Bidirectional alterations in ALFF across slow-5 and slow-4 frequencies in the brains of postherpetic neuralgia patients

Abstract

Lili Gu,1,* Shunda Hong,2,* Jian Jiang,2 Jiaqi Liu,2 Xintian Cao,1 Qing Huang,2 Xianjun Zeng,2 Fuqing Zhou,2 Daying Zhang1 1Department of Pain, The First Affiliated Hospital, Nanchang University, Nanchang, Jiangxi, People’s Republic of China 2Department of Radiology, The First Affiliated Hospital, Nanchang University, Nanchang, Jiangxi, People’s Republic of China *These authors contributed equally to this work Purpose: Postherpetic neuralgia (PHN) detrimentally affects brain function. Recent studies have suggested that frequency-dependent changes in electroencephalography in chronic pain patients and blood oxygenation level dependent (BOLD) fluctuations can reflect neuronal activity in different frequencies. The current study aimed to investigate PHN-related brain oscillatory activity in a specific frequency band by using the amplitude of low-frequency fluctuation (ALFF) method.Materials and methods: ALFF changes were analyzed across different frequencies (slow-4 band: 0.027–0.073 Hz; slow-5 band: 0.01–0.027 Hz; and typical band: 0.01–0.08 Hz) in the brains of PHN patients and compared with those in the brains of healthy controls (HCs) during resting-state fMRI. Eighteen HCs and PHN patients underwent fMRI scanning.Results: In the typical band, compared with HCs, PHN patients showed prominently decreased ALFF in the right prefrontal cortex (Brodmann area 10/46) and increased ALFF in the bilateral brain stem/cerebellum anterior lobe (BS/CAL). In the slow-4 band, PHN patients exhibited significantly decreased ALFF in the bilateral cuneus/lingual gyrus and the right prefrontal cortex. In the slow-5 band, PHN patients presented significantly increased ALFF in the bilateral BS/CAL and left parieto-occipital cortex. Moreover, the increased ALFF in the left parieto-occipital cortex in the slow-5 band was positively correlated with VAS scores (P=0.022), and the increased ALFF in the bilateral BS/CAL in the slow-5 band was positively correlated with disease duration (P=0.020).Conclusion: Our results suggested that the intrinsic brain activity of PHN patients was abnormal and frequency dependent, especially the bidirectional alteration in ALFF across the slow-4 and slow-5 frequencies in the brains of PHN patients. Keywords: amplitude of low-frequency fluctuation, postherpetic neuralgia, functional magnetic resonance imaging, resting state, pain 

Keywords

• amplitude of low-frequency fluctuation
• postherpetic neuralgia
• functional magnetic resonance imaging
• resting state
• pain