Grant: CIHR Fellowship

Normally, a variety of sensory signals from the limbs are sent through the spinal cord to the brain where they generate feelings of touch, movement, temperature, and pain. Some of these signals are important for controlling movements in the legs, such as during standing and walking. Limb amputation results in a loss of sensory information from the missing limb, resulting in a higher risk of falling in people with a leg amputation. The loss of sensory signals after limb amputation also leads to the emergence of painful sensations known as phantom limb pain (PLP), which are often described as burning, stabbing, or aching sensations in the missing limb. Approximately 70% of people with a limb amputation suffer from PLP, which persists throughout their lifetime. Electrical pulses can be used to stimulate sensory nerves at the point where they enter the spinal cord. Sensory nerve stimulation can produce sensations in the missing limb and can activate reflexes that cause the remaining muscles to contract. Sensory nerve stimulation using implanted electrodes can also reduce PLP, suggesting that it may have therapeutic effects. We propose a non-invasive method of sensory nerve stimulation that uses stick-on electrodes placed on the lower back next to the spine. We will stimulate for one hour daily for one week and measure the effects on reflexes, PLP, and standing and walking stability in people with a leg amputation. After electrical stimulation, we expect them to have reduced PLP and improved standing and walking stability. We will also test if the sensory nerve stimulation has a lasting effect and will repeat the measurements one week after the stimulation has stopped. This will be the first study to investigate a new, non-pharmacological and non-invasive method for reducing PLP and improving balance and walking stability in lower limb amputees. This work has the potential to drastically improve the lives of people with a lower limb amputation.