Determination of Hemodynamic Response Using fNIRS in Lower Extremity Amputee and Replant Patients

This study investigates cortical reorganisation and hemodynamic responses in individuals with lower extremity amputation and replantation using functional near-infrared spectroscopy (fNIRS). A total of 15 healthy controls, four left lower limb amputees and one replantation patient were included. Oxyhemoglobin (oxy-Hb) activations were measured during 10 unilateral lower limb motor tasks (toe, ankle, knee and hip movements). Non-parametric analyses revealed significant differences in cortical activation between amputees and controls, particularly during knee flexion and extension. Three-dimensional contrast maps demonstrated that oxy-Hb activity in amputees extended from the M1-leg area into somatosensory regions, reflecting neuroplastic remapping. In contrast, the replantation patient exhibited activation patterns closer to the control group, especially in knee and hip tasks. These findings indicate that fNIRS can sensitively capture hemispheric dynamics during unilateral lower limb movements and highlight neuroplastic adaptations following amputation and replantation. Such insights may guide future neuroprosthetic design and rehabilitation strategies.