Carpal tunnel release surgery restores force control but not force coordination in CTS patients

Efficient manipulation of objects is crucial for daily interactions with the world. Compression neuropathies like carpal tunnel syndrome (CTS) can have detrimental effects on hand function, which can be improved by surgical intervention. Twelve patients with CTS grasped and lifted an instrumented handle while maintaining static equilibrium under different torque conditions. We compared fingertip forces and grip force variability across trials before and after surgery. Additionally, we evaluated the coordination of fingertip forces using a metric defined as synergy index to determine if there were improvements in coordination post-surgery. It was expected that there would be a decrease in fingertip forces and intertrial grip force variability indicative of recovery as well as an enhancement in synergy indices reflecting improved coordination. As expected, there was a decrease in the grip forces and intertrial variability of grip forces after surgery. However, the synergy indices were statistically similar before and after surgery, indicating that there was no change in neural strategies for coordination. Despite enhanced sensory conduction post-surgery, the central nervous system's operational strategies for motor control remained unchanged. These findings suggest that while grip force regulation improves, the underlying coordination mechanisms do not adapt in response to the surgery. The findings of this study indicate that peripheral feedback does not modulate the synergies while performing a task, suggesting that neural coordination may not change with compression neuropathies or during recovery.