Spinal cord stimulation is a surgical procedure considered a last resort for patients with chronic pain that other treatments cannot alleviate. The procedure involves implanting leads into the spine and electrically stimulating the spinal cord.
Since the spinal cord transmits sensations from the body to the brain, the leads are strategically positioned to target the pain site. This allows patients to feel the stimulation in the area of discomfort, helping them manage their pain.
According to research from Kobe University, a 10-minute brain scan has been shown to predict the effectiveness of spinal surgery for alleviating intractable pain. This breakthrough provides doctors with a valuable biomarker, allowing them to inform better patients considering spinal cord stimulation about the potential outcomes of the risky procedure.
The Kobe University anesthesiologist UENO Kyohei says: “A big issue is that the procedure is effective for some but not for other patients, and which is the case is usually evaluated in a short trial of a few days to two weeks before permanent implantation. Although this trial is short, it is still an invasive and risky procedure. Therefore, clinicians have long been interested in predicting a patient’s responsiveness to the procedure through non-invasive means.”
fMRI has become a standard tool to visualize how the brain processes information. More precisely, the brain scan can reveal which parts of the brain are activated in response to a stimulus, helping to identify regions that are functionally connected with one another.
Ueno said, “In an earlier study, we reported that for the analgesic ketamine, pain relief correlates negatively with how strongly connected two regions of the default mode network are before the drug’s administration.”
“The default mode network, which plays an important role in self-related thought, has previously been implicated in chronic pain. Another relevant factor is how the default mode network connects with the salience network, which regulates attention and the response to stimuli. Therefore, we wanted to examine whether the correlation of the activities within and between these networks could be used to predict responsiveness to spinal cord stimulation.”
The researchers discovered that patients who responded better to spinal cord stimulation therapy had weaker connectivity between a specific region of the default mode network and one in the salience network.
Ueno comments, “This not only provides an attractive biomarker for predicting treatment effectiveness but also supports the idea that an abnormal connection between these networks may contribute to the development of intractable chronic pain in the first place.”
While fMRI scans are one option, combining pain questionnaires with various clinical indices has also proven to be a reliable predictor of responsiveness to spinal cord stimulation.
The researchers note that, although the cost of an MRI scan is a topic of debate, the burden on both patients and healthcare providers would be significantly reduced if a single 10-minute resting-state fMRI scan could predict treatment responsiveness.
The study involved 29 patients with various forms of intractable chronic pain. The diversity of these patients likely contributed to a lower overall responsiveness to spinal cord stimulation compared to similar studies. It made it harder to assess the link between brain function and treatment outcomes precisely.
However, the researchers note, “From a clinical perspective, the ability to predict outcomes for patients with different conditions could provide significant utility.”
Ueno adds, “We believe that more accurate evaluations will be possible with more cases and research in the future. We are also investigating which brain regions are most affected by different spinal cord stimulation patterns. Although we are still in the early stages of this research, our ultimate goal is to use functional brain imaging as a biomarker to personalize spinal cord stimulation therapy and identify the optimal treatment for each patient.”
Journal Reference:
- Kyohei Ueno et al. Resting-state brain functional connectivity in patients with chronic intractable pain who respond to spinal cord stimulation therapy. British Journal of Anaesthesia. DOI: 10.1016/j.bja.2024.10.011
