Bypass neural interfaces for paralysis: clinical translation, challenges and future directions.

Advances in neural recording, real-time decoding and bioelectronic stimulation have enabled a new class of systems that re-establish functional communication across disrupted neural pathways. In the context of paralysis, these neural bypass interfaces link upstream neural intent to effector activation downstream of the lesion, effectively circumventing sites of injury within the nervous system to restore volitional movement. In this review, we define neural bypass interfaces as an emerging category of bioelectronic medicine, distinct from conventional brain-computer interfaces and neuromodulation technologies. We first outline key neurophysiological and systems-level considerations underlying bypass design, before tracing their evolution from bench to bedside. We then focus on the clinical translation challenges that govern real-world deployment, specifically signal stability and fidelity, stimulation performance, decoding robustness, closed-loop integration and long-term implant viability. Importantly, this review highlights two emerging directions that may shape the next generation of neural bypasses: the use of the spinal cord itself as a source of neural intent, and the development of bidirectional bypasses integrating sensory feedback to enable more adaptive, physiologically aligned control. Ultimately, neural bypasses may go beyond simply restoring movement to drive biological recovery, redefining neurorestorative therapies for paralysis.