Sensory Sensitivity Over Time After Lower Limb Amputation and Its Association with Phantom Limb Pain

Area of Science:

• Neuroscience
• Pain Research
• Clinical Medicine

Background:

• Phantom limb pain (PLP) is a common post-amputation complication with unclear mechanisms.
• Existing research on PLP is largely cross-sectional, limiting understanding of its longitudinal course.
• Sensory processing alterations, assessed via Quantitative Sensory Testing (QST), are linked to PLP, but temporal changes are poorly understood.

Purpose of the Study:

• To longitudinally characterize sensory sensitivity changes in the first year post-amputation.
• To investigate the association between these sensory changes and PLP presence and intensity.
• To explore the evolving nature of sensory processing in amputees.

Main Methods:

• Longitudinal within-subject design with 11 lower limb amputees and 11 matched controls.
• Sensory function assessed using the standardized DFNS QST protocol at two time points (T1 and T2).
• Measures included thresholds (warm, heat pain, mechanical, pressure), wind-up ratio, mechanical pain sensitivity, and allodynia at residual and contralateral limbs.

Main Results:

• PLP prevalence increased from T1 to T2 in the amputee cohort.
• Amputees with PLP showed altered sensory thresholds (e.g., higher WDT, MDT) at the residual limb compared to contralateral sites and controls.
• Signs of central sensitization, including allodynia and increased wind-up ratio, were observed in amputees with PLP over time.

Conclusions:

• PLP is associated with dynamic changes in peripheral sensory processing and increasing central sensitization.
• Findings suggest PLP involves an interplay between evolving sensory abnormalities and central pain amplification.
• The study highlights the importance of longitudinal assessment in understanding PLP mechanisms.