Key findings:

Key findings of this study on carpal tunnel syndrome (CTS) include: high-resolution ultrasonography (HRUS) is effective in visualizing and measuring the cross-sectional area (CSA) of the median nerve (MN) at the level of the pisiform bone; HRUS is a non-invasive, sensitive, and specific method for diagnosing CTS, providing reliable assessment of its severity.

What is known and what is new?

The known aspect in this abstract is the uncertainty surrounding the exact cause of carpal tunnel syndrome (CTS), with both mechanical compression and vascular compromise considered as potential factors. The new contribution is the evaluation of high-resolution ultrasonography (HRUS) and magnetic resonance imaging (MRI) as diagnostic tools for CTS, highlighting HRUS as a non-invasive and reliable method.

What is the implication, and what should change now?

The implication of this study is that high-resolution ultrasonography (HRUS) should be considered as a primary diagnostic tool for carpal tunnel syndrome (CTS) due to its effectiveness, non-invasive nature, and ability to assess severity. Changes needed include promoting the use of HRUS in clinical settings and further research to establish its diagnostic accuracy compared to nerve conduction studies

The median nerve compression neuropathy, often known as carpal tunnel syndrome (CTS), is the most widespread kind of peripheral entrapment neuropathy. It affects 90% of the population and is more common among middle-aged women. Everyone knows it is a major contributor to sick days taken by employees. The surgical decompression rate in the United Kingdom ranges from 43 to 74 per 100,000 people, and the prevalence of CTS is 7–16%, which is significantly greater than the 5% prevalence in the United States. For the diagnosis of CTS, a thorough medical history, a precise physical examination, and, where necessary, electro-diagnostic investigations (EDS) are required. For the purpose of assessing the median nerve within the carpal tunnel, high-resolution ultrasonography (HRUS) has recently arisen as a practical, easy, inexpensive, quick, precise, and noninvasive imaging technique. While some writers argue that the function of ultrasonic US scanning in CTS diagnosis remains unproven and others suggest its limited benefit in CTS diagnosis, On the other hand, a 2004 methodology by Wong et al. [1] suggested using US to rate the severity of CTS, and secondary EDS was only done when US findings were negative. The approach relied on patients suspected of having CTS. Using ultrasonography (US), one may find CTS patients with an enlarged median nerve cross-section area (CSA), as well as other space-occupying lesions such as ganglia, fibromata, neural tumors, and tenosynovitis. Comparing US and EDS in a recent prospective analysis indicated that the two methods had similar sensitivity levels. MRI scans appear to be useful in determining whether an uncommon cause of CTS is present, implicated, as well as in the meticulous anatomical restoration that assists procedures involving endoscopes! Magnetic resonance imaging (MRI) case studies are conducted on the researchers who discovered specific changes in the median nerves of CTS patients. The carpal tunnel influences diagnoses. The closest .The median nerve displays T2 hyperintensity, flattening, and enlargement. The picture also shows a more pronounced transverse carpal ligament (TCL) bending. These were considered to be the hallmark symptoms of idiopathic CTS. Initial research has shown promising results, with MRI offering minor advantages over “US.” 

 Clinical presentation of CTS patients

1: Symptoms

Intermittent numbness of the thumb, index, middle, and radial parts of the ring finger is the primary symptom of carpal tunnel syndrome. Pain is prevalent but not specific; weakness is uncommon; and numbness in the distribution of the median nerve is the most distinctive symptom of the illness. The most significant factors that were shown to be predictive of a positive nerve conduction study (NCS) in research including more than 8,000 patients suspected of having carpal tunnel syndrome were symptoms that worsen at night and those located on the radial aspect of the hand. The lumbrical muscles, which arise from flexor tendons distal to the carpal tunnel, can migrate into the distal tunnel when the fingers are bent, which causes a physiological rise in carpal tunnel pressure at night and the propensity for the wrists to flex while sleeping, leading to nocturnal aggravation. Subjective swelling of the hands or wrists is a common symptom reported by CTS patients, even if no outward signs of edema are visible. Permanent nerve injury, atrophy of some thenar eminence muscles, and palmar abduction weakness are all symptoms of chronic tendonitis.

  2: Signs: 

A. Provocative Tests

Phalen and Tinel's tests are two provocative methods for diagnosing carpal tunnel syndrome; in Phalen's test, the patient is instructed to maintain a wrist flex posture for 60 seconds (Fig. 2). If this causes paraesthesia or pain in the median nerve distribution, then it is a favorable reaction.

 To perform Tinel's test, tap the back of the hand on top of the wrist. If this produces paraesthesia in the fingers that are innervated by the median nerve, then it is considered a favorable response.

These tests have stated sensitivity of 10–90% and specificities of 33–100%. In 2008, El Miedany and his co-worker showed that both Phalen's and Tinel's tests were in fact more sensitive and specific for the diagnosis of tenosynovitis than for the diagnosis of CTS. As a result, they concluded that there is an increased dependence on NCS as a diagnostic gold standard in CTS diagnosis.

Examiners use the pressure provocation test, also known as McMurthry's sign, to determine if a patient has any tingling or numbness in their hands by pressing on the carpal tunnel for 30 seconds. The Tourniquet Test, also known as Gilliat's Test, is a neurological evaluation that uses an inflated cuff to put pressure on the median nerve, causing tingling or numbness in the hands.

In the Hand Elevation Test, the patient is asked to raise their hands aloft for two minutes in order to induce CTS symptoms.

B. Flick maneuver

When asked what they do when their wrist pain is intense, a patient showing a "flick" action with their hands and wrists is a positive indicator of carpal tunnel syndrome. Flick maneuver sensitivity is still higher than that of Phalen and Tinel.

(See Figure 2): Phalen assay.

 Investigations of CTS 

Electro-Diagnostic Studies (EDS)

The EDS consists of electromyography (EMG) and nerve conduction studies (NCS), which can assess both sensory and motor nerves. For NCS, one can use surface electrodes, and for EMG, which tests the muscle from the inside, one can use needle electrodes. The NCS tracks the rate at which nerve impulses are conducted. NCS, the gold standard for this condition, is the most prevalent method for confirming a CTS diagnosis. The American Academy of Orthopaedic Surgeons (AAOS) recommends EDS to ensure adequate preparation of all patients for surgery. EDS can confirm peripheral nerve compression, localize lesions, understand pathophysiology, and grade severity.

Around 15% of individuals identified with clinically-based CTS have found NCS to provide both false-negative and false-positive findings.

 Gray-Scale Sonography

Enhanced US to assess normal musculoskeletal system structures and identify and characterize subtle disease alterations has been made possible by the introduction of high-resolution transducers. Research by Buchberger et al. [2]was the first to show that ultrasonography could accurately diagnose CTS. Accurate evaluation of superficial anatomical features is made possible by high-frequency (10–15 MHz) probes equipped with advanced near-field focusing. Peripheral nerves may now be accurately portrayed with high-frequency probes and seem typical on ultrasonography scans of the hands and wrists. This allows for the correct imaging of tendons, joints, nerves, and arteries. The use of ultrasound in carpal tunnel syndrome is advantageous for several reasons: first, it can confirm the clinical diagnosis in cases where the patient refuses invasive nerve conduction studies; second, it can show anatomical variations, such as the presence of a median artery or median nerve proximal bifurcation, which can change the surgical approach; and third, it can rule out local expansile masses like ganglia. Furthermore, it is used in sonography-guided interventions and treatments.

or (A) and (B), 

1. Power Doppler pictures of the patient's median nerve are shown in 

2. Figure 8.

    

In (B), the fourth spectral waveform is visible.

MRI finding in CTS: 

Carpal tunnel syndrome is characterized by abnormalities in magnetic resonance imaging (MR).The symptoms of carpal tunnel syndrome include thickening of the flexor retinaculum, an elevated carpal tunnel height (also known as palmar bowing of the flexor retinaculum) as measured from the flexor retinaculum convexity to the underlying carpal bone (best seen at the level of the hamate) (fig 11 B), median nerve swelling, and elevated signal intensity within the nerve on T2-weighted images, likely due to compression-induced edema (fig 11 A). People frequently observe swelling of the median nerve at the level of the pisiform, which is proximal to the carpal tunnel. Patients with carpal tunnel syndrome have a median nerve cross-sectional area that is much larger than that of unaffected persons. For the most accurate comparison of nerve cross-sectional area at radiocarpal joint and pisiform bone level, axial MR images are the way to go. For carpal tunnel syndrome patients, the nerve size at the pisiform level should be approximately double or triple that at the radiocarpal joint level. One way to measure nerve flattening is to compare the ratio of the nerve's main and minor axes at two different locations: the distal radioulnar junction and the hook of the hamate. In most cases, a ratio of three suggests illness. When examining a healthy person, the flexor retinaculum should be either flat or slightly convex at the level of the hamate hook. Finding the distance between the hamate's hook and the tubercle of the trapezium, then dividing it by the palmar displacement of the retinaculum, gives the degree of bending (Fig. 11B). It ranges from 0 to 0.15 (mean 0.05) in healthy individuals and from 0.14 to 0.26 (mean 0.18) in those with carpal tunnel syndrome. It may be difficult to detect an elevated T2 signal within the typical median nerve, similar to many others. Neurones across the body frequently show a marginally amplified signal. On the other hand, a severely elevated signal is pretty indicative of a damaged nerve. As a result of fibrosis, the nerve may have a weak signal intensity throughout all MRI sequences in patients with chronic carpal tunnel syndrome. There may also be a shrinkage of the lateral muscles. Recently, Sugimoto demonstrated two bizarre patterns of increases in Individuals with intravenous gadolinium injection developing carpal tunnel syndrome, which affects the median nerve. We assumed that nerves showing significant enhancement with contrast were edematous, while those showing little enhancement were ischemic. Bending or straightening the wrists often caused the enhanced nerve-controlled wrists to revert to an unenhanced pattern. This alteration led to a worsening of carpal tunnel syndrome symptoms. A circulatory disruption may be the cause of carpal tunnel syndrome, according to the authors.

The axial T2-weighted STIR MR image (TR/TE, 2,320/14; inversion time, 150 milliseconds) in Fig. 10 shows a higher signal intensity (asterisk) for the median nerve compared to the hypothalamic muscle (arrowhead). Retinal thickening locations are shown by arrows.

Fig. 11. Carpal tunnel syndrome. (A) The axial fat-suppressed T2-weighted picture at the proximal carpal tunnel (arrowhead) shows enhanced signal intensity and median nerve expansion.

We show the increased bowing ratio by dividing the palmar displacement of the retinaculum by the distance between the hook of the hamate and the tubercle of the trapezium. We then apply this ratio to the axial proton-density-weighted image at the transverse carpal ligament level.

Treatment of CTS

Conservative methods and surgical procedures are the two main approaches to treating CTS. Patients with mild to moderate CTS symptoms are typically offered conservative treatment options, which may include oral and transvenous steroids, vitamins B6 and B12, nonsteroidal anti-inflammatory drugs, ultrasound, yoga, carpal bone mobilization, hand splints, and other similar measures. Marshall et al. conducted a recent comprehensive analysis, which found that individuals with clinical CTS who received steroid injections experienced a more significant improvement in their symptoms one month after the injections, compared to those who received a placebo. However, there was no noticeable improvement in symptoms beyond the first month.

Surgically severing the transverse carpal ligament is the sole known method of illness modification.

The Al-Sadir Medical City in the Al-Najaf Health Directorate conducted a prospective cross-sectional study on 30 female patients with unilateral or bilateral carpal tunnel syndrome (CTS) between March 2011 and January 2013. We randomly selected the patients from the orthopaedic department of the teaching hospital's outpatient clinic, and analyzed a total of 50 diseased hands. We used the clinical examination and negative nerve conduction study (NCS) to examine fifty healthy volunteers who did not exhibit any symptoms of CTS. 

The gender, age, and BMI of the control participants were a perfect match for the patients. The university ethics council of Kufa University/Faculty of Medicine approved the study methodology, and all patients and healthy volunteers verbally agreed. An experienced orthopaedic surgeon made the clinical diagnoses, and an experienced neurophysiology specialist confirmed them by NCS. 

The 50 patients included in the study had the characteristic clinical symptoms of CTS for periods ranging from 2 months to 3 years. 

Patients and controls alike did not suffer from any systemic conditions like diabetes, rheumatoid arthritis, or thyroid problems, and neither group had a history of injuries to the upper extremities. People who were pregnant or had a tentative diagnosis of cervical radiculopathy were also excluded.

Part 3.1.2: Tools AL-Sadir Medical City's Middle Euphrates Neurosciences Centre saw patients undergoing NCS examinations. An Italian-made Micro-Med System plus-EMG, model 2001, was used for the electromyoneurography (Fig. 12).

Fig. 12. shows a photograph of the nerve conduction investigation machine (Micro-Med system with ENG).

Fig.13 Shows (A) HD11XE Philips 2009 US, and it’s (B) broadband L12-3 MHz linear transducer

Using a broadband 3–12 MHz linear transducer (Fig. 13.B) and an HD11XE Philips 2009 ultrasound unit (Fig. 13.A), the individuals were investigated using ultrasonic imaging. (B) Part A  .  

Patients underwent magnetic resonance imaging (MRI) with close-type philips. 

Fig.14. shows the Achieva 1.5 Tesla MR. Figure 14 displays an MRI machine of the 1.5 Tesla variety.

Fig.14 Shows close type 1.5 Tesla MRI machine

All individuals underwent a thorough evaluation of their upper extremities, including a clinical examination, neurocognitive testing (NCS), sonographic imaging, and magnetic resonance imaging (MRI) of both metastases. We determined the subjects' body mass index (BMI) by dividing their weight (in kilogrammes) by their squared height (in meters). NCS classified patients with CTS into three categories: mild, moderate, and severe. We rated the severity of CTS electrophysiologically, adhering to the practice parameter that every neurophysiological laboratory should have its own reference values, using the local severity scale of the neurophysiology department. A senior radiologist specialising in musculoskeletal imaging closely supervised the researcher as they conducted the sonographic and magnetic resonance imaging evaluations. During this period, both the radiologist and the researcher were unaware of the outcomes of the clinical examination and electrodiagnostic testing. Most of the US-examined participants sat with their palms facing the examiner, their wrists held in a neutral position, and their fingers slightly bent. They stretched and bent their forearms in a supinated manner. We conducted real-time transverse imaging of the median nerve, spanning from the distal forearm to the outflow of the carpal tunnel, after linking the ultrasound probe with ultrasonic gel. We measured the cross-sectional area (CSA) of the median nerve. Duncan et al. (1999) and Luis Alemán et al. (2008) [3, 4] outlined the following assessment protocol: (1) We placed the transducer perpendicular to the median nerve to avoid deforming it. On the other hand, we took axial images at the level of the pisiform bone. We selected the image that best defined the borders of the median nerve. Finally, we took the median nerve CSA measurements from the inner border of the perineural echogenic rim, which corresponds to the perineurium surrounding the hypoechoic median nerve (2,62). We took the measurements using the direct approach, which involves directly tracing the nerve's boundary using electronic callipers (See Fig.15.B for tracking technique). (A) (B) (Fig. 15): The patient with moderate carpal tunnel syndrome underwent an ultrasound of the wrist near the carpal tunnel entrance, as shown in (A) side view and (B) side view. We can measure the CSA of the median nerve, pisiform bone, ulnar artery, and u in the Guyon canal using the tracing method (B). A photograph of a researcher Next, the Al-Sader radiological department, located in the middle of the Euphrates center, used magnetic resonance imaging (MRI) to compare the individuals. Please tell me where I can find a surface coil for my Philips Achieva 1.5 Tesla MR machine.M. Keberle, Department of Radiology, University of Würzburg, Klinikstrasse 8, D-97070 Würzburg, Germany, 2000, instructed subjects and patients to lie down during the imaging procedure.  The technique involved extending the arm aloft and placing the palm on the surface coil. 

To prevent tangential slice measurements from producing false data, the imaging protocol included axial T1-weighted spin-echo (SE) images with a TR570 ms and TE20 ms, axial T2-weighted turbo-spinecho (TSE) images with a TR2880 ms and TE 99 ms, and axial T2 STIR images at the level of the distal radioulnar joint, pisiform bone, and hamate bone.We angled the slice 20° proximally.  (Fig.16). The imaging setup included a 120 mm FOV and a 512 x 256 T2 matrix. Radack et al. [5] described a 3 mm segment with a 0.3 mm interslice gap. Radack et al. [5] have proposed that the imaging of the median nerve in CTS relies on demonstrating increased signal intensity and nerve enlargement in the proximal carpal tunnel.  According to research, these two criteria are the gold standard for imaging characteristics used to diagnose CTS.Research has shown that alternative measurements, like the flattening ratio and the palmar bending of the retinaculum at the hamate bone level, are less accurate (84–87).  We measured the median nerve cross-sectional area from the perineurium at the pisiform bone level using a viewing console. We utilised the computer's built-in software. The subjective evaluation of peri-neural edema was based on an increase in signal intensity in the median nerve (Fig.16). Chapter 16. The upper portion of the picture displays axial scans for median nerve slice measurements at the level of the distal radioulnar joint and the pisiform. The first image shows the enlarged MN with increased signal intensity, while the second shows the proximally inclined slice angulation that was used for precise measurements at the hamate level. 

Analyses based on statistical data (3.3): The median nerve CSA at the carpal tunnel entrance was measured and displayed as descriptive statistics (mean ± SD).We used one-way ANOVA (analysis of variance) models and Student's t-tests for statistical analysis to compare the means of continuous quantitative variables between groups.  We determined statistical significance when the p-value was less than 0.05, or 63. We used SPSS (Statistical Package for the Social Sciences) version 19 to manipulate and analyse the data. To determine the sensitivity, specificity, accuracy, PPV, and NPV of US and MR imaging for CTS diagnosis of CTS, we used NCS and clinical examination as our gold standard. 

A set of equations was utilised: 

Sensitivity=TP/(TP+FN) = TP/All sick Positive predictive value (PPV) = TP/(TP+FP) = TP/All positives, and specificity is defined as TN/(FP+TN) = TN/All healthy. 

For all patients, the accuracy is the number of true results, where TP is the true positive and FN is the false negative. TN divided by the sum of FN and TN, or TN divided by all negative outcomes, is the net present value (NPV).

Fig.15. Wrist US at the carpal tunnel inlet for patients with mild CTS (A) medial and (B) lateral aspect  of the wrist .(B)the tracing method for measuring the CSA of the MN UA :ulnar artery and un: ulnar nerve in the Guyon canal; Pbone: pisiform bone; MN:median nerve.(researcher image)

Fig.16. The upper part of the image shows axial scans for slice measurements of the median nerve at the level of the distal radioulnar joint and the pisiform

 Distribution of study sample according to the age and body mass index (BMI):

Thirty women diagnosed with carpal tunnel syndrome (CTS) and fifty women who were statistically similar to the patients in terms of age and body mass index (BMI) made up the study group (Table.1). Because of this, there is no difference in age, gender, or body mass index between the treatment and control groups. 

Table.1: The mean, standard deviation, and range of age and BMI for patient and control groups.

4.2: Bilaterality and distribution of severity of the diseased wrists according to Nerve Conduction Study (NCS):

Of the thirty patients with CTS, 20 (66.7%) had bilateral, and 10(33.3%) had unilateral diseased wrists.

Of the 50 diseased wrists, 15 (30%) had mild, 14(28%) moderate, and 21 (42%) had severe CTS as shown in figure 17.

Fig.17  Demonstrate the percentage of the diseased wrists according to the severity of the CTS determined by NCS.

4.3: Ultrasonic measurements of The Cross Section Area (CSA) of the Median Nerve (MN) for patients and controls:

The mean CSA of the MN at the tunnel inlet (at the level of the pisiform bone) in CTS patients was significantly greater than that of the control group's CSA as shown in (Table.2).

In addition the mean CSA of the MN was calculated in patients with mild, moderate, and in patients with severe CTS, compared to CSA for the control group as shown in (Fig.18) and (Table.3). Each of these subgroups CSA shows significant difference from the median nerve CSA of the control group. Furthermore, a significant difference is also noted between each of these three patients subgroups with each other as shown in (Table.4).

               Table.2 Comparison between patients and controls regarding CSA

CSA: Cross Section Area of the median nerve.

CTS: Carpal Tunnel Syndrome.

SD : Standard Deviation.

Fig.18  Shows the difference between (mean ± SD) CSA of controls, mild, moderate and severe forms of CTS at the tunnel inlet.

 Table.3 : The CSA of the MN for the different severities of CTS versus those with normal at nerve   conduction testing

CSA: Cross Section Area of the median nerve.

CTS: Carpal Tunnel Syndrome.

n: number of the wrists.

Table.4: Multiple comparisons among controls and other subgroups and between the three patients subgroups.

4.4: Sensitivity, Specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) of  ultrasound for the diagnosis of CTS:

From statistical point of view the sensitivity & specificity were calculated for  mean values of  CSA at the carpal tunnel inlet (Table.5), the mean CSA of the MN of healthy volunteers ± 2SD  was  considered as the cut-off value, this yielded a sensitivity of (92%), a specificity of (100%), P value < 0.001, a PPV of (100%), a NPV of (96.2%) and an accuracy of (97.33%).

Table.5 The Ultrasound findings of patient group in correlation to control group compared to NCS and Clinical Examination

Sensitivity=92%

Specificity=100%

Ppv=100%

Npv=96.2%

Accuracy=97.33%

4.5: Sensitivity, Specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) of  MRI for the diagnosis of CTS:

From statistical point of view the sensitivity & specificity were calculated for  mean values of  CSA at the carpal tunnel inlet (Table.6), the mean CSA of the MN of healthy volunteers ± 2SD  was  considered as the cut-off value, in addition to other signs of CTS noted mainly increased MN signal intensity & palmar bowing of flexor retinaculum , these  yielded a sensitivity of (96%), a specificity of (100%), P value < 0.001, a PPV of (100%), a NPV of (98%) and an accuracy of (98.67%). 

Table.6 The MRI findings of patient group in correlation to control group compared to NCS and Clinical Examination

Sensitivity=96%

Specificity=100%

Ppv=100%

Npv=98%

Accuracy=98.67%

1: Distribution of study sample according to age and Body Mass Index (BMI):

Distribution of the Study Sample: In this study, the age mean of 41.5±6.5 years was shown to be associated with carpal tunnel syndrome (CTS), which is in agreement with other researchers (Table 1). Researchers Phalen in 1966 [6] found that CTS patients' peak ages were between 40 and 60 years old and researchers Nevbahar et al. in 2010 and El Miedany et al. in 2004 [7, 8] found that patients' ages ranged from 35 to 68 and 29 to 67 years old, respectively. As shown in Table 1, the average body mass index (BMI) of the participants in the research was 30.1±4.8 kg/m2. This is in line with the average body mass index (BMI) of 26.86.4 for the 949 participants analyzed by Werner et al. (1994) [9].The researchers found that those with a BMI greater than 29 are 2.5 times more likely to be diagnosed with CTS (64), compared to those with a BMI less than 20. There may be an association between body mass index (BMI), hand physiognomies (small or strong wrists), and the cross-section area (CSA) of the median nerve (MN), according to Andrea et al. (2011) [10]. A 2012 study by Jessie et al. [11] observed the largest effect of body mass index on ulnar nerve size. Based on these findings, we opted for a control group whose body mass index was similar to that of the patients. It is well known that gender has a role in MN size; for example, Andrea et al. (2011) [10] recorded that males had a 2.2 mm2 larger CSA of MN proximal to carpal tunnel than women. Our decision to include exclusively female patients was based on the persistent scarcity of male patients during the research period, even though Karadag et al. (2010) [12] included 54 patients (4/50 men). For this reason, we matched patients in the control group with respect to age, gender, and body mass index (BMI) in order to exclude confounding variables that may have affected NCS and CSA measures in the MN. 5.2: 

Bilaterality of CTS: 

Twenty patients (66.7%) exhibited bilateral CTS, whereas the other twenty-one patients had unilateral CTS; in all cases, the afflicted hand was the dominant one. Lia et al. (2006) [13] reported that the condition affects 88.67% of patients bilaterally, followed by 11.32% on the right hand and 0% on the left hand, which is in agreement with the findings of other authors, who found that the symptoms were bilateral in 83.3% of the studied patients. 

5.3: We assessed medical professionals and healthy individuals by measuring the cross-section area (CSA) of the median nerve using ultrasound. The researcher conducted the sonographic evaluation under the supervision of a senior radiologist. However, this did not compromise the reliability of the examination. In 2008, Luis Alemán and colleagues demonstrated that median nerve CSA measurements were reproducible when using a standardized protocol, regardless of the observer's level of experience or training. We took the measurements using the direct approach, which involves directly tracing the nerve's boundary using electronic callipers. The diagnostic reliability of the direct approach is higher than that of the indirect method (ellipsoid formula), according to Duncan et al. (1999) [3] and other writers. We focus on measuring CSA at the tunnel inlet because previous research has shown that it is the most predictive measure for the diagnosis of CTS, and because sonographic measurement of the median nerve CSA at the tunnel inlet has been suggested as a viable alternative to NCS as the first diagnostic test for CTS. Studies have shown that CSA measurements taken at the carpal tunnel outlet are not reliable among readers [14]; the nerve may be hard to see at the outlet in people with thick palmar skin; and there is a lot of variation in the readings because the nerve typically splits into digital branches at this location. Patients at the tunnel exit had a significantly higher CSA of the MN than the control group, according to 2009 research by Mohammadi & colleagues. Compared to the control group's mean CSA of 6.27±0.99 mm2 (p < 0.001), the study found that the mean CSA of the MN at the tunnel intake was considerably higher in CTS patients (14.4±4.2) mm2. According to Nevbahar et al. (2010) [7], who found a substantially different mean CSA in CTS (13.37±3.62) mm2 compared to the control group (9.4 ± 2.31 mm2) (p < 0.001), this is supported by Table 2. The study's findings, as displayed in Table 4, likewise demonstrated statistically significant differences (P<0.001) across the three patient groupings. In several global publications, disagreements have arisen about whether or not the US is helpful in determining the severity of CTS. Consistent with previous research, our findings support US's utility in grading CTS severity. Karadag et al. (2010) [12]  in Turkey, El Miedany et al. (2004) [8] in Egypt, and Lee et al. (1999) [15] all found that the US was helpful in this regard. Karadag et al. (2010) [12] found that sonographic measurement of CSA could provide information about the severity of median nerve involvement, and using US could cost-effectively decrease the number of NCS in patients with suspected CTS. El Miedany et al., [8]  in their study, proposed US cut-off points that differentiate between different grades of CTS, just as our own findings. According to Lee et al., [15] the US assessment of the CSA is a reliable indicator of the severity of MN neuropathy. According to the author, electromyography results of moderate to severe illness are associated with an ultrasound measurement of more than 15 mm2, which is statistically different from a value indicating mild to moderate disease (P<0.05). Although there was a statistically significant difference between the control and patient groups in terms of MN CSA at the tunnel inlet, there was no significant difference among the three patient categories (p > 0.05), according to research from Iran by Mohammadi et al. in 2009 [17]. However, as demonstrated in Spain by Moran et al. (2009) [14], the United States is unable to assign a severity rating to CTS.

5.4: Ultrasound Diagnostic Utility for CTS: Sensitivity, Specificity, Positive and Negative Predictive Values In this study, clinical examination and NCS were considered the gold standard for diagnosing CTS, allowing us to assess US sensitivity and specificity. When assessing ultrasound's sensitivity and specificity for CTS diagnosis, studies have employed either EDS (2,5) or clinical diagnosis as the reference standard, or both. This study's findings that the US had a sensitivity of 92.8% and a specificity of 100% when measuring the median nerve's CSA at the entrance of the carpal tunnel are consistent with previous research showing a sensitivity of up to 94% and a specificity of up to 98% for the diagnosis of carpal tunnel syndrome. In an effort to maximize the test's specificity and sensitivity, several studies' authors have used receiver operating curves to arbitrarily choose cutoff values for the MN's CSA (68). The study by El Miedany et al. [16] statistically determined the cut-off point, specificity, and sensitivity for a pathological mean CSA by using the upper limit of a 95% confidence interval. The actual area is 10.03 mm2. Using a cutoff point of 9 mm2, a meta-analysis of the published data by John et al. (2011) [18] revealed specificities ranging from 51% to 97% and sensitivity levels of 80% to 90% (68). 

5.5: MRI's Positive and Negative Predictive Values for CTS Diagnosis, Sensitivity, and Specificity. This study considered clinical examination and NCS as the gold standard for diagnosing CTS, and used MRI to determine its sensitivity and specificity. We found that the most common signs of CRT were an increase in median nerve signal intensity in the T2W STIR sequence and an increase in median nerve CSA at the carpal tunnel entrance. Monitoring software recorded the median nerve CSA, and the supervisor, a senior radiologist with an interest in MSK, noticed these alterations. Consistent with previous research, the current study found that magnetic resonance imaging (MRI) has a sensitivity of 96% and a specificity of 100%. Studies by J.G. Jarvic (2009), D.M. Radack (1997), Britz, Gavin W.M.D. (1995) [19-21], also found high levels of sensitivity and specificity for MRI. However Jarvik et al. 's 2002 [22] prospective cohort research found that while magnetic resonance imaging (MRI) is reliable, its diagnostic accuracy is only modest. Although MRI offers more anatomical features and high spatial resolution, the current study found little difference between HRUS and MRI in terms of sensitivity and specificity.

1: High-resolution ultrasonography (HRUS) makes it easy to see the median nerve (MN) and quantify its cross-sectional area (CSA) at the pisiform bone level.

2: A non-invasive, sensitive, and specific way to diagnose carpal tunnel syndrome is by ultrasonographically measuring the median nerve (MN).

3: HRUS is an accurate way to measure how bad carpal tunnel syndrome (CTS) is.MRI has high spatial resolution and shows more anatomical detail of the carpal tunnel than HRUS. It can also reveal a possible cause of CTS, such as a space-occupying lesion or anatomical variation in the median nerve, in addition to having similar sensitivity and specificity.

5: When there is uncertainty about the diagnosis or treatment of CTS, endoscopic surgery can be performed, and an MRI can be used to rule out pathological causes.

 Recommendation

1. To aid in CTS diagnosis, we advise using HRUS as a secondary test.

2: To validate our early findings, more research with larger samples is required. To establish typical values for the median nerve CSA at the carpal tunnel entrance in both sexes, more research is required.

4: To determine the usefulness of MRI in postoperative and recurring instances of CTS, more research is required.

Funding: No funding sources.

Conflict of interest: None declared.

Ethical approval: The study was approved by the Institutional Ethics Committee of Basra Health Department Basra Teaching General Hospital.

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