Low-frequency BOLD fluctuations demonstrate altered thalamocortical connectivity in diabetic neuropathic pain

Franco Cauda,Dario Cocito,Sergio Duca,Gianluca Isoardo,Federico D'Agata,Katiuscia Sacco,Filippo Migliorati,Giuliano Geminiani

doi:10.1186/1471-2202-10-138

Abstract

BackgroundIn this paper we explored thalamocortical functional connectivity in a group of eight patients suffering from peripheral neuropathic pain (diabetic pain), and compared it with that of a group of healthy subjects. We hypothesized that functional interconnections between the thalamus and cortex can be altered after years of ongoing chronic neuropathic pain.ResultsFunctional connectivity was studied through a resting state functional magnetic resonance imaging (fMRI) paradigm: temporal correlations between predefined regions of interest (primary somatosensory cortex, ventral posterior lateral thalamic nucleus, medial dorsal thalamic nucleus) and the rest of the brain were systematically investigated. The patient group showed decreased resting state functional connectivity between the thalamus and the cortex.ConclusionThis supports the idea that chronic pain can alter thalamocortical connections causing a disruption of thalamic feedback, and the view of chronic pain as a thalamocortical dysrhythmia.

Highlights

In this paper we explored thalamocortical functional connectivity in a group of eight patients suffering from peripheral neuropathic pain, and compared it with that of a group of healthy subjects
BMC Neuroscience 2009, 10:138 http://www.biomedcentral.com/1471-2202/10/138 dynamics [4], and this dynamical aspect of the oscillations is consistent with Llinas's view of chronic pain as a thalamocortical dysrhythmia [5], where the slow rhythm is produced by a disruption of thalamocortical feedback
Several studies have reported anatomic, functional and biochemical changes in the thalamic region in patients suffering from chronic neuropathic pain suggesting that regions of the thalamus which have lost their normal somatosensory input or that show alterations in the metabolic balance can contain neurons which exhibit abnormal spontaneous and evoked activity and that electrical stimulation of these regions can produce the sensation of burning dysesthesia [7,20,21,22,23,24]

Summary

Introduction

In this paper we explored thalamocortical functional connectivity in a group of eight patients suffering from peripheral neuropathic pain (diabetic pain), and compared it with that of a group of healthy subjects. We hypothesized that functional interconnections between the thalamus and cortex can be altered after years of ongoing chronic neuropathic pain It is already known [1] that certain brain disorders, such as schizophrenia, Alzheimer's disease, autism, epilepsy and Parkinson's are associated with abnormal neural synchronization. Several studies have reported anatomic, functional and biochemical changes in the thalamic region in patients suffering from chronic neuropathic pain suggesting that regions of the thalamus which have lost their normal somatosensory input or that show alterations in the metabolic balance can contain neurons which exhibit abnormal spontaneous and evoked activity and that electrical stimulation of these regions can produce the sensation of burning dysesthesia [7,20,21,22,23,24]. Iadarola and colleagues [25] using positron emission tomography found a unilateral decrease in thalamic activity in patients with chronic neuropathic pain suggesting that this condition can cause functional alterations in thalamic pain processing circuits

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