Quantifying the Impact of C7 Spinal Nerve Harvest on Spontaneous, Patient-Initiated Movement of the Donor Upper Extremity.

Background: Transfer of a healthy C7 spinal nerve is a tool for upper extremity reanimation in patients with severe brachial plexus injury (BPI). Its use remains controversial owing to concern for neurological injury to the donor arm. Utilizing wearable motion-sensor technology, we aimed to quantify donor arm morbidity after C7 spinal nerve harvest in patients with pan-BPI, reporting both the time and magnitude of donor arm movement in a real-world setting compared to healthy controls.

Methods: Seventeen patients who underwent contralateral C7 (CC7) transfer for traumatic pan-BPI at least 2 years prior were compared to 14 healthy controls. Each participant wore an accelerometer on both arms for 7 consecutive days. The vector time (VT), or time of movement measured in hours/day, and the vector magnitude (VM), or magnitude of arm movement measured as a single vector magnitude per second, were collected and compared between groups. The correlation between VT and VM and time from C7 spinal nerve harvest was also calculated.

Results: At mean 7.7 years after C7 spinal nerve harvest, there was no difference between donor and control arms for VT (5.76±1.55] vs 5.45±1.22 hours, P = 0.56) or VM (2242236±753853 vs 1919223±579723 activity counts, P = 0.20), regardless of donor arm dominance. The C7 harvest cohort used the injured arm 53% of the time and with 27% of the power of the donor arm.

Conclusions: There was no significant difference in time or magnitude of arm movement between donor arms and the arms of healthy controls.