN.
Headache. 2021;61(6):817-837. © 2021 Blackwell Publishing