Proxies and patterns: the assessment of Human Assumed Central Sensitization
Proxies and patterns: the assessment of Human Assumed Central Sensitization
This PhD thesis of Ingrid Schuttert focuses on Human Assumed Central Sensitization (HACS) in patients with chronic low back pain (CLBP). HACS refers to the assumption that central sensitization, an increased sensitivity of the central nervous system, is present in humans based on reported symptoms, clinical signs, and recognizable patterns. Because central sensitization cannot be directly measured in humans, indirect assessment methods are used, such as quantitative sensory testing (QST) and questionnaires, including the Central Sensitization Inventory (CSI).
This thesis examined which definitions and assessment methods are used for HACS, how often HACS occurs in CLBP, the potential role of a selective nerve root block in patients complaining from CLBP radiating into the leg, and whether sex differences exist. A systematic review showed that many different definitions and methods are applied, resulting in a lack of uniform assessment. Based on these findings, a HACS grading system was developed that combines multiple assessment tools.
The CSI was revalidated for Dutch patients with chronic pain, resulting in a recommended cut-off value of 30/100, but with different cut-off values for women (33/100) and men (25/100). Comparing patients with and without radiating low back pain demonstrated that both sex and the presence of radiating pain influence HACS outcomes. Furthermore, the use of a single proxy increases the risk of overestimating HACS, while combining multiple methods provides a more comprehensive picture.
The findings emphasize the importance of standardized assessment of HACS in patients with chronic low back pain and contribute to the way to establish HACS with better supported probability, also in daily practice. However, the presence of HACS does not appear to be a determining factor for eligibility for pain treatments such as nerve root blocks.