Typical and atypical trigeminal neuralgia. Neither an indipendent disease nor a mere progression of disease. Towards a third hypothesis with therapeutical implications.

Anno
2017
Proponente -
Struttura
Sottosettore ERC del proponente del progetto
Componenti gruppo di ricerca
Componente Categoria
Franco Burla Componenti il gruppo di ricerca
Abstract

Trigeminal neuralgia (TN) is an exemplary condition of neuropathic facial pain. The clinical diagnosis is relatively easy in patients with typical paroxysmal attacks. Almost 50% of the patients, however, have an atypical phenotype with both paroxysmal and continuous pain, which is distributed in the same territory of the paroxysmal pain. Whereas patients with typical TN are easily diagnosed, and respond fairly well to medical and surgical treatment, those with this atypical form are more difficult to diagnose and to treat. There were two opposite theories about the pathophysiology of the atypical form: investigators proposed either that the continuity of pain merely resulted from progressive damage to the trigeminal nerve in the course of disease or that a central mechanism was involved.
In the past year we were able to exclude both theories, because in patients with the atypical form we found significant abnormalities of the C-related laser evoked potentials, i.e. damage to the unmyelinated fibres. Hence now we believe there must be a different mechanism, probably entailing a greater mechanical insult to the trigeminal root, from the very beginning.
We plan to verify two aspects: 1) using a skin biopsy punch in patients with the atypical form we will measure the intraepidermal nerve fibre density, which must be reduced if the primary damage also involves the ganglion cell bodies or be normal if the site of damage is, as in the typical form of neuralgia, near the root entry zone, and 2) using dedicated 3T, 3D MRI scans we will measure in both typical and atypical forms the degree of atrophy of the trigeminal root. If skin biopsy is normal, thus excluding a supplementary damage to the ganglion, and the atrophy of the root is more severe in the atypical forms, than we will be able to propose the view that the concomitant continuous pain of atypical trigeminal neuralgia is due to a stronger mechanical compression that entails damage to the unmyelinated fibres.

ERC
Keywords:
name

© Università degli Studi di Roma "La Sapienza" - Piazzale Aldo Moro 5, 00185 Roma