Abstract
BackgroundRecent data suggests that in chronic pain there are changes in gray matter consistent with decreased brain volume, indicating that the disease process may produce morphological changes in the brains of those affected. However, no study has evaluated cortical thickness in relation to specific functional changes in evoked pain. In this study we sought to investigate structural (gray matter thickness) and functional (blood oxygenation dependent level – BOLD) changes in cortical regions of precisely matched patients with chronic trigeminal neuropathic pain (TNP) affecting the right maxillary (V2) division of the trigeminal nerve. The model has a number of advantages including the evaluation of specific changes that can be mapped to known somatotopic anatomy.Methodology/Principal FindingsCortical regions were chosen based on sensory (Somatosensory cortex (SI and SII), motor (MI) and posterior insula), or emotional (DLPFC, Frontal, Anterior Insula, Cingulate) processing of pain. Both structural and functional (to brush-induced allodynia) scans were obtained and averaged from two different imaging sessions separated by 2–6 months in all patients. Age and gender-matched healthy controls were also scanned twice for cortical thickness measurement. Changes in cortical thickness of TNP patients were frequently colocalized and correlated with functional allodynic activations, and included both cortical thickening and thinning in sensorimotor regions, and predominantly thinning in emotional regions.ConclusionsOverall, such patterns of cortical thickness suggest a dynamic functionally-driven plasticity of the brain. These structural changes, which correlated with the pain duration, age-at-onset, pain intensity and cortical activity, may be specific targets for evaluating therapeutic interventions.
Highlights
Neuroplastic functional and structural changes in chronic pain have been shown in a number of human studies
When the trigeminal neuropathic pain (TNP) cohort was compared to the healthy controls (HC), we observed bilateral thinning in the lowest sections of the somatosensory cortex that somatotopically represents the craniofacial region in SI, which extended inferiorly to SII ipsilateral to the pain (Figure 2)
When the TNP group was compared with the HC group, we found significant bilateral thinning in ventral Dorsolateral Prefrontal Cortex (DLPFC), mainly along the anterior and posterior frontal inferior sulci, which extended to the dorsal DLPFC in the contralateral side to the pain (p,0.011)
Summary
Neuroplastic functional and structural changes in chronic pain have been shown in a number of human studies. More recent studies using a highly sensitive MRI method with submillimeter measures of cortical gray matter [5] have contributed to the understanding that, like the functional activation, the pattern of structural changes may vary across chronic pain disorders [6]. Such alterations in the structure and function of the cortex in chronic pain patients may be correlated as recently described in stroke patients [7]. The model has a number of advantages including the evaluation of specific changes that can be mapped to known somatotopic anatomy
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
