Ultrasound-Guided, Single-Entry, Dual-Target Hydrodissection for Carpal Tunnel Syndrome: A Technical Note With Cadaveric Validation

Ultrasound-guided hydrodissection (HD) is an emerging minimally invasive treatment for carpal tunnel syndrome (CTS); however, achieving circumferential perineural spread around the median nerve may require repeated needle repositioning, multiple skin entries, or combined in-plane and out-of-plane maneuvers, thereby increasing procedural complexity. This technical report describes a novel ultrasound-guided single-entry dual-target HD technique for CTS that sequentially addresses the undersurface of the transverse carpal ligament (TCL) and the perineural plane surrounding the median nerve through a standardized scanning approach initiated at the first carpometacarpal (1st CMC) joint and maintained during medial transducer translation across the carpal tunnel. The technique uses a structured in-plane distal-to-proximal trajectory to maintain continuous needle visualization while reaching both targets through a single skin entry. Importantly, the approach targets the deep surface of the TCL but does not constitute TCL release. For cadaveric validation, the same procedural approach was performed in one fresh-frozen cadaver using both wrists. Under ultrasound guidance, 10 mL of methylene blue was injected per wrist using a 23-gauge, 6-cm needle, followed by dissection. Cadaveric dissection demonstrated dye surrounding the median nerve on both its superficial and deep aspects, supporting circumferential perineural halo formation, with proximal longitudinal spread from the entry site. These findings support the anatomical plausibility of the intended HD plane. This structured single-entry dual-target approach may offer a practical technical framework for CTS hydrodissection; however, further prospective and comparative studies are required to determine its clinical efficacy, safety, and relative advantages over existing ultrasound-guided CTS techniques.