Amplitude of sensory nerve action potential in early stage diabetic peripheral neuropathy： an analysis of 500 cases

Early diagnosis of diabetic peripheral neuropathy is important for the successful treatment of diabetes mellitus. In the present study, we recruited 500 diabetic patients from the Fourth Affiliated Hospital of Kunming Medical University in China from June 2008 to September 2013：221 cases showed symptoms of peripheral neuropathy （symptomatic group） and 279 cases had no symptoms of peripheral impairment （asymptomatic group）. One hundred healthy control subjects were also recruited. Nerve conduction studies revealed that distal motor latency was longer, sensory nerve conduction velocity was slower, and sensory nerve action potential and amplitude of compound muscle action potential were significantly lower in the median, ulnar, posterior tibial and common peroneal nerve in the diabetic groups compared with control subjects. Moreover, the alterations were more obvious in patients with symptoms of peripheral neuropathy. Of the 500 diabetic patients, neural conduction abnormalities were detected in 358 cases （71.6%）, among which impairment of the common peroneal nerve was most prominent. Sensory nerve abnormality was more obvious than motor nerve abnormality in the diabetic groups. The amplitude of sensory nerve action potential was the most sensitive measure of peripheral neuropathy. Our results reveal that varying degrees of nerve conduction changes are present in the early, asymptomatic stage of diabetic peripheral neuropathy.     

糖尿病周围神经病电生理特点及与血糖水平的关系

目的研究糖尿病周围神经病的神经电生理特点以及与血糖水平的关系。方法分析2013年3月~2014年3月于本院神经内科住院的108例糖尿病周围神经病患者,测定其正中、尺、胫、腓总神经的运动传导速度(MCV)和复合肌肉动作电位波幅(CMAP),以及正中、尺、腓肠神经、腓浅神经的感觉传导速度(SCV)和感觉神经动作电位波幅(SNAP),比较上、下肢和运动、感觉神经异常情况,分析糖化血红蛋白(HbA1C)、餐后2 h血糖对神经传导速度(NCV)的影响。结果糖尿病患者下肢运动神经病变重于上肢,且差异明显(P<0.05)。感觉神经损害重于运动神经,且差异明显(P     

糖尿病周围神经病病情分级与电生理的相关性

目的探讨糖尿病周围神经病病情分级与电生理的相关性。方法依据糖尿病性周围神经病的诊断标准确定入选对象;依据糖尿病周围神经病病情分级对入选对象进行临床分级;应用丹麦产DANTEC CANTATA型肌电图仪,进行运动神经和感觉神经传导功能检查。结果腓肠神经、正中神经诱发感觉动作电位波幅(SNAP)和腓总神经复合肌肉动作电位波幅(CMAP)随病情分级的升高而明显减低(P<0.05);腓肠神经、正中神经感觉传导速度(SCV)和腓总神经、正中神经运动传导速度(MCV)3级与1、2两级比较显著减慢(P<0.05)。结论神经电生理改变,尤其感觉神经电生理改变,易此作为糖尿病周围神经病情程度评定的指标。     

Determination of nerve conduction abnormalities in patients with impaired glucose tolerance

Recent studies have shown that impaired glucose tolerance (IGT) is associated with dysfunction in the peripheral and autonomic nerves. The aim of this study was to determine the electrophysiological abnormalities of IGT. To determine electrophysiological abnormality in the large sensorimotor and sudomotor autonomic nerves with IGT patients, 43 patients and 34 healthy subjects have been studied. Subjective neuropathy symptoms, neurological examination and the electrophysiological findings were evaluated. When conduction of large somatic fibers only was evaluated, the ratio of electrophysiological abnormality was found to be 21%. In addition, where sympathetic skin response was evaluated the sudomotor autonomic abnormality ratio was 28% in upper extremities, 53% in lower extremities, and 16% in upper and lower extremities together. The percentages of abnormal electrophysiological parameters in different motor and sensory nerves were 39.5% in the peroneal motor nerve, 20.9% in the median motor and sural sensory nerves, 18.6% in the median sensory nerve, 16.3% in the tibial motor nerve, 14% in the ulnar sensory nerve, and 2.3% in the ulnar motor nerve. While distal motor latency was the most frequent abnormal parameter in the median and tibial motor nerves, the amplitude changes in the peroneal and ulnar motor nerves were also prominent. In sensory evaluation, the onset latency in the median-ulnar sensory nerves and the amplitude in the sural sensory nerve were found to be evident abnormalities.     

Peripheral neuropathy in children on long-term phenytoin therapy

Nerve conduction studies of the ulnar, median, posterior tibial, peroneal and sural nerves were performed in 21 epileptic children aged 6 to 17 years on long-term phenytoin therapy. Auditory brain stem evoked responses were obtained in 16 patients to evaluate the effect of phenytoin on central nervous system synapses. Of the 21 patients examined, 15 (71.4%) showed abnormal findings. The most frequent abnormality was slowed motor conduction velocity of the ulnar nerve (33.3%) and posterior tibial nerve (23.8%), followed by slowed sensory conduction velocity of the sural nerve (20%), lowered H/M ratio (14.3%), slowed motor conduction velocity of the peroneal nerve (14.3%) and of the median nerve (14.2%). A significant correlation was noted between the total dosage and duration of therapy with PHT and the reduction of motor conduction velocity in the posterior tibial nerve. Auditory brain stem evoked responses showed no significant differences in each peak latency between the patients and the normal control group. The study indicates that long-term phenytoin therapy can cause latent impairment of peripheral nerve function in children with no clinical evidence of peripheral neuropathy.     

Peripheral neuropathy in genetic mitochondrial diseases

Peripheral neuropathy is an underrecognized but common occurrence in genetic mitochondrial disorders. To gain insight into the frequency and clinical presentation of this complication, nerve conduction studies were performed on 43 subjects with congenital lactic acidosis enrolled in a controlled clinical trial of oral dichloroacetate. Median and peroneal motor conduction studies and median and sural sensory conduction studies were performed on each patient. The mean amplitude of the peroneal motor nerve (P < 0.001) and the conduction velocities of the median (P < 0.001) and peroneal (P < 0.001) motor nerves were uniformly lower in our subjects than in healthy literature control subjects. There were no significant differences in sensory nerve conduction studies. A generalized reduction in motor nerve conduction velocity was the dominant electrophysiological abnormality in the patients in this study and was independent of age, sex, or congenital mitochondrial disorder. We postulate that cellular energy failure is the most likely common cause of peripheral neuropathy in patients with genetic mitochondrial diseases, owing to the high demand for adenosine triphosphate via aerobic carbohydrate metabolism by nerve tissue.     

Interrelationship among nerve conduction velocity, amplitudes of compound muscle and compound nerve action potentials in diabetic neuropathy]

In order to clarify the relationship among amplitudes of compound nerve action potential (CNAP), compound muscle action potential (CMAP) and nerve conduction velocity parameters, data of nerve conduction studies were analyzed in 102 patients with diabetes mellitus. In motor conduction studies CMAP amplitudes after stimulations at the distal nerve trunk, and the polyneuropathy index (PNI), a mean percentage of normal for 12 indices from 4 nerves concerning to the velocity or long distance latency, were evaluated. CNAP was recorded in the median and ulnar nerves from an intrafascicularly inserted microelectrode at the elbow after wrist stimulation. CMAP amplitudes were high in the median and ulnar nerves, and were reduced in the tibial and peroneal nerves. A close relationship was found between PNI and CNAP amplitudes. Among CMAP amplitude parameters tibial nerve, not median or ulnar nerves, had a good correlation with PNI and CNAP amplitude. Along with the progression of diabetic neuropathy, neuropathic signs or symptoms become conspicuous, and nerve conduction velocity drops as is expressed by the PNI level, which reflects the change in nerve conduction velocity in the upper and lower limbs. At the same time CNAP amplitude or CMAP amplitude in the tibial nerve decreases, but in nerves of the upper limb CMAP amplitude doesn't always decrease. So, tibial nerve is best among CMAP amplitude parameters in evaluating the degree of diabetic neuropathy. It is necessary to judge the degree of diabetic neuropathy after due consideration of these facts.     

Peripheral neuropathy response to erythropoietin in type 2 diabetic patients with mild to moderate renal failure

This study assessed the added effect of 6 months of erythropoietin (EPO) administration in patients suffering from diabetic neuropathy with mild to moderate chronic kidney disease (CKD) managed with gabapentin. Twenty diabetic patients with mild to moderate CKD were included; 12 in gabapentin and 8 in EPO+gabapentin group. The subjects underwent nerve conduction studies (NCS) at the initiation of the investigation and after 6-month treatment. NCS were made in deep and superficial peroneal, tibial, and sural nerves. After 6 months, in both the groups, proximal motor latency (PML) nonsignificantly improved in deep peroneal and tibial nerves; conversely, dorsal motor latency (DML) got slightly impaired in these two nerves. A nonsignificant disruption and improvement was observed in deep peroneal and tibial motor nerve conduction velocity (MNCV), respectively, in gabapentin group. Although the F-wave of tibial and deep peroneal nerves remained stable in gabapentin group, a nonsignificant improvement was observed in EPO+gabapentin group. H-reflex of tibial nerve and all the evaluated parameters of sural and superficial peroneal nerves remained constant in all patients. Thus, it can be concluded that 6-month administration of EPO+gabapentin, or gabapentin alone in mild to moderate CKD patients with diabetic neuropathy could not improve nerve performance.     

Conduction velocity study in type 1 diabetic patients

The role of metabolic abnormalities in the development of diabetic neuropathy is controversial. To investigate the peripheral nerve function and the influence of hyperglycemia on nerve conduction in insulin-dependent diabetes, a one-year neurophysiological study was carried out in 30 type 1 diabetic patients ranging in age from 2-16 years. During the 12-month follow-up period the glycosylated hemoglobin determination, motor conduction velocity of the peroneal nerve and the motor and sensory conduction of the tibial nerve were assessed 3 times, at the beginning of the study and every 6 months thereafter. The sensory latency was found significantly delayed in these patients as compared with the controls. The degree of sensory conduction slowing correlated well with the glycosylated hemoglobin concentrations and improved with the reduction in hyperglycemia.     

The importance of studying sural nerve conduction and late responses in the evaluation of alcoholic subjects

Motor conduction velocities of median, ulnar, peroneal, and tibial nerves and sensory conduction velocities of median and ulnar nerves were studied in 30 alcoholic subjects and a similar group of control subjects. The results were compared to sural nerve conduction velocities and late response latencies (H reflex, F response). The latter two techniques improved the diagnostic yield by 20%: Whereas 73% of our patients showed an abnormality of conduction with conventional techniques, 93% had an abnormality of sural nerve conduction, late response latencies, or both. Abnormalities of motor and sensory conduction, which were more prominent in the lower limbs than the arms, could be documented in patients who did not have any clinical evidence of peripheral neuropathy. The electrophysiologic studies performed in the present study suggest that "axonal degeneration" is the underlying pathologic process in alcoholic peripheral nerve disease.     

The medial plantar and medial peroneal cutaneous nerve conduction studies for diabetic polyneuropathy

Objective of this study was to determine which nerve conduction is more sensitive electrophysiologically in the diagnosis of polyneuropathy in diabetics by evaluating the sensory conduction in medial plantar nerve and medial peroneal (dorsal) cutaneous nerves. Additionally to investigate the relation between Neuropathy Symptom Score (NSS) and Neuropathy Disability Score (NDS) values used in the diagnosis of these conduction studies. Forty patients with diagnosis diabetic neuropathy were included into this study. In diabetic polyneuropathic patient group, both medial plantar and medial dorsal cutaneous nerve sensory action potential were not bilaterally obtained in 19 patients (47.5%). Sensitivity and specificity of medial dorsal cutaneous nerve and medial plantar nerve sensory conduction abnormalities in diagnosis of diabetic polyneuropathy were higher compared to sural nerve conduction abnormalities. This study showed that both medial plantar and medial dorsal cutaneous nerve conduction study performed bilaterally was a highly sensitive and specific method in diagnosis of diabetic neuropathy.     

F-wave latency,the most sensitive nerve conduction parameter in patients with diabetes mellitus

In this study we examined the diagnostic sensitivity of minimal F-wave latency, F-wave persistence, motor nerve conduction velocity (MCV), and amplitude of the compound motor action potential (CMAP) of the median, ulnar, tibial, and peroneal nerves, and of sensory conduction velocity (SCV) and sensory nerve action potential (SNAP) amplitude of the sural nerve in 82 diabetic patients. For the median, ulnar, and tibial nerves the Z scores of the minimal F-wave latency were significantly larger than those of the MCV, and for all four motor nerves the Z scores of the minimal F-wave latency were significantly larger than those of the amplitude of the CMAP. The Z scores of the peroneal minimal F-wave latency exceeded those of peroneal MCV, sural SCV, and sural SNAP. F-wave persistence did not differ significantly from the reference values. In conclusion, minimal F-wave latency is the most sensitive measure for detection of nerve pathology and should be considered in electrophysiological studies of diabetic patients. © 1997 John Wiley & Sons, Inc. Muscle Nerve 20: 1296–1302, 1997     

Symmetry and temporal variability of neurography]

The aims of the present study are to document side-to-side differences and temporal variability, between two trials (T1 and T2 at a time interval of 3 months) of nerve conduction measurements collected from 30 healthy subjects (mean age 22 +/- 2 years). METHODS: The protocol at T1 consisted of motor nerve conduction studies of median, ulnar, peroneal and tibial nerves bilaterally, with measurement of (a) motor response size (amplitude and area); (b) terminal latency; (c) minimal, mean and maximal F-wave latency; (d) motor conduction velocity; and (e) F-wave occurrence. T1 also involved sensory nerve conduction studies of median, ulnar, radial, lateral and medial cutaneous, sural and superficial peroneal nerves bilaterally, with measurement of sensory potential size (amplitude and area) and computation of sensory conduction velocity. The protocol at T2 consisted of identical measurements from the dominant side. RESULTS AND CONCLUSION: There was a negative relationship between the variability of parameters evaluating nervous conduction and the length of the nerve segment under study. Thus, the smallest side-to-side and temporal variabilities are measured for minimal F-wave latencies (on average 2-3%). The limits of symmetry and temporal variability are particularly useful for diagnosis of unilateral peripheral neuropathy or neurophysiological follow-up of patients with neuropathy, when the variability of the parameter under study is weak and when there is a high correlation between values recorded on the left and on the right or at T1 and T2. This was the case for motor response size of tibial and ulnar nerves, sensory potential size of radial nerve and minimal F-wave latencies from each studied motor nerve.     

Evaluation of atrophy of foot muscles in diabetic neuropathy -- a comparative study of nerve conduction studies and ultrasonography.

OBJECTIVE: To evaluate the relation between the findings at nerve conduction studies and the size of small foot muscles determined by ultrasonography. METHODS: In 26 diabetic patients the size of the extensor digitorum brevis muscle (EDB) and of the muscles between the first and second metatarsal bone (MIL) was determined. Motor nerve conduction studies of the peroneal and tibial nerves were performed with determination of the amplitudes of the CMAPs and of the nerve conduction velocities (NCV). Further, a standardised clinical examination was performed providing a neurological impairment score. RESULTS: Seventeen patients fulfilled the criteria for diabetic neuropathy. The cross-sectional area of the EDB muscle and the thickness of the MIL muscle were 116 +/- 65 mm2 and 29.6 +/- 8.2 mm, respectively. Close relations were established between muscle size and the amplitude of the CMAP of the peroneal (r=0.77, p<0.001) and of the tibial nerve (r=0.70, p<0.01). Further there were close relations between the muscle size and the NCV of the peroneal (r=0.62, p<0.01) and of the tibial nerve (r=0.71, p<0.001). CONCLUSIONS: The amplitude of the CMAP of the peroneal and of the tibial nerves is closely related to the size of the small foot muscles as determined by ultrasonography. SIGNIFICANCE: In diabetic patients motor nerve conduction studies can reliably determine the size of small foot muscles.     

Medial dorsal superficial peroneal nerve studies in patients with polyneuropathy and normal sural responses

We studied medial dorsal superficial peroneal (MDSP) nerves in 52 patients with clinical evidence of mild chronic sensorimotor polyneuropathy and normal sural nerve responses, in order to assess the diagnostic sensitivity and usefulness of MDSP nerve testing in electrodiagnostic practice. To determine the effect of age on MDSP nerve parameters, 98 normal subjects were also examined. Electrodiagnostic evaluation involved studies of motor nerve conduction in tibial, peroneal, and median nerves; sensory nerve conduction in sural, MDSP, median, and radial nerves; tibial and peroneal nerve F waves; H reflexes from the soleus muscles; and needle electromyography of gastrocnemius and abductor hallucis muscles. Among the patients, 49% had low-amplitude sensory responses in MDSP nerves and 57% had either slowing of sensory conduction velocity or no sensory responses on proximal stimulation. MDSP nerve amplitude, tibial nerve motor velocity, and H reflexes were the most sensitive for detection of mild chronic symmetrical axonal sensorimotor polyneuropathy. MDSP nerve testing should be included in the routine electrodiagnostic evaluation of patients with suspected polyneuropathy and normal sural nerve responses.     

Peripheral neuropathy in multiple sclerosis: a clinical and electrophysiologic study

Peripheral nerve abnormalities are uncommon in multiple sclerosis (MS). When present, they are usually attributed to factors associated with advanced disease, such as malnutrition or cytotoxic drugs. We prospectively evaluated 22 mildly disabled MS patients with sensory complaints for evidence of neuropathy using the Neuropathy Symptom Score (NSS), clinical examination, and electrophysiologic studies of peripheral nerves. Distal latency, F-wave response, and nerve conduction velocity (NCV) and amplitude in the ulnar, median, tibial, peroneal and sural nerves were examined. Neuropathy was recorded if electrophysiologic abnormalities were detected in at least two peripheral nerves in the same patient. The most frequent electrophysiologic abnormalities noted were prolonged F-wave response and low motor amplitude in the peroneal nerve, slow sensory conduction velocities of the ulnar and sural nerves, and prolonged distal latencies in the sensory ulnar and sural nerves. Electrophysiologic abnormalities were found in 33 of 244 nerves examined (14.7%) and occurred in 10 patients (45.5%). Neuropathic symptoms were mild and did not correlate with electrophysiologic abnormalities. Age, disease duration, disease course and neurologic disability as evaluated by the Kurtzke Expanded Disability Status Scale, were not associated with the presence of neuropathy. Our findings indicate a high frequency of sensory-motor neuropathy in a selected group of MS patients.     

Autonomic and electrophysiological studies in patients with signs or symptoms of diabetic neuropathy

Thirty-five patients with symptoms or signs of diabetic neuropathy were tested for autonomic neuropathy by measuring heart rate and blood pressure changes during an orthostatic tilt test, a single deep breath and the Valsalva manoeuvre and these results were related to electrophysiological measurements made on the common peroneal and sural nerves. The sural sensory action potential (SAP) was more strongly correlated with these tests of autonomic function (particularly with the brake index of the orthostatic tilt test (P less than 0.001) and the fall in systolic blood pressure 1 min after tilt (P less than 0.001], than the common peroneal nerve compound motor action potential, its minimum F wave latency or nerve conduction velocities. Patients with a detectable sural SAP had significantly higher brake indices than those with absent sural SAPs. Significant correlations were also obtained with the common peroneal motor nerve conduction velocity (MNCV) and autonomic tests and patients with MNCV less than and greater than 38 m/sec showed significant differences in many autonomic tests. The sural SAP amplitude, being less susceptible to factors that influence nerve conduction velocity, may be useful in identifying patients with an autonomic neuropathy.     

Increased nerve conduction in diabetics after a year of improved glucoregulation

We studied median, ulnar and peroneal motor nerve conduction velocity (NCV) and median sensory action potential (SAP) latency and amplitude in 18 insulin-dependent diabetic patients who were begun on a continuous subcutaneous insulin infusion (CSII) program. With institution of this therapy, significant decreases in mean blood glucose and glycosylated hemoglobin occurred. After 12 months of CSII treatment, median, peroneal, and ulnar motor NCVs all increased significantly. The average NCV increase was 2.5 m/s. Median SAP amplitude and latency did not significantly change. In a second group of 12 diabetic patients with the same mean age and comparable initial NCV and SAP measures, no significant changes in motor NCVs or SAPs occurred after 12 months of conventional insulin treatment. These results indicated the need for further long-term studies of the role of strict glucose control in the prevention of diabetic neuropathy.     

Guillain-Barré syndrome. A clinical electrophysiological and biochemical study

Fifty-six consecutive patients with Guillain-Barré syndrome representing 49% of all cases of peripheral neuropathy (except those due to diabetes mellitus and leprosy) admitted to the Postgraduate Institute of Medical Education and Research, Chandigarh over a period of three years were studied. All patients developed weakness of limbs within one day to three weeks. Attenuation of deep tendon jerks (98%) paresthesia (66%), cranial nerve involvement (41%) and antecedent infection (32%) were the common clinical features. The common patterns of motor weakness were predominantly proximal in all the four limbs (45%) or predominantly proximal in lower limbs along with distal muscles in upper limbs (29%). Electrodiagnostic studies revealed prolonged distal (motor) latency (82%), reduced motor nerve conduction velocity (74%), sensory nerve conduction abnormality (85%) and evidence of denervation (41%). Evoked motor response of median, ulnar, common peroneal and tibial nerves exhibited significant increase in duration and reduction in amplitude. The maximum incidence of electrophysiological abnormality occurred between four to 12 weeks after the onset of neurological symptoms. Four patients died and 11 showed poor recovery. Long intervals (greater than 3 weeks) between peak deficit and onset of recovery and coexistence of reduced motor nerve conduction velocity with evidence of denervation on EMG were found to be associated with poor recovery.     

Prostaglandin E1 in conjunction with high doses of vitamin B12 improves nerve conduction velocity of patients with diabetic peripheral neuropathy

BACKGROUND： Prostaglandin El improves diabetic peripheral neuropathy in symptoms and sensory threshold. Vitamin Bi and methyl-vitamin BI2 improve microcirculation to peripheral nerve tissue and promote neurotrophy. OBJECTIVE： To observe motor nerve and sensory nerve conduction velocity in patients with diabetic peripheral neuropathy, prior to and after treatment with prostaglandin El, vitamin B I and different doses of vitamin B 12. DESIGN, TIME AND SETTING： Randomized, controlled experiment, performed at the Department of Neurology, Beijing Hantian Central Hospital, between February 2002 and September 2007. PARTICIPANTS： A total of 122 patients with type 2 diabetic peripheral neuropathy; 73 males and 49 females were included. All patients met the diagnostic criteria of diabetes mellitus, as determined by the World Health Organization in 1999 and 2006, and also the diagnostic criteria of diabetic peripheral neuropathy. For each subject, conduction disorders in the median nerve and in the common peroneal nerve were observed using electromyogram. Also, after diet and drug treatment, the blood glucose level of subjects was observed to be at a satisfactory level for more than two weeks, and the symptoms of diabetic peripheral neuropathy were not alleviated. METHODS： All patients were randomly divided into the following three groups. A control group （n = 40）, in which, 100 mg vitamin B1 and 500 μg vitamin BI2 were intramuscularly injected. A vitamin B12 low-dose treated group （ n = 42）, in which 10 μ g prostaglandin E1 in 250 mL physiological saline was intravenously injected once a day and 100 mg vitamin BI and 500 11 g vitamin BI2 was intramuscularly injected once a day. Lastly, a vitamin B12 high-dose treated group （n = 40）, in which administration was the same as in the vitamin B12 low-dose treated group, except that 500 11 g vitamin BI2 was replaced by 1mg vitamin B12. Administration was performed for four weeks for each group. MAIN OUTCOME MEASURES： The motor nerve and sensory nerve con