Functional Connectivity of the Default Mode Network and Its Association With Pain Networks in Irritable Bowel Patients Assessed via Lidocaine Treatment

Abstract

The default mode network (DMN), a group of brain regions implicated in passive thought processes, has been proposed as a potentially informative neural marker to aid in novel treatment development. However, the DMN’s internal connectivity and its temporal relationship (ie, functional network connectivity) with pain-related neural networks in chronic pain conditions is poorly understood, as is the DMN’s sensitivity to analgesic effects. The current study assessed how DMN functional connectivity and its temporal association with 3 pain-related networks changed after rectal lidocaine treatment in irritable bowel syndrome patients. Eleven females with irritable bowel syndrome underwent a rectal balloon distension paradigm during functional magnetic resonance imaging in 2 conditions: natural history (ie, baseline) and lidocaine. Results showed increased DMN connectivity with pain-related regions during natural history and increased within-network connectivity of DMN structures under lidocaine. Further, there was a significantly greater lag time between 2 of the pain networks, those involved in cognitive and in affective pain processes, comparing lidocaine to natural history. These findings suggest that 1) DMN plasticity is sensitive to analgesic effects, and 2) reduced pain ratings via analgesia reflect DMN connectivity more similar to pain-free individuals. Findings show potential implications of this network as an approach for understanding clinical pain management techniques. Perspective This study shows that lidocaine, a peripheral analgesic, significantly altered DMN connectivity and affected its relationship with pain-related networks. These findings suggest that the DMN, which is hypothesized to represent non-goal-oriented activity, is sensitive to analgesic effects and could be useful to understand pain treatment mechanisms.

Imaging brain mechanisms in chronic visceral pain

“…Potential therapeutic effects of intrarectal lidocaine on IBS visceral hypersensitivity have previously been reported [70]. The same group assessed how functional connectivity of the default mode network (DMN) and its temporal association with 3 pain-related networks was modulated by rectal lidocaine treatment in IBS patients [44]. During lidocaine, increased within-network connectivity of DMN structures was observed, suggesting that DMN plasticity is sensitive to analgesic effects, and that reduced pain ratings via analgesia reflect DMN connectivity more similar to pain-free individuals.…”

Neurobiology of fibromyalgia and chronic widespread pain

“…Furthermore, in these studies the degree of increased connectivity was related the intensity of ongoing, spontaneous pain (Napadow et al, 2010). Several other groups have shown a strong relationship between ongoing spontaneous pain, and hyperconnectivity between the insula and the default mode network in other chronic pain conditions (Letzen et al, 2013, Loggia et al, 2013). Other brain regions may be hypo-connected in fibromyalgia and other centralized pain states.…”

Immediate Changes After Manual Therapy in Resting-State Functional Connectivity as Measured by Functional Magnetic Resonance Imaging in Participants With Induced Low Back Pain

“…[9] Recently, Letzen et al (2013) used FC between the default mode network and brain regions associated with pain processing to investigate lidocaine induced analgesia. [6] While, Zyloney et al (2010) used FC between the Periaqueductal Gray (PAG) and cortical regions to investigate differential effects underlying analgesia from of genuine and sham electro-acupuncture. [10] With the evidence supporting efficacy of MT to reduce pain intensity and pain sensitivity, it is reasonable to assume that the underlying therapeutic effect of MT is likely to include a higher cortical component.…”