New clues emerge about chronic pain and the immune system
A recent study led by researchers at the University of Arizona suggests there may be a connection between chronic pain and eosinophilia, a relatively rare immune condition. The finding could pave the way for immune biomarkers that help predict treatment response for chronic pain patients.
What the study examined
The team reviewed medical records of 212 patients with high-impact chronic pain who underwent two common therapies: spinal cord stimulation (SCS) and intrathecal pain pumps. These devices are used to manage severe, persistent pain when other treatments fail. To assess the potential link with eosinophilia, the researchers focused on 114 patients who had routine blood tests within a month prior to their device implantation.
Eosinophilia: a brief context
Eosinophilia is characterized by elevated levels of eosinophils, a type of white blood cell involved in defending the body against allergens and certain infections. It is typically found in fewer than 1% of the general population and can accompany a range of autoimmune and inflammatory conditions. While the condition is uncommon, its presence can signal an underlying immune system imbalance.
Key findings
The study found that 14 of the 114 patients (about 12%) had eosinophilia before undergoing spinal cord stimulation or intrathecal drug pump implantation. In contrast, eosinophilia affects a much smaller portion of the general population. The researchers emphasized that this is an observational finding and does not prove causation, but it raises important questions about how the immune system might interact with chronic pain and its treatment.
Implications for treatment and research
Although patients with eosinophilia did not show worse outcomes with their pain treatments, the discovery invites speculation about whether eosinophilia could serve as a biomarker for predicting who will respond to certain therapies. About 70% of spinal cord stimulation patients experience some reduction in pain, but individual responses vary. The researchers asked whether eosinophilia—and by extension immune activity—might help identify likely responders or non-responders.
“Few studies have examined a connection between eosinophilia and pain,” said lead author Dr. Julie Pilitsis, highlighting the potential for risk factor identification that could tailor chronic pain management. The study also prompts questions about whether treatments that reduce inflammation might influence eosinophilia and, by extension, pain outcomes.
What comes next?
The authors stress that more work is needed to determine whether eosinophilia could function as a reliable biomarker for chronic pain treatment decisions. Future research could explore whether anti-inflammatory strategies or targeted immune therapies might benefit patients who exhibit eosinophilia alongside chronic pain. Importantly, the study found no direct correlation between inflammatory conditions like rheumatoid arthritis and eosinophilia in this cohort, suggesting a more nuanced relationship between immune activity and pain.
Context within the broader field
Chronic pain is increasingly viewed through an inflammatory lens, with scientists seeking objective biomarkers to improve diagnosis and personalize treatment. If eosinophilia or related immune signals prove relevant to chronic pain, clinicians may gain new tools to predict outcomes and optimize interventions such as SCS or intrathecal pumps.
Team and affiliations
In addition to Julie Pilitsis, the study lists colleagues from the University of Arizona’s Department of Neurosurgery and the Comprehensive Center for Pain and Addiction, with collaborations extending to Florida Atlantic University. The work contributes to ongoing efforts to bridge neuromodulation therapies with immune system science.
As researchers continue to untangle the relationship between the immune system and chronic pain, patients and clinicians alike await further studies that could translate this early signal into practical, personalized care.
