Residual muscle activity associated with phantom limb movements after transhumeral amputation without surgical reinnervation: a preliminary ultrasound study.
Susannah Engdahl, Ahmed Bashatah, György Lévay and 4 others
PMID 42374491WHAT IT FOUND
In one man with a transhumeral amputation who did not have nerve surgery, ultrasound showed that moving individual phantom fingers produced distinct muscle patterns in his upper arm.
This suggests phantom movements could control prostheses without targeted muscle reinnervation, but it is a single case.
Key findings
01Ultrasound imaging revealed distinct patterns of muscle activation in the residual limb associated with each phantom hand movement.
02Muscle activation patterns for phantom hand movements were clearly distinct from those for intentional elbow movements.
03The participant could produce 11 phantom hand movements with distinct muscle activation patterns in the upper arm without targeted muscle reinnervation.
STILL TO COME
How it was doneWhat they found
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What it does not show
The study involved only one participant, so findings cannot be generalized to other individuals with transhumeral amputation. Repetitions were collected sequentially, which may have influenced consistency or caused fatigue, making the activation patterns appear more or less separable than they would be in real-world use. Differences in probe position and phase length between the 2019 and 2025 sessions make direct comparison of the datasets difficult. The underlying mechanism for the observed muscle activation is unknown because surgical records were unavailable and the MRI did not show native reinnervation. The definition of 'unique' muscle activation patterns is not standardized across studies, complicating comparison with prior EMG research.
Declared interests
Funded by the National Institutes of Health and the U.S. Department of Defense.
The easy way to misread this
Do not assume this method works for all transhumeral amputees. This is a single case report showing potential in one individual, not evidence that ultrasound control is a viable or established treatment option for the wider population.