Nerve Action Potentials Research Articles

321-OR: Differential Associations of Obesity and Metabolic Syndrome with Polyneuropathy in Early Type 2 Diabetes and Normal Glucose Tolerance

There is increasing evidence for a role of the metabolic syndrome (MetS) during development of distal sensorimotor polyneuropathy (DSPN). We hypothesized that MetS components are differentially associated with measures of DSPN in individuals with normal glucose tolerance (NGT) and early type 2 diabetes (T2D). Electrophysiological and quantitative sensory testing was performed in 180 participants with NGT and 355 with recent-onset T2D (known diabetes duration <1 year) matched for age from the German Diabetes Study (NGT/T2D [mean±SD]: age: 43.9±14.0/45.1±7.7 years; sex: 61/65% male; BMI: 26.8±5.0/32.3±6.5 kg/m²; HbA1c: 5.2±0.3/6.5±1.0%). Intraepidermal nerve fiber density (IENFD) was assessed in 218 individuals (NGT/T2D: n=117/101). Subsets of participants were followed for 5 years (NGT/T2D: n=48/53). MetS was defined according to International Diabetes Federation (2006) and DSPN according to Toronto consensus criteria (2011). After adjustment for age, sex, height, smoking and HbA1c, a lower IENFD was associated with higher weight (β=-0.306), number of MetS components (NMetSC; β=-0.222) and presence of central obesity (β=-0.292), while higher malleolar vibration perception threshold was associated with weight (β=0.219) in NGT (P<0.05), but not in T2D. Median motor nerve conduction velocity and sural sensory nerve action potential were inversely associated with weight (β=-0.182/-0.286), NMetSC (β=-0.127/-0.128), presence of central obesity (β=-0.163/-0.165), and MetS (β=-0.169/-0.203) in T2D (P<0.05). Higher weight predicted the presence of DSPN at 5 years (β=0.652, P=0.001) in NGT, while increasing NMetSC and MetS prevalence predicted a decline in IENFD over 5 years (β=-0.533/-0.388, P=0.001/0.013) in T2D. This suggests that obesity indices can predict DSPN over 5 years in NGT, while MetS and its components are differentially associated with measures of DSPN in early, well-controlled type 2 diabetes compared with NGT. Disclosure G.Sipola: None. A.Strom: None. M.Bombrich: None. R.Wagner: Advisory Panel; Daiichi Sankyo, Speaker's Bureau; Novo Nordisk, Sanofi. D.Ziegler: None. M.Roden: Advisory Panel; Eli Lilly and Company, Consultant; TARGET PharmaSolutions, Inc., Research Support; Boehringer-Ingelheim, Novo Nordisk, Novartis, Sanofi. G.J.Bönhof: None. Gds group: n/a. Funding German Federal Ministry of Health; Ministry of Innovation, Science, Research and Technology of the state North Rhine-Westphalia; German Federal Ministry of Education and Research

Nerve conduction studies through landmark based recording and effects of hand length

As per existing guidelines, the distance between stimulator and recording electrodes in nerve conduction studies (NCS) should be the same (fixed) in all the subjects, i.e., it should not be based on anatomical landmarks. However, there are no studies comparing fixed distance recordings with landmark based NCS. We postulated that hand length can influence the NCS parameters in fixed distance recordings and this can be nullified using landmark based recordings. To test this theory, we performed NCS in 48 normal subjects as per standard guidelines (standard protocol) and then compared it to NCS with ulnar styloid as the landmark (modified protocol). NCS were performed on median and ulnar nerves of the right upper limb. Three motor NCS parameters including distal latency, compound muscle action potential (CMAP) amplitudes and nerve conduction velocities were measured. Sensory nerve action potential (SNAP) amplitudes and conduction velocities were the two sensory parameters measured. On analysis, ulnar motor conduction velocity was the only parameter affected by hand length in both standard and modified protocols. Modified protocol did not have any additional advantage to the standard protocol advised by NDTF. We conclude that the NDTF guidelines are therefore reasonable when considering the effects of hand length. Possible reasons for this result including anatomical and anthropometric explanations are discussed.

479-P: Natural Course of Declining Nerve Function during the First 10 Years of Well-Controlled Type 2 Diabetes

There is a lack of evidence on the long-term changes of nerve function in individuals with type 2 diabetes (T2D) compared to those with normal glucose tolerance (NGT). Therefore, we assessed motor and sensory nerve conduction velocities (MNCV, SNCV), sensory nerve action potentials, vibration perception threshold (VPT) and thermal detection threshold of lower extremities in 45 individuals with T2D (known diabetes duration [mean±SD]: 164±95 days) and NGT from the German Diabetes Study (GDS) at baseline (BL) and 5-year follow-up. Individuals were matched pairwise for age (T2D/NGT: 52.9±10.4/52.9±10.3 years) and sex (64/64% male). In addition, 103 individuals with T2D were followed over 10 years. At BL, 1/6 indices was lower in T2D vs NGT (peroneal MNCV: 45.6±4.0 vs 47.2±2.8 m/s; P<0.05). After five years, one index deteriorated in T2D (peroneal MNCV: 45.3±4.1 vs 43.5±3.8 m/s) and one in NGT (malleolar VPT: 1.29±1.88 vs 2.25±3.06 µm) (all P<0.05). After adjustment for BL values and pairwise matching, nerve function similarly declined over the first five years in T2D and NGT (e.g. Δperoneal MNCV; figure). A comparable deterioration was observed in individuals with T2D over 10 years (figure). Parallel decline in small and large fiber function in both NGT and well controlled T2D indicates that the main events leading to impaired nerve function in well controlled T2D might occur earlier than previously assumed. Disclosure A.Strom: None. K.Strassburger: None. G.Sipola: None. D.Ziegler: None. R.Wagner: Advisory Panel; Daiichi Sankyo, Speaker's Bureau; Novo Nordisk, Sanofi. M.Roden: Advisory Panel; Eli Lilly and Company, Consultant; TARGET PharmaSolutions, Inc., Research Support; Boehringer-Ingelheim, Novo Nordisk, Novartis, Sanofi. G.J.Bönhof: None. Gds group: n/a. Funding German Federal Ministry of Health; Ministry of Innovation, Science, Research and Technology of the state North Rhine-Westphalia; German Federal Ministry of Education and Research

Phenotypic variability in TRPV4-associated neuropathies and neuronopathies: a case series

TRPV4‑associated neuromuscular diseases represent a clinical spectrum of neuropathies and motor neuron disorders. To date, 3 phenotypic forms are distinguished. There are Charcot–Marie–Tooth disease type 2C, distal hereditary motor neuropathy type 8 (DHMN8), scapulo‑peroneal spinal muscular atrophy (SPSMA). Here we report 3 families with DNMN8 and one family with SPSMA. In all cases, DNA‑analysis revealed single nucleotide variants in the TRPV4 gene previously reported as pathogenic. In 3 probands, a combination of signs of both motor and motor‑sensory neuropathies led to difficulties in the establishment of the clinical diagnosis. Patients had mild sensory disturbances in the feet, but in all of these cases nerve conduction study revealed normal sensory nerve action potentials. Considering the prevailing signs of motor neuropathy, these patients were diagnosed with DNMN8. Clinical signs of sensory disturbances are regarded as not contradicting the diagnosis, since they can be observed in various forms of distal motor neuropathies. The clinical features of SPSMA in one patient corresponded to those previously described in the literature. The involvement of the shoulder girdle muscles and the peroneal muscles and neurogenic changes in needle electromyography allow suspecting SPSMA clinically. A distinctive features of TRPV4‑associated neuromuscular diseases are the vocal cords paresis, sensorineural hearing loss and respiratory failure, however they are not obligatory according to our clinical reports.

The relationship between neuron-specific enolase, high sensitivity C reactive protein, and diabetic peripheral neuropathy in Chinese patients with type 2 diabetes: A prospective nested case–control analysis

BackgroundDiabetic peripheral neuropathy (DPN) involves a very complex pathogenesis, and there is no neuro-specific marker for risk prediction. Neuron-specific enolase (NSE), a key enzyme in glycolysis, has a broad spectrum neurotrophic and neuroprotective effect on neurons, and also cause injury and inflammatory response of peripheral nerves. The relationship between neuron-specific enolase, highly sensitive c-reactive protein (hsCRP), and diabetic peripheral neuropathy remains unclear. We aimed to investigate whether elevated serum NSE and hsCRP levels increased the risk of DPN in patients with type 2 diabetes.Materials and methodsIn this prospective nested case–control study, a total of 1072 eligible subjects with type 2 diabetes constituted the follow-up cohort. Demographic data and parameters including serum NSE and hsCRP were collected at baseline. Two neuropathy screening scales (MNSI and MDNS) were used to assess DPN during follow-up period. Nerve conduction studies were performed at the end of follow-up. Conditional logistic regression was used to inspect the risk factors of the incidence of DPN.ResultsDuring an average follow-up period of 5.1 years, 176 subjects developed DPN. Serum NSE and hsCRP levels at baseline were significantly higher in DPN group than in matched non-DPN groups (p < 0.001). NSE was positively correlated with age and hsCRP (p < 0.001). The amplitude of sensory nerve action potential and compound muscle action potential of the lower extremity nerves were significantly decreased in the high tertile of NSE. After adjustment for matching and confusing factor, conditional logistic regression showed the risk of DPN in the high tertile of NSE level was still 3.176 times higher than that in the low tertile of NSE level (p < 0.001).ConclusionElevated serum NSE levels predicted the high incidence of DPN in Chinese patients with type 2 diabetes for an average of 5.1 years, which may be associated with increased neuroinflammatory response caused by high NSE levels, but further studies are needed.

No Major Nerve Regeneration Seems to Occur during Recovery of Ulnar Neuropathy at the Elbow.

Introduction: There are three main potential mechanisms of recovery after nerve lesion: (1) resolution of conduction block, (2) collateral reinnervation, and (3) nerve regeneration. Their relative contributions in recovery after focal neuropathies are not well established. Methods: In a group of previously reported prospective cohort of patients with ulnar neuropathy at the elbow (UNE), I performed a post-hoc analysis of their clinical and electrodiagnostic findings. I compared amplitudes of the compound muscle action potential (CMAP) and sensory nerve action potential (SNAP) on ulnar nerve stimulation, as well as qualitative concentric needle electromyography (EMG) findings in the abductor digiti minimi muscle on the initial and follow-up examinations several years later. Results: Altogether, 111 UNE patients (114 arms) were studied. During median follow-up period of 880 days (range: 385-1545 days), CMAP amplitude increased (p = 0.02), and conduction block in the elbow segment recovered (from median 17% to 7%; p < 0.001). By contrast, SNAP amplitude did not change (p = 0.89). On needle EMG, spontaneous denervation activity diminished (p < 0.001), motor unit potential (MUP) amplitude increased (p < 0.001), and MUP recruitment remained unchanged (p = 0.43). Conclusions: Findings of the present study indicate that nerve function in chronic focal compression/entrapment neuropathies seems to improve mainly due to the resolution of the conduction block and collateral reinnervation. Contribution of nerve regeneration seems to be minor; the majority of axons lost in chronic focal neuropathies probably never recover. Further studies using quantitative methods are needed to validate present findings.

Role of Fibrinogen in Type-2 Diabetes Mellitus with Diabetic Neuropathy and its Preliminary Mechanism.

Diabetic peripheral neuropathy (DN) is the most common complication of type 2 diabetes mellitus (T2DM). This study aimed to explore the role of fibrinogen (FIB) in T2DM neuropathy and its preliminary mechanism. Ten male Sprague-Dawley rats were divided into a normal control group (NC group) and a T2DM neuropathy model group (DN group). The DN group was given a high-energy diet and streptozotocin, while the NC group was given a normal diet and a citric acid buffer. The expression levels of related proteins were analysed. Electrophysiology: Compared with the NC group, the conduction latency of the somatosensory-evoked potential and nerve conduction velocity was prolonged in the DN group, while the motor nerve action potential was decreased. As seen under a light microscope, the peripheral nerve fibres in the DN group were swollen, and the nerve fibres in the posterior funiculus of the spinal cord were loose or missing. Moreover, as seen under an electron microscope, the peripheral nerve demyelination of the DN group was severe, with microvascular blood coagulation, luminal stenosis, and collapse. Compared with the NC group, in the DN group, the expression of FIB was positively correlated with the expression of both ionised calcium-binding adaptor molecule-1 and glial fibrillary acidic protein. Compared with the NC group, in the DN group, the expression of platelet/endothelial cell adhesion molecule-1 and B-cell lymphoma 2 was negatively correlated. The increased concentration of FIB may be the cause of neuropathy, and its mechanism may be related to its promotion of inflammatory response, blood coagulation, and vascular stenosis.

Comparison of ulnar, median, and sural sensory nerve conduction studies between demyelinating and axonal forms of Guillain-Barré Syndrome

Background: Guillain-Barré syndrome (GBS) is an important neurological disease that can cause disability. Axonal GBS and acute inflammatory demyelinating polyradiculoneuropathy (AIDP) are two important subgroups.&#x0D; Methods: Patients with clinical and electrodiagnostic features compatible with GBS were included in this retrospective study. The patients were divided into two groups neurophysiologically as Axonal GBS and AIDP. Medical research council (MRC) scores of the patients' muscles, median / ulnar / posterior tibial / peroneal / sural nerve conduction study findings were included in the analyses. Sural sparing pattern was considered as the absence of median/ulnar compound nerve action potential (CNAP) and present sural nerve CNAP (SS-M/SS-U).&#x0D; Results: Twelve AIDP and 10 Axonal GBS patients were included in the study. MRC scores were not different between the two groups (p=0.895). CNAPs of the right median and ulnar nerves were smaller in AIDP patients than in Axonal GBS patients (p

Study of ultrasound and nerve electromyogram in diagnosis of carpal tunnel syndrome and its severity in the elderly

ABSTRACT Objective: To explore the diagnostic value of ultrasound and nerve electromyography (EMG) in the diagnosis of carpal tunnel syndrome (CTS) and its severity in the elderly. Methods: The data of 140 elderly CTS patients were retrospectively analyzed. The data of 80 patients with other diseases with similar symptoms and high suspicion of CTS during the same period were retrospectively analyzed. Pearson method was used to analyze the correlation between cross-sectional area (CSA) and motor nerve conduction velocity (MCV), distal motor latency (DML), compound muscle action potential (CMAP), sensory conduction velocity (SCV), middle-latency (ML) and sensory nerve action potential (SNAP) levels. The value of CSA, MCV, DML, CMAP, SCV, ML and SNAP in the diagnosis of CTS and its severity was analyzed by receiver operating characteristic (ROC) curve. Results: CSA in mild, moderate and severe groups was positively correlated with DML (P < 0.001) and negatively correlated with CMAP (P < 0.001). The area under the curve (AUC) values of CSA, MCV, DML, CMAP, SCV, ML and SNAP in the diagnosis of normal people and mild CTS were 0.877, 0.787, 0.921, 0.730, 0.860, 0.688 and 0.904. The AUC values of CSA, DML, CMAP, SCV, ML and SNAP in the diagnosis of mild and moderate CTS were 0.863, 0.890, 0.760, 0.848, 0.850 and 0.739, respectively. The AUC values of CSA, MCV, DML and CMAP in the diagnosis of mild and moderate CTS were 0.683, 0.660, 0.870 and 0.693. Conclusion: Ultrasound and nerve EMG are effective in the diagnosis of CTS.

Impacts of whole-body vibration on denervated skeletal-muscle atrophy in rats.

Whole-body vibration has been considered as a countermeasure against muscle atrophy. However, its effects on muscle atrophy are poorly understood. We evaluated the effects of whole-body vibration on denervated skeletal muscle atrophy. Whole-body vibration was performed on rats from Day 15 to 28 after denervation injury. Motor performance was evaluated using an inclined-plane test. Compound muscle action potentials of the tibial nerve were examined. Muscle wet weight and muscle fiber cross-sectional area were measured. Myosin heavy chain isoforms were analyzed in both muscle homogenates and single myofibers. Whole-body vibration resulted in a significantly decreased inclination angle and muscle weight, but not muscle fiber cross-sectional area of fast-twitch gastrocnemius compared to denervation only. In denervated gastrocnemius, a fast-to-slow shift was observed in myosin heavy chain isoform composition following whole-body vibration. There were no significant changes in muscle weight, muscle fiber cross-sectional area, and myosin heavy chain isoform composition in denervated slow-twitch soleus. These results imply that whole-body vibration does not promote recovery of denervation-induced muscle atrophy.

Six-month periodic fasting does not affect somatosensory nerve function in type 2 diabetes patients.

Current strategies for preventing diabetic sensorimotor polyneuropathy (DSPN) are limited mainly to glucose control but rapid decrease of glycemia can lead to acute onset or worsening of DSPN. The aim of this study was to examine the effects of periodic fasting on somatosensory nerve function in patients with type 2 diabetes (T2D). Somatosensory nerve function was assessed in thirty-one patients with T2D (HbA1c 7.8 ± 1.3% [61.4 ± 14.3 mmol/mol]) before and after a six-month fasting-mimicking diet (FMD; n=14) or a control Mediterranean diet (M-diet; n=17). Neuropathy disability score (NDS), neuropathy symptoms score (NSS), nerve conduction velocity and quantitative sensory testing (QST) were analyzed. 6 participants of the M-Diet group and 7 of the FMD group underwent diffusion-weighted high-resolution magnetic resonance neurography (MRN) of the right leg before and after the diet intervention. Clinical neuropathy scores did not differ between study groups at baseline (64% in the M-Diet group and 47% in the FMD group had DSPN) and no change was found after intervention. The differences in sensory NCV and sensory nerve action potential (SNAP) of sural nerve were comparable between study groups. Motor NCV of tibial nerve decreased by 12% in the M-Diet group (P=0.04), but did not change in the FMD group (P=0.39). Compound motor action potential (CMAP) of tibial nerve did not change in M-Diet group (P=0.8) and increased in the FMD group by 18% (P=0.02). Motor NCV and CMAP of peroneal nerve remained unchanged in both groups. In QST M-diet-group showed a decrease by 45% in heat pain threshold (P=0.02), FMD group showed no change (P=0.50). Changes in thermal detection, mechanical detection and mechanical pain did not differ between groups. MRN analysis showed stable fascicular nerve lesions irrespective of the degree of structural pathology. Fractional anisotropy and T2-time did not change in both study groups, while a correlation with the clinical degree of DSPN could be confirmed for both. Our study shows that six-month periodic fasting was safe in preserving nerve function and had no detrimental effects on somatosensory nerve function in T2D patients. https://drks.de/search/en/trial/DRKS00014287, identifier DRKS00014287.

Impact of cannabidiol and lamotrigine on parameters of action potentials in sciatic nerves of frogs

Cannabidiol causes inhibitory effects on sodium channels, but its action on nerve impulses is not understood. Lamotrigine blocks the nerve impulses, however, it is not known if this action is of extracellular or intracellular origin. With the use of nerve chambers, we are hoping to elucidate this unknown mechanism. We hypothesize that these two chemicals may modify components of action potentials of nerve fibers in frogs. Action potential recording was made possible by the IWorx Data Quest system and a nerve chamber. Action potential data was analyzed by looking at two different components—the peaks of depolarization and the difference between the peak of depolarization and the nadir of repolarization. For every 50 minutes of recording, the data was divided into three clusters—before chemicals, after 10 minutes of treatment, and 30 minutes after treatment. In frogs, we found the high dosage (1.0 milligram/milliliter (mg/mL)) of cannabidiol had no effect on the maximum amplitude of depolarization among the three data clusters—saline, 10 minutes after cannabidiol, and 30 minutes after cannabidiol. The high dosage of cannabidiol also had no effect on the repolarization of action potentials when compared among the above three data clusters. In addition, in frogs we found the low dosage (0.1 mg/mL) of cannabidiol showed a significant difference in the maximum amplitude of depolarization when the saline data cluster was compared to the 10-minute cluster after cannabidiol cluster. Likewise, there was a significant difference on the repolarization of action potentials when the saline data cluster was compared to the 10-minute cluster after cannabidiol cluster and when the 10-minute cluster was compared to the 30-minute cluster after cannabidiol cluster. High dosage of lamotrigine showed a significant difference on the maximum amplitude of depolarization when the saline cluster was compared to the 10-minute cluster after lamotrigine on action potentials. Low dosage of lamotrigine data is currently being collected to be analyzed and presented cumulatively with all the data. This research is being supported and funded by the Department of the Biological Sciences at the University of Tennessee at Martin. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Sex-specific impact of aging on muscle sympathetic neural discharge patterns during incremental rhythmic handgrip exercise

Sex-disparities exist in the risk of developing hypertension throughout the lifespan, with a greater prevalence of hypertension amongst postmenopausal females compared to similarly aged males. Though the underlying mechanisms are multifactorial, exaggerated sympathetic neuro-cardiovascular reactivity may be an important contributor. Indeed, postmenopausal females exhibit exaggerated exercise pressor responses compared to young adults, and older males. However, the interactive effects of age and sex on muscle sympathetic nerve activity (MSNA) and action potential (AP) coding patterns during exercise remains unclear. We hypothesized that older females would exhibit the greatest increase in MSNA and AP recruitment during exercise and post-exercise circulatory occlusion (PECO) relative to young males and females, as well as older males. MSNA and AP discharge patterns (microneurography and continuous wavelet transform) were assessed in 12 young males (YM (mean±SD); 26±4, years), 11 young females (YF; 25±4 years), 11 older males (OM; 71±11 years), and 12 older females (OF; 71±4 years) during incremental rhythmic handgrip exercise to fatigue followed by 2 minutes of PECO. At peak exercise, OM demonstrated a smaller change from baseline (Δ) in MSNA burst incidence (BI) compared to all other groups (YM: Δ8±9, YF: Δ9±8, OM: Δ-6±8, OF: Δ6±7 bursts/100heartbeats; all ANOVA post-hoc P&lt;0.05), whereas ΔMSNA burst frequency (BF), Δburst amplitude (BA), and Δtotal activity were not different between groups (all P&gt;0.05). Conversely, YM demonstrated greater ΔAPs/burst (YM: Δ5±3, OM: Δ0.4±3, OF: Δ2±2 APs/burst; post-hoc P&lt;0.05) and ΔAP clusters/burst (YM: Δ2±1, OM: Δ0.1±1, OF: Δ0.7±0.7 Clusters/burst; post-hoc P&lt;0.05) compared to OM and OF, but not compared to YF (Δ2±3 APs/burst and Δ0.9±0.8 clusters/burst; both P≥0.07). However, no group differences were observed in the recruitment of larger axons (YM: Δ6±2, YF: Δ4±2, OM: Δ2±5, OF: Δ4±3 clusters; P=0.33). Contrary to exercise, group-by-time interactions existed during PECO for ΔMSNA BF ( P&lt;0.01), ΔBI ( P&lt;0.01), and Δtotal activity ( P&lt;0.01) where greater increases occurred during the first minute of PECO in young compared to older adults (all post-hoc P&lt;0.05), whereas in the final minute of PECO, MSNA ΔBF and ΔBI were only greater in YM compared to OM and OF (all P&lt;0.05), and total activity was greater in YM and YF compared to OF only (all P&lt;0.05). No group-by-time interactions were observed for ΔMSNA BA ( P=0.37), ΔAPs/burst ( P=0.94), ΔAP clusters/burst ( P=0.95) or Δtotal AP clusters ( P=0.41) during PECO. Altogether, MSNA and AP reactivity during exercise was not exaggerated in OF, but age-related reductions in AP recruitment were observed in males. During PECO, MSNA responses were lower in older relative to young adults but, AP recruitment was unaltered by age. Thus, exaggerated MSNA or AP reactivity may not explain the greater prevalence of hypertension in OF. Supported by the Natural Sciences and Engineering Council of Canada, and IEEM Indirect Funds. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Causes of Dorsal Cutaneous Branch of the Ulnar Nerve Neuropathy Among Patients Undergoing Electrodiagnostic Studies: A Series of 14 Patients.

Isolated neuropathy of the dorsal cutaneous branch of the ulnar nerve (DCBUN) is rare and most cases are secondary to trauma, often iatrogenic.The topography of sensory abnormalities and abnormal electrodiagnostic (EDX) findings are crucial in confirming DCBUN neuropathy. Materials and methods: This is a retrospective study of patients with isolated involvement of the DCBUN from among patients referred for EDX studies for upper extremity symptoms.All patients underwent a focused neurological examination followed by EDX studies.Ultrasound (US) studies were performed in two patients. Results: Of the 14 patients with DCBUN neuropathy, decreased pinprick sensation in the distribution of the DCBUN was noted in 11 (78%) patients.DCBUN sensory nerve action potential (SNAP) was not recordable in 13 (92%) patients.In one patient who had a recordable SNAP, the latency was prolonged, and the amplitude was decreased.Four (28%) patients had incidental EDX abnormalities suggestive of entrapment of the median nerve at the carpal tunnel.The most common cause of DCBUN neuropathy was trauma in 13 (92%) patients, of which eight were iatrogenic.No specific etiology was detected in one patient (7%).Of the two patients who underwent US studies, one had increased cross-sectional area (CSA) at the wrist with prominent fascicles and hyperechoic scar tissue, while the CSA was normal in the other patient. Although rare, DCBUN neuropathy can be readily confirmed by typical clinical features and EDX findings.Surgeons should be aware of the anatomy and clinical features of DCBUN neuropathy and avoid injuring the nerve during surgical procedures at the wrist and forearm.

Neuromuscular Disorders (Neuropathy and Myopathy) Associated with Late Onset of Stills Disease (P9-5.021)

<h3>Objective:</h3> NA <h3>Background:</h3> Adult-onset Still’s disease (AOSD) is a rare inflammatory disorder characterized by a classical triad of spiking fever, arthritis, and evanescent rash. Neurological involvement in AOSD is quite infrequent with reported prevalence less than 10%. <h3>Design/Methods:</h3> 52-year-old male with medical history of AOSD, obstructive sleep apnea and bipolar disorder presented to neurology clinic for muscle fatigue and weakness. Patient was diagnosed with AOSD based on Yamaguchi criteria. <h3>Results:</h3> Physical examination was notable for reduced sensation to light touch and pinprick in four toes bilaterally excluding 5th toe. Normal muscle tone, strength, and reflexes were noted. Cranial nerve examination was normal. Extended myositis panel was negative. Patient underwent MRI of the pelvis which showed mild to moderate myositis to the gluteal muscles and anterior compartments in bilateral thighs. Patient underwent EMG which demonstrated mildly prolonged peak latency with normal amplitude in sensory nerve action potential (SNAP) in right median nerve. Mildly slowed conduction velocity with normal distal latency and normal amplitude was also noted on compound muscle action potential (CMAP) in right median nerve. EMG of right lower extremity demonstrated increased recruitment of small amplitude short duration polyphasic MUAPs observed in the vastus lateralis and tibialis anterior muscles. The EMG findings were consistent with non-irritable myopathy. Given rest of the myositis work up was unremarkable, the presentation was likely related to neurological manifestations of ASOD. Patient was continued on prednisone ands weekly Tocilizumab. <h3>Conclusions:</h3> AOSD is a rare disorder pathophysiology for which is not completely understood. Neurological manifestation in AOSD have been reported occasionally including aseptic meningitis, cranial nerve palsy, encephalitis, and cerebral infarction. Case report of Parkinsonian symptoms associated with AOSD have also been reported. We here report myositis during the course of AOSD which has not been previously reported and hope to enhance information regarding the spectrum of neurological involvement in AOSD <b>Disclosure:</b> Dr. Khosa has nothing to disclose. Dr. Khosa has nothing to disclose. Dr. Mishra has nothing to disclose. Dr. Trikamji has nothing to disclose. Dr. Freundlich has nothing to disclose.

MRI negative Varicella zoster virus (VZV) plexopathy in a young man with history of malignancy (P2-4.001)

<h3>Objective:</h3> To emphasize the importance of including VZV plexopathy in differential diagnosis in young individuals and to prevent the delay in diagnosis and treatment <h3>Background:</h3> VZV-associated plexopathy in mainly patients over 60 years old. Post herpetic neuralgia is a well-known complication of Herpes Zoster (HZ), however segmental zoster paresis secondary to HZ was reported in 1–20% of the cases in literature. MRI findings may be positive in up to 70% of the patients. <h3>Design/Methods:</h3> N/A <h3>Results:</h3> 43 years-old man with history of grade 2 left frontal oligodendroglioma which was treated with 2 partial resections, radiation and adjuvant procarbazine/lomustine presented with left upper extremity pain and developed a blistering rash in dermatomal pattern in left proximal upper extremity 2 weeks after the initial symptoms. He was diagnosed with shingles and treated with steroids and acyclovir with minimal improvement. 6 weeks after presentation, physical exam revealed left deltoid, supraspinatus and infraspinatus weakness with normal muscle stretch reflexes and decreased sensation on C5 dermatome. EMG revealed absent left lateral antebrachial cutaneous sensory nerve action potentials (SNAP) amplitude, and a small left radial SNAP amplitude compared to the right side. Evidence of ongoing denervation with reinnervation was seen in the left upper trunk supplied muscles. MRI of the brachial plexus was negative for any abnormalities. Patient was diagnosed with VZV-associated plexopathy, improved with pregabalin and physical therapy. <h3>Conclusions:</h3> Our patient was significantly younger than expected in HZ group. MRI usually shows T2 hyperintensities and thickening of the nerve roots in patients with VZV-associated plexopathy. However, the presentation, onset of symptoms, characteristics of the rash and clinical course was diagnostic of HZ, and the weakness pattern, supported by the EMG findings were diagnostic for VZV-associated plexopathy. <b>Disclosure:</b> Dr. Gul has nothing to disclose. Ms. Ahmed has nothing to disclose. Dr. McGraw has nothing to disclose. Dr. Alshiekh Nasany has nothing to disclose.

Etiological study of superficial radial nerve neuropathy: series of 34 patients.

Superficial radial nerve (SRN) neuropathy is a rare focal neuropathy leading to pain and paresthesia of the dorsolateral aspect of the hand. Reported causes include trauma, extrinsic compression, or it may be idiopathic. We describe the clinical and electrodiagnostic (EDX) features of 34 patients with SRN neuropathy of varied etiology. This is a retrospective study of patients with upper limb neuropathy referred for EDX studies who were found to have SRN neuropathy based on clinical and EDX findings. Twelve patients also had ultrasound (US) evaluations. Decreased pinprick sensation was noted in the distribution of the SRN in 31 (91%) patients, and a positive Tinel's sign was observed in 9 (26%). Sensory nerve action potentials (SNAPs) were not recordable in 11 (32%) patients. Of the patients who had a recordable SNAP, the latency was delayed, and the amplitude was decreased in all cases. Of the 12 patients who underwent US studies, 6 (50%) had an increased cross-sectional area of the SRN at or immediately proximal to the site of injury/compression. A cyst was located adjacent to the SRN in 2 patients. The most common cause of SRN neuropathy was trauma in 19 (56%) patients, of which 15 were iatrogenic. A compressive etiology was identified in 6 patients (18%). No specific etiology was detected in 10 patients (29%). This study is aimed at raising the awareness among surgeons about the clinical features and varied causes of SRN neuropathy; such knowledge may potentially lessen iatrogenic causes of injury.

Effects of Nitric Oxide on the Activity of P2X and TRPV1 Receptors in Rat Meningeal Afferents of the Trigeminal Nerve.

Nitric oxide is one of the endogenous molecules that play a key role in migraine. However, the interaction between NO and the main players in the nociceptive activity of the meningeal trigeminal afferents-TRPV1 and P2X3 receptors-remains unstudied. In the current project, the effects of acute and chronic NO administration on the activity of TRPV1 and P2X3 receptors in the peripheral afferents were studied using electrophysiological recording of action potentials of the trigeminal nerve in the rat hemiskull preparations. The data obtained indicate that exogenous and endogenous NO increased the activity of the trigeminal nerve independent on the inhibition of the TRPV1 and P2X3 receptors. The activity of the trigeminal nerve triggered by ATP changed neither in acute incubation in the NO donor-sodium nitroprusside (SNP) nor in the chronic nitroglycerine (NG)-induced migraine model. Moreover, the chronic NG administration did not increase in the number of degranulated mast cells in the rat meninges. At the same time, the capsaicin-induced activity of the trigeminal nerve was higher with chronic NO administration or after acute NO application, and these effects were prevented by N-ethylmaleimide. In conclusion, we suggested that NO positively modulates the activity of TRPV1 receptors by S-nitrosylation, which may contribute to the pro-nociceptive action of NO and underlie the sensitization of meningeal afferents in chronic migraine.

Gadolinium enhancement in cervical dorsal roots in a patient with acute autonomic and sensory neuropathy: a case report

BackgroundWe report an enhancement of the dorsal roots on gadolinium-enhanced cervical magnetic resonance imaging (MRI) in a patient with acute autonomic and sensory neuropathy (AASN).Case presentationA 38-year-old woman visited our university hospital for dizziness and fainting while rising from sitting or lying down and a tingling sensation in the whole body, including her limbs, torso, and abdomen, which was sustained for 15 days. The patient had hyperalgesia in nearly her entire body and slight motor weakness in her bilateral upper and lower limbs. Autonomic dysfunction was confirmed using autonomic testing. Furthermore, the nerve conduction study showed an absence of sensory nerve action potentials in all evaluated peripheral nerves. Cervical MRI was performed 18 days after dysautonomia onset. In the axial T1-gadolinum-enhanced MRIs, enhancement in cervical ventral and dorsal nerve roots and the posterior column of the spinal cord were observed, and the axial T2-weighted MRI showed high signal intensity in the posterior column of the cervical spinal cord. Considering the clinical, electrophysiological and imaging findings, the patient was diagnosed with AASN. A total dose of 90 g (2 g/kg) of intravenous immunoglobulin was administered over 5 days. At the follow-up at 4 years after AASN symptom onset, the hyperalgesia and orthostatic hypotension symptoms improved. However, her systolic blood pressure intermittently decreased to < 80 mmHg.ConclusionGadolinium-enhanced MRI may facilitate the accurate and prompt diagnosis of AASN.

Anti-cancer therapeutic agents and carpal tunnel syndrome: Clinical, electrodiagnostic, and ultrasound findings in seven patients.

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy and rarely develops after drug therapy. This study describes the clinical, electrodiagnostic (EDX), and ultrasound (US) findings in seven patients who experienced CTS due to anti-cancer therapeutic agents. All patients underwent EDX testing, and four patients had an US study. CTS occurred in four patients with aromatase inhibitors, two with immune checkpoint inhibitors, and one with a selective estrogen receptor modulator. The mean duration between initiation of the anti-cancer therapeutic agents and symptom onset was 6 weeks (range: 2-12 weeks). Decreased digit sensation was noted in all patients; wasting and weakness of the abductor pollicis brevis (APB) was observed in three (42.8%) patients. The compound muscle action potentials (CMAP) of the APB and sensory nerve action potentials of the second or third digit could not be recorded in two (28.5%) and four (57.1%) patients, respectively. The needle EMG detected fibrillations and positive sharp waves in the APB in two patients. The motor unit potentials of the APB were decreased with large polyphasics in three (42.8%) patients. Of the four patients who underwent US testing, all had increased cross-sectional area of the median nerve at the carpal tunnel inlet, three (75%) had thenar muscle atrophy, and two (50%) had a loss of fascicular pattern. Three (42.8%) patients underwent a CTR. Physicians should be cognizant of the relationship between anti-cancer therapeutic agents and CTS. EDX studies and US play important roles in the diagnostic assessment of such patients.