Virtual Reality Training Improves Phantom Limb Pain in Partial Hand Limb Loss—study
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Phantom limb pain is a perplexing condition. This phenomenon stems from the brain’s persistent perception of the missing limb, leading to sensations and discomfort in body parts that no longer exist. There have been various treatment approaches, like mirror therapy, but recent studies have highlighted the potential benefits of virtual reality-based interventions in managing phantom limb pain.
Virtual reality has emerged as a cutting-edge tool in healthcare settings for its immersive and interactive nature. Some healthcare providers have already been using the technology for post-stroke rehabilitation. Researchers wanted to determine if virtual reality training could help address phantom limb pain. The study results were published in the Frontiers in Human Science journal in December 2023.
The study participant
The study participant was a 42-year-old woman with severe phantom limb pain. She lost two to five of her fingers after a workplace accident almost a decade ago.
She described the pain she felt daily as a maximum of 100/100 mm, averaging about 82/100 mm daily on the Visual Analog Scale. The pain from the fingers penetrated the palm. She had to quit her job and would often be confined to the bed during the day.
Even though she had tried mirror therapy at a different hospital, she had to discontinue the treatment because she felt discomfort and a strong aversion while looking at the mirror.
During virtual reality training, the study participant continued to take brotizolam, duloxetine hydrochloride, etizolam, neurotropin tablets, suvorexant, and tramadol hydrochloride for pain management. The dosage of the drugs and frequency of rehabilitation remained unchanged throughout the study.
Virtual reality training
The study participant used a head-mounted display and a controller fixed to the amputated limb. The task involved grasping a virtual ball. Every time the virtual hand holds the ball, the controller would vibrate, inducing a motor illusion.
After each session, the participant received feedback on shoulder joint movement and daily activities.
During the training, the participant reported that the pain intensity decreased gradually. She also experienced improvements in specific types of pain, such as sharp, throbbing, and stabbing pain—all of which are somatosensory-related types of pain.
She also reported that the penetrating session to the palm was reduced during the second half of the training period.
Furthermore, the researchers found that the virtual reality training not only reduced phantom limb pain intensity but also enhanced the study participant’s ability to perform daily tasks, such as washing, cooking, and even carrying her newborn grandchild.
Why virtual reality training works
Previous studies attributed phantom limb pain to losing feedback between finger movement and sensory information after limb loss. This disrupts the sensory-motor loop, causing pathological pain.
Virtual reality training somehow reintegrates the sensory-motor loop by inducing the illusion of finger movement in virtual space. This works by aligning visual and somatosensory information.
Besides the benefit of the visual illusions, the researchers also discovered that the vibrations from the controller played a significant role in prompting motor illusions, helping reintegrate the sensory-motor loop for the study participant.
The bottom line
This study found that virtual reality training not only reduces the intensity of phantom limb pain but also enhances a person’s ability to perform daily tasks, leading to increased independence and improved quality of life.
Although virtual reality training initially reduces somatosensory-related pain, sustaining this is challenging. Further research is needed to assess the effectiveness of virtual reality training for individuals with higher-level amputations, such as forearm and upper-arm limb loss, as well as to establish the ideal frequency and duration of the intervention.
