Background
Clinical spectrum of immunoglobulin M (IgM) monoclonal gammopathy varies from IgM monoclonal gammopathy of unknown significance (IgM-MGUS) to hematological malignancies. We evaluated the clinical features, electrophysiological characteristics, and prognosis of patients with peripheral neuropathy associated with IgM monoclonal gammopathy (PN-IgM MG).
Methods
We retrospectively evaluated 25 patients with PN-IgM MG. Peripheral neuropathy was classified as axonal, demyelinating, or undetermined, based on electrophysiological studies. We classified the enrolled patients into the IgM-MGUS and malignancy groups, and compared the clinical and electrophysiological features between the groups.
Results
Fifteen patients had IgM-MGUS and 10 had hematologic malignancies (Waldenström’s macroglobulinemia: two and B-cell non-Hodgkin’s lymphoma: eight). In the electrophysiological evaluation, the nerve conduction study (NCS) criteria for demyelination were met in 86.7% of the IgM-MGUS group and 10.0% of the malignancy group. In particular, the distal latencies of the motor NCS in the IgM-MGUS group were significantly prolonged compared to those in the malignancy group (median, 9.1 ± 5.1 [IgM-MGUS], 4.2 ± 1.3 [malignancy], p = 0.003; ulnar, 5.4 ± 1.9 [IgM-MGUS], 2.9 ± 0.9 [malignancy], p = 0.001; fibular, 9.3 ± 5.1 [IgM-MGUS], 3.8 ± 0.3 [malignancy], p = 0.01; P-posterior tibial, 8.3 ± 5.4 [IgM-MGUS], 4.4 ± 1.0 [malignancy], p = 0.04). Overall treatment responses were significantly worse in the malignancy group than in the IgM-MGUS group (p = 0.004), and the modified Rankin Scale score at the last visit was higher in the malignancy group than in the IgM-MGUS group (2.0 ± 1.1 [IgM-MGUS], 4.2 ± 1.7 [malignancy], p = 0.001), although there was no significant difference at the initial assessment.
Conclusions
The risk of hematological malignancy should be carefully assessed in patients with PN-IgM MG without electrophysiological demyelination features.

Background
Pain and autonomic dysfunction are prominent symptoms in some patients with carpal tunnel syndrome (CTS). Infrared thermography (IRT) has been used to evaluate CTS by measuring the cutaneous temperature and sympathetic vasomotor function.
Methods
This study enrolled the 66 hands of 33 subjects, some of which had clinical CTS and the others were healthy. The enrolled patients completed the Boston Carpal Tunnel Questionnaire (BCTQ) and Historical-Objective scale, and underwent nerve conduction studies (NCSs) and IRT. Skin temperature was measured at the fingertips and the thenar and hypothenar regions in each hand. We analyzed (1) the correlations between self-reported severity, physician-assessed severity, and test results, and (2) the sensitivity and specificity of IRT in diagnosing CTS.
Results
No significant correlation was observed between the results of the BCTQ, NCS, and IRT. IRT had a low sensitivity and high specificity in diagnosing CTS.
Conclusions
IRT cannot replace NCS in diagnosing CTS, nor did it provide an advantage in combination with NCS. However, lower temperatures at the median nerve in some hands with moderate-to-severe CTS suggested the involvement of sympathetic nerve fiber function. Follow-up studies with a larger-scale and complementary design are required to elucidate the relationships.

Citations

• Infrared medical thermography, medical applications, and its basic principles: A review
  Ali Faisal Abdulkareem, Auns Qusai Hashim, N. Aldahan, A.J. Ramadhan
  BIO Web of Conferences.2024; 97: 00140.     CrossRef

Congenital myasthenic syndromes (CMSs) are rare genetic disorders characterized by weakness and fatigue resulting from impaired neuromuscular transmission. Genetic testing can confirm the diagnosis for some types of CMS; however, variations in genotype, clinical phenotypes, age at disease onset, and responses to treatment make diagnosis very difficult. Here we present two adult patients who had significant decremental responses in repetitive nerve stimulation testing and multi-minicore pathology, and who responded to treatment with a cholinesterase inhibitor.

Electrodiagnostic tests (EDX) is essential for the diagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP). EDX could provide information about demyelinating pathology in the peripheral nerves. According to phenotypes, CIDP could be classified several phenotypes, which has different clinical manifestations, EDX could present a different distribution pattern of demyelinating lesions. In addition, EDX could be useful markers for predicting treatment response of prognosis of CIDP.

Nerve conduction study (NCS) is an electrophysiological tool to assess the overall function of cranial and peripheral nervous system, therefore NCS has been diagnostically helpful in the identification and characterization of disorders involving nerve roots, peripheral nerves, muscle and neuromuscular junction, and are frequently accompanied by a needle Electromyography. Furthermore, NCS could provide valuable quantitative and qualitative results into neuromuscular function. Usually, motor, sensory, or mixed nerve studies can be performed with using NCS, stimulating the nerves with the recording electrodes placed over a distal muscle, a cutaneous sensory nerve, or the entire mixed nerve, respectively. And these findings of motor, sensory, and mixed nerve studies often show different and distinct patterns of specific abnormalities indicating the neuromuscular disorders. The purpose of this special article is to review the neurophysiologic usefulness of NCS, to outline the technical factors associated with the performance of NCS, and to demonstrate characteristic NCS changes in the setting of various neuromuscular conditions.

Citations

• Confirmation of epidural anesthesia with bupivakain in cats by ınfrared thermographic ımaging and SEP
  Muammer Ayberk Kara, Özlem Şengöz Şirin
  Ankara Üniversitesi Veteriner Fakültesi Dergisi.2025; 72(2): 165.     CrossRef
• The Use of Nerve Conduction Study to Evaluate the Effects of Frozen Sock Treatment on Docetaxel-Induced Peripheral Neuropathy in Breast Cancer Patients: A Prospective Clinical Trial
  Eun-Young Kim, Mi-Yeon Lee, Bum-Chun Suh
  Journal of Clinical Medicine.2025; 14(3): 864.     CrossRef
• Pmp2+ Schwann Cells Maintain the Survival of Large-Caliber Motor Axons
  Mikolaj M. Kozlowski, Amy Strickland, Ana Morales Benitez, Robert E. Schmidt, A. Joseph Bloom, Jeffrey Milbrandt, Aaron DiAntonio
  The Journal of Neuroscience.2025; 45(13): e1362242025.     CrossRef
• Volume loss during muscle reinnervation surgery is correlated with reduced CMAP amplitude but not reduced force output in a rat hindlimb model
  Alexis L. Lowe, Maria V. Rivera Santana, Taylor Bopp, Kiara N. Quinn, Johnnie Johnson, Christopher Ward, Tae Hwan Chung, Sami Tuffaha, Nitish V. Thakor
  Frontiers in Physiology.2024;[Epub]     CrossRef
• A combined functional dorsal nerve model of the foot
  Muhammad Z. Ul Haque, Peng Du, Leo K. Cheng
  Mathematical Biosciences and Engineering.2022; 19(9): 9321.     CrossRef
• Anatomical considerations for obturator nerve block with fascia iliaca compartment block
  Thomas Fichtner Bendtsen, Erik Morre Pedersen, Bernhard Moriggl, Peter Hebbard, Jason Ivanusic, Jens Børglum, Thomas Dahl Nielsen, Philip Peng
  Regional Anesthesia & Pain Medicine.2021; 46(9): 806.     CrossRef
• Peripheral Nerve Regeneration Using a Nerve Conduit with Olfactory Ensheathing Cells in a Rat Model
  Jong-Yoon Lee, Young-Ho Kim, Boo-Young Kim, Dae-Hyun Jang, Sung-Wook Choi, So-Hyun Joen, Hyungyun Kim, Sang-Uk Lee
  Tissue Engineering and Regenerative Medicine.2021; 18(3): 453.     CrossRef
• Protective Effects of Oxytocin and Progesterone on Paclitaxel-Induced Neuropathy in Rats
  Mehmet Ekici, Muharrem Balkaya1
  Neurological Sciences and Neurophysiology.2021; 38(4): 262.     CrossRef

Electrodiagnostic studies such as nerve conduction studies (NCS) and needle electromyography (EMG) provide important and complementary information for evaluating patients with suspected neuromuscular disorders. NCS and needle EMG are reasonably safe diagnostic investigations and are generally associated with only mild transient discomfort when performed by experienced physicians. However, there is the risk of complications in some patients, because NCS involve the administration of electric current and EMG involves inserting a needle percutaneously into muscle tissue. This article reviews the potential risks of NCS and needle EMG.

Citations

• Bioelectric medicine: unveiling the therapeutic potential of micro-current stimulation
  Hana Lee, Seungkwan Cho, Doyong Kim, Taehyun Lee, Han Sung Kim
  Biomedical Engineering Letters.2024; 14(3): 367.     CrossRef
• Needle electromyography does not meaningfully impact findings in MR‐neurography/−myography
  Stefan Sondermann, Tobias Boppel, Katharina Fieseler, Peter Schramm, Tobias Bäumer, Peter Trillenberg
  Muscle & Nerve.2024; 69(4): 409.     CrossRef

Background: Early detection of neuropathy may prevent further progression of this complication in the diabetic patients. The purpose of this study was to evaluate the prevalence of early neuropathic complication in patients with newly diagnosed type 1 and type 2 diabetes. Methods: Nerve conduction studies (median, ulnar, posterior tibial, peroneal, and sural nerves) were performed for 49 type 1 (27 males, mean 14.1±7.5 years) and 40 type 2 (27 males, 42.0±14.1 years) diabetic patients at onset of diabetes. Children with age at onset under 4 years and adults over 55 years were excluded to eliminate the aging effect and the influence of obstructive arteriosclerosis. Neuropathy was defined as abnormal nerve conduction findings in two or more nerves including the sural nerve. Results: Mean HbA1c level was 12.6±3.3% for type 1 and 10.5±2.9% for type 2 diabetes. The prevalence of neuropathy was 12.2% for type 1, and 35.0% for type 2 diabetes, respectively. There were significant trends in the prevalence of neuropathy with increasing age (p<0.05). The effect of the mean level of glycosylated hemoglobin on the prevalence of polyneuropathy at onset of diabetes was borderline (p=0.0532). Neither sex of the patients nor the type of diabetes affected the neurophysiologic abnormalities at the diagnosis. Conclusions: Even in a population with diabetes at the diagnosis, the prevalence of subclinical neuropathy was not low. Neuropathy has been significantly associated with increasing age indicating the possibility of longer duration of undetected diabetes among them, especially in type 2 diabetes.

Background: Meralgia paresthetica (MP) is a mononeuropathy affecting the lateral femoral cutaneous nerve. The disease is often diagnosed clinically, but electrophysiological tests play an important role. The aim of this study is to clarify clinical characteristics of MP as well as the role of sensory nerve conduction study (NCS) in the diagnosis of MP. Methods: Sixty-five consecutive patients with clinical diagnosis of MP between March 2001 and June 2012 were retrospectively reviewed at a single tertiary center. General demographics, clinical characteristics and sensory NCS findings were investigated. Measurements of sensory NCS included the baseline-to-peak amplitude, side-to-side amplitude ratio and the conduction velocity. To compare between the normal and abnormal NCS groups, independent t-tests and chisquare test were performed. Results: Sixty-five patients had male predominance (56.9%) with mean age of 48.4±13.4 years (range: 16-75). Seven patients (13.5%) had undergone operation or procedure before the symptom onset. The sensory nerve action potentials were obtainable in 52 (80%) of 65 clinically diagnosed MP patients. Sensory NCS revealed abnormalities in 38 patients (73.1%), and others (n=14, 26.9%) showed normal findings. Between the normal and abnormal NCS groups, there is no statistically significant difference on demographics or clinical features. Conclusions: We clarify the clinical features and sensory NCS findings of MP patients. Due to several limitations of sensory NCS, the diagnosis of MP could be accomplished both clinically and electrophysiologically.

Citations

• A cook with ‘burning in the thigh’ and a ‘hotspot’ in the groin!
  Wai Lun Moy
  Oxford Medical Case Reports.2021;[Epub]     CrossRef

Background
ad Aims : Nerve conduction study is invaluable in clinical neurology, especially for assessing peripheral neuropathies. Abnormal nerve conduction studies may result not only from peripheral nerve dysfunction itself, but also from other various mechanical, technical, and physiological factors such as age, sex, height and temperature. So we conducted this study to establish the our own normal values. Methods : In this study, from March. 1997 to July. 1998, 40 Korean adults among person came to Health Promotion extremity and distal segments. Physiological factors such as age, height and temperature affect the results of nerve conduction studies in multiple regression analysis. The sex difference is recognized over peroneal motor nerve. There are no sex difference in amplitude transformed into normal distribution. The significant physiological factor affecting

The measurement of nerve conduction is an expression of the pathophysiological state of the nerves and an essential tool for the study of various neuropathies. The clinical usefulness of nerve conduction studies(NCS) in the diagnosis of diffuse and focal neuropathies has been thoroughly validated. This article decribes the general guidelines for performing nerve conduction studies including H-reflex and F-wave. And the basic skills of NCS, the factors (physiological and nonphysioloigcal) affecting nerve conduction and clinical applications will be briefly discussed.

Purpose
: Carpal tunnel syndrome(CTS) is a disorder of median nerve at wrist. it is usually diagnosed through clinical manifestation and nerve conduction study(NCS). However, sometimes, NCS does not provide a reliable evidence to reach the diagnosis. Thus, authors performed this study to determine whether NCS was correlated with specific parameters measured on magnetic resonance imaging (MRI) which might become a potential complemental diagnostic tool. Methods : We performed MRI in 34 wrists of 18 patients with clinical manifestations of CTS and pathologic nerve conduction values and analyzed them at levels of the distal radioulnar joint, pisiform and hook of hamate. Results : Increase in the cross-sectional area of the median nerve a the pisiform level and flattening, increased signal intensity, and contrast enhancement of the median nerve at levels of the pisiform and hook of hamate were statistically significant, Change in cross sectional areas between the distal radioulnar joint and hamate and the signal intensities at levels of pisiform and hamate were well correlated with the median nerve conduction velocity. Conclusions : Characteristic MRI findings in CTS reported previously were well demonstrated and some of MRI parameters are well correlated with nerve conduction study. MRI, despite cost, may help in evaluating CTS.

Background
: Carpal tunnel syndrome(CTS) is the most common entrapment neuropathy that refers to a group of signs and symptoms resulting from compression of the median nerve at the wrist. The course of CTS on older patients is different from the younger patients. This difference may be the result of different underlying mechanisms. The different nerve conduction studies of CTS may signify different approaches in management. This study was done to assess the differences in nerve conduction study of CTS I younger and older patients. Methods : This study involved 224 patients who visited Gachon Medical School, Gil Medical Center and was diagnosed by nerve conduction study from October 1997 to October 1999. We compared the results of nerve conduction study to age, especially in between those under 60 years and those 60 years or over CTS patients. Nerve conduction study consists of motor studies of both median nerve(terminal latency, compound action potential) and sensory studies(nerve conduction velocity, nerve action potential). And we also evaluated the variable between younger and older patients group. Those variables include sex, symptom period, laterality, abnormal physical findings and radiculopathy. Results : We found that a significant increase of terminal latency(p<0.1), but a decrease in compound motor action potential(p<0.05) in older patient's group. There was no significant differences in sensory nerve conduction velocity and action potential between those under 60 years and those 60 years or even patients. And also there was no significant difference in sex, symptom period, laterality, abnormal physical findings, radiculopathy between older and younger patients. Conclusions: This study showed a significant increase in the terminal latency and a decrease I compound action potential in older patients. The different nerve conduction studies of CTS by age effect may need different approaches in management.

Anorexia nervosa(AN) is a disorder characterized by disturbance of body image, fear of gaining weight, severe weight loss and, in female, amenorrhea. Compared with normal persons, patients with AN have neuropathic symptoms more frequently. But electrophysiologic abnormalities have rarely been reported. We experienced a case with recurrent neuropathic symptoms after severe weight loss. Further evaluation revealed AN. Electrophysiologic study showed sensorimotor polyneuropathy and focal neuropathy with conduction block. As far as we know, this feature of neuropathy in AN has not been described. We describe unusual feature of neuropathy in our patient with literature review.

Electrodiagnostic studies can be a valuable method in the diagnosis and follow-up study of various neuromuscular diseases. They must be used as an extension of the clinical evaluation, however, and not as routine tests. After the physician decides what kinds of pathophysiology could explain the patient? signs and symptoms, he or she is then in a position to request specific electromyography (EMG) studies to shed light on diseases that could affect the anterior horn cells, nerve roots, peripheral nerve, neuromuscular junctions, or muscles. Nerve conduction studies (NCS) assess peripheral motor and sensory functions by recording the evoked response to stimulation of peripheral nerves. Motor NCS require stimulation of a peripheral nerve while recording from a muscle innervated by that nerve. Sensory NCS are performed by stimulating a mixed nerve while recording from a cutaneous nerve or by stimulating a cutaneous nerve while recording from a mixed or cutaneous nerve. Motor and sensory NCS studies have been used clinically for many years to identify the location of peripheral nerve disease in single nerves and along the length of nerves and to differentiate these disorders from diseases of muscle or the neuromuscular junction. NCS also can help to distinguish between axonal degeneration, segmental demyelination, and abnormal nerve irritability. But it is important to recognize the inherent limitations of the EMG study. First, the kinds of tests and the muscles or nerves to be tested must be determined by clinical findings. Then, the EMG findings must be interpreted in light of the clinical findings because no EMG results are pathognomonic of a specific disease entity. For these reasons, it is essential that the clinical problem be assessed throughly and that a careful neurological examination be performed before the electrophysiologic study.

Background
and Objectives: A nerve conduction study (NCS) has been known as a useful method to evaluate thetherapeutic effect of operation in carpal tunnel syndrome (CTS). To evaluate the temporal relationship between symptomaticand electrophysiological improvement, we compared the preoperative symptoms and electrophysiological resultswith postoperative those.Methods: We analyzed the NCS changes before and after minimal release of carpal tunnel in 26 patients (34 hands)with CTS. The time of postoperative symptomatic changes, postoperative electrophysiological changes and temporalrelationship between symptomatic and electrophysiological changes were evaluated.Results: The mean age was 49

The Lateral dorsal cutaneous branch of sural nerve (LDCB) is a terminal sensory branch of lower extremities. It canbe injured frequently in peripheral nerves. However, the normal data of each component of nerve conduction study(NCS) of were not studied at this time. The Nerve Conduction Study of LDCB adults were assessed for amplitude, area,duration and nerve conduction velocity (NCV) in normal fifty. We also evaluated how age, sex and dexterity affect thevarious components of NCS. The Mean amplitude of LDCB was 9.45

B a c k g r o u n d s: The pathway of the sural nerve (SN) is variable, but usually divided into medial and lateral suralbranches joining the posterior tibial nerve (PTN) and the peroneal nerve (PN). The sural nerve may be affected by PNpalsy. The frequency or the severity of SN involvement in peroneal palsy is not known. The purpose of the study is toinvestigate the frequency and the severity of the SN involvement by the peroneal nerve palsy.Methods: Total 85 patients were included with peroneal palsy. Amplitudes of distal peroneal, sural, and superficialperoneal nerves (SPN) were compared between normal and paralyzed sides. The frequency and severity of SN involvementby peroneal palsy were investigated.Results: Mean age was 48.4

Background
Carpal tunnel syndrome (CTS) is a common condition characterized by entrapment neuropathy of themedian nerves. Clinical manifestations are the most important findings for diagnosis and assessment of therapeuticeffects. But, objective indicators, such as electrophysiological findings, are also valuable supplementary tools. Thisstudy investigated the relationship between clinical grading and sensory nerve conduction velocity (SNCV) of medianproper palmar digital nerve (MPPDN) in CTS patients.Method: This study was done on 90 upper limbs of 53 patients with CTS (men: 6, women: 47, age: 26~69 years,mean age; 52 years). Each SNCV of MPPDN was recorded with bar electrode using antidromic method. Each SNCVwas compared with clinical grading of CTS. The clinical grades of CTS were designated as follows; group 1 is mildsymptoms, 2 is moderate symptoms, and 3 is severe and longstanding symptoms.Result: In thumb, the SNCV of MPPDN was not different significantly between 3 groups (p=0.817). In the index finger,the SNCV was the fastest in the group 1, but faster in group 3 than in group 2 (p=0.001). In the middle and ring fingers,SNCV was decreased in higher clinical grading groups (middle finger: p=0.015, ring finger: p=0.044).Conclusion: SNCV of MPPDN of middle and ring finger correlated with the clinical grading of CTS. SNCV of indexfinger was the fastest in group 1. But SNCV of thumb did not correlate with the clinical grading of CTS.

B a c k g r o u n d: The study of the medial antebrachial cutaneous nerve (MABCN) is an underused electrodiagnostic tool. But its use is often crucial for assessing mild lower brachial plexus or MABCN lesions, and sometimes for differentiating an ulnar mononeuropathy from a lower brachial plexopathy. This study was designed to know the difference of amplitude and velocity in a stimulation method (orthodromic vs antidromic), side of an arm and sex according by age.Method: MABCN conduction studies were performed orthodromically and antidromically in 90 subjects (42 women and 48 men, ranging from 22 to 79 years of age). We divided subjects into three groups by age (group 1: 20-39 years, group 2: 40-59 years, group 3: 60-79 years). The mean sensory nerve action potential amplitudes and sensory nerve conduction velocities in each group was compared by stimulation method, side of an arm and sex.Result: The amplitudes and velocities made a significant difference between orthodromic and antidromic method in all age groups. At comparison in amplitude and velocity by side of an arm, only amplitude was significantly higher in right arm than left by any stimulation method. The amplitudes and velocities were of no statistically differences in sexexcept amplitude checked orthodromically in right arm.Conclusion: This study suggests that there is the differences in conduction study of MABCN by stimulation method and side of an arm.

Background
The most distal sensory fibers of the feet are often affected first in polyneuropathy. However, they are not evaluated in routine nerve conduction studies. Thus we evaluated the dorsal sural sensory nerve in patients with sensorimotor polyneuropathy with normal sural response, in order to assess the usefulness in electrodiagnostic practice.Methods: In this study, 53 healthy subjects and 27 patients with clinical evidence of sensorimotor polyneuropathy were included. In all subjects, peripheral motor and sensory nerve studies were performed on the upper and lower limbs including dorsal sural nerve conduction studies. On electrodiagnostic testing, all patients had normal sural responses.Results: The dorsal sural sensory nerve action potentials (SNAPs) mean amplitude was 13.12

Among the various physiological factors that affect nerve conduction velocity (NCV), temperature is the most important. Because the influence of temperature is the most important source of error. It is known from animal experiments that conduction is eventually completely blocked at low temperatures, the myelinated A fibers being the first affected and the thin fibers of group C the last. Many studies showed that the NCV decreases linearly with lowering temperature within the physiological range. The distal motor latency increased by 0.2 msec/

Background
Meralgia paresthesia (MP) is characterized by sensory impairment in the anterolateral aspect of the thigh and usually caused by a lateral femoral cutaneous nerve (LFCN) lesion. It is well known that several physiologic factors including age, obesity, and sex can affect nerve conduction. This study aimed to determine whether body mass index (BMI) and age can influence on the conduction velocity and action potential amplitude of the LFCN.
Methods: Fifty six individuals without any previous neuromuscular disease participated in this study. LFCN was studied orthodromically,distally from the anterior superior iliac spine. The values, such as sensory nerve action potential (SNAP) amplitude and sensory nerve conduction velocity (NCV) were obtained. SNAP of the LFCN were formed on both sides in forty three individuals.
Results: No difference of demographic factors was observed between two groups divided according to the presence of SNAP formation. BMI had a significant relationship with SNAP amplitude and NCV of the LFCN. Moreover, Multiple regression analyses of nerve conduction values showed the significant correlation of body mass index and age with nerve conduction velocity.
Conclusions: We may suggest that nerve conduction of the LFCN can be affected by age and BMI. Further study to obtain normal nerve conduction data and compare these data with those of meralgia paresthetica patients should be continued.

Intraoperative neuromonitoring (INM) is well known to be useful method to reduce intraoperative complications during the surgery of nervous system lesions. Evoked potentials are most commonly used among the electrophysiological tests. Brainstem auditory evoked potentials are for detecting the problems along the auditory pathways including the eighth cranial nerve and brainstem. Somatosensory evoked potentials are applied for preventing the spinal cord lesions. The INM is affected by many factors. In order to perform an optimal INM, the confounding factors including technical, anesthetical, and individual factors should be kept well under control. INM has frequent electrophysiologic changes during the surgery and it might be helpful to keep one

Diabetic polyneuropathy (DPN) is the most frequently encountered form of neuropathy in diabetic patients, and it either relentlessly progresses or remains relatively stable for many years, not showing any trend towards improvement. From this point of view, early detection of DPN is very important to prevent the irreversible change of the peripheral nerve from diabetic insults. Although a number of clinical symptoms and/or deficit scales have been developed for clinical or research purposes, nerve conduction study (NCS) has been known one of the most objective and sensitive tools to detect peripheral nerve dysfunctions in diabetic patients. NCS, however, also have several shortcomings. The next two consecutive articles will focus on debates about diagnostic usefulness of NCS and on recent updates of other diagnostic tests including quantitative sensory testings and skin biopsy in the field of diabetic polyneuropathy.

Diabetic polyneuropathy (DPN) is the most common form of diabetic neuropathy, and causes a significant morbidity with an impact on the quality of life in the patients with diabetes. Since DPN frequently induces foot deformity and ulceration, which finally leads to foot amputation, the early detection and treatment is very important for the prevention of a permanent structural change. In the early stage of DPN, the diagnostic methods which can evaluate the function or structure of small nerve fibers should be employed because small nerve fibers are first involved in the course of DPN. However, the nerve conduction study cannot reflect the function of the small nerve fibers, and thus, has a definite limitation in the early diagnosis of DPN. For the early detection of DPN, electrodiagnostic data should be interpreted on a clinical context, along with the careful evaluation of the small nerve fiber functions using the tests such as the analysis of intraepidermal nerve fiber density.

Although various criteria on the diagnosis of diabetic neuropathy are applied from trial to trial, being tailored in concert with its purpose, the utmost evidences of the diagnosis are subjective symptoms and objective signs of neurologic deficit. The application and interpretation of auxiliary electrophysiological test including nerve conduction study (NCS) should be made on the context of clinical pictures. The evaluation of the functions of small, thinly myelinated or unmyelinated nerve fibers has been increasingly stressed recently with the advent of newer techniques, e.g., measurement of intraepidermal fiber density, quantitative sensory testing, and autonomic function test. And the studies with those techniques have shed light to the nature of the evolution of diabetic neuropathy. The practical application of these techniques to the diagnosis of diabetic neuropathy in the individual patients, however, should be made cautiously due to several shortcomings: limited accessibility, wide overlapping zone between norm and abnormality with resultant unsatisfactory sensitivity and specificity, difficulty in performing subsequent tests, unproven quantitative correlation with clinical deficit, and invasiveness of some technique. NCS, as an extension of clinical examination, is still the most reliable electrophysiological test in evaluating neuropathy and gives the invaluable information about the nature of neuropathy, whereas the newer techniques need more refinement of the procedure and interpretation, and the accumulation of large scaled data of application to be considered as established diagnostic tools of peripheral neuropathy.

Background
: The term

Background
The medial plantar nerve (MPN) is a distal branch of the posterior tibial nerve, and various methods of nerveconduction study for MPN have been introduced so far. Hemmi et al described a new method (Hemmi's method) forrecording medial plantar sensory nerve action potentials (SNAPs), which is considered as a simple and reliable method formeasuring medial plantar SNAPs. This study was aimed to establish the normal values for the MPN conduction study amongKoreans and to compare the sensitivities of three different methods for MPN conduction study (Hemmi, Oh, and Saeed'smethod) in detecting evidence of peripheral neuropathy among diabetic patients. Methods: In 27 healthy subjects, MPN conductionstudy using Hemmi