Background Carpal tunnel syndrome (CTS) is the most common compressive neuropathy in rheumatology. Ultrasound guided steroid injection can provide more efficiency compared with blind injection.
Objectives The aim of this study was to define the effectiveness of ultrasound guided steroid injection in patients with carpal tunnel syndrome.
Methods This prospective study enrolled 21 patients (42 hands) with carpal tunnel syndrome who were confirmed by nerve conduction study. The clinical severity of CTS were assessed by three clinical scales; Boston carpal tunnel syndrome questionnaire (BCTQ), quantitative clinical scale by Simovic (Simovic clinical scale) and Historical-Objective (Hi-Ob) scale. Sonographic evaluation was performed by one ultrasound expert rheumatologist. Cross sectional area, circumference, anterior-posterior diameter and thickness of median nerve were measured at the carpal tunnel inlet level by ultrasound. In nerve conduction studies, sensory nerve action potential, sensory nerve conduction velocity, distal motor latency and compound muscle action potential were recorded. Clinical scale assessment, nerve conduction studies, and sonographic evaluation were performed at baseline before injection and repeated at 2 weeks, 5 weeks, 13 weeks after injection. Linear mixed model and multiple regression test were used and p<0.05 was used for statistical significance.
Results After ultrasound guided steroid injection, median nerve cross-sectional area (p=0.0281), circumference (p=0.0281) and transverse diameter (p=0.045) at 2 weeks were significantly decreased compared with baseline visit. This improvement was maintained until 3 months. Clinical improvement measured by Boston questionnaire symptom score (p=0.0012), Simovic clinical scale (p=0.0021) and Historical-Objective scale (p=0.0004) were also significantly improved at 2 weeks visit compared with baseline. There was no complication after injection. Nerve conduction studies showed improvement over time: motor terminal latency was decreased (4.70±1.76 ms to 3.98±1.43 ms), motor ampulitude (9.74±4.12 mV to 11.40±5.31 mV) and Mean sensory velocity (33.81±6.39 m/s to 36.48±2.65m/s) were increased after 4 weeks visit. (table 1)
In multiple regression analysis, the change of three ultrasonographic parameters (cross-sectional area, circumference, transverse diameter) were positively correlated with BCTQ symptom score (p=0.0004), Simovic clinical scale (p=0.0007) and motor latency (p=0.0002).
Conclusions In patients with CTS in rheumatology clinical practice, ultrasound guided steroid injection into the carpal tunnel can relieve nerve compression symptoms effectively and safely. This is followed by the improvement of ectrophysiological paramaters after 4 weeks later of injection. Moreover, ultasonographic parameters of median nerve measurement were positively correlated with nerve conduction parameters.
Disclosure of Interest None declared