Background: Carpal tunnel syndrome (CTS) is the commonest entrapment neuropathy. The aim of this study was
to assess the accuracy and validity of high resolution musculoskeletal ultrasound (US) in the diagnosis of CTS in the
Saudi population.
Methods: Sixty patients were diagnosed clinically to have CTS involving 89 wrists that were confirmed by
neurophysiologic studies. Each affected wrist was characterized as idiopathic or associated with either diabetes
mellitus or hypothyroidism and were assigned a severity grade based on results of neurophysiologic studies.
Seventy-six healthy wrists from fifty age, sex and BMI matched healthy subjects were included in the control group.
High resolution ultrasound (US) was performed to assess median nerve cross sectional area distal (CSAd) at the
entry to the carpal tunnel and proximally (CSAp) at the level of pronator quadratus muscle with a further
calculation of their difference (ΔCSA) and their mean average or CSAd+CSAp/2 (CSApd).
Results: There was a significant difference between both groups regarding mean ± SD of CSAd, CSAp, ΔCSA, and
CSApd (p = 0.0001). A positive significant correlation was also found between the CSAd, Δ CSA and the CSApd
measurements with neurophysiologic severity grade of CTS (P = 0.001). A ΔCSA threshold of 2.5mm2 showed the
highest sensitivity and specificity to diagnose CTS in Saudis.
Conclusion: High resolution ultrasound is a valid and accurate diagnostic modality in carpal tunnel syndrome and
correlated to CTS severity. A ΔCSA greater than 2.5mm2 is considered a valid diagnostic value for CTS in our Saudi
population. CTS in our patients with diabetes tend to have greater median nerve US measurement values.