Sensory phenotypes in complex regional pain syndrome and chronic low back pain—indication of common underlying pathomechanisms

PAIN Reports, 2023 · DOI: http://dx.doi.org/10.1097/PR9.0000000000001110 · Published: January 1, 2023

Simple Explanation

This study explores the underlying mechanisms of chronic pain by examining sensory profiles in patients with complex regional pain syndrome (CRPS) and chronic low back pain (LBP). It aims to identify common sensory phenotypes across different chronic pain conditions, irrespective of specific diagnoses. Quantitative sensory testing (QST) was used to assess sensory changes in both the most painful area and a pain-free area of the body. This helps to understand both local and widespread changes in how the body processes sensory information. The study found two main sensory profiles, or clusters, among the patients. These clusters didn't neatly separate the CRPS and LBP patients, suggesting that similar pain mechanisms might be at play in both conditions.

Study Duration

November 2019 and April 2022

Participants

81 chronic pain patients (20 CRPS, 61 LBP) and 63 healthy controls

Evidence Level

Cross-sectional study

Key Findings

1
Two clusters were identified based on QST measures in the painful area, with patients from both CRPS and LBP cohorts present in each cluster.
2
Cluster 1 exhibited increased pain sensitivities in both painful and control areas, suggesting central sensitization as a potential underlying mechanism.
3
Cluster 2 showed a sensory profile similar to healthy controls, indicating that sensitization may not be the primary driver of pain in this group, or that QST was not sensitive enough to detect it.

Research Summary

The study aimed to identify common sensory phenotypes across different chronic pain cohorts (CRPS and LBP) to understand potential underlying mechanisms. Cluster analysis of quantitative sensory testing (QST) data revealed two distinct sensory phenotypes that did not align with the specific pain diagnoses. The findings suggest that shared pathomechanisms may exist irrespective of pain diagnosis, and different mechanisms may contribute to pain even within the same diagnosis.

Practical Implications

Mechanism-Targeted Treatment

Treatment strategies should be based on identified pain mechanisms (sensory phenotypes) rather than solely on the clinical diagnosis.

Comprehensive Pain Management

Effective pain management requires a comprehensive approach addressing physiological, psychological, and social factors, not just the sensory aspects.

Further Research

Further research is needed to identify more objective measures and explore the role of deep tissue sensitization and psychosocial factors in chronic pain.

Study Limitations

1
Lack of a validation set for the cluster analysis.
2
No sample size estimation was performed before the study, potentially reducing the study’s statistical power
3
Patients were not taken off their pain medication owing to ethical concerns, medication may have influenced some of the study outcomes.

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