Idiopathic Trigeminal Neuralgia
Clinical signs and symptoms, at this time, seem to be identical with those of CTN, but further research is needed. Comparing demographics of ITN with CTN, females are affected more commonly, and the patients are younger at disease onset.[86,87]
It is of interest to compare the efficacy of MVD between the two groups. Most previous studies do not distinguish efficacy rates based on morphological changes of the trigeminal nerve, but a few studies indicate that MVD is more efficacious in CTN versus ITN.[88–91] In one Danish neurosurgical study of 59 primary patients with TN, MVD was significantly more efficacious in men as opposed to women, but this possible sex difference is yet to be replicated in other similar high-quality studies.
The striking issue with ITN is that by definition there is no compression from a NVC and no other known causative factors. Further research is needed to elucidate pain mechanisms. Furthermore, neuropathic pain is defined as "pain arising as a direct consequence of any lesion or disease affecting the somatosensory system." Diffusion tensor imaging studies provide early data to indicate that patients with ITN also have de- and dysmyelination of the trigeminal root of unknown origin. These studies need replicating and expanding so that ITN can confidently be regarded as a neuropathic pain.
Headache. 2021;61(6):817-837. © 2021 Blackwell Publishing