Sensory Nerve Action Potentials Research Articles

High serum levels of CCL11/Eotaxin-1 are associated with diabetic sensorimotor polyneuropathy and peripheral nerve function but not with cardiac autonomic neuropathy in people with type 2 diabetes

ABSTRACT Aims To investigate whether higher serum CCL11/Eotaxin-1, a biomarker for aging and neurodegenerative and neuroinflammatory disorders, is associated with diabetic sensorimotor polyneuropathy (DSPN), peripheral nerve dysfunction, and cardiac autonomic neuropathy in people with type 2 diabetes. Methods This cross-sectional study included 106 patients with type 2 diabetes and 40 healthy controls, matched for the age and sex distribution of the diabetes group as a whole. The CC chemokines CCL11/Eotaxin-1 and CCL22/MDC were measured in fasting serum samples. DSPN and peripheral nerve function were assessed by neurological examination and nerve conduction studies, and cardiac autonomic function, by heart rate variability (HRV) and corrected QT (QTc) time. The cardio-ankle vascular index (CAVI) was measured as a marker for arterial stiffness. Results Serum CCL11/Eotaxin-1 levels were significantly higher in diabetic patients than in healthy controls (183 ± 63.5 vs. 113.1 ± 38.5 pg/ml, p < 0.001), but serum CCL22/MDC levels were not significantly different between the two groups. In the diabetes group, the serum CCL11/Eotaxin-1 level was positively correlated with ulnar and sural nerve conduction velocities (p = 0.0009, p = 0.0208, respectively) and sensory nerve action potential (p = 0.0083), and CAVI (p = 0.0005), but not with HRV indices or QTc time, and serum CCL22/MDC was not significantly correlated with any indices of nerve conduction. In a model adjusted for age and duration of diabetes, serum CCL11/Eotaxin-1 was still associated with ulnar nerve conduction velocity (p = 0.02124). Serum CCL11/Eotaxin-1, but not CCL22/MDC, was significantly higher in patients with than in those without DSPN (208.2 ± 71.6 vs. 159.1 ± 45.1 pg/ml, respectively; p < 0.0001). Conclusions Serum CCL11/Eotaxin-1 is elevated in patients with DSPN and is associated with peripheral nerve dysfunction, in particular sensory nerve conduction velocity, suggesting that serum CCL11/Eotaxin-1 may be a potential biomarker for DSPN. Clinical Trial Registration University Hospital Medical Information Network (UMIN) Clinical Trials Registry (UMIN000040631).

Supercharge end-to-side nerve transfer from anterior interosseous nerve to augment intrinsic recovery in high ulnar nerve injuries of varying magnitudes

High ulnar nerve injuries result in intrinsic muscle weakness and are inconvenient for patients. Moreover, conventional surgical techniques often fail to achieve satisfactory motor recovery. A potential reconstructive solution in the form of the supercharge end-to-side (SETS) anterior interosseous nerve (AIN) transfer method has emerged. Therefore, this study aims to compare surgical outcomes of patients with transected and in-continuity high ulnar nerve lesions following SETS AIN transfer. Between June 2015 and May 2023, patients with high ulnar palsy in the form of transection injuries or lesion-in-continuity were recruited. The assessment encompassed several objective results, including grip strength, key pinch strength, compound muscle action potential, sensory nerve action potential, and two-point discrimination tests. The muscle power of finger abduction and adduction was also recorded. Additionally, subjective questionnaires were utilized to collect data on patient-reported outcomes. Overall, the patients were followed up for up to 2 years. Patients with transected high ulnar nerve lesions exhibited worse baseline performance than those with lesion-in-continuity, including motor and sensory functions. However, they experienced greater motor improvement but less sensory recovery, resulting in comparable final motor outcomes in both groups. In contrast, the transection group showed worse sensory outcomes. Our findings suggest that SETS AIN transfer benefits patients with high ulnar nerve palsy, regardless of the lesion type. Nonetheless, improvements may be more pronounced in patients with transected lesions.

Comparative multimodal sensory testing in multifocal motor neuropathy and multifocal variant of chronic inflammatory demyelinating polyradiculoneuropathy

Comparative multimodal sensory testing in multifocal motor neuropathy and multifocal variant of chronic inflammatory demyelinating polyradiculoneuropathy

Cross-Sectional Study of the Relationship Between Medial Plantar Nerve Conduction Studies and Severity of Diabetic Neuropathy.

Diabetic peripheral neuropathy (DPN), a complication of diabetes, is detected only in later stages. Medial plantar nerve (MPL) can identify earlier stages of neuropathy. We evaluated the correlation of MPL sensory nerve action potentials (SNAPs) and severity of DPN measured using the Toronto Clinical Neuropathy Score (TCNS). In this hospital-based, cross-sectional study, we recruited diabetic subjects referred for suspected DPN. Neuropathy was graded with TCNS. Sural nerve conduction studies were performed using standard techniques. MPL studies were conducted using the modified Ponsford technique. All evaluations were performed on Nihon Kohden (model MEB 9200K). Averaged MPL SNAP was correlated with TCNS using Pearson's correlation coefficient. To estimate a correlation of 0.4 with 80% power (P = 0.05), we needed 46 subjects. Linear regression was conducted to adjust for age, duration, and diabetic control. Receiver operating characteristic (ROC) curve analysis was performed to obtain the cutoff for MPL SNAP values using the Youden index. Fifty-one subjects with a mean age of 53.5 years (8.7) and mean duration of diabetes of 10.2 years (7.2) were included. MPL SNAPs were recordable in 12 patients, and the mean amplitude was 5.15 (2.9) µV. There was correlation between MPL SNAP and TCNS (r = -0.43, P = 0.02). No confounding was seen. Use of MPL SNAP resulted in diagnosis of DPN in an additional six (11.8%) patients. The ROC curve suggested that MPL SNAP cutoff of 1.05 µV had an accuracy of 67% in identifying neuropathy as defined by TCNS. MPL SNAP has a moderate correlation with clinical score and identifies more diabetic neuropathy than sural nerve.

Values and diagnostic accuracy of sensory nerve action potentials in control participants and participants with diabetes with and without clinical diabetic neuropathy, based on neuropathy scale measurements.

The assessment of the normative values of sensory nerve action potentials (SNAP) and their diagnostic accuracies using validated neuropathy-assessment tools to classify participants into groups with and without neuropathy was not previously described in the literature. The Utah Early Neuropathy Scale (UENS), Michigan neuropathy-screening instrument, and nerve conduction data were collected prospectively. We described and compared the values of the sural, superficial peroneal sensory (SPS), and superficial radial SNAP amplitude in different age groups for three groups. Group 1 (G1)-control participants (UENS <5), group 2 (G2)-participants with diabetes without clinical diabetic neuropathy (UENS <5), and group 3 (G3)-participants with clinical diabetic neuropathy (UENS ≥5). We also described the diagnostic accuracy of single-nerve amplitude and a combined sensory polyneuropathy index (CSPNI) that consists of four total points (one point for each of the following nerves if their amplitude was <25% lower limit of normal: right sural, left sural, right SPS, and left SPS potentials). We assessed 135 participants, including 41, 37, and 57 participants in G1, G2, and G3, respectively, with age median (interquartile ranges) of 51 (45-56), 47 (38-56), and 54 (51-61) years, respectively, whereas 19 (46.3%), 18 (48.7%), and 32 (56.14%) of them were males, respectively. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) scores were 68.4%, 92.3%, 86.7%, and 80% for the sural amplitude; 86%, 58.3%, 62%, and 84% for the SPS amplitude; 66.7%, 94.4%, 90.5%, and 78.2% for the CSPNI of 3; and 54.4%, 98.6%, 96.9%, and 73.2% for the CSPNI of 4, respectively. Sural nerve had a high specificity for neuropathy; however, the CSPNI had the highest specificity and PPV, whereas the SPS had the highest sensitivity and NPV.

Central nervous system involvement in chronic inflammatory demyelinating polyradiculoneuropathy—MRS and DTI study

ObjectiveThe current research aimed to analyze the alterations within the motor cortex and pyramidal pathways and their association with the degree of damage within the peripheral nerve fibers in patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). To achieve that goal, we investigated the microstructural changes within the pyramidal white matter tracts using diffusion tensor imaging (DTI) parameters, evaluated metabolic alterations in both precentral gyri using magnetic resonance spectroscopy (MRS) ratios, and correlated them with the neurographic findings in patients with CIDP.MethodsThe spectroscopic ratios of NAA/Cr, Cho/Cr, and mI/Cr from both precentral gyri and the values of fractional anisotropy (FA), axial diffusivity (AD), and mean diffusivity (MD) from both of the corticospinal tracts were correlated with the results of neurological and neurographic findings. The comparison of DTI parameters between the patients and controls was performed using Student’s t-test or the Mann–Whitney U test. Due to the lack of normal distribution of most variables, Spearman’s Rho rank coefficient was used to test all correlations. All analyses were performed at a significant level of alpha = 0.05 using STATISTICA 13.3.ResultsCompared to the control group (CG), the patient group showed significantly lower ratios of NAA/Cr (1.66 ± 0.11 vs. 1.61 ± 0.15; p = 0.022), higher ratios of ml/Cr in the right precentral gyrus (0.57 ± 0.15 vs. 0.61 ± 0.08; p = 0.005), and higher levels of Cho/Cr within the left precentral gyrus (0.83 ± 0.09 vs. 0.88 ± 0.14, p = 0.012). The DTI parameters of MD from the right CST and AD from the right and left CSTs showed a strong positive correlation (0.52–0.53) with the sural sensory nerve action potential (SNAP) latency of the right sural nerve. There were no other significant correlations between other DTI and MRS parameters and neurographic results.SignificanceIn our study, significant metabolic alterations were found in the precentral gyri in patients with CIDP without clinical symptoms of central nervous system involvement. The revealed changes reflected neuronal loss or dysfunction, myelin degradation, and increased gliosis. Our results suggest coexisting CNS damage in these patients and may provide a new insight into the still unknown pathomechanism of CIDP.

Effect of High-Intensity Laser Therapy on Carpal Tunnel Syndrome Patients: A Systematic Review and Meta-analysis.

To provide a strong foundation for the use of high-intensity laser therapy in carpel tunnel syndrome, we conducted a systematic review and meta-analysis to investigate the outcomes of short- and long-term follow-up studies. This is a systematic review and meta-analysis. Sample sizes of included studies ranged from 16 to 98 patients ( N = 308). Overall, a significant difference between the treatment and control groups were found across majority of the measures. Studies using a 4-wk follow-up period, however, only found significantly greater benefits for high-intensity laser therapy in visual analog scale compared with placebo ( P = 0.0191), transcutaneous electrical nerve stimulation ( P = 0.0026), and low-intensity laser therapy 20 J/cm 2 ( P < 0.0002), and exercise ( P < 0.0001). For improvement in visual analog scale score over a long treatment period, high-intensity laser therapy was also preferred over control group ( P < 0.0071). Insufficient evidence exists to determine effect of high-intensity laser therapy on nerve conduction examinations. The only statistically significant differences observed in examinations were in relation to sensory nerve action potential ( P = 0.0083) and sensory nerve conduction velocity ( P = 0.0468). Moderate evidence exists regarding efficacy of high-intensity laser therapy compared with placebo, high-intensity laser therapy + wrist splint, and exercise in a short period of follow-up time but evidence on long-term follow-up is limited.

Electrophysiological variations of Guillain-Barre syndrome in Bangladesh- Hospital based study

Introduction: Guillain-Barre syndrome (GBS) is an immune mediated disorder of peripheral nerves which usually presents by rapidly evolving ascending weakness &amp; mild sensory loss and hypo- or areflexia. Electrodiagnostic study (EDS) is the basis for classification of different subtypes of the disease. EDS also has a crucial role in diagnosis, ruling out of some differential diagnosis like myopathic and motor neuron disorders and confirming the neuropathic nature of GBS. The benefit of immunotherapy is greatest when introduced early. In addition, electrophysiological characteristic can predict the prognosis of patients with GBS. This study was conducted to determine the predominant subtype and electrophysiological pattern of GBS in the context of Bangladesh. Objectives: Objective of this study was to compare the electrophysiological variations among different electrophysiological subtypes of GBS. Methods: It is an observational cross sectional study conducted in Department of Medicine and Neurology, Sir Salimullah Medical College &amp; Mitford Hospital and National Institute of Neuroscience (NINS), Dhaka, over a period of one year &amp; four months. Total 30 patients were selected by purposive sampling technique. Demographic data were collected from the patients and recorded in structured case report form. Clinical examination and relevant investigations were done meticulously. Collected questionnaire were checked to identify any error in data. Data was analyzed with SPSS version 21 software. Result: In this study, maximum numbers of patients 53% were between 21-30 years of age group with mean value 27.47±8.1 years. Male to female ratio was 1.7:1. Frequency of Guillain-Barre syndrome is predominance at middle age group. Commonest presentation was limb weakness (parapledgia or quadripledgia) in 60% patients, paresthesias &amp; numbness (40%), pain (100%) and deviation of mouth (63%) of GBS patients. Cerebrospinal fluid shows a mild pleocytosis (5 to 50 cells/µl) in majority of cases was found in 76% of patients. Whereas elevated CSF Protein (&gt;45 mg/dl) was seen in all GBS patient. Increased distal motor latency (DML) was found in 93% patients, whereas 7% patients had normal DML. In the case of the lower limbs, increased distal motor latency was predominant. Decreased amplitude of sensory nerve action potential (SNAP) was seen in 83% patients while 16% patients had normal. Slowing of motor conduction velocities, decreased amplitude as well as increase in distal motor latencies were observed, being more pronounced in the lower limbs. F-wave was completely absent in 20.0% patients while 20% patients showed decreased conduction velocity with prolonged latency. Sensory nerve action potential revealed that decreased sensory conduction velocity (SCV) was seen in 26%, absent SCV in 10% and normal SCV in 63% patients. Present study demonstrated that Acute inflammatory demyelinating polyneuropathy (AIDP) was the commonest type of Guillain-Barré syndrome, present in 56% of patient. Around 30% of the patients belonged to acute motor axonal polyneuropathy (AMAN) and 13% were acute motor sensory axonal polyneuropathy (AMSAN). Conclusion: In this study AIDP was the most frequent subtype. The characteristic findings supportive of AIDP include prolonged distal motor latencies, reduced conduction velocities, conduction blocks at non-entrapment sites, temporal dispersion and prolonged F wave latencies. J MEDICINE 2024; 25: 11-16

Sensory nerve conduction studies in infants, children and teenagers – An update

ObjectiveNerve conduction studies (NCS) in children remain technically challenging and depend on the cooperation of the child. Motor NCS are not compromised by analgosedation but data for sensory NCS are lacking. Here, we ask whether sensory NCS is influenced by analgosedation. We also compare the present data with NCS studies from the 1990s regarding anthropometric acceleration of the contemporary paediatric population. MethodsSensory NCS of the median nerve and sural nerve were performed in 182 healthy subjects aged 1 to 18 years during general anaesthesia and in 47 of them without analgosedation. ResultsSensory NCS was not influenced by midazolam or propofol. The sensory nerve action potential (SNAP) amplitude and the nerve conduction velocity (NCV) of the sural nerve as well as the SNAP of the median nerve show no significant age dependence in age range 1–18 years. The sensory NCV of the median nerve increased age-dependent. ConclusionsIn clinical practice, analgosedation can be used for diagnostic NCS. Sensory NCS data show no relevant secular trend over the last 30 years. Differences due to technical inconsistency predominate. SignificanceAnalgosedation can improve diagnostic quality of sensory NCS in children. Additionally, we provide sensory NCS values from a large pediatric cohort.

Sural nerve involvement in patients with acute inflammatory demyelinating polyneuropathy variant of Guillain-Barre syndrome with sural sparing at initial presentation

Introduction: Neurophysiological testing is a valuable tool in the diagnosis of Guillain-Barre syndrome (GBS). Sural sparing is a usual feature of acute inflammatory demyelinating polyneuropathy (AIDP) type GBS. However, sural involvement has been reported in later stages of GBS. It is important to identify patterns of sural nerve involvement to differentiate GBS from its mimickers and to stage the disease. This research aimed to detect the pattern of sural nerve involvement in AIDP-GBS cases with normal electrophysiological responses in the sural nerve at the beginning.Objectives: To determine the location and timing of sural nerve involvement in AIDP-GBS.Methods: This prospective follow up study included diagnosed cases of AIDP-GBS with preserved bilateral sural responses. Nerve conduction and somatosensory evoked potentials (SSEP) were done on admission and weekly thereafter for four consecutive weeks. The last evaluation was done four weeks after the fourth study.Results: All patients (100%) showed normal distal sural responses over the initial four weeks of follow up. They continued to remain normal up to eight weeks in eight patients (53.3%). Two patients had gradual prolongation of their sural SSEP on consecutive studies. One of them had gradual reduction of sural sensory nerve action potential and nerve conduction velocity along with the prolongation of sural SSEP latencies. The difference of SSEP latency increments in the left sural nerve of these two patients was statistically significant (p&lt;0.05). The right sural SSEP latency difference was not significant.Conclusion: Sparing of the distal sural sensory response was demonstrated in 100% of AIDP-GBS cases during the first four weeks of follow up. More than 50% of the cohort demonstrated preserved sural sensory responses for eight weeks from the initial presentation. Two out of fifteen patients showed statistically significant proximal sural sensory pathway involvement with increasing SSEP latencies. This finding suggests that in some patients, the sural sensory pathway may get affected at its proximal segments or at the central nervous system before the distal nerve is affected.

Intensive Care Unit-Acquired Weakness after Liver Transplantation: Analysis of Seven Cases and a Literature Review.

Intensive Care Unit (ICU)-Acquired Weakness (ICU-AW) is a generalized muscle weakness that is clinically detected in critical patients and has no plausible etiology other than critical illness. ICU-AW is uncommon in patients undergoing orthotopic liver transplantation (OLT). Our report sheds light on the highest number of ICU-AW cases observed in a single center on OLT patients with early allograft dysfunction. Out of 282 patients who underwent OLT from January 2015 to June 2023, 7 (2.5%) developed generalized muscle weakness in the ICU and underwent neurophysiological investigations. The neurologic examination showed preserved extraocular, flaccid quadriplegia with the absence of deep tendon reflexes in all patients. Neurophysiological studies, including electromyography and nerve conduction studies, showed abnormalities with fibrillation potentials and the rapid recruitment of small polyphasic motor units in the examined muscles, as well as a reduced amplitude of the compound muscle action potential and sensory nerve action potential, with an absence of demyelinating features. Pre-transplant clinical status was critical in all patients. During ICU stay, early allograft dysfunction, acute kidney injury, prolonged mechanical ventilation, sepsis, hyperglycemia, and high blood transfusions were observed in all patients. Two patients were retransplanted. Five patients were alive at 90 days; two patients died. In non-cooperative OLT patients, neurophysiological investigations are essential for the diagnosis of ICU-AW. In this setting, the high number of red blood cell transfusions is a potential risk factor for ICU-AW.

Effect of metformin nanoemulsion through AMP-activated protein kinase (AMPK)-mediated autophagy on diabetic neuropathy

Metformin (MET) is the preferred first-line treatment for patients with type 2 diabetes. However, the mechanism of diabetic peripheral neuropathy (DPN) is still unclear. To improve the oral utilization of metformin, a metformin nanoemulsion (MET-NE) was prepared to investigate its effects on DPN and its underlying mechanism. In this study, a DPN model was established in Wistar rats induced by streptozotocin (STZ). The diabetic rats were randomly divided into four groups: the diabetic model group (DM group), the metformin tablet-treated group (MET group), the metformin nanoemulsion-treated group (MET-NE group), and a normal control group consisting of five normal Wistar rats. All groups were administered the treatment orally for a period of 10 weeks. The findings of the study demonstrated that both MET and MET-NE significantly reduced blood glucose levels, glycated serum protein levels, food intake, and water intake in DM rats. It was also observed that MET-NE was more effective than MET in reducing blood glucose levels. Additionally, both MET and MET-NE treatments significantly increased the motor nerve conduction velocity (MNCV), sensory nerve conduction velocity (SNCV), and sensory nerve action potential (SNAP) amplitude in DM rats. Furthermore, these treatments improved mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL), resulting in a reduced sensitivity to pain stimuli. Moreover, both MET and MET-NE treatments promoted the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) proteins, as well as increased the activity of autophagic proteins in the sciatic nerve. However, no significant differences were observed between MET and MET-NE treatments in terms of these effects. In conclusion, the MET-NE demonstrated a rapid decrease in blood glucose levels and improved glucose tolerance and metabolism, which was found to be superior to MET. Furthermore, MET-NE significantly improved the neurophysiological function and sciatic nerve pain threshold in DPN rats. These beneficial effects may be attributed to the regulation of AMPK-mediated autophagy by MET-NE.

The effect of polyneuropathy severity on nerve conduction and pain syndrome in patients with type 2 diabetes

Background. The article examines the relationship between nerve conduction indicators and polyneuropathy severity in patients with type 2 diabetes. The influence of polyneuropathy severity on nerve conduction was studied, as well as the effect of insulin therapy on these indicators. Objective: to determine the influence of polyneuropathy severity and the need for additional insulin administration in patients with type 2 diabetes on nerve conduction indicators and the development of pain syndrome. Materials and methods. Eighty patients with type 2 diabetes were examined, 49 men and 31 women. All of them underwent general clinical and biochemical laboratory tests to evaluate the hematopoietic system, li-ver, kidneys, fat and carbohydrate metabolism. The need for insulin therapy was assessed by the C-peptide level. To verify the diagnosis of diabetic polyneuropathy, complaints, clinical and instrumental examination data were evaluated. The main indicators of nerve conduction were taken into account when determining polyneuritis disorders, namely: рeroneal motor nerve conduction velocity, sensory nerve action potential of the sural nerve, sensory nerve conduction velocity of the sural nerve. Results. A dependence of nerve conduction on polyneuropathy severity was revealed, рeroneal motor nerve conduction velocity was the lowest in the group with severe polyneuropathy. A correlation was also found between the levels of sensory indicators (sensory nerve action potential and sensory nerve conduction velocity) and polyneuropathy severity, nerve conduction velocity decreases with an increase in the latter. The influence of polyneuropathy severity on the painful or painless form has been found. Among patients with severe polyneuropathy, the painful form was observed more often. No relationship was found between the need for insulin therapy and the painful or painless form of polyneuropathy. Conclusions. Indicators of nerve conduction depend on polyneuropathy severity. The presence and severity of pain syndrome directly depends on polyneuropathy severity. The need for additional insulin administration affects sensory indicators but has no effect on the development of the painful form of polyneuropathy.

Sensory nerve action potential in patients with functional neurological disorders with sensory manifestations.

Functional neurological disorder (FND) has various clinical manifestations. Even though diagnostic criteria for FND have been proposed, FND characteristics with sensory manifestations have not been elucidated. Therefore, we aimed to investigate the association between sensory nerve action potential (SNAP) amplitudes and FND with sensory manifestations. We included 76 outpatients with FND with sensory manifestations whose nerve conduction studies were performed retrospectively. Additionally, we defined 121 patients with other neurological diseases who did not have peripheral neuropathy as disease controls. The SNAP amplitudes were compared between the two groups. We also explored the relationship between SNAP amplitudes and FND-specific clinical symptoms in patients with FND. No differences were observed in SNAP amplitudes adjusted for age between patients with FND who had sensory manifestations and disease control patients. Additionally, no differences were observed between patients with FND who had and did not have FND-specific clinical symptoms. The SNAP amplitude in patients with FND who had sensory manifestations was equivalent to that in controls.

Association of Sensory Nerve Action Potential Amplitude and Velocity With Type 2 Diabetic Peripheral Neuropathy.

There is ongoing controversy regarding the predominant type of nerve injury in diabetic peripheral neuropathy, whether it is demyelination or axonal degeneration. This study aimed to investigate the association between nerve conduction study parameters, specifically nerve conduction velocity and the amplitude of the action potential, with diabetic peripheral neuropathy and determine their potential as early indicators of the condition. A cross-sectional study was conducted involving diagnosed type 2 diabetes mellitus patients, who were divided into two groups: Group I (n = 111) with symptomatic diabetic peripheral neuropathy and Group II (n = 109) without clinically detectable peripheral neuropathy. Age and sex-matched healthy controls (n = 100) were also included. Nerve conduction velocity measurements were performed on both upper and lower limbs, with motor nerve conduction study focusing on the dominant side using the median and posterior tibial nervesand sensory nerve conduction study using the median and sural nerves. The nerve conduction studies revealed significantly lower sensory nerve action potential amplitudes and compound muscle action potential amplitudes in the median, posterior tibial, and sural nerves of the diabetic groups compared to the control subjects. Furthermore, these changes were more prominent in patients with peripheral neuropathy. Among the 220 diabetic patients analyzed, 135 (61.36%) exhibited nerve conduction abnormalities. The highest rate of abnormality was observed in the sural nerve, followed by the posterior tibial and median nerves. The most common abnormality detected in diabetic patients was a decrease in sensory nerve action potential, followed by a decrease in sensory nerve conduction velocity. The study findings suggest an association between reduced sensory nerve action potential amplitude and diabetic peripheral neuropathy. These results highlight the potential of sensory nerve action potential and velocity as a sensitive indicator of peripheral neuropathy in diabetic patients.

Electrophysiologic pattern of carpal tunnel syndrome among patients with and without diabetes mellitus

Background: Carpal tunnel syndrome (CTS) is the most common compression neuropathy in the upper limb in general population. Female gender, obesity, increase of age, diabetes mellitus (DM), hypothyroidism, pregnancy, rheumatoid arthritis, osteoarthritis and occupational factors like repetitive work are the main risk factors for CTS. The objective of this study was to determine whether the nerve conduction study measurement of the median nerve (MN) at the wrist differ between diabetic and non-diabetic CTS patients. Methods: This cross-sectional study was conducted at Electrodiagnostic Lab of BIRDEM General Hospital and Popular Medical College Hospital, Dhaka during the period of October 2017 to August 2019. Five hundred and seventeen hands from 377 patients were sampled according to inclusion criteria. Participants were assigned to two groups: Group 1 (CTS with DM) and Group 2 (CTS without DM). NCS study were performed using Nihon Kohden electrodiagnostic machine. Measurements at the MN was taken under consideration for study. Severity of CTS was graded according to Canterbury electrophysiologic grading scale and parameters were compared among diabetic and non-diabetic participants. Data were analyzed using Statistical Package for the Social Sciences SPSS version 23 (SPSS Inc., Chicago, IL, USA). Results: The 377 participants comprised 144 and 233 in Group 1 and Group 2, respectively. Out of 377 patients, 334 (88.59%) were females and there was no statistically significant difference between two groups. The average age was 50.66±10.2 years in diabetic participants and 43.34±10.7 years in non- diabetic participants. In the study population moderate CTS (Grade 3) was the most frequent (46.4%) followed by very severe (Grade 5) CTS. There was no statistically significant difference in incidence between diabetic and non-diabetic patients. Analysis of electrophysologic parameters of MN showed statistically significant difference in mean MN sensory nerve action potential (SNAP) amplitude (P 0.003), compound muscle action potential (CMAP) amplitude (p 0.05, right) and CMAP latency (p 0.02, right and 0.05, left) between diabetic and non –diabetic patients. Inter-group comparison revealed that impaired glycaemic status and duration of diabetes in diabetic population had a minimal influence in the electrophysiological severity of CTS in either hands. Conclusion: Some nerve conduction study parameters of the MN differ significantly between diabetic and non-diabetic patients with CTS and may provide both diagnostic and predictive results across the entire spectrum of CTS. BIRDEM Med J 2023; 13(3): 136-142

Facial nerve neurographies in intensive care unit-acquired weakness

BackgroundPatients with an intensive care unit-acquired weakness (ICU-AW) often present clinically with severe paresis of the limb and trunk muscles while facial muscles appear less affected. To investigate whether the facial nerves are partially spared from this condition, we performed both peripheral and cranial nerve conduction studies in critically ill patients.MethodsIn patients requiring prolonged ICU therapy, the motor and sensory nerve conduction velocities of the peroneal, ulnar and facial nerves and the muscle action potentials of the associated muscles, as well as the orbicularis oculi reflexes were assessed shortly after admission, and on ICU days 7 and 14.ResultsEighteen patients were included in the final data analysis (average age 54.2 ± 16.8 years, 8 females). The amplitudes of the peroneal nerve compound muscle action potentials (CMAPs) were reduced in all patients at ICU days 7 and 14 (F(1.39; 23.63) = 13.85; p < 0.001). There was no similar decrease in the CMAP amplitudes of the ulnar or facial nerve. Other parameters of nerve function (latencies, sensory and motor nerve conduction velocities, sensory nerve action potentials) remained unchanged. The reproducibility of the orbicularis oculi reflex was reduced during the disease course, while its latencies did not change significantly during the disease course.ConclusionsThere is a relative preservation of CMAPs in facial and hand as opposed to foot muscles. This is compatible with the clinical observation that the facial muscles in patients with ICU-AW are less severely affected. This may be primarily a function of the nerve length, and consequently more robust trophic factors in shorter nerves.Trial registration This study was prospectively registered in the German Clinical Trial Register on April 20th 2020 (DRKS00021467).

Nerve Conduction Differences in a Large Clinical Population: The Role of Age and Sex.

The normal limits of nerve conduction studies are commonly determined by testing healthy subjects. However, in comprehensive real-life nerve conduction electrodiagnostic (EDX) evaluations, multiple nerves are tested, including normal nerves, for purposes of comparison with abnormal ones. This study aims to evaluate the average values of normal nerve conduction studies in a large population and examined the influence of age and sex. EDX parameters were extracted from an electronic database of studies performed from May 2016 to February 2022. Established normal values were used to determine the classification of a nerve study as normal. We identified 10,648 EDX reports with 5077 normally interpreted nerve conduction studies (47.6%) of which 57% (n = 2890) were for females. The median age of studies with no abnormalities was 45.1 years (range < 1 to 92) overall and 42.5 years (range: 0.16 -89.5 years) for males and 47.5 years (range:<1 -91.7) for females. Correlations between age and amplitude, latency, and velocity (p < 0.001) were observed in most nerves. Amplitude correlated negatively with age in adults in all nerves with a mean of -0.44 (range: -0.24 to -0.62). However, in the pediatric population (age < 18 years), amplitude as well as velocity increased significantly with age. In the adult cohort, sex differences were noted, where females had higher mean sensory nerve action potentials in ulnar, median, and radial evaluations (p < 0.001). In older patients (aged > 70 years) with normally interpreted EDX studies (845 records of 528 patients), sural responses were present in 97%. This real-life study confirms that advanced aging is associated with decreased nerve conduction amplitudes, increased latency, and the slowing of conduction velocity. The findings also indicate higher sensory amplitudes and conduction velocities in females. Sural nerve responses were identified in most adults over age 70.

Miller Fisher syndrome: an updated narrative review.

Miller Fisher syndrome (MFS) is considered a rare variant of Guillain-Barré syndrome (GBS), a group of acute-onset immune-mediated neuropathies characterized by the classic triad of ataxia, areflexia, and ophthalmoparesis. The present review aimed to provide a detailed and updated profile of all aspects of the syndrome through a collection of published articles on the subject, ranging from the initial description to recent developments related to COVID-19. We searched PubMed, Scopus, EMBASE, and Web of Science databases and gray literature, including references from the identified studies, review studies, and conference abstracts on this topic. We used all MeSH terms pertaining to "Miller Fisher syndrome," "Miller Fisher," "Fisher syndrome," and "anti-GQ1b antibody." An extensive bibliography was researched and summarized in the review from an initial profile of MFS since its description to the recent accounts of diagnosis in COVID-19 patients. MFS is an immune-mediated disease with onset most frequently following infection. Anti-ganglioside GQ1b antibodies, detected in ~85% of patients, play a role in the pathogenesis of the syndrome. There are usually no abnormalities in MFS through routine neuroimaging. In rare cases, neuroimaging shows nerve root enhancement and signs of the involvement of the central nervous system. The most consistent electrophysiological findings in MFS are reduced sensory nerve action potentials and absent H reflexes. Although MFS is generally self-limited and has excellent prognosis, rare recurrent forms have been documented. This article gives an updated narrative review of MFS with special emphasis on clinical characteristics, neurophysiology, treatment, and prognosis of MFS patients.

Age-Related Changes in Neurologic Examination and Sensory Nerve Amplitude in the General Population: Aging of the Peripheral Nervous System.

Chronic axonal polyneuropathy is a common disease of the peripheral nervous system with increasing prevalence with age. Typical neurologic signs are present in patients with polyneuropathy but may also occur in individuals without disease. Owing to limited knowledge on normal aging of the peripheral nervous system, it can be difficult to distinguish peripheral nerve dysfunction due to disease from variations in normal aging. Therefore, we described the changes in neurologic examination and nerve conduction studies that accompany aging in the general population. In this cross-sectional population-based study, we screened participants for chronic polyneuropathy in a controlled environment using standardized methods including a symptom questionnaire, neurologic examination, and nerve conduction studies (NCS). Inclusion criteria were 40 years or older and living in a suburb of Rotterdam, the Netherlands. Participants not diagnosed with chronic polyneuropathy, based on the discussion of findings in the screening by an expert team, were included to determine the effect of age (range 41-96 years) on features of neurologic examination and NCS using frequency calculations and quantile regression analysis. In total, 4,179 participants (mean age 64.5 ± 12.7 years, 54.9% female) were included of whom 3,780 (90.5%) did not fulfil the criteria for polyneuropathy. In the population without polyneuropathy, the frequency of normal features at neurologic examination declined with age, most pronounced for vibration sense at the hallux (from 6.6 [SD ± 1.5] in 40-49 years to 3.6 [SD ± 3.1] in 80 years or older) and Achilles tendon reflexes (absent in 9% in 40-49 years up to 33% in 80 years or older). Superficial pain sensation and patellar tendon reflexes remained stable over time. Sural sensory nerve action potential (SNAP) amplitude declined with age from 11.2 μV in 40-49 years to 3.3 μV in 80 years or older. Nonrecordable SNAP amplitudes were found in 25.1% of the participants older than 80 years, more often in men (30.3%) than in women (21.0%). This study showed the effect of age on features of neurologic examination and sural nerve amplitude in the general population. These findings are helpful to distinguish features suggesting polyneuropathy from variations of normal aging of the peripheral nervous system.