Altered low-frequency oscillation amplitude of resting state-fMRI in patients with discogenic low-back and leg pain

Abstract

ObjectiveThe aim of this study was to explore the amplitude of intrinsic low-frequency oscillations (LFOs) in patients with discogenic low-back and leg pain (LBLP).Participants and methodsWe obtained and compared the LFO amplitude from 25 right-handed discogenic LBLP patients (13 males; mean age 55.16±1.83 years) and 27 well-matched healthy controls (15 males; mean age 52.96±1.63 years). The LFO amplitude was examined using the voxel-wise amplitude of low-frequency fluctuations (ALFFs), and partial correlation analysis was performed to determine the relationship between the regions with altered ALFF values and clinical parameters in discogenic LBLP patients.ResultsCompared with healthy controls, the patients with discogenic LBLP showed a significant increase in ALFF in the affective system of the pain matrix (left anterior cingulate cortex, right anterior insula/frontal operculum, and bilateral orbitofrontal cortex) and information-processing regions (middle occipital/temporal gyrus). In addition, a significant decrease in ALFF was observed in the default mode network (DMN; inferior parietal lobule (IPL) and medial prefrontal cortex [mPFC]) and the processing system of the pain matrix (basal ganglia/thalamus/midbrain, postcentral gyrus [PoCG], and fusiform gyrus). Several regions with altered ALFF were associated with disease duration, visual analog scale scores, Barthel index, and fine sensory modality measurements (two-point tactile discrimination of the left and/or right leg). Further operating characteristic curves analysis suggested that the mean ALFF values in the right IPL, left IPL/PoCG, left anterior cingulate cortex, and left mPFC could serve as markers to separate individuals with discogenic LBLP from healthy subjects.ConclusionOur results revealed widespread abnormalities in ALFF in the pain matrix and information-processing regions as well as a decrease in ALFF in the DMN. These results open up an important new avenue to better understand the nature of the link between intrinsic activity and peripheral pain and sensory impairment in discogenic LBLP patients.

Altered intrinsic brain activity and regional cerebral blood flow in patients with chronic neck and shoulder pain

“…A study suggested that patients with blindness had changes in the thickness of the middle occipital gyrus [47]. Another study reported that patients with discogenic low back and leg pain showed increased ALFF in the left middle occipital gyrus [16]. However, our study had inconsistent findings for this region.…”

“…Resting-state functional magnetic resonance imaging (rs-fMRI), widely used in chronic pain diseases [11][12][13][14][15], is an effective tool to evaluate the intrinsic neural activity of the human brain [16,17]. The rs-fMRI analysis methods mainly include amplitude of low-frequency fluctuation (ALFF), regional homogeneity (ReHo) [9], and functional connectivity (FC) [10].…”

Loss of nucleus accumbens low-frequency fluctuations is a signature of chronic pain

“…Functional connectivity results suggest that, as pain becomes chronic (i.e., >1 y), the NAc subcircuitries fc show dynamic changes. We therefore studied power spectral density (PSD) (20, 21) because this approach uncovered meaningful differences among clinical populations (22) including chronic pain patients (23)(24)(25)(26)(27)(28)(29). We calculated PSD for different frequency bands defined in previous neurophysiological and fMRI studies (21,30,31) in bilateral NAc and compared among groups using a hypothesis-based approach.…”

Oxytocin modulates intrinsic neural activity in patients with chronic low back pain

“…The thalamus, on the other hand, has an important function in pain perception as a target of ascending spinal activity and some studies indicate altered functioning (Fenton et al, 2015). Zhou et al (2018) reported a decrease in ALFF in the thalamus in discogenic low back and leg pain patients, while an increase in ALFF in the thalamus was observed after pain‐exacerbating maneuvers in chronic low back pain patients (Zhang et al, 2019).…”

“…Indeed, a growing body of research shows altered intrinsic neural activity in chronic pain (Alshelh et al, 2017; Baliki & Apkarian, 2015; Zhang et al, 2019). In addition, Zhou et al (2018) reported increased amplitude of low‐frequency fluctuations (ALFF) in regions of the pain matrix such as anterior insula or orbitofrontal cortex, as well as decreased ALFF in basal ganglia, thalamus and midbrain in patients with discogenic low‐back and leg pain. It is noteworthy that several other studies have shown disrupted functional connectivity in patients with chronic back pain, particularly in cortical midline regions (i.e., medial prefrontal cortex, cingulate cortex, amygdala and insula (Kregel et al, 2015; Tagliazucchi, Balenzuela, Fraiman, & Chialvo, 2010).…”