الفهرس 
Anatomy of the Carpal Tunnel and Median NerveOnly 14 pages are availabe for public view
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Abstract
Carpal tunnel syndrome (CTS), caused by compression of the median nerve within the carpal tunnel, is the most prevalent peripheral nerve entrapment disease, affecting thousands of citizens worldwide. The prevalence of CTS has been reported to be around 5% in the general population. The risk factors for CTS include repeated and excessive use of the wrist and hand, awkward postures, heavy lifting, and vibrations as well as personal predictors as female gender, obesity, older age, and smoking.
Diagnosis of ICTS is usually based on clinical examination and nerve conduction study (NCS).
History and clinical symptoms include numbness, tingling and pain along themedian nerve distribution area. Symptoms usually worsen during sleep or after prolonged wrist flexion and extension. Physical examination tests, such as Phalen’s test or Tinel’s test, are performed to detect any subtle symptoms. In severe cases, ICTS may leads to weakness and atrophy of thenar muscles.
Nerve conduction studies was considered to be the most accurate method to diagnose ICTS as it gives details about sensory and motor involvement, severity and guides the decision for surgical treatment.
However, NCS has its own cons: it is painful, does not allow visualization of anatomic nerve abnormalities (such as bifid nerve which is the most common anatomic anomaly in ICTS or structures around the nerve leading to its compression (such as accessory muscles, ganglion cysts, tophi, arthritis, and tenosynovitis) and some data shows that it still give a considerable amount of false negatives (16-34%).
High resolution ultrasound (US) was introduced as a suitable, cheap, rapid, accurate and non-invasive imaging method for evaluating the median nerve, it shows nerve morphology along its course and detects changes in the nerve through the deferent sonographic parameters (including nerve area, echogenicity, mobility and vascularity), exclude anatomical variants and space occupying lesions.
Using US, measuring the cross-sectional area of the median nerve (mCSA) at the pisiform level, is considered the most accurate method for evaluating ICTS.
The aim of this study was to evaluate the diagnostic utility of using the ulnar nerve cross-sectional as an internal control in patients with idiopathic carpal tunnel syndrome to overcome the variability of median nerve crosssectional area due to the differences in body weight, age and sex.
This was a case control study was conducted in the department of diagnostic radiology on collaboration with physical medicine, rheumatology and rehabilitation department, Menoufia University Hospital, Shebin Elkom, Egypt on 50 patients with CTS and 50 matched controls. The study was conducted from September 2021 to August 2022.
Summary of our results:
Sonographic measurement of m-CSA: u-CSA ratio was slightly superior to m-CSA in the diagnosis of ICTS when measured at the same level of pisiform. Patients with ICTS also had higher m-SR and Palmer bowing compared to the healthy volunteers, while flattening ratio was insignificant In our study we tried to overcome the variability in age , sex, gender and BMI, According to the data generated by the ROC curve, 2.88 was selected as the cut-off point of m-CSA: u-CSA ratio, while 11.2 mm2 was selected for the cut-off point of m-CSA. m-CSA: u-CSA ratio demonstrates higher sensitivity (85.0%) and specificity (82.0%) compared to m-CSA (sensitivity: 82.0%, specificity: 80.0%). Using the different parameters combined could result in better interpretation.