Aims: The main aim of the present study was to assess the clinical outcome after ultrasound-guided hydrodissection and triamcinolone injection into the carpal tunnel in patients with severe carpal tunnel syndrome. Materials and Method: Participants—The prospective study design of the present observational investigation measured the therapeutic effect of ultrasound-guided hydrodissection and corticosteroid injection of the carpal tunnel in 36 consecutive participants with carpal tunnel syndrome, following American Academy of Neurology (AAN) clinical criteria, and classified as severe in the baseline neurophysiological study. Each participant completed the Boston and Disabilities of the Arm, Shoulder and Hand (DASH) questionnaires and underwent median motor and sensory nerve conduction studies (NCS) at baseline and 6 months after injection. Median nerve ultrasonography was assessed at baseline (prior to steroid injection) and at 3 and 6 months after injection. The ultrasound examination included measurement of the median nerve cross-sectional area at the distal wrist crease (DWC) and 12 cm proximal to calculate the wrist-to-forearm median nerve area ratio. Injection—At the initial visit, an ultrasound-guided hydrodissection and steroid injection was performed. In all cases, a baseline electrical and ultrasonography measurements were recorded prior to the injection. Ultrasound imaging of the median nerve was done using an ultrasound device, with a 8.0 a 13 MHz linear-array transducer. We used a linear array transducer with a 8-13 Mhz frecuency range which is the standard for musculoskeletal ultrasound examination. A 21-gauge needle was used for 2 punctures. After proper disinfection of the volar aspect of the wrist, the entry point of the first puncture was located at the ulnar side of the wrist, as described by Smith et al. for the transverse ulnar (short-axis or axial) approach. For the sagittal (long-axis or sagittal) approach, the puncture was performed following the indications by Grassi et al. A combination of lidocaine (1 ml), 40 mg of triamcinolone acetonide (1 ml), and saline serum (9 ml) was injected into the area surrounding the median nerve. Statistical Analysis—Changes in the following variables were assessed at 3 and 6 months after the index procedure: Boston symptom and function scores, DASH score, median nerve motor and sensory latencies (converted to velocity for sensory studies), as well as the median nerve cross-sectional area. Results: The following mean baseline values were recorded: Boston score: 2.99, DASH score: 47.03, motor latency 5.74 ms, sensory velocity 25.52 m/s, DWC area of 13.93 mm2, wrist-to-forearm ratio (WFR) of 6.56 mm2. The following variables showed significant changes within treatment responder patients at 6 months follow-up: 26.8% improvement upon Boston score (P < .001), 39.9% upon DASH score (P = .006), 19.6% decrease at DWC area (P < .001), 19.6% decrease of the WFR (P = .001). Conclusions: Ultrasound-guided hydrodissection and corticosteroid injection of the carpal tunnel seems an effective treatment for severe carpal tunnel syndrome in the short-term, with a success rate estimated at 56% of the patients.
