Neuroimaging shows that spinal cord stimulation reduces emotional aspect of chronic pain.

Neuropathic pain is deﬁned as pain initiated or caused by a primary lesion or dysfunction in the nervous system. Chronic

neuropathic leg pain is the most common form of neuropathic pain with an estimated annual prevalence between 9.9% and 25% in the general population. Now, a study from researchers at The Ohio State University shows that patients who have chronic pain can reduce their emotional response to the pain through spinal cord stimulation. The team state that their findings provide insights into the role of the brain’s emotional networks in relieving chronic pain. The study is published in the journal Neuromodulation: Technology at the Neural Interface.

Previous studies show that the default mode network (DMN) is the resting state network of the brain and plays a key role in the cognitive and emotional aspects of pain perception. It’s also associated with functional connectivity hubs and brain networks. The resting DMN has been shown to be abnormal in patients with chronic painful conditions, implicating the impact of such chronic conditions on areas beyond pain perception. Spinal cord stimulation is a well-established therapeutic option for patients with refractory chronic back and leg pain. However, the neurophysiological basis of pain relief due to spinal cord stimulation and related cortical processing of sensory information, as well as the DMN are not completely understood. The current study uses fMRI to map the areas of the brain involved in pain perception and modulation.

The current study investigated 10 patients who were living with severe chronic leg pain and who were implanted with a spinal cord stimulator to reduce their pain. Seed-based analysis of the resting state functional connectivity was conducted using seeds in regions established as participating in pain networks or in the DMN, in addition to the network analysis. Results show significant differences in resting state connectivity between spinal cord stimulation off and optimal state were seen between several regions related to pain perception, including the left frontal insula, right primary and secondary somatosensory cortices, as well as in regions involved in the DMN, such as the precuneus.

Data findings show decreased connection strength between somatosensory and limbic areas and increased connection strength between somatosensory and DMN with optimal spinal cord stimulation resulting in pain relief. The lab state that this suggests pain relief from spinal cord stimulation may be reducing negative emotional processing associated with pain, allowing somatosensory areas to become more integrated into default mode activity. The group conclude that spinal cord stimulation reduces the affective component of pain resulting in optimal pain relief, and provides decreased connectivity between somatosensory and limbic brain regions associated with optimal pain relief.

The team surmise that their study is the first to show that therapeutic spinal cord stimulation can reduce the emotional connectivity and processing in certain areas of the brain in those with chronic pain. For the future, the researchers state that being able to modulate the connections between the brain areas involved in emotions and those linked to sensations may be an important mechanism involved in pain relief linked to spinal cord stimulation.

Source: The Ohio State University Wexner Medical Center