Mr. Xue Deng, Dr. Yong Hu, and Dr. Ip Wing-Yuk were dedicated to the concept of the study design, subject recruitment, and draft and revision of the manuscript. Ms. Lai-Heung Phoebe Chau and Ms. Suk-Yee Chiu were dedicated to subject liaison, data collection, and the manipulation of NCS. Dr. Kwok-Pui Leung was dedicated to the electrophysiological diagnosis, clinical guidance, and the manipulation of the ultrasounds.

All the procedures have been approved by the University of Hong Kong/Hospital authorities Hong Kong West Institutional Review Board (HKU/HA HKW IRB, Ref. Number: UW17-129).
This protocol is applicable to patients who demonstrated clinical symptoms such as numbness, tingling, or pain over the median nerve-innervated area of the hand, with a positive outcome in Tinel&#39;s sign and Phalen&#39;s test. Those subjects with comorbidities, such as diabetes mellitus, cancer, rheumatoid arthritis, and ...

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It is challenging to set up a universal standard for the measurement of NCS due to the influence of demographic and physical factors such as age, gender, ethnicities, and body weight, etc.14. Regarding SNAP amplitude,&#160;there is a difference between the orthodromic (the direction of currency runs proximally toward the body) and antidromic (the direction of currency runs distally away from the body) technique, as the SNAP amplitude measured by the orthodromic method is smaller than the ...

CTS is pathologically&#160;a disorder with segmental demyelination, whereas secondary axonal degeneration, which is indicative of surgical decompression, may coexist as the disease progresses1. However, the current diagnostic and severity gradation scale (from mild to very severe grade) for CTS cannot clearly indicate any coexistence of axonal degeneration, resulting in confusion when choosing the appropriate treatment. Conventional methods for confirming axonal degeneration, such as needle EMG and nerve biopsy, can be sensitive and accurate, but they are both restricted in the clinical practice due to their invasiveness2.
To overcome these shortcomings, ultrasound has been introduced for assisting&#160;diagnosing3,4,5 and grading of the severity of CTS6,7,8. Also, previous study successfully identified its cut-off values for discriminating axonal degeneration associated with CTS, with overall satisfactory sensitivity and specificity9. This study aims at introducing this efficient and noninvasive protocol to the practice in the clinical context. The rationale of this protocol is to combine the neurophysiological and structural information provided by NCS and ultrasounds to indicate the pathological progress1,10. It is assumed to be more accurate to describe the pathological progress than the current severity gradation system, helping clinicians to better figure out a plan of care. Compared to other conventional neuroimaging techniques such as diffusion tensor imaging (DTI), this evidence-based approach can&#160;be more easily applied in clinical settings&#160;with lower costs11.

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screening of axonal degeneration in carpal tunnel syndrome using ultrasonography and nerve conduction studies

Axonal degeneration, indicative of surgical decompression, may coexist in carpal tunnel syndrome (CTS) as the disease progresses. However, the current diagnostic and severity gradation system cannot clearly indicate its coexistence, resulting in&#160;confusion of appropriate treatment prescription. There are also constraints in conventional methods for&#160;differentiation as well. This study aims at introducing an innovative, efficient, and quick screening protocol to differentiate axonal degeneration associated with CTS, using ultrasound and nerve conduction studies (NCS). It starts by using NCS to perform orthodromic stimulation at the wrist, to obtain the sensory conduction of the median and the ulnar nerves respectively. Meanwhile, the motor conduction&#160;of the median nerve is collected by stimulating the palm, wrist, and elbow, followed by the stimulation of the ulnar nerve at the wrist,&#160;below and above the elbow. Then, an ultrasound assessment is performed, using a linear array transducer, with cross-sectional area (CSA) and perimeter (P) at the wrist and at the one-third distal forearm calipered. Ratios (R-CSA, R-P) and changes from wrist to one-third distal forearm (&#916;CSA and &#916;P) are calculated according to a standard format. Potential axonal degeneration coexisting in CTS will be screened according to the criteria of NCS and cut-off values of ultrasound measurements established in a previous study. In terms of its noninvasiveness, low cost, convenience, and efficiency, it is easy to apply ultrasound complimentarily in clinical practice to prescreen patients with potential coexisting axonal degeneration. Nevertheless, the ultrasonographic imaging cannot directly reflect axonal degeneration. It still relies on conventional but invasive methods&#160;such as electromyography (EMG) and biopsy&#160;for confirmation if needed.

As was described in Table 1, associated axonal degeneration has been&#160;primarily screened out should the subject fulfill the criteria of NCS as follows: (1) the sensory conduction velocity of the median nerve is less than 42m/s and/or (2) the distal sensory latency is more than 4.6 ms or the distal motor latency is more than 3.2 ms; (3) the SNAP amplitude at the wrist is less than 10 &#181;V with the CMAP amplitude drop being no more than 20%. Those with temporal dispe...

Watch this Scientific Journal Video about Screening of Axonal Degeneration in Carpal Tunnel Syndrome Using Ultrasonography and Nerve Conduction Studies at JoVE.com

Screening of Axonal Degeneration in Carpal Tunnel Syndrome Using Ultrasonography and Nerve Conduction Studies

Here we present a protocol using nerve conduction studies and ultrasound to screen potential axonal degeneration associated with carpal tunnel syndrome. The criteria for differentiation are established. Compared to conventional approaches, this method is noninvasive, convenient, and efficient, with an overall satisfactory accuracy, sensitivity, and specificity.

Axonal degeneration, indicative of surgical decompression, may coexist in carpal tunnel syndrome (CTS) as the disease progresses. However, the current ...

This non invasive approach using nerve conduction studies and ultrasound is used to specifically and sensitively assess the axonal degeneration in carpal tunnel syndrome patients. This method can be used by clinicians to directly assess the pathological stage of the disease, and can be easily applied for better treatment region planning. Demonstrating the procedure will be Phoebe Chau, an enrolled nurse, and Kwok-Pui Leung, a physician, both from my laboratory.To measure the conduction in the median sensory nerve, first have the patient wash their hands with warm water. After drying, place the recording ring electrode at the proximal interphalangeal joint, and the reference ring electrode over the distal interphalangeal joint. Place the other recording electrodes at the wrist, between the tendons of the flexor carpal radialis, and the palmaris longus.12cm proximal to the recording ring electrode, and ideally proximal to the distal wrist crease. After making sure that the ground electrode is between the stimulation and recording sites, apply super maximal stimulus 10 times to the median nerve via the attached electrodes over the index finger. To measure the conduction in the ulnar sensory nerve, place the recording ring electrode halfway on the proximal phalanx of the 5th digit, and the reference ring electrode 4cm distal to the recording ring electrode.Place the other recording electrodes near the tendon of the flexor carpi ulnaris, 12cm proximal to the recording ring electrode, making sure the ground electrode is between the stimulation and recording sites. Then apply a super maximal stimulus 10 times to the ulnar nerve via attached electrodes over the 5th finger. To measure the conduction in the median motor nerve, place the recording ring's electrode in the most prominent eminence of the thenar area at the motor point of the abductor pollicis brevis, and place the reference ring electrode on the proximal phalanx of the thumb.Then use an electronic stimulator to stimulate at the mid-palm, three to four centimeters distal to the distal wrist crease, and 6.5 centimeters proximal to the recording ring electrode at the wrist, between the tendons of the flexor carpi radialis and the palmaris longus. In the medial aspect of the antecubital space of the elbow, just lateral to the brachial artery. To measure the conduction in the ulnar motor nerve, place the recording ring electrode over the belly of the abductor digiti minimi.The reference ring electrode to the distal phalanx of the 5th digit, and the ground electrode, between the stimulation and the recording sites. Then stimulate at the wrist, 7cm proximal to the recording ring electrode, just lateral or medial to the flexor carpi radialis tendon. Below and above the elbow, 5cm distal and proximal to the ulnar groove.For ultrasound measurements, seat the patient on a plinth with their hands resting in a horizontal supination position, and the fingers semi extended. Place some ultrasound gel over the probe of the transducer, the wrist site, and the distal 1/3 forearm. Next, use a 13 to 14 megahertz linear array transducer to perform a transverse scan at the inlet of the carpal tunnel.Freeze the real time imaging and continuously caliper the hyperechoic epineurium of the median nerve at the inlet of the carpal tunnel. Then scan proximally along the innervated area of the median nerve to the site of the 1/3 distal forearm. Freeze the real time imaging, and caliper the hyperechoic epineurium of the median nerve at the 1/3 distal forearm.After screening for associated axonal degeneration, those patients with any ultrasound parameter values above the corresponding cutoff values are considered as suffering from the potential coexistence of axonal degeneration. Alternatively, the ultrasound readings can be considered as indicators of potential axonal degeneration, should the subject not fulfill the nerve conduction studies criteria. For example, in this representative study, significant differences were found between patients with demyelination and associated axonal degeneration, indicating that this protocol can be an effective tool in screening axonal degeneration associated with carpal tunnel syndrome.Further, in this group of patients who did not fulfill the nerve conduction criteria and were enrolled with ultrasound measurements generated descriptively, the ultrasound measurement data suggested that all of these patients were potentially associated with coexisting axonal degeneration based on their ultrasound measurements alone. In nerve conduction study, sanitized chemical procedure, and side-to-side comparisons are both important as they can increase the reliability of the assessment. Although the tomography is the gold standard for confirming axonal degeneration, further validation study can be used to evaluate the reliability and validity between the tomography and our assessment package.During the ultrasound assessment, make sure the ultrasound parameters are consistent and select the appropriate frequency and probe size. This technique path is the way for researchers to explore innovative uses of ultrasound for diagnosing carpal tunnel syndrome, and may have the potential to be used for predicting treatment effectiveness.

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11.0K Views.  The University of Hong Kong. This non invasive approach using nerve conduction studies and ultrasound is used to specifically and sensitively assess the axonal degeneration in carpal tunnel syndrome patients. This method can be used by clinicians to directly assess the pathological stage of the disease, and can be easily applied for better treatment region planning. Demonstrating the procedure will be Phoebe Chau, an enrolled nurse, and Kwok-Pui Leung, a physician, both from my laboratory.To measure the conduction...