Primary Motor Area Activity in Phantom Limb Imagery of Traumatic Unilateral Lower Limb Amputees With Phantom Limb Pain

Abstract

Introduction: Estimates of the worldwide increase in amputees raises the awareness to solve long-standing problems. Understanding the functional brain modifications after a lower limb amputation (LLA) is one of the first steps towards proposing new rehabilitation approaches. Functional modifications in the central nervous system due the amputation could be involved in prosthesis use failures and Phantom Limb Pain (PLP), increasing costs and overwhelming the health services. Objective: This study analyses orphan primary motor area (M1-Orphan) hemodynamic and metabolic behaviour, which previously controlled the limb that was amputated, in comparison with the M1-Preserved, responsible for the intact limb (IL) during phantom limb imagery moving during Mirror Therapy (MT), compared to Isolated Intact Limb Movement Task (I-ILMT). Methodology: A case-control study with unilateral traumatic LLA with moderate PLP who measured [oxy-Hb] and [deoxy-Hb] in the M1 area by Functional Near InfraredSpectroscopy (fNIRS) during the real (I-ILMT) and MT task. Results: Sixty-five patients, with 67.69% of men, young (40.32 ± 12.91), 65.63% amputated due motorcycle accidents, 4.71 ± 7.38 years ago, predominantly above the knee (57.14%). The M1 activation in the orphan cortex did not differ from the activation in the intact cortex during MT ( P > .05). Conclusion: The perception of the Phantom limb moving or intact limb moving is metabolically equivalent in M1, even in the absence of a limb. In other words, the amputation does not alter the brain metabolism in control of phantom movement.