Roger Allen, PhD, PT
Purpose/Hypothesis: Prior research established that free thyroxine (FT4) sharply increases ten days after significant psychogenic stressors and these elevations are correlated with episodic pain flares in patients with various neuropathic pain conditions. This relationship has yet to be studied in patients with phantom limb pain (PLP). This study’s purpose was to investigate the relationship between psychogenic stress, subsequent peaks in FT4 and PLP flares.
Number of Subjects: Participants were two males with PLP due to amputation. Participant 1 had intact thyroid function, while Participant 2 had a history of thyroidectomy and was taking synthetic thyroxine.
Materials/Methods: Over 10 weeks, participants provided daily ratings of pain and stress using visual analog scales (VAS) and daily blood samples for FT4 analysis. Ratings of stress were compared to pain and FT4 using serial lag correlations of 0-14 days. Concordance between FT4 levels and perceived pain was assessed with same-day correlations.
Results: The participant with intact thyroid function showed elevations in both FT4 and pain ten days after significant stressors, and pain flares correlated with high FT4 levels. These relationships were absent in the post-thyroidectomy patient, who did not show delayed FT4 or pain elevations in response to stress.
Conclusions: These findings support the hypothesis that stress-related FT4 levels are associated with episodic PLP flares occurring ten days after salient stressors, consistent with studies investigating other neuropathic pain conditions.
Clinical Relevance: This research supports the notion that latent stress-related pain perception is mediated via central pain pathways.
University of Puget Sound
Ip, Arista; Fazzini, Eva; and Allen, Roger PhD, PT, "Relationship between delayed pain flares, psychogenic stress and free thyroxine in patients with phantom limb pain." (2017). Physical Therapy Research Symposium. 30.