Systematic Review of Autonomic Nervous System Functioning in Pediatric Chronic Pain.

Objectives: Chronic pain is a common and debilitating health problem that impacts up to one third of children and adolescents. The pathophysiological mechanisms of chronic pain are complex, but considerable research links dysfunction of the autonomic nervous system (ANS) and chronic pain in adults. No review of ANS functioning has been conducted in pediatric chronic pain. We systematically reviewed studies examining ANS activity among youth with primary chronic pain conditions.

Methods: A systematic search of PsycINFO, PubMed, and CINAHL was conducted using specific search terms. Articles were included if studies measured heart rate, blood pressure, heart rate variability, galvanic skin responses, or pupillometry among children or adolescents with a chronic pain condition. Studies examining these factors in the context of a specific disease-related pain condition were excluded.

Results: Of the 1304 articles screened, 15 studies met the criteria for inclusion in this review. All included studies were cross-sectional and primarily included youth with abdominal pain. Results revealed preliminary evidence of reduced parasympathetic activity among youth with pain as measured by heart rate variability. However, results were mixed across ANS indices. Measurement and procedural differences, in addition to a lack of control groups in some studies, limit the interpretability of the reviewed findings.

Discussion: Additional studies with larger and more diverse samples of youth with various chronic primary pain conditions are needed to delineate possible relationships among ANS functioning and the development and maintenance of chronic pain in children and adolescents. Clinical implications and avenues for future research are discussed.