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Give me thesis protocol on the topic Diagnostic utility of median nerve ultrasonography for predicting electrodiagnostic severity in patients with carpal tunnel syndrome With the headings Introduction Background Aim of the study Objectives Methodology Sample size Inclusion criteria Exclusion criteria Methods Conclusion

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median nerve ultrasonography electrodiagnostic severity carpal tunnel syndrome cross sectional study ultrasound CSA systematic review

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"carpal tunnel syndrome" AND ultrasonography

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"carpal tunnel syndrome" AND "electrodiagnostic" AND ultrasonography

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PMID: 39472854

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PMID: 34897298

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PMID: 38965008

Thesis Protocol

Title

Diagnostic utility of median nerve ultrasonography for predicting electrodiagnostic severity in patients with carpal tunnel syndrome

Introduction

Carpal tunnel syndrome (CTS) is the most frequent entrapment neuropathy of the upper limb. It results from compression of the median nerve within the carpal tunnel and commonly presents with nocturnal paresthesia, pain, numbness in the median-nerve distribution, weakness, and, in advanced disease, thenar muscle wasting.
Electrodiagnostic studies (EDS), including nerve conduction studies (NCS) with or without electromyography, provide objective confirmation and functional grading of median neuropathy at the wrist. However, EDS can be uncomfortable, time-consuming, operator-dependent, and not readily available in all settings.
High-resolution ultrasonography is a non-invasive, rapid, and relatively inexpensive technique that can demonstrate median nerve enlargement at the carpal tunnel inlet, altered echotexture, flattening distally, and structural abnormalities. Median nerve cross-sectional area (CSA), particularly at the pisiform level, is the most commonly evaluated sonographic parameter. Whether this anatomical measurement can predict EDS severity requires evaluation in the local population.

Background

CTS occurs due to raised pressure within the carpal tunnel, impairing intraneural circulation and median nerve function. The syndrome is diagnosed clinically and supported by EDS and imaging when appropriate. EDS commonly demonstrates slowing of median sensory conduction across the tunnel and prolongation of median distal motor latency. Rheumatology, 2-Volume Set describes ultrasound findings as proximal median nerve swelling with distal flattening, while sensory conduction velocity and distal motor latency remain key electrodiagnostic measures for confirmation.
Ultrasound-based median nerve CSA generally increases with CTS severity. In a prospective study of 96 wrists, median nerve CSA at the inlet and wrist-to-forearm ratio rose significantly across mild, moderate, and severe EDS categories (Rayegani et al., 2024). Another prospective study reported that an inlet CSA of at least 12 mm² predicted moderate-to-severe CTS with sensitivity of 82.4% and specificity of 87.7% (Potuznik et al., 2023).
A recent diagnostic meta-analysis found pooled sensitivity and specificity of 88% and 84%, respectively, for median nerve CSA at the carpal tunnel inlet, while also showing that optimal CSA thresholds differ between populations (Luo et al., 2025). Thus, a locally conducted study using standardized EDS and ultrasound protocols is justified.

Aim of the Study

To determine the diagnostic utility of median nerve ultrasonography for predicting electrodiagnostic severity in patients with clinically suspected carpal tunnel syndrome.

Objectives

Primary objective

  1. To assess the association between median nerve cross-sectional area on ultrasonography and electrodiagnostic severity of CTS.

Secondary objectives

  1. To compare median nerve CSA at the carpal tunnel inlet among mild, moderate, and severe CTS groups.
  2. To determine the relationship between wrist-to-forearm ratio and electrodiagnostic severity.
  3. To identify the optimal ultrasound CSA cutoff for predicting moderate-to-severe CTS.
  4. To calculate the sensitivity, specificity, positive predictive value, negative predictive value, and area under the receiver operating characteristic curve of ultrasound parameters for moderate-to-severe CTS.
  5. To assess the correlation of sonographic parameters with median sensory latency, sensory conduction velocity, distal motor latency, and compound muscle action potential amplitude.

Methodology

Study design

Hospital-based analytical cross-sectional study.

Study setting

The study will be conducted in the Departments of Physical Medicine and Rehabilitation/Neurology/Radiology of [Name of Institution/Hospital].

Study duration

Twelve months, including recruitment, data collection, analysis, and thesis writing.

Study population

Adults with symptoms and clinical findings suggestive of CTS who are referred for electrodiagnostic evaluation.

Study procedure

Eligible participants will undergo:
  1. Detailed clinical assessment.
  2. Standardized nerve conduction studies.
  3. High-resolution ultrasonography of the median nerve.
Ultrasound and EDS should preferably be completed on the same day or within seven days. The ultrasonographer should be blinded to the EDS severity grade, and the neurophysiologist should be blinded to ultrasound measurements.

Unit of analysis

To avoid statistical dependence from including two wrists of the same person, the primary analysis will include one study wrist per participant. If both wrists fulfill eligibility criteria, the more symptomatic hand will be selected. If symptoms are equal, one wrist will be selected by random allocation.

Sample Size

Sample size is calculated for detecting a correlation between median nerve CSA and electrodiagnostic severity.
Using an anticipated correlation coefficient of r = 0.35, two-sided alpha of 0.05, and power of 80%:
[ n = \left[\frac{(Z_{\alpha/2}+Z_{\beta})}{0.5 \times \ln\left(\frac{1+r}{1-r}\right)}\right]^2 + 3 ]
Where:
  • (Z_{\alpha/2}) = 1.96
  • (Z_{\beta}) = 0.84
  • (r) = 0.35
The calculated minimum sample size is approximately 62 participants. After allowing for 10% incomplete data or exclusions:
[ 62 + 10% = 68.2 ]
Therefore, the final sample size will be 70 participants (70 wrists).
If the institutional protocol permits inclusion of bilateral wrists, analysis must use a mixed-effects model or generalized estimating equations to account for within-person correlation.

Inclusion Criteria

  1. Age 18 years or older.
  2. Symptoms suggestive of CTS, including numbness, tingling, pain, or nocturnal paresthesia in the median nerve distribution.
  3. Clinical findings compatible with CTS, such as positive Phalen test, Tinel sign, or carpal compression test.
  4. Willingness to undergo both EDS and ultrasonography.
  5. Written informed consent.

Exclusion Criteria

  1. Previous carpal tunnel release surgery on the study wrist.
  2. Previous major wrist trauma, fracture, or surgery causing distortion of carpal tunnel anatomy.
  3. Known cervical radiculopathy, brachial plexopathy, or proximal median neuropathy.
  4. Generalized peripheral neuropathy, including severe diabetic polyneuropathy.
  5. Ulnar neuropathy or another coexisting upper-limb entrapment neuropathy that may confound symptoms.
  6. Space-occupying lesion at the wrist, such as tumor, ganglion cyst, or abscess, when identified clinically or sonographically.
  7. Pregnancy, if excluded by local departmental protocol because of transient pregnancy-associated CTS.
  8. Inability to cooperate with EDS or ultrasonographic examination.
  9. Refusal or withdrawal of consent.

Methods

1. Clinical assessment

A structured case-record form will document:
  • Age, sex, dominant hand, occupation, and body mass index
  • Duration and laterality of symptoms
  • Nocturnal symptoms and functional impairment
  • History of diabetes mellitus, hypothyroidism, rheumatoid arthritis, and other relevant comorbidities
  • Phalen test, Tinel sign, carpal compression test, sensory loss, and thenar weakness/atrophy
  • Boston Carpal Tunnel Questionnaire score, if available

2. Electrodiagnostic study

Standard EDS will be performed using a calibrated electromyography machine, maintaining skin temperature above 32°C.
The following variables will be recorded:
  • Median sensory distal latency
  • Median sensory nerve conduction velocity across the wrist
  • Median sensory nerve action potential amplitude
  • Median motor distal latency to abductor pollicis brevis
  • Median compound muscle action potential amplitude
  • Comparative median-ulnar sensory studies, when required
  • Needle electromyography of abductor pollicis brevis in suspected severe CTS
CTS severity will be classified using a predefined and locally accepted electrophysiological grading system, such as:
  • Mild CTS: Sensory conduction abnormality with normal median motor distal latency.
  • Moderate CTS: Sensory abnormality with prolonged median distal motor latency.
  • Severe CTS: Absent or markedly reduced median sensory response, marked motor latency prolongation and/or reduced motor amplitude, with or without denervation changes in abductor pollicis brevis.
The exact latency and amplitude thresholds will be defined according to the laboratory's validated normative values before data collection.

3. Ultrasonographic assessment

A high-frequency linear-array transducer, preferably 10 to 18 MHz, will be used. Participants will be examined in a sitting position with the forearm supinated, wrist in neutral position, and fingers relaxed.
The median nerve will be identified in the transverse plane. The following measurements will be obtained:
  1. Median nerve CSA at carpal tunnel inlet: At the level of the pisiform bone.
  2. Median nerve CSA at distal forearm: Approximately 10 to 12 cm proximal to the wrist crease.
  3. Wrist-to-forearm ratio (WFR):
    [ WFR = \frac{\text{CSA at carpal tunnel inlet}}{\text{CSA at distal forearm}} ]
  4. Median nerve echogenicity.
  5. Nerve flattening at the carpal tunnel outlet, if measurable.
  6. Presence of bifid median nerve, persistent median artery, flexor tenosynovitis, or other anatomical variants.
CSA will be measured by direct tracing along the inner border of the hyperechoic epineurium. Three measurements will be obtained at each site, and the mean value will be used for analysis.

4. Outcome measures

Primary outcome:
  • Relationship between median nerve CSA at the carpal tunnel inlet and electrodiagnostic severity of CTS.
Secondary outcomes:
  • Diagnostic accuracy of CSA and WFR for moderate-to-severe CTS.
  • Association of CSA/WFR with individual NCS parameters.
  • Optimal CSA cutoff based on ROC curve analysis.

5. Statistical analysis

Data will be analyzed using SPSS, R, or equivalent statistical software.
  • Categorical variables will be presented as frequency and percentage.
  • Continuous variables will be presented as mean ± standard deviation or median with interquartile range, according to distribution.
  • Normality will be assessed using the Shapiro-Wilk test.
  • CSA and WFR will be compared across EDS severity groups using one-way ANOVA or Kruskal-Wallis test.
  • Spearman rank correlation will assess relationships between ultrasound values and ordinal EDS severity.
  • Pearson or Spearman correlation will evaluate relationships between ultrasound parameters and individual NCS variables.
  • Multivariable ordinal logistic regression will assess whether CSA independently predicts EDS severity after adjustment for age, sex, body mass index, symptom duration, diabetes, and hypothyroidism.
  • ROC curve analysis will identify the CSA and WFR cutoffs for predicting moderate-to-severe CTS.
  • Sensitivity, specificity, positive predictive value, negative predictive value, and area under the curve will be calculated.
  • A p-value less than 0.05 will be considered statistically significant.

6. Ethical considerations

Ethical approval will be obtained from the Institutional Ethics Committee before recruitment. Written informed consent will be taken from every participant. Participant information will be coded, stored securely, and used only for research purposes. EDS and ultrasonography are standard diagnostic procedures; no additional invasive intervention will be performed for this study.

Conclusion

This study will evaluate whether median nerve ultrasonography, particularly CSA at the carpal tunnel inlet and the wrist-to-forearm ratio, can predict electrodiagnostic severity in CTS. A significant association would support ultrasound as a useful, non-invasive adjunct for early triage, severity estimation, and prioritization of patients who may need prompt electrodiagnostic assessment or surgical referral. Ultrasound should be considered complementary to, rather than a replacement for, EDS because EDS provides functional information and helps identify alternative neuropathies.

Give me abstract on Utility of Median Nerve Ultrasonography in Assessing Electrophysiological Severity of Carpal Tunnel Syndrome”

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"carpal tunnel syndrome" AND ultrasonography

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median nerve ultrasound electrodiagnostic severity carpal tunnel syndrome cross-sectional area 2024 study

Abstract

Background: Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy of the upper limb, caused by compression of the median nerve at the wrist. Electrodiagnostic studies (EDS) are widely used to confirm CTS and classify its physiological severity, but they may be uncomfortable, time-consuming, and less accessible in resource-limited settings. High-resolution ultrasonography is a rapid, non-invasive technique that can demonstrate median nerve enlargement and structural changes. Median nerve cross-sectional area (CSA) at the carpal tunnel inlet and the wrist-to-forearm ratio may correlate with electrophysiological severity.
Aim: To evaluate the utility of median nerve ultrasonography in assessing electrophysiological severity of carpal tunnel syndrome.
Methods: This hospital-based analytical cross-sectional study will recruit 70 adult patients with clinically suspected CTS. One symptomatic wrist per participant will be assessed. All participants will undergo standardized nerve conduction studies and high-resolution ultrasonographic examination of the median nerve. Electrodiagnostic severity will be categorized as mild, moderate, or severe according to predefined laboratory criteria based on sensory and motor nerve conduction parameters. Ultrasonographic measurements will include median nerve CSA at the carpal tunnel inlet, CSA at the distal forearm, and wrist-to-forearm ratio. The ultrasonographer will be blinded to the electrodiagnostic findings. Median nerve CSA and wrist-to-forearm ratio will be compared across electrophysiological severity categories. Correlation analyses, multivariable regression, and receiver operating characteristic curve analysis will be used to assess the ability of ultrasound parameters to predict moderate-to-severe CTS.
Expected Results: It is anticipated that median nerve CSA at the carpal tunnel inlet and wrist-to-forearm ratio will increase progressively with increasing electrophysiological severity. Ultrasound-derived CSA is expected to demonstrate useful diagnostic accuracy for identifying moderate-to-severe CTS.
Conclusion: Median nerve ultrasonography may serve as a practical, non-invasive adjunct to electrodiagnostic testing for estimating CTS severity. However, it should complement rather than replace EDS, which provides functional assessment of median nerve impairment.
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