# Amplitude of low-frequency fluctuations in classical trigeminal neuralgia patients with purely paroxysmal and concomitant continuous pain

## TL;DR

This study compares brain activity differences in two types of trigeminal neuralgia using MRI scans to understand their distinct neural mechanisms.

## Contribution

The study identifies distinct patterns of spontaneous brain activity in two subtypes of classical trigeminal neuralgia using sALFF and dALFF analyses.

## Key findings

- PP-CTN patients showed reduced sALFF in regions like the left calcarine fissure and putamen compared to healthy controls.
- CCP-CTN patients exhibited increased sALFF in the superior frontal gyrus and insula compared to both healthy controls and PP-CTN patients.
- Both subtypes showed altered dALFF in the anterior cingulate gyrus and cuneus, with CCP-CTN showing additional changes in the insula and brainstem.

## Abstract

Purely paroxysmal neuralgia (PP-CTN) and concomitant continuous pain (CCP-CTN) are different subtypes of classical trigeminal neuralgia (CTN). Our aim was to explore the common and unique spontaneous brain activity abnormalities between subtypes.

A total of 101 PP-CTN patients, 52 CCP-CTN patients, and 122 age- and sex-matched healthy controls (HCs) were included. All the subjects underwent resting-state functional magnetic resonance imaging, and changes in spontaneous brain activity were observed via whole-brain static amplitude of low-frequency fluctuation (sALFF) and dynamic amplitude of low-frequency fluctuation (dALFF).

Compared with HCs, PP-CTN patients presented significantly lower sALFF values in the left calcarine fissure and surrounding cortex (CAL), left putamen, and left Rolandic operculum (ROL). Compared with HCs, CCP-CTN patients presented significantly increased sALFF values in the left superior frontal gyrus (SFG), right medial superior frontal gyrus (MSFG), left putamen, right insula, and brainstem. Compared with the PP-CTN group, the CCP-CTN group presented significantly greater sALFF values in the left CAL, left SFG, right MSFG, left putamen, right insula, left ROL and brainstem. The results of the dALFF analysis revealed that, compared with HCs, PP-CTN patients presented increased dALFF values in the anterior cingulate gyrus (ACG) and decreased dALFF values in the right cuneus. Compared with HCs, CCP-CTN patients presented increased dALFF values in the ACG, right insula, and brainstem and decreased dALFF values in the right cuneus. Compared with the PP-CTN group, the CCP-CTN group presented increased dALFF values in the right insula and brainstem.

Our findings reveal different neural mechanisms between PP-CTN and CCP-CTN patients, providing important neuroimaging evidence to better understand the pathophysiology of different subtypes of CTN.