AB285. SOH26AB_0307. Ultrasound-guided hydrodissection of the spinal accessory nerve in the management of shoulder pain and dysfunction

Abstract: The spinal accessory nerve (SAN) is vulnerable to entrapment or iatrogenic injury along its superficial course in the posterior cervical triangle, leading to shoulder pain, trapezius weakness, and functional impairment. Traditional management involves physiotherapy, nerve blocks, or surgical exploration, yet persistent dysfunction is common. Ultrasound-guided hydrodissection has emerged as a minimally invasive technique to release fascial adhesions and restore nerve mobility. By injecting fluid to separate the SAN from surrounding tissues, hydrodissection aims to relieve mechanical irritation and improve neuromuscular function. Ultrasound guidance allows precise needle placement and dynamic visualisation of the nerve, offering both diagnostic and therapeutic benefits. A case review of the literature and institutional experience was undertaken, focusing on the anatomy, sonographic identification, technique, and clinical outcomes of ultrasound-guided SAN hydrodissection. Evidence from case series and emerging observational data suggests that targeted SAN hydrodissection can produce meaningful improvements in shoulder pain, trapezius strength, and range of motion in patients with post-surgical, traumatic, or compressive neuropathies. Common injectates include normal saline, 5% dextrose, or local anaesthetic, often delivered under in-plane guidance with 25–27 G needles. Reported complications are infrequent and minor. The technique’s safety and accessibility make it an attractive option for outpatient pain or rehabilitation settings. Ultrasound-guided hydrodissection of the SAN represents a promising, low-risk intervention for selected patients with shoulder dysfunction due to SAN entrapment or neuropathy. It combines precise imaging guidance with therapeutic decompression, offering an alternative to more invasive approaches. Further controlled studies are needed to establish standardised protocols, long-term outcomes, and integration into multidisciplinary shoulder pain management.

Keywords: Hydrodissection; spinal accessory nerve (SAN); pain; ultrasound