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 other peripheral neuropathies, are not eligible for this protocol.
1. Measurement of the Nerve Conduction Studies
<ol>
	<li>Ask the patient to wash his/her hands with warm water. Dry the hands before placing the electrodes. Keep the hand skin temperature above 32 &#176;C.</li>
	<li>Measure the conduction in the median sensory nerve (Figure 1).
	<ol>
		<li>Place the recording (E1) ring electrode at the proximal interphalangeal joint while the reference electrode (E2) is attached over the distal interphalangeal joint.</li>
		<li>Place the recording electrodes at the wrist between the tendons of the flexor carpal radialis and palmaris longus (12 cm proximal to the E1 electrode) and, ideally, proximal to the distal wrist crease. Ensure that the ground electrode is between the stimulation and recording sites.</li>
		<li>Apply supramaximal stimulus 10x to the median nerve via the attached electrodes over the index finger.</li>
		<li>Collect the averaged readings of the distal sensory latency, the sensory nerve action potential (SNAP) amplitude, and the conduction velocities displayed in the NCS system.</li>
	</ol>
	</li>
	<li>Measure the conduction in the ulnar sensory nerve (Figure 1).
	<ol>
		<li>Place the E1 ring electrode halfway on the proximal phalanx of the fifth digit while the E2 ring electrode should be located 4 cm distal to the E1 ring electrode.</li>
		<li>Place the recording electrodes near the tendon of the flexor carpi ulnaris (12 cm proximal to the E1 ring electrode). Ensure that the ground electrode is between the stimulation and recording sites.</li>
		<li>Apply supramaximal stimulus 10x to the ulnar nerve via attached electrodes over the fifth finger.</li>
		<li>Collect the averaged readings of the distal sensory latency, the SNAP amplitude, and the conduction velocities of the ulnar nerve displayed in the NCS system.</li>
	</ol>
	</li>
	<li>Measure the conduction in the median motor nerve (Figure 2).
	<ol>
		<li>Place the recording electrode E1 in the most prominent eminence of the thenar area at the motor point of the abductor pollicis brevis (APB).</li>
		<li>Place the reference electrode E2 on the proximal phalanx of the thumb.</li>
		<li>Stimulate at the mid-palm (3 to 4 cm distal to the distal wrist crease), 6.5 cm proximal to the E1 at the wrist (between the tendons of the flexor carpi radialis and palmaris longus) and the elbow (medial aspect of the antecubital space, just lateral to the brachial artery), using an electronic stimulator.</li>
		<li>Collect the supramaximal readings of the distal motor latency, the compound motor nerve action potential (CMAP) amplitude, and the conduction velocities displayed in the NCS system.</li>
	</ol>
	</li>
	<li>Measure the conduction in the ulnar motor nerve (Figure 3).
	<ol>
		<li>Place the E1 over the belly of the abductor digiti minimi while the E2 is attached to the distal phalanx of the fifth digit. The ground electrode is between the stimulation and the recording sites.</li>
		<li>Stimulate at the wrist (7 cm proximal to the E1 electrode, just lateral or medial to the flexor carpi radialis tendon), below and above the elbow (5 cm distal and proximal to the ulnar groove) (Figure 3).</li>
		<li>Collect the supramaximal readings of the distal motor latency, the CMAP amplitude, and the conduction velocities of the ulnar nerve displayed in the NCS system.</li>
	</ol>
	</li>
</ol>
2. Measurements Using Ultrasound
<ol>
	<li>Ensure that the patient is seated on a plinth facing the examiner, with their hands resting in a horizontal supination position and the fingers semi-extended (Figure 4).</li>
	<li>Place some ultrasound gel over the probe of the transducer, the wrist site, and the distal one-third forearm (Figure 4).</li>
	<li>Perform a transverse scan using a 14 - 13 MHz linear array transducer 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 (Figure 5).</li>
	<li>Scan proximally along the innervated area of the median nerve to the site of the one-third distal forearm. Freeze the real-timing imaging and caliper the hyperechoic epineurium of the median nerve at the one-third distal forearm (Figure 6).</li>
</ol>
3. Screening of Potential Coexisting Axonal Degeneration in Carpal Tunnel Syndrome
<ol>
	<li>Screen the possible coexisting axonal degeneration primarily based on the NCS criteria listed in Table 1. 
	NOTE: Those patients who fulfilled the criteria for associated axonal degeneration according to the NCS criteria in Table 1 will be primarily screened for the potential coexistence of axonal degeneration.</li>
	<li>Consider the ultrasound readings as complementary information for screening axonal degeneration. 
	NOTE: The patient will be considered associated with the coexistence of axonal degeneration should any of the measured readings of the ultrasound parameters be above the cut-off value(s).</li>
	<li>Take the ultrasound readings into account when the NCS readings failed to fulfill the NCS criteria from Table 1 (e.g., the NCS signal is absent or a conduction block or temporal dispersion occurs). 
	NOTE: The patient can also be considered as potentially associated with axonal degeneration should any of the measured readings of the ultrasound parameters be above the cut-off value(s). Further golden standard testing, such as EMG or biopsy, can be applied for confirmation if needed.</li>
</ol>

<ol>
	<li>Caetano, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Axonal+degeneration+in+association+with+carpal+tunnel+syndrome.">Axonal degeneration in association with carpal tunnel syndrome.</a> Arquivos de Neuro-Psiquiatria. 61 (1), 48-50 (2003).</li><li>Werner, R. A., Andary, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrodiagnostic+evaluation+of+carpal+tunnel+syndrome.">Electrodiagnostic evaluation of carpal tunnel syndrome.</a> Muscle Nerve. 44 (4), 597-607 (2011).</li><li>Duncan, I., Sullivan, P., Lomas, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sonography+in+the+diagnosis+of+carpal+tunnel+syndrome.">Sonography in the diagnosis of carpal tunnel syndrome.</a> AJR. American journal of roentgenology. 173 (3), 681-684 (1999).</li><li>Miyamoto, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carpal+Tunnel+Syndrome-+Diagnosis+by+Means+of+Median+Nerve+Elasticity-Improved+Diagnostic+Accuracy+of+US+with+Sonoelastography.">Carpal Tunnel Syndrome- Diagnosis by Means of Median Nerve Elasticity-Improved Diagnostic Accuracy of US with Sonoelastography.</a> Radiology. 270 (2), 481-486 (2014).</li><li>Azami, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+diagnostic+value+of+ultrasound+compared+with+nerve+conduction+velocity+in+carpal+tunnel+syndrom.">The diagnostic value of ultrasound compared with nerve conduction velocity in carpal tunnel syndrom.</a> International Journal of Rheumatic Diseases. 17, 612-620 (2014).</li><li>Altinok, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasonographic+assessment+of+mild+and+moderate+idiopathic+carpal+tunnel+syndrome.">Ultrasonographic assessment of mild and moderate idiopathic carpal tunnel syndrome.</a> Clinical Radiology. 59, 916-925 (2004).</li><li>Zhang, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Does+the+ratio+of+the+carpal+tunnel+inlet+and+outlet+cross-sectional+areas+in+the+median+nerve+reflect+carpal+tunnel+syndrome+severity.">Does the ratio of the carpal tunnel inlet and outlet cross-sectional areas in the median nerve reflect carpal tunnel syndrome severity.</a> Neural Regeneration Research. 10 (7), 1172-1176 (2015).</li><li>Klauser, A. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sonographic+cross-sectional+area+measurement+in+carpal+tunnel+syndrome+patients:+can+delta+and+ratio+calculations+predict+severity+compared+to+nerve+conduction+studies.">Sonographic cross-sectional area measurement in carpal tunnel syndrome patients: can delta and ratio calculations predict severity compared to nerve conduction studies.</a> European Radiology. 25 (8), 2419-2427 (2015).</li><li>Deng, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exploratory+use+of+ultrasound+to+determine+whether+demyelination+following+carpal+tunnel+syndrome+co-exists+with+axonal+degeneration.">Exploratory use of ultrasound to determine whether demyelination following carpal tunnel syndrome co-exists with axonal degeneration.</a> Neural Regeneration Research. 13 (2), 317-323 (2018).</li><li>Moon, H. 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O., Alrefey, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diffusion+tensor+imaging+of+mild-moderate+carpal+tunnel+syndrome-+correlation+with+nerve+conduction+study+and+clinical+tests.">Diffusion tensor imaging of mild-moderate carpal tunnel syndrome- correlation with nerve conduction study and clinical tests.</a> Clinical Rheumatology. 36 (10), 2319-2324 (2017).</li><li>Weber, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conduction+block+and+abnormal+temporal+dispersion--diagnostic+criteria.">Conduction block and abnormal temporal dispersion--diagnostic criteria.</a> Electroencephalography and Clinical Neurophysiology. 37 (5), 305-309 (1997).</li><li>Kiernan, C. M., Mogyoros, I., Burke, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conduction+block+in+carpal+tunnel+syndrome.">Conduction block in carpal tunnel syndrome.</a> Brain. 122 (5), 933-941 (1999).</li><li>Fong, S. Y., Goh, K. J., Shahrizaila, N., Wong, K. T., Tan, C. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+demographic+and+physical+factors+on+nerve+conduction+study+values+of+healthy+subjects+in+a+multi-ethnic+Asian+population.">Effects of demographic and physical factors on nerve conduction study values of healthy subjects in a multi-ethnic Asian population.</a> Muscle Nerve. 54 (2), 244-248 (2016).</li><li>Valls-Sole, J., Leote, J., Pereira, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antidromic+vs+orthodromic+sensory+median+nerve+conduction+studies.">Antidromic vs orthodromic sensory median nerve conduction studies.</a> Clinical Neurophysiology Practice. 1, 18-25 (2016).</li><li>Wong, S. M., Griffith, J. F., Hui, A. C., Tang, A., Wong, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Discriminatory+sonographic+criteria+for+the+diagnosis+of+carpal+tunnel+syndrome.">Discriminatory sonographic criteria for the diagnosis of carpal tunnel syndrome.</a> Arthritis &amp; Rheumatology. 46 (7), 1914-1921 (2002).</li><li>Mondelli, M., Filippou, G., Gallo, A., Frediani, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diagnostic+utility+of+ultrasonography+versus.+nerve+conduction+studies+in+mild+carpal+tunnel+syndrome.">Diagnostic utility of ultrasonography versus. nerve conduction studies in mild carpal tunnel syndrome.</a> Arthritis &amp; Rheumatology. 59 (3), 357-366 (2008).</li><li>Wong, S. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carpal+tunnel+syndrome:+diagnostic+usefulness+of+sonography.">Carpal tunnel syndrome: diagnostic usefulness of sonography.</a> Radiology. 232 (1), 93-99 (2004).</li><li>Baiee, R. H., AL-Mukhtar, N. J., Al-Rubiae, S. J., Hammoodi, Z. H., Abass, F. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neurophysiological+Findings+in+Patients+with+Carpal+Tunnel+Syndrome+by+Nerve+Conduction+Study+in+Comparing+with+Ultrasound+study.">Neurophysiological Findings in Patients with Carpal Tunnel Syndrome by Nerve Conduction Study in Comparing with Ultrasound study.</a> Journal of Natural Sciences Reserach. 5 (16), 111-128 (2015).</li><li>Filius, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multidimensional+ultrasound+imaging+of+the+wrist:+Changes+of+shape+and+displacement+of+the+median+nerve+and+tendons+in+carpal+tunnel+syndrome.">Multidimensional ultrasound imaging of the wrist: Changes of shape and displacement of the median nerve and tendons in carpal tunnel syndrome.</a> Journal of Orthopaedic Research. 33 (9), 1332-1340 (2015).</li></ol>

The authors have nothing to disclose.

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 antidromic method15. In our laboratory, orthodromic stimulation has generally been applied clinically such that we set 10 &#181;V as the cut-off value of determining axonal damage. A higher SNAP amplitude is required should the antidromic technique be applied.
On the other hand, for the measurement of ultrasound, we took the inlet of the carpal tunnel and the one-third distal forearm as the bony markers for measurement. These measurement sites were consistent with previous studies, bearing a comparatively higher accuracy for diagnosing the disease3,4,8,16,17,18, which may also increase the accuracy of discrimination&#160;consequently, increase the accuracy of discrimination. In addition, one of the most innovative aspects of this method is that the cut-off values of the ultrasound parameters can take a complementary role when the electric signal of NCS is absent or did not fulfill the NCS criteria for differentiation as they displayed overall satisfactory sensitivity and specificity in a previous study9. Compared to previous cut-off values identified for severity gradation8,19,20, these cut-off values are believed to be more indicative clinically for treatment prescription as they can reflect pathological progress beyond the conventional severity grade.
Nevertheless, there are also constraints using this method. First, the specificity is inferior to the sensitivity in this protocol, as can be seen from the ultrasound findings among subjects in group C, all of which were considered with potential associated axonal degeneration based on the ultrasound cut-off readings. This can be explained as&#160;we have not yet established a concrete assessment package to confirm axonal degeneration based on various ultrasound parameters. Besides, the nature of ultrasound imaging also cannot directly display axonal degeneration. It still relies on the golden standard test to confirm axonal degeneration. Also, there is yet no universal agreement upon NCS criteria for discriminating axonal degeneration9. Further studies are required to examine its reliability by comparison with the golden standard test. Despite these limitations, we still propose this method as an efficient screening approach as it can quickly inform clinicians at an early stage in a noninvasive manner, thus avoiding deterioration.
Bearing overall satisfactory accuracy, sensitivity, and specificity, the combinative use of ultrasound and NCS cannot only compensate for technical pitfalls of NCS (absent signals, etc.) by providing anatomical and structural information, but also it can&#160;disclose or identify the pathological progress lying underneath. This method can be applied easily in routine clinical practice for the initial screening of the potential coexistence of axonal degeneration associated with CTS. A more refined plan of care can be attainable using this method.

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.

<table border="0" cellpadding="0" cellspacing="0" style="width:465px;" width="466">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Nicolet Viking EDX</td>
			<td style="width:71px;">Nicolet</td>
			<td style="width:119px;">RY111820G</td>
			<td style="width:61px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MyLab Twice</td>
			<td style="width:71px;">ESAOTE</td>
			<td style="width:119px;">101620000</td>
			<td></td>
		</tr>
	</tbody>
</table>

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 dispersion (a CMAP amplitude drop of &#62;20%) and/or conduction block (a CMAP amplitude drop of &#62;50%) will be excluded. Regarding the criteria of the NCS parameters, which include conduction velocity, distal latency, SNAP amplitude, exclusion of conduction block12&#160;and temporal dispersion13, they were all set based on previously well-established references and our laboratory practical standard.
Then, the measured readings of the ultrasound parameters will also be taken into account. The CSA is the coronal size of the nerve measured by tracing the hyperechoic epineurium, while the P is the circumference of the traced hyperechoic epineurium. R-CSA/R-P is calculated by the CSA/P measured at the carpal inlet divided by that measured in the one-third distal forearm. &#916;CSA/&#916;P is the change of CSA/P from the wrist to the one-third distal forearm. The cut-off values and the sensitivity, specificity, and accuracy of the ultrasound parameters were determined by plotting receiver operative characteristics (ROC) curves, which were identified in a previous study9. The positive predictive value and negative predictive value are also displayed in Table 1. Those patients with any ultrasound parameter value(s) above the correspondent cut-off value(s) will be considered as suffering from the potential coexistence of axonal degeneration. Alternatively, the ultrasound readings can also be considered as indicators of potential axonal degeneration, should the subject not fulfill the NCS criteria in Table 1.
A group of 80 subjects who fulfilled the NCS criteria in Table 1 was enrolled via convenience sampling to examine the effectiveness of the protocol. They were assigned to group A (demyelination only, n1 = 45) and group B (associated axonal degeneration, n2 = 35), based on the NCS criteria in Table 1. By between group comparison, significant differences were found in NCS and ultrasound measurements (Table 2). The results indicate this protocol can be effective in screening axonal degeneration associated with CTS.
On the other hand, another group of 46 subjects (group C), who did not fulfill the NCS criteria in Table 1, were enrolled with ultrasound measurements generated descriptively. Based on the ultrasound performance, the enrolled subjects were all potentially associated with coexisting axonal degeneration (Table 2).
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/58681/58681fig1.jpg" /> 
Figure 1: Measurement of the conduction in the sensory&#160;median and ulnar nerve. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58681/58681fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/58681/58681fig2.jpg" /> 
Figure 2: Measurement of the conduction in the motor median nerve. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58681/58681fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/58681/58681fig3.jpg" /> 
Figure 3: Measurement of the conduction in the motor ulnar nerve. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58681/58681fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/58681/58681fig4.jpg" /> 
Figure 4: Measurement by ultrasound. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58681/58681fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/58681/58681fig5.jpg" /> 
Figure 5: Measurement of the inlet of the carpal tunnel and its ultrasound imaging. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58681/58681fig5large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/58681/58681fig6.jpg" /> 
Figure 6: Measurement of the one-third distal forearm and its ultrasound imaging. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58681/58681fig6large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table fo:keep-together.within-page="1">
	<tbody>
		<tr>
			<td colspan="7">Criteria for determining axonal degeneration according to measurement of nerve conduction studies</td>
		</tr>
		<tr>
			<td colspan="7">(1) Conduction velocity of the median sensory nerve &#60;42m/s (less than 75% of the lower limit of normal, and/or 
			(2) Distal sensory latency &#62; 4.6 ms or distal motor latency &#62;3.2 ms (more than 130% of the upper limit of normal) 
			(3) Sensory nerve action potential (SNAP) amplitude at the wrist &#60;10 &#956;V with compound motor action potential (CMAP) amplitude drop &#8804; 20%; 
			(4) Exclude conditions of CMAP amplitude drop &#62;20%, which may be indicative of temporal dispersion and/or conduction block (CMAP amplitude drop &#62;50%)</td>
		</tr>
		<tr>
			<td colspan="7">Criteria for determining axonal degeneration according to ultrasound measurement</td>
		</tr>
		<tr>
			<td></td>
			<td>Cut-off values</td>
			<td>Accuracy</td>
			<td>Sensitivity (%)</td>
			<td>Specificity (%)</td>
			<td>Positive Predicative Value (%)</td>
			<td>Negative Predicative Value (%)</td>
		</tr>
		<tr>
			<td>(1) CSA(mm2)</td>
			<td>12</td>
			<td>0.71</td>
			<td>80%</td>
			<td>48.90%</td>
			<td>75.90%</td>
			<td>45.10%</td>
		</tr>
		<tr>
			<td>(2) P(mm)</td>
			<td>16.27</td>
			<td>0.748</td>
			<td>88.60%</td>
			<td>51.10%</td>
			<td>85.20%</td>
			<td>41.50%</td>
		</tr>
		<tr>
			<td>(3) R-CSA</td>
			<td>1.85</td>
			<td>0.725</td>
			<td>85.70%</td>
			<td>48.90%</td>
			<td>81.50%</td>
			<td>43.40%</td>
		</tr>
		<tr>
			<td>(4) R-P</td>
			<td>1.48</td>
			<td>0.676</td>
			<td>80%</td>
			<td>40%</td>
			<td>72%</td>
			<td>49.10%</td>
		</tr>
		<tr>
			<td>(5) &#916;CSA(mm2)</td>
			<td>6.98</td>
			<td>0.758</td>
			<td>77.10%</td>
			<td>62.20%</td>
			<td>77.80%</td>
			<td>38.60%</td>
		</tr>
		<tr>
			<td>(6) &#916;P(mm)</td>
			<td>5.77</td>
			<td>0.717</td>
			<td>80%</td>
			<td>46.70%</td>
			<td>80.60%</td>
			<td>36.40%</td>
		</tr>
	</tbody>
</table>
Table 1:&#160;Criteria for determining axonal degeneration associated with carpal tunnel syndrome by nerve conduction studies and ultrasound. Remarks: R-CSA or R-P = CSA or P at the wrist/CSA or P at the one-third distal forearm; &#916;CSA or &#916;P = CSA or P at the wrist minus CSA or P at the one-third distal forearm.
<table fo:keep-together.within-page="1">
	<tbody>
		<tr>
			<td></td>
			<td>Group A(n1=45)</td>
			<td>Group B(n2=35)</td>
			<td>Group C(n3=46)</td>
		</tr>
		<tr>
			<td colspan="4">Demographics</td>
		</tr>
		<tr>
			<td>Gender#</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Female</td>
			<td>35</td>
			<td>31</td>
			<td>45</td>
		</tr>
		<tr>
			<td>Male</td>
			<td>10</td>
			<td>4</td>
			<td>1</td>
		</tr>
		<tr>
			<td>Age</td>
			<td>58.58(8.44)</td>
			<td>65.4(7.96)*</td>
			<td>58.98(7.08)</td>
		</tr>
		<tr>
			<td>Handedness</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Right</td>
			<td>23</td>
			<td>20</td>
			<td>23</td>
		</tr>
		<tr>
			<td>Left</td>
			<td>22</td>
			<td>15</td>
			<td>23</td>
		</tr>
		<tr>
			<td>Severity grade*</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Mild</td>
			<td>20</td>
			<td>9</td>
			<td>29</td>
		</tr>
		<tr>
			<td>Mild to moderate</td>
			<td>8</td>
			<td>0</td>
			<td>4</td>
		</tr>
		<tr>
			<td>Moderate</td>
			<td>14</td>
			<td>7</td>
			<td>7</td>
		</tr>
		<tr>
			<td>Moderate to severe</td>
			<td>1</td>
			<td>6</td>
			<td>5</td>
		</tr>
		<tr>
			<td>Severe</td>
			<td>2</td>
			<td>13</td>
			<td>1</td>
		</tr>
		<tr>
			<td colspan="4">Nerve Conduction Studies</td>
		</tr>
		<tr>
			<td>Median Motor Nerve</td>
			<td>Group A</td>
			<td>Group B</td>
			<td>Group C</td>
		</tr>
		<tr>
			<td>Palmar DML</td>
			<td>1.99(.27)</td>
			<td>2.1(.21)</td>
			<td>1.92(.23)</td>
		</tr>
		<tr>
			<td>Palmar CMAP</td>
			<td>8.46(2.51)</td>
			<td>7.68(2.26)</td>
			<td>8.91(2.4)</td>
		</tr>
		<tr>
			<td>Wrist ML</td>
			<td>4.74(1.13)</td>
			<td>6.25(1.62)*</td>
			<td>4.5(1.5)</td>
		</tr>
		<tr>
			<td>Wrist CMAP</td>
			<td>8.32(2.5)</td>
			<td>7(2.0)#</td>
			<td>8.12(2.72)</td>
		</tr>
		<tr>
			<td>Wrist MCV</td>
			<td>27.28(7.46)</td>
			<td>20.4(6.17)*</td>
			<td>33.32(11.15)</td>
		</tr>
		<tr>
			<td>Median Sensory nerve</td>
			<td>Group A</td>
			<td>Group B</td>
			<td>Group C</td>
		</tr>
		<tr>
			<td>DSL</td>
			<td>3.22(.43)</td>
			<td>3.61(.46)*</td>
			<td>2.82(.68)</td>
		</tr>
		<tr>
			<td>SNAP</td>
			<td>12.82(4.41)</td>
			<td>6.21(2.23)*</td>
			<td>13.77(4.93)</td>
		</tr>
		<tr>
			<td>SCV</td>
			<td>36.39(6.3)</td>
			<td>33.74(4.23)</td>
			<td>46.02(6.26)</td>
		</tr>
		<tr>
			<td colspan="4">Ultrasound Measurements</td>
		</tr>
		<tr>
			<td>Ultrasound parameters</td>
			<td>Group A</td>
			<td>Group B</td>
			<td>Group C</td>
		</tr>
		<tr>
			<td>CSA(mm2)</td>
			<td>12.5(4.0)</td>
			<td>16.54(6.81)*</td>
			<td>14.18(3.55)</td>
		</tr>
		<tr>
			<td>P(mm)</td>
			<td>16.71(2.86)</td>
			<td>19.64(4.08)*</td>
			<td>18.31(2.5)</td>
		</tr>
		<tr>
			<td>R-CSA</td>
			<td>2.03(0.67)</td>
			<td>2.79(1.01)*</td>
			<td>2.69(.74)</td>
		</tr>
		<tr>
			<td>R-P</td>
			<td>1.63(.39)</td>
			<td>1.9((0.47)*</td>
			<td>1.84(.26)</td>
		</tr>
		<tr>
			<td>&#916;CSA(mm2)</td>
			<td>6.17(3.76)</td>
			<td>10.4(6.13)*</td>
			<td>8.73(2.97)</td>
		</tr>
		<tr>
			<td>&#916;P(mm)</td>
			<td>6.22(3.28)</td>
			<td>9.08(4.04)*</td>
			<td>8.25(1.99)</td>
		</tr>
		<tr>
			<td>*&#60;0.01;#&#60;0.05;</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td colspan="4">DML(ms): distal motor latency, CMAP(mV): compound motor action potential, ML(ms): Motor latency; MCV(m/s): motor conduction velocity; MCV: motor conduction velocity; DSL(ms): distal sensory latency; SNAP(&#956;V): sensory nerve action potential; SCV(m/s): sensory conduction velocity ;W-CSA(mm2): wrist cross-sectional area, W-P (mm): wrist perimeter; R-CSA: ratio of cross sectional area of wrist over one third distal forearm, R-P: ratio of perimeter of wrist over one third distal forearm, DCSA (mm2): changes of cross-sectional area from wrist to one third distal forearm, DP (mm): changes of perimeter from wrist to one third distal forearm</td>
		</tr>
	</tbody>
</table>
Table 2: Demographics and performance of nerve conduction studies and ultrasound measurements of the enrolled subjects.

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 ...

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11.1K Views.  The University of Hong Kong. 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.

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

Recording and Analysis of Circadian Rhythms in Running-wheel Activity in Rodents

When rodents have free access to a running wheel in their home cage, voluntary use of this wheel will depend on the time of day1-5. Nocturnal rodents, including rats, hamsters, and mice, are active during the night and relatively inactive during the day. Many other behavioral and physiological measures also exhibit daily rhythms, but in rodents, running-wheel activity serves as a particularly reliable and convenient measure of the output of the master circadian clock, the suprachiasmatic nucleus (SCN) of the hypothalamus. In general, through a process called entrainment, the daily pattern of running-wheel activity will naturally align with the environmental light-dark cycle (LD cycle; e.g. 12 hr-light:12 hr-dark). However circadian rhythms are endogenously generated patterns in behavior that exhibit a ~24 hr period, and persist in constant darkness. Thus, in the absence of an LD cycle, the recording and analysis of running-wheel activity can be used to determine the subjective time-of-day. Because these rhythms are directed by the circadian clock the subjective time-of-day is referred to as the circadian time (CT). In contrast, when an LD cycle is present, the time-of-day that is determined by the environmental LD cycle is called the zeitgeber time (ZT).
Although circadian rhythms in running-wheel activity are typically linked to the SCN clock6-8, circadian oscillators in many other regions of the brain and body9-14 could also be involved in the regulation of daily activity rhythms. For instance, daily rhythms in food-anticipatory activity do not require the SCN15,16 and instead, are correlated with changes in the activity of extra-SCN oscillators17-20. Thus, running-wheel activity recordings can provide important behavioral information not only about the output of the master SCN clock, but also on the activity of extra-SCN oscillators. Below we describe the equipment and methods used to record, analyze and display circadian locomotor activity rhythms in laboratory rodents.

Circadian rhythms in voluntary wheel-running activity in mammals are tightly coupled to the molecular oscillations of a master clock in the brain. As such, these daily rhythms in behavior can be used to study the influence of genetic, pharmacological, and environmental factors on the functioning of this circadian clock.

When rodents have free access to a running wheel in their home cage, voluntary use of this wheel will depend on the time of day1-5. Nocturnal rodents, ...

An Ex Vivo Laser-induced Spinal Cord Injury Model to Assess Mechanisms of Axonal Degeneration in Real-time

Injured CNS axons fail to regenerate and often retract away from the injury site. Axons spared from the initial injury may later undergo secondary axonal degeneration. Lack of growth cone formation, regeneration, and loss of additional myelinated axonal projections within the spinal cord greatly limits neurological recovery following injury. To assess how central myelinated axons of the spinal cord respond to injury, we developed an ex vivo living spinal cord model utilizing transgenic mice that express yellow fluorescent protein in axons and a focal and highly reproducible laser-induced spinal cord injury to document the fate of axons and myelin (lipophilic fluorescent dye Nile Red) over time using two-photon excitation time-lapse microscopy. Dynamic processes such as acute axonal injury, axonal retraction, and myelin degeneration are best studied in real-time. However, the non-focal nature of contusion-based injuries and movement artifacts encountered during in vivo spinal cord imaging make differentiating primary and secondary axonal injury responses using high resolution microscopy challenging. The ex vivo spinal cord model described here mimics several aspects of clinically relevant contusion/compression-induced axonal pathologies including axonal swelling, spheroid formation, axonal transection, and peri-axonal swelling providing a useful model to study these dynamic processes in real-time. Major advantages of this model are excellent spatiotemporal resolution that allows differentiation between the primary insult that directly injures axons and secondary injury mechanisms; controlled infusion of reagents directly to the perfusate bathing the cord; precise alterations of the environmental milieu (e.g., calcium, sodium ions, known contributors to axonal injury, but near impossible to manipulate in vivo); and murine models also offer an advantage as they provide an opportunity to visualize and manipulate genetically identified cell populations and subcellular structures. Here, we describe how to isolate and image the living spinal cord from mice to capture dynamics of acute axonal injury.

An Ex Vivo Laser-induced Spinal Cord Injury Model to Assess Mechanisms of Axonal Degeneration in Real-time

We present a protocol utilizing two-photon excitation time-lapse microscopy to simultaneously visualize the dynamics of axon and myelin injuries in real time. This proposed protocol permits studies of both intrinsic and extrinsic factors which can influence central myelinated axon fate after injury and contribute to permanent clinical disability.

Injured CNS axons fail to regenerate and often retract away from the injury site. Axons spared from the initial injury may later undergo secondary axonal ...

External Excitation of Neurons Using Electric and Magnetic Fields in One- and Two-dimensional Cultures

A neuron will fire an action potential when its membrane potential exceeds a certain threshold. In typical activity of the brain, this occurs as a result of chemical inputs to its synapses. However, neurons can also be excited by an imposed electric field. In particular, recent clinical applications activate neurons by creating an electric field externally. It is therefore of interest to investigate how the neuron responds to the external field and what causes the action potential. Fortunately, precise and controlled application of an external electric field is possible for embryonic neuronal cells that are excised, dissociated and grown in cultures. This allows the investigation of these questions in a highly reproducible system.
In this paper some of the techniques used for controlled application of external electric field on neuronal cultures are reviewed. The networks can be either one dimensional, i.e. patterned in linear forms or allowed to grow on the whole plane of the substrate, and thus two dimensional. Furthermore, the excitation can be created by the direct application of electric field via electrodes immersed in the fluid (bath electrodes) or by inducing the electric field using the remote creation of magnetic pulses.

Neuronal cultures are a good model for studying emerging brain stimulation techniques via their effect on single neurons or a population of neurons. Presented here are different methods for stimulation of patterned neuronal cultures by an electric field produced directly by bath electrodes or induced by a time-varying magnetic field.

A neuron will fire an action potential when its membrane potential exceeds a certain threshold. In typical activity of the brain, this occurs as a result ...

Modeling Neuronal Death and Degeneration in Mouse Primary Cerebellar Granule Neurons

Cerebellar granule neurons (CGNs) are a commonly used neuronal model, forming an abundant homogeneous population in the cerebellum. In light of their post-natal development, abundance, and accessibility, CGNs are an ideal model to study neuronal processes, including neuronal development, neuronal migration, and physiological neuronal activity stimulation. In addition, CGN cultures provide an excellent model for studying different modes of cell death including excitotoxicity and apoptosis. Within a week in culture, CGNs express N-methyl-D-aspartate (NMDA) receptors, a specific ionotropic glutamate receptor with many critical functions in neuronal health and disease. The addition of low concentrations of NMDA in conjunction with membrane depolarization to rodent primary CGN cultures has been used to model physiological neuronal activity stimulation while the addition of high concentrations of NMDA can be employed to model excitotoxic neuronal injury. Here, a method of isolation and culturing of CGNs from 6 day old pups as well as genetic manipulation of CGNs by adenoviruses and lentiviruses are described. We also present optimized protocols on how to stimulate NMDA-induced excitotoxicity, low-potassium-induced apoptosis, oxidative stress and DNA damage following transduction of these neurons.

This protocol describes a simple method for isolating and culturing primary mouse cerebral granule neurons (CGNs) from 6-7 day old pups, efficient transduction of CGNs for loss and gain of function studies, and modelling NMDA-induced neuronal excitotoxicity, low-potassium-induced cell death, DNA-damage, and oxidative stress using the same culture model.

Cerebellar granule neurons (CGNs) are a commonly used neuronal model, forming an abundant homogeneous population in the cerebellum. In light of their ...

In Vivo Electrophysiological Measurement of the Rat Ulnar Nerve with Axonal Excitability Testing

Electrophysiology enables the objective assessment of peripheral nerve function in vivo. Traditional nerve conduction measures such as amplitude and latency detect chronic axon loss and demyelination, respectively. Axonal excitability techniques &#34;by threshold tracking&#34; expand upon these measures by providing information regarding the activity of ion channels, pumps and exchangers that relate to acute function and may precede degenerative events. As such, the use of axonal excitability in animal models of neurological disorders may provide a useful in vivo measure to assess novel therapeutic interventions. Here we describe an experimental setup for multiple measures of motor axonal excitability techniques in the rat ulnar nerve.
The animals are anesthetized with isoflurane and carefully monitored to ensure constant and adequate depth of anesthesia. Body temperature, respiration rate, heart rate and saturation of oxygen in the blood are continuously monitored. Axonal excitability studies are performed using percutaneous stimulation of the ulnar nerve and recording from the hypothenar muscles of the forelimb paw. With correct electrode placement, a clear compound muscle action potential that increases in amplitude with increasing stimulus intensity is recorded. An automated program is then utilized to deliver a series of electrical pulses which generate 5 specific excitability measures in the following sequence: stimulus response behavior, strength duration time constant, threshold electrotonus, current-threshold relationship and the recovery cycle.
Data presented here indicate that these measures are repeatable and show similarity between left and right ulnar nerves when assessed on the same day. A limitation of these techniques in this setting is the effect of dose and time under anesthesia. Careful monitoring and recording of these variables should be undertaken for consideration at the time of analysis.

In Vivo Electrophysiological Measurement of the Rat Ulnar Nerve with Axonal Excitability Testing

Axonal excitability techniques provide a powerful tool to examine pathophysiology and biophysical changes that precede irreversible degenerative events. This manuscript demonstrates the use of these techniques on the ulnar nerve of anesthetized rats.

Electrophysiology enables the objective assessment of peripheral nerve function in vivo. Traditional nerve conduction measures such as amplitude and ...

Ablation of a Neuronal Population Using a Two-photon Laser and Its Assessment Using Calcium Imaging and Behavioral Recording in Zebrafish Larvae

To identify the role of a subpopulation of neurons in behavior, it is essential to test the consequences of blocking its activity in living animals. Laser ablation of neurons is an effective method for this purpose when neurons are selectively labeled with fluorescent probes. In the present study, protocols for laser ablating a subpopulation of neurons using a two-photon microscope and testing of its functional and behavioral consequences are described. In this study, prey capture behavior in zebrafish larvae is used as a study model. The pretecto-hypothalamic circuit is known to underlie this visually-driven prey catching behavior. Zebrafish pretectum were laser-ablated, and neuronal activity in the inferior lobe of the hypothalamus (ILH; the target of the pretectal projection) was examined. Prey capture behavior after pretectal ablation was also tested.

Here, we present a protocol to ablate a genetically labeled subpopulation of neurons by a two-photon laser from Zebrafish larvae.

To identify the role of a subpopulation of neurons in behavior, it is essential to test the consequences of blocking its activity in living animals. Laser ...

Facial Nerve Surgery in the Rat Model to Study Axonal Inhibition and Regeneration

This protocol describes consistent and reproducible methods to study axonal regeneration and inhibition in a rat facial nerve injury model. The facial nerve can be manipulated along its entire length, from its intracranial segment to its extratemporal course. There are three primary types of nerve injury used for the experimental study of regenerative properties: nerve crush, transection, and nerve gap. The range of possible interventions is vast, including surgical manipulation of the nerve, delivery of neuroactive reagents or cells, and either central or end-organ manipulations. Advantages of this model for studying nerve regeneration include simplicity, reproducibility, interspecies consistency, reliable survival rates of the rat, and an increased anatomic size relative to murine models. Its limitations involve a more limited genetic manipulation versus the mouse model and the superlative regenerative capability of the rat, such that the facial nerve scientist must carefully assess time points for recovery and whether to translate results to higher animals and human studies. The rat model for facial nerve injury allows for functional, electrophysiological, and histomorphometric parameters for the interpretation and comparison of nerve regeneration. It thereby boasts tremendous potential toward furthering the understanding and treatment of the devastating consequences of facial nerve injury in human patients.

This protocol describes a reproducible approach to facial nerve surgery in the rat model, including descriptions of various inducible patterns of injury.

This protocol describes consistent and reproducible methods to study axonal regeneration and inhibition in a rat facial nerve injury model. The facial ...

Use of In Vivo Single-fiber Recording and Intact Dorsal Root Ganglion with Attached Sciatic Nerve to Examine the Mechanism of Conduction Failure

Single-fiber recording has been a classical and effective electrophysiological technique over the last few decades because of its specific application for nerve fibers in the central and peripheral nervous systems. This method is particularly applicable to dorsal root ganglia (DRG), which are primary sensory neurons that exhibit a pseudo-unipolar structure of nervous processes. The patterns and features of the action potentials passed along axons are recordable in these neurons. The present study uses in vivo single-fiber recordings to observe the conduction failure of sciatic nerves in complete Freund&#8217;s adjuvant (CFA)-treated rats. As the underlying mechanism cannot be studied using in vivo single-fiber recordings, patch-clamp-recordings of DRG neurons are performed on preparations of intact DRG with the attached sciatic nerve. These recordings reveal a positive correlation between conduction failure and the rising slope of the after-hyperpolarization potential (AHP) of DRG neurons in CFA-treated animals. The protocol for in vivo single fiber-recordings allows the classification of nerve fibers via the measurement of conduction velocity and monitoring of abnormal conditions in nerve fibers in certain diseases. Intact DRG with attached peripheral nerve allows observation of the activity of DRG neurons in most physiological conditions. Conclusively, single-fiber recording combined with electrophysiological recording of intact DRGs is an effective method to examine the role of conduction failure during the analgesic process.

Single-fiber recording is an effective electrophysiological technique that is applicable to the central and peripheral nervous systems. Along with the preparation of intact DRG with the attached sciatic nerve, the mechanism of conduction failure is examined. Both protocols improve the understanding of the peripheral nervous system&#39;s relationship with pain.

Single-fiber recording has been a classical and effective electrophysiological technique over the last few decades because of its specific application for ...

Portable Thermographic Screening for Detection of Acute Wallenberg's Syndrome

Wallenberg&#39;s syndrome (WS) is a type of brainstem infarction. WS patients often show Horner&#39;s syndrome, dissociated sensory disturbance, truncal ataxia, and hoarseness. However, they rarely show tactile sensory disturbance and paralysis of the extremities. Additionally, acute brainstem infarction is often not apparent in magnetic resonance images. These symptomatic and imaging characteristics sometimes lead to misdiagnosis of WS as a non-stroke disease, including auditory vertigo. Although careful neurological examination is necessary to prevent misdiagnosis of WS, this type of examination may be difficult for non-neurologists to whom affected patients initially present. Lateral differences in body surface temperature (BST) constitute a recognized and widespread symptom of WS. We previously reported that most acute WS patients exhibit lateral differences in BST at multiple locations and that these lateral differences in BST could easily be detected by thermographic measurement. Here, we present the method for use of portable thermography to detect acute WS, using a simple, rapid, noninvasive, and cost-effective approach. To assess lateral differences in BST among patients with suspected WS, BST was measured as soon as possible in the examination room or in the patient&#39;s bedroom. Measurements were performed bilaterally at four locations where images could easily be acquired (face, palm of the hand, abdomen, and dorsum of the foot) using a portable thermal camera. When lateral differences in BST are observed macroscopically, especially in multiple locations on the same side, a diagnosis of WS should be suspected. Macroscopic assessment of BST laterality can be made within 2 min of the acquisition of thermographic images. This method may be useful in preventing misdiagnosis of acute WS as a non-stroke disease, especially when such patients initially present to non-neurologists.

Acute Wallenberg&#39;s syndrome can be misdiagnosed as a non-stroke disease, such as auditory vertigo. Thus, careful neurological examination, which is sometimes difficult for non-neurologists, is necessary for precise diagnosis. Here, we present a simple, rapid, noninvasive, and cost-effective method for detection of acute Wallenberg&#39;s syndrome using portable thermography.

Wallenberg&#39;s syndrome (WS) is a type of brainstem infarction. WS patients often show Horner&#39;s syndrome, dissociated sensory disturbance, truncal ...

Assessing Early Stage Open-Angle Glaucoma in Patients by Isolated-Check Visual Evoked Potential

Recently, the isolated-check visual evoked potential (icVEP) technique was designed and has been reported to detect glaucomatous damage earlier and faster. It creates low spatial frequency/high temporal frequency bright stimuli and records cortical activity initiated primarily by afferents in the magnocellular ON pathway. This pathway contains neurons with larger volumes and axonal diameters, and it is preferentially damaged in early glaucoma, which can result in visual field loss. The study presented here uses standard operative procedures (SOP) of icVEP to obtain reliable results. It can detect visual function loss using a signal-to-noise ratio (SNR) corresponding to the defects of retinal nerve fiber layer (RNFL) in early stage open-angle glaucoma (OAG). A setting of 10 Hz and condition of 15% positive-contrast (bright) are selected to differentiate OAG patients and control subjects, with each check containing eight runs. Each run persists for 2 s (for 20 total cycles). A flowchart is constructed, which consists of pupil size and intraocular pressure over a 30 min rest period before each examination. Additionally, the testing order of eyes is performed to obtain reliable electroencephalographic signals. VEPs are recorded and analyzed automatically by software, and SNRs are derived based on a multivariate statistic. An SNR of &#8804; 1 is considered abnormal. A receiver-operating-characteristic (ROC) curve is applied to analyze the accuracy of group classification. Then, the SOP is applied in a cross-sectional study, showing that icVEP can detect glaucomatous visual function abnormality in the central visual field in the form of SNR. This value also correlates with the thickness thinning of RNFL and produces high classification accuracy for early stage OAG. Thus, it serves as a useful and objective diagnostic technology for the early detection of glaucoma.

The isolated-check visual evoked potential (icVEP) method is implemented here to assess the magnocellular ON pathway that is initially damaged in glaucoma. The study shows standard operative procedures using icVEP to obtain reliable results. It is proved to serve as a useful objective diagnosing technology for the early detection of glaucoma.

Recently, the isolated-check visual evoked potential (icVEP) technique was designed and has been reported to detect glaucomatous damage earlier and ...

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

Summary

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Chapters in this video

Recording and Analysis of Circadian Rhythms in Running-wheel Activity in Rodents

An Ex Vivo Laser-induced Spinal Cord Injury Model to Assess Mechanisms of Axonal Degeneration in Real-time

External Excitation of Neurons Using Electric and Magnetic Fields in One- and Two-dimensional Cultures

Modeling Neuronal Death and Degeneration in Mouse Primary Cerebellar Granule Neurons

In Vivo Electrophysiological Measurement of the Rat Ulnar Nerve with Axonal Excitability Testing

Ablation of a Neuronal Population Using a Two-photon Laser and Its Assessment Using Calcium Imaging and Behavioral Recording in Zebrafish Larvae

Facial Nerve Surgery in the Rat Model to Study Axonal Inhibition and Regeneration

Use of In Vivo Single-fiber Recording and Intact Dorsal Root Ganglion with Attached Sciatic Nerve to Examine the Mechanism of Conduction Failure

Portable Thermographic Screening for Detection of Acute Wallenberg's Syndrome

Assessing Early Stage Open-Angle Glaucoma in Patients by Isolated-Check Visual Evoked Potential