Ultrasound examination predicts 6‐month progression in carpal tunnel syndrome patients

Abstract

Carpal tunnel syndrome (CTS) is a peripheral neuropathy resulting from chronic median nerve compression. Chronic compression leads to neurological changes that are quantified through nerve conduction studies (NCS). Although NCS represents the gold standard in CTS assessment, they provide limited prognostic value. Several studies have identified ultrasound as a tool in diagnosing and potentially predicting the progression of CTS in patients. The purpose of this study was to evaluate the predictive value of ultrasound examination in CTS patients. Twenty patients recruited at their first visit with the neurologist completed two NCS and ultrasound examinations approximately 6 months apart. Ultrasound examination consisted of B‐mode, pulse‐wave Doppler and colour Doppler ultrasound videos and images to quantify median nerve cross‐sectional area, intraneural blood flow velocity in three wrist postures (15° flexion, neutral, and 30° extension), and displacement of the flexor digitorum superficialis (FDS) tendon and the adjacent subsynovial connective tissue (SSCT) of the middle finger during repetitive finger flexion‐extension cycles. A questionnaire was administered to assess the work‐relatedness of CTS. Linear regression analyses revealed that intraneural blood flow velocity (R2 = 0.36, p = .03), assessed in wrist flexion, and relative FDS‐SSCT displacement (R2 = 0.27, p = .04) and shear strain index (R2 = 0.28, p = .04) were significant predictors of nerve sensory and motor changes at 6 months. Results suggest the possibility of using a battery of ultrasound measures as viable markers to predict median nerve functional changes within 6 months.

Relative motion between the flexor digitorum superficialis tendon and subsynovial connective tissue is time dependent

“…[17][18][19] Ultrasound has been used to assess flexor tendon gliding, in vivo, as a shear-strain index (SSI), representing relative displacement between tendon and adjacent SSCT as a percentage of overall tendon displacement. [19][20][21][22][23][24][25][26][27][28][29][30] Researchers have shown the SSI is related to SSCT thickness 19 and predicts median nerve sensory and motor changes in CTS patients. 21 Furthermore, using both in vitro and in vivo methods, physical risk factors have been shown to influence the SSI, including wrist flexion/extension position, 24,31 speed of work, 32,33 and task duration.…”

“…[19][20][21][22][23][24][25][26][27][28][29][30] Researchers have shown the SSI is related to SSCT thickness 19 and predicts median nerve sensory and motor changes in CTS patients. 21 Furthermore, using both in vitro and in vivo methods, physical risk factors have been shown to influence the SSI, including wrist flexion/extension position, 24,31 speed of work, 32,33 and task duration. 27 While these studies provide valuable information of a plausible injury pathway implicating the SSCT, the SSI has been reported a single metric.…”

“…Ultrasound has been used to assess flexor tendon gliding, in vivo, as a shear‐strain index (SSI), representing relative displacement between tendon and adjacent SSCT as a percentage of overall tendon displacement 19–30 . Researchers have shown the SSI is related to SSCT thickness 19 and predicts median nerve sensory and motor changes in CTS patients 21 .…”

Time‐varying changes in median nerve deformation and position in response to quantified pinch and grip forces

“…Carpal tunnel syndrome (CTS) is a peripheral neuropathy caused by entrapment and compression of the median nerve (MN) within the confines of the carpal tunnel, 1 which has a very small cross‐sectional area of 158–183 mm 2 at the distal border of the carpal tunnel 2–4 . However, the underlying pathomechanisms of CTS are multifactorial, including increased hydrostatic pressure, 5,6 ischemic‐induced reductions in intraneural blood flow, 7,8 and fibrosis and thickening of the subsynovial connective tissue (SSCT) shared by the flexor tendons and MN 9–12 . With respect to the latter, SSCT compliance in healthy individuals is vital to facilitate gliding and deformation of tendons and nerve in the carpal tunnel, thus providing a means to reduce shear‐related stress and compression 13,14 .…”