The Role of Sensory Fiber Demography in Trigeminal and Postherpetic Neuralgias

Abstract

A supplemental appendix to this article is published electronically only at http://jdr.sagepub.com/supplemental. AbstrActIn this study, we systematically investigated fiber demography, based on function and distribution, from the periphery to their destinations in the various central (sub) nuclei in the trigeminal brainstem nuclear sensory complex. Conventional and novel compelling information is provided, demonstrating that the ratio and somatotopy of types A and C sensory fibers at the site of a lesion can elucidate important puzzles in TNP disorders. For instance, we explain how of a major shift in the fibers' direction and ratio at the level of the trigeminal root entry zone (REZ) influences the pathophysiology of preand typical trigeminal neuralgia. As a result, there is a high A/C ratio of oral and peri-oral fibers in the supero-medial region of the REZ, which is mostly susceptible to vascular compression. However, this A/C ratio varies considerably at lower proportions in other areas along the peripheral trigeminal pathway, where an injury (viral, vessel compression, or trauma) can lead to a broader spectrum of fiber involvement and, consequently, pain outcome. In summary, we explain how fiber demography can influence pain quality, location, temporal features, progress, and treatment prognosis of TNP in those patients who develop it.

Electrophysiological characteristics of the frontal nerve in patients with herpetic ophthalmic neuralgia

“…Nervous tissue lesions due to VZV are usually observed from the dorsal root ganglion through nerve fibers to the endings . V1 has a large concentration of unmyelinated fibers and a lower A/C fiber ratio than V2 and V3 . However, in our study, the abnormal SNAP amplitude of the affected SONs and STN, which was less than the lower limit of the SNAP, indicated the presence of axonal damage in large fibers.…”

Quality of life in chronic trigeminal neuralgia patients

“…It is known that TN has a higher prevalence between subjects above 50 years old 9 . Mean age results found for group I are in accordance with other authors 10 .…”

Neurophysiological aspects of the trigeminal sensory system: an update

“…The distribution of different fibers shifts toward the nuclei and could explain certain pathological behaviors as illustrated by DaSilva and DosSantos (2012). Importantly, fiber demography and ratio, as well as the somatotopic arrangement of myelinated and non-myelinated fibers, has been implicated in several infectious and noninfectious injuries to the trigeminal system.…”