Relationships Among Phantom Limb Pain, Peripheral Sensations, and Cognition in People with Lower-Limb Loss

Introduction: After amputation, altered sensory input leads to cortical reorganization that partly explains phantom limb pain (PLP). However, many factors impact the PLP phenomenon, and modern conceptualizations of chronic pain including PLP integrate both peripheral inputs and central interpretation. Clinicians without functional MRI could benefit from clinical measures related to PLP to assess clinical presentations. The purpose of this pilot study was to identify peripheral sensation and cognition measures related to PLP to inform outcome measure selection in future PLP research. Methods: This cross-sectional analysis included people with PLP of any age, sex, and amputation cause or level. Assessments included patient-reported residual limb pain and PLP using the Prosthesis Evaluation Questionnaire, peripheral sensation measures (light touch, temperature, vibration, two-point discrimination), and cognition measures (laterality recognition, trail making, clock drawing). Unadjusted Spearman. coefficients were reported. Results: Eleven volunteers (48.5 +/- 13.2 years) with lower-limb amputations (seven transtibial) of various causes (nine medical) participated. More severe PLP symptoms were associated with impaired peripheral sensation (light touch, rho = 0.514; temperature, rho = 0.756) and poorer cognition (laterality recognition, rho = 0.524; trailmaking, rho = 0.565). Residual limb pain was not correlated with cognition measures (rho < 0.4). Conclusions: This pilot study identified clinical measures assessing cognition and peripheral sensation impairments associated with worse PLP symptoms. Phantom limb pain was related to temperature and light touch sensation measures, but two-point discrimination was not associated with PLP consistent with past research. Laterality recognition was associated with PLP per prior research, and the association of PLP with the Trail Making Test in this pilot study suggests that the Trail Making Test may be an additional cognition measure potentially useful in future clinical research to document the PLP experience.