Imaging of trigeminal neuralgia

Trigeminal neuralgia is one of the most frequent neuropathy of the cranial nerves, whose prevalence has been reported between 0.03% and 0.3% in the general population. This condition is a communal manifestation of several possible etiologies. The classical type of trigeminal neuralgia is defined as sudden, usually unilateral, severe, brief, stabbing recurrent episodes of pain in the distribution of one or more branches of the trigeminal nerve, with no cause other than a neurovascular compression. Secondary trigeminal neuralgia is the term used to group a large amount of different diseases, which are alike in developing the symptoms of trigeminal neuralgia, due to an insult to the V CN which triggers the complex pathogenesis of pain. These conditions include inflammatory diseases, infections, neoplasms, autoimmune diseases, vascular diseases other than neurovascular conflict, and treatment-related disorders. Generally, the possible mechanisms which lead to the development of neuralgia include nerve distortion/compression by an external mass or damage to the nerve fibers due to an acute or chronic insult. The radiological investigation plays a pivotal role in the diagnosis of trigeminal neuralgia, and MRI constitutes the gold imaging standard in most cases. The trigeminal nerve is a mixed sensory-motor nerve which can be divided anatomically into five segments: brainstem segment, cisternal segment, Meckel’s cave segment, cavernous sinus segment, and extracranial segment. In this paragraph, an anatomy-based imaging approach is proposed to investigate the many causes of trigeminal neuralgia, highlighting the importance of choosing the appropriate sequences and parameters, in the light of a target-suited protocol.