Trigeminal neuropathy is a condition characterized by a specific pattern and location of facial pain. Clinical features involve unilateral and paroxysmal attacks of very intense pain in one or more areas innervated by the trigeminal nerve. The pathogenesis is frequently unclear and the vast majority of cases remain idiopathic. A thorough patient history and a physical examination are crucial steps of the workup, whereas imaging studies and neurophysiological testing are often necessary to solidify the diagnosis.
Trigeminal neuropathy is an important neuropathic disorder that can have a considerable impact on the quality of life   . This condition is often regarded as idiopathic, although vascular compression of the trigeminal nerve seems to be the most probable cause in the majority of patients  . Tumors and demyelinating diseases (for example multiple sclerosis) have been described as potential etiologies as well  . The main symptom of this condition, namely facial pain, stems from the irritation of the trigeminal nerve and its branches - ophthalmic (V1), maxillary (V2), and mandibular (V3) nerves    . The pain is characterized as stabbing, superficial, electric shock-like, sharp, or intense pain, and regarded as a very debilitating condition   . It is virtually always unilateral, but isolated reports show that bilateral occurrence has been encountered in about 30% of multiple sclerosis patients affected by trigeminal neuropathy . The onset is paroxysmal, lasting seconds to minutes, and is often precipitated by a seemingly benign event, such as a light touch, on the affected side of the face   . One or more divisions of the trigeminal nerve are involved while the pain never spreads to parts of the head and neck which are not innervated by the trigeminal nerve    .
The diagnostic workup of patients in whom trigeminal neuropathy is suspected should start with a comprehensive patient history during which the physician must cover the duration of symptoms and the characteristics of pain, including its pattern of occurrence as well as severity and location   . Together with the obtained information, the physical examination can provide important clues to the etiology of the disease. Reduced sensitivity of the trigeminal branches, either partial or total (hypoesthesia and anesthesia, respectively), during the neurological examination is a crucial finding in this patient population and should prompt a more detailed investigation . Imaging studies, mainly magnetic resonance imaging (MRI), are highly useful in recognizing an ongoing process in the brain that could induce trigeminal neuropathy    . MRI is particularly useful for detecting vascular malformations that compress the trigeminal nerve and currently serves as a gold-standard for the examination of craniofacial pain . Some authors recommend X-rays and computed tomography (CT) scans to exclude other, more common, pathologies  . In addition, neurophysiological trigeminal reflex testing has shown to be equally effective compared to MRI in identifying trigeminal neuropathy  .