Higher Sensory Cortical Energy Metabolism in Painful Diabetic Neuropathy: Evidence From a Cerebral Magnetic Resonance Spectroscopy Study

Abstract

Alterations in the resting-state functional connectivity and hyperperfusion of pain processing areas of the brain have been demonstrated in painful diabetic peripheral neuropathy (DPN). However, the mechanisms underlying these abnormalities are poorly understood; thus there is good rationale to explore whether there is higher energy consumption in the pain processing areas of the brain. We performed a 31P magnetic resonance spectroscopy study to explore cellular energy usage (bioenergetics) in the primary somatosensory (S1) cortex in a well-characterized cohort of participants with painful and painless DPN. S1 phosphocreatine (PCr):ATP, a measure of energy consumption, was significantly reduced in painful compared with painless DPN. This is indicative of greater S1 cortical energy consumption in painful DPN. Furthermore, S1 PCr:ATP correlated with pain intensity during the MRI. S1 PCr:ATP was also significantly lower in painful-DPN individuals with moderate/severe pain compared with those with low pain. To our knowledge, this is the first study to demonstrate higher S1 cortical energy metabolism in painful compared with painless DPN. Moreover, the relationship between PCr:ATP and neuropathic pain measures shows that S1 bioenergetics is related to the severity of neuropathic pain. S1 cortical energetics may represent a biomarker of painful DPN and could have the potential to serve as a target for therapeutic interventions.

Article highlights: Energy consumption within the primary somatosensory cortex appears to be greater in painful compared with painless diabetic peripheral neuropathy. The measure of energy metabolism, PCr:ATP, within the somatosensory cortex correlated with pain intensity and was lower in those with moderate/severe compared with low pain. To our knowledge. this is the first study to indicate higher cortical energy metabolism in painful compared with painless diabetic peripheral neuropathy, and thus has the potential to act as a biomarker for clinical pain trials.