Neural Engineering Seminar:
Speaker: Lindsey Hauck
Advisor: Dr. Hamid Charkhar
Title: Investigating Differences in Elicited Sensation between Individuals with Lower Limb Amputation
Abstract: There are 1.6 million Americans living with limb loss, with 65% of them experiencing lower limb loss. These individuals face many challenges, including decreased balance confidence, gait instability, higher fall risk, and lower social participation. Many of these issues are heightened for individuals with transfemoral amputation, due to the loss of the knee joint. To address some of these challenges, our lab has developed a neural interface using composite flat-interface nerve cuff electrodes (C-FINEs) implanted around the sciatic nerve or its branches. Through stimulating the nerve via these electrodes, plantar sensation can be restored. We have successfully implemented this device with three individuals with transtibial amputation and have recently implemented the system for an individual with transfemoral amputation. Due to the proximity of the implanted electrodes to the level of amputation, we wanted to investigate if there were any differences in the success of using the device for restoring plantar sensation. We compared the sensory thresholds, quantity of viable contacts for restoring overall sensation and plantar sensation, and locations of elicited sensation between two individuals with different levels of amputation. Sensory thresholds were found to be higher for the individual with transfemoral amputation, but plantar sensation was able to be elicited with similar success.
To better compare sensation intensities between participants, we developed a novel method to quantify elicited sensation intensities in the lower limb. In this method, participants matched the elicited sensation in their intact limb by pushing on the foot pedal of a dynamometer with their intact limb. This output torque was normalized and used to quantify the intensity of the elicited sensation. Using torque as an output method instead of self-reported sensation resulted in a consistent intensity range between participants, but measurements had large variations. Overall, our work in these two areas demonstrates preliminary success of our neural interface for individuals with lower limb loss regardless of level of amputation, as well as the potential of using torque as a method to compare sensation intensities between participants.