Left Sural Nerve Research Articles

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<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.

Neurofilaments As Serum Biomarkers of Brentuximabvedotin-Induced Peripheral Neurotoxicity in CD30 + Lymphoma Patients: A Prospective Single-Center Study

Introduction: Brentuximab vedotin (Bv) is increasingly being used for the treatment of CD30+ lymphomas, being Bv-induced peripheral neurotoxicity (BvPN) one of the greatest concerns for treating physicians. The mechanisms of BvPN are still partially known, and currently, no biomarker to predict this side effect and its severity is available. Neurofilament (NfL) is a neuron specific protein; high levels can be detected in peripheral blood with ongoing neuronal damage. It can be useful to quantify the extend of chemotherapy induced peripheral neurotoxicity due to axonal injury but its role in early detecting and predicting severity of BvPN is unknown. The objective of this study is to determine the association between pNfL and BvPN in lymphoma patients receiving Bv. Methods: This is anobservational prospective study that includes patients treated with Bv as a single drug (n=12, 30%) or in combination with other chemotherapy agents (n=28, 70%), being neurotoxic chemotherapy drugs in 15 out of 28 (53,5%). Patients were recruited from January 2021 to June 2023. All patients were assessed using the Total Neuropathy Score (TNS), which measures the severity of peripheral nerve damage (higher values equals worse neuropathy) and the Common Toxicity Criteria for Adverse Events toxicity scale at the following timepoints: before, periodically (every 1-2 cycles), and at three, six and twelve months after the end of Bv-based treatment. Nerve conduction studies (NCS) in upper and lower limbs before and after Bv-based treatment were performed. Serial pNfL were collected at the same timepoints and quantified using the SIMOA technique. Changes in pNfL were correlated with clinical data, depending on the degree of BvPN. Results: Fortypatients are included in the present analysis, with a predominance of males (n=22, 55%) and a median age of 47.5 [21-81] years. The majority of patients had Hodgkin lymphoma (HL, n=25, 62.5%), followed by mycosis fungoides (n=8, 20%) and peripheral T-cell lymphoma (n=7, 17.5%). Of the whole series, 85% of patients developed some degree of BvPN (55% grade 1, 30% grade 2). Baseline pNfL level was normal [15.09 ± 11.90 pg/mL] in most of the patients (n=35, 87.5%). and, as expected, they were correlated with age (r= 0.482, p=0.002) and the amplitude of the left (r= -0.408, p=0.048) and right (r= -0.380, p=0.061) sural (sensory) nerves. pNfL levels early increased with Bv-based therapy and rapidly decreased within the follow-up period (Figure). When completing half of the planned Bv-based therapy, the total increase in pNfL was significantly higher in those receiving combination schedules including other neurotoxic agents (40.07 vs 21.81 pg/mL, p<0.001), without differences according to BvPN development (p=0.7). At the end of treatment, no differences in pNfL were observed with regards to BVPN severity: No BVPN: 52.71±39.77 pg/mL; grade 1: 61.22 ±21.36 pg/mL, and grade 2: 55.46 ± 45.80 pg/mL. In all patients, TNS scores increased during treatment and decreased within the follow-up period (see Figure). Conclusion: NfL is a sensitive blood biomarker that dynamically responds to Bv-based therapy. Our results suggest that additional mechanisms beyond the axonal damage may be associated with BvPN. The present study provides new insights into the pathophysiology of BvPN.

A prospective observational study to assess peripheral neuropathy in patients receiving weekly paclitaxel chemotherapy

Background: Peripheral neuropathies are disorders of peripheral nerve cells and fibres. Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect of anticancer treatment, and it can affect the patient's long-term survival. The prevalence of CIPN is around 38%. Peripheral neurotoxicity (PN) is a side effect of paclitaxel that can lead to treatment discontinuation. The intensity and severity of neuropathy is more with patients receiving weekly paclitaxel chemotherapy. Methods: 60 patients of CA breast receiving weekly paclitaxel monotherapy who fulfilled inclusion and exclusion criteria were enrolled in the study. Clinical examination and grading of neuropathy was done according to NCI-CTCAE version 4.0. All patient had undergone nerve-conduction studies at baseline and 3 months after baseline. Results: 50% of patients, developed signs symptoms of peripheral neuropathy, out of which tingling sensation was the most common symptom (40%). The incidence of grade 1 peripheral neuropathy at 3 and 6 months were 35%, and 31.66%, while grade 2 neuropathy was noted in 18.33%, and 14.75% of patients, respectively. There was a significant difference in the SNAP value between baseline and 3 months for right ulnar nerve, right and left sural nerve and CMAP for right median nerve, right ulnar nerve, right and left tibial nerves which suggests development of neuropathy during 3 months of paclitaxel chemotherapy. Conclusions: This study provides information on the incidence and severity of peripheral neuropathy in patients receiving weekly paclitaxel chemotherapy, which can help physician in further management.

High intensity-transcutaneous electrical nerve stimulation does not inhibit temporal summation of the nociceptive flexion reflex

Pain facilitation contributes to chronic pain conditions. Transcutaneous electrical nerve stimulation (TENS) is used to alleviate pain. The effects of conventional TENS on chronic pain have been limited, and its effects on pain facilitation are controversial. Because the analgesic effects of TENS depend on the setting parameters (e.g., pulse intensities or treatment time), the optimal TENS settings to maximize analgesic effects under various pain conditions have been investigated. High-intensity TENS (HI-TENS), which involves tolerable-level pulse intensities for a short duration, is another conventional TENS method that used to alleviate pain. However, the effects of HI-TENS on pain facilitation remain unclear. The temporal summation of pain is widely used to evaluate pain facilitation, and the temporal summation-nociceptive flexion reflex (TS-NFR) is a neuropsychological parameter that can be used to evaluate pain facilitation. We aimed to investigate the effects of HI-TENS on the TS-NFR in healthy participants. Participants were randomly allocated into HI-TENS (n = 15) and control groups (n = 16). HI-TENS was administered at the left lateral lower leg for 1 min. The TS-NFR elicited by three noxious stimuluses at the left sural nerve was obtained from electromyography of the left biceps femoris. The nociceptive flexion reflex (NFR) was obtained by a single noxious stimulus. We measured the thresholds of the NFR and the TS-NFR at baseline and post-intervention. The application of HI-TENS significantly increased the NFR threshold (p = 0.013) but not the TS-NFR threshold (p > 0.05). These results suggest that HI-TENS does not inhibit pain facilitation.

Effect of Anaemia on Sensory Nerve Conduction in Diabetic Peripheral Neuropathy: A Cross-sectional Study

Introduction: Diabetic Peripheral Neuropathy (DPN) occurs in more than 50% of patients with Type 2 Diabetes Mellitus (T2DM). Though multi-factorial pathogenesis has been claimed for the occurrence of DPN, the exact mechanism is unclear. Recently, it was found that the prevalence of anaemia is two to three times higher in diabetic patients even with preserved renal function. Aim: To compare the sensory nerve conduction study variables such as latency (ms), amplitude (μV) and Nerve Conduction Velocity (NCV) (m/s) of the median, ulnar and sural nerves in DPN patients with anaemia to those without anaemia. Materials and Methods: This cross-sectional study was conducted in the Department of Neurology, PSG Hospital, Coimbatore, Tamil Nadu, India, December 2017 to December 2018 with 80 DPN subjects, included both males and females of age group from 35 to 70 years, grouped into those without anaemia (n=40) and those with anaemia (n=40). Subjects were considered to have anaemia based on the World Health Organisation (WHO) classification of haemoglobin. Sensory nerve conduction studies were performed on right and left median, ulnar and sural nerves. Logistic regression was performed in DPN without and with anaemia to rule out confounding variables. Independent t-test and Mann-Whitney U test were used to compare the variables between the groups with normal and skewed distribution, respectively. The p-value <0.05 was considered to be statistically significant. Results: Among 80 study participants, 38 (47.50%) were male and 42 (52.50%) were female. About 20 (50%) were male and 20 (50%) were female in group A (DPN without anaemia). Seventeen (42.50%) were male and 23 (57.50%) were female in group B (DPN with anaemia). Among DPN subjects with anaemia, 57.50% had mild anaemia and 42.50% had moderate anaemia. In the present study, normocytic normochromic anaemia was the predominant form of anaemia seen. NCV of right median nerve, right ulnar nerve, right sural nerve and left sural nerve were significantly reduced in DPN with anaemia when compared to DPN without anaemia with values <0.001, <0.001, 0.001 and <0.001, respectively. The amplitude of right sural nerve and left sural nerve were significantly reduced in DPN with anaemia, compared to DPN without anaemia with p-values <0.001 and 0.017, respectively. Conclusion: DPN patients with anaemia had lower NCV and amplitude of sensory nerves, when compared to those without anaemia. Hence, even mild to moderate anaemia could be a possible risk factor that exacerbates the severity of DPN.

Neurolymphomatosis in Recrudescent Diffuse Large B-cell Lymphoma.

Neurolymphomatosis is an uncommon manifestation of lymphoma, often presenting with painful polyneuropathy or polyradiculopathy and concomitant distal extremity weakness. Differentiation from other etiologies resulting in similar neuropathic symptoms such as compressive or inflammatory pathologies can be difficult and often results in delayed diagnosis. Here we describe a case of neurolymphomatosis affecting a 64-year-old man with a history of diffuse large B-cell lymphoma (DLBCL) in remission presenting with a right-sided foot drop following a gunshot wound. MRI at that time demonstrated thickening and enhancement of the cauda equina nerve roots. Over the course of the subsequent eight months, he developed left lower extremity sensory symptoms, left-sided foot drop and signs of upper motor neuron involvement, including left facial weakness, dysphonia, and dysphagia. 18F-FDG PET/CT revealed intensely avid left lumbosacral nerve roots, bilateral lower extremity and left upper extremity neurovascular bundles. Left sural nerve biopsies showed infiltration of DLBCL and confirmed neurolymphomatosis. We highlight the role of 18F-FDG PET/CT, with histological verification, for the diagnosis of an extended course of neurolymphomatosis occurring in the absence of typical painful neuropathy but with cranial and peripheral neuropathies.

Shear Wave Elastography of the Sural Nerve in Healthy Subjects: A Pilot Study

The goal of this study is to evaluate the potential ability of shear wave elastography (SWE) to evaluate the sural nerve (SN) in healthy subjects. Methods and Results: Thirty-six SNs were evaluated in 18 healthy adult subjects. Subjects were examined in the prone position with the ankle in the neutral position, and the knees fully extended; a linear transducer was used [L18-4, MHZ] (EPIQ Elite SW 5.0.1, Philips). Nerve conduction studies were performed with the Nihon-Cohden Neuropack device. The mean cross sectional area of the SN at both sides was 4.03±1.16mm2. The mean shear elastic modulus of the right SN in the SA was 24.92±6.08 kPa, while in the LA it was 26.45±5.66 kPa. The mean shear elastic modulus of the left SN in the SA was 24.1±4.1 kPa [range 19-33.13], while in the long axis it was 23.9±4.9 kPa [range 16.4-30.77]. The cross sectional area of the SN correlated positively with height (P<0.05), weight (P<0.001), and body mass index (P<0.01). Conclusion: SWE could play a complementary role in future evaluation of SN pathologies.

Correlation of nerve conduction study parameters with thyroid hormone in newly diagnosed hypothyroid patients

Background: Thyroid hormones act on many organs including central and peripheral nervous system for maintaining metabolic homeostasis. Entrapment neuropathies are most common in hypothyroidism. Nerve conduction parameters are impaired even in newly diagnosed cases of hypothyroid. Aims and Objectives: This study aims to study the correlation between thyroid hormone and nerve conduction study (NCS) parameters in newly diagnosed hypothyroid patients. Materials and Methods: This cross-sectional, descriptive study included newly diagnosed hypothyroid patients (n=30; age: 31.96±9.12). In all subjects, NCS was performed in median, ulnar, tibial motor nerve and median, ulnar, sural sensory nerve using Nihon Kohden machine in Neurophysiology lab 2, B. P. Koirala Institute of Health Science. Thyroid function test (TFT) was analyzed by ELISA. The association between thyroid hormone and NCS parameters was done using Pearson’s correlation. Results: In NCS sensory parameters; SNAP amplitude of the left sural nerve showed significant positive correlation with t3 (lt; r=0.451, P=0.012). Among motor parameters, distal latency of left median nerve showed significant negative correlation with t3 whereas nerve conduction velocity of the left median nerve showed positive correlation with t3. In rest of the nerve, the association between NCS parameters and TFT (t3, t4, and TSH) parameters did not show any significant changes. Conclusion: Our study reveals that in newly diagnosed cases of hypothyroidism, nerve impairment occurs in which the left side is affected much earlier than right side and further its severity can be correlated with level of T3 rather than TSH.

P-PN021. A case series of cryoglobulinemia with different clinical presentations and different nerve conduction studies (NCS) findings

Introduction . Neuropathy in cryoglobulinemia can be due to hyperviscosity (type I) or non obstructive immune complex mediated inflammatory vasculitis (type II and III). Methods . Case series: Our first patient was a 72-year-old gentleman with 5-month duration of severe asymmetrical neuropathic pain and rapidly progressive weakness in right peroneal and bilateral ulnar distribution associated with significant weight loss and pain, but no sphincter and autonomic dysfunction. He denied fever, arthritis, Raynaud’s phenomenon, rash and edema. His NCS revealed bilateral ulnar and right peroneal neuropathy. Left sural nerve biopsy revealed vasculitis, and cryoglobulin was found to be positive. Myeloma panel was suggestive of Kappa monoclonal gammopathy with normal flow cytometry and bone marrow. We concluded it as cryoglobulinemic vasculitis with Kappa light chain MGUS presenting with mononeuritis multiplex. Second patient was a 56-year-old man, HCV treated one year ago with undetectable viral load currently, and had generalized Myasthenia Gravis, presented with burning sensation of bilateral feet and erythematous macules, blanching papules on ankles, arms with normal power and reflexes. Nerve conduction study was normal and supported the clinical diagnosis of small fiber neuropathy due to cryoglobulinemia with treated HCV. Third case, a 70-year-old lady, presented with tingling sensation of both lower limbs with impaired sensation of up to ankles, distal toes weakness (3/5) and absent ankle reflexes for 2 months. Her NCS showed distal sensorimotor axonal polyneuropathy. She was found to be anti-HCV positive and cryoglobulinemia with viral load of 1 × 10 6 IU/ml. All our patients had no history of exposure to heavy metals, metabolic, infection screening and ENA, ANCA, anti-CCP were negative and cryoglobulin was positive. Conclusion . Nerve conduction study can add to the clinical for diagnosis of various types of polyneuropathy (mononeuritis multiplex, large fiber peripheral neuropathy, small fiber neuropathy) as depicted in our cases.

FOOT DROP AFTER SPINAL ANAESTHESIA FOLLOWING EMERGENCY APPENDECTOMY

Spinal anesthesia is the preferred anesthetic technique for cesarean section. Neurological complications are very rare and often transient after spinal anesthesia. A 11-year old male child present with pain abdomen in emergency department and underwent emergency appendectomy on 12-07-2019. During operation spinal anesthesia was induced. On 15-07-2019 patients was discharged from hospital. Patient revisited Neurology OPD with complaints of Foot Drop on 31-07-2019. Patient investigated with MRI and Nerve Conduction Studies. On MRI was found diffuse disc bulge at L3, L4, L5 level causing bilateral neural foramina narrowing and in nerve conduction study was found neuropathy of left peroneal and sural nerves. Patient was treated conservatively. Foot drop is a neurological disorder, which occurs following natural childbirth and spinal anesthesia due to direct needle trauma or local anesthetic toxicity. This complication is transient and usually resolves within a few days

Normal neurophysiologic parameters of the sural nerve among adult healthy Sudanese population

Background: Nerve conduction studies (NCSs) are of central importance for the assessment of peripheral nervous system disorders. They help in the diagnosis, extent distribution of neural lesion as well as the prognosis of a disease process. The aim of this study is to establish normative NCS reference data of the sural nerve in Sudanese population for our EMG electrodiagnostic center; and to survey the effects of age, gender, height, weight and temperature on conduction Parameters. Methods: The study was conducted in Elmagzoub Neuroscience Electrodiagnostic Centre; supported by the Faculty of Medicine, National Ribat University, Khartoum, Sudan. NCSs were performed in 210 sural nerves of 105 adult healthy Sudanese subjects using standardized techniques. Results: The Right sural nerve SNAP parameters in the whole subjects were set as (mean ±standard deviation) for onset latency. peak latency, amplitude and conduction velocity. The values were 2.73±0.42 ms, 3.32±0.46 ms, 8.39±3.49 uV and 52.05±8.47 m/s, respectively. The Left sural nerve SNAP parameters in the whole study group were 2.71±0.50 ms, 3.29 ±0.52 ms, 8.54±4.56 uV and 52.66 ±8.95, respectively. Conclusion: The sural sensory nerve conduction parameters compared favorably with the existing literature. Age showed a positive correlation with latencies, and negative correlation with amplitude and velocity. Gender has conspicuous effect on all sural nerve conduction parameters. Height showed an effect on latency and conduction velocity whereas BMI revealed a negative correlation with amplitude and conduction velocity of sural nerve.

Calf Pain-Brazilian Jujitsu Fighter

HISTORY: 29 yo male Brazilian jujitsu fighter with a history of Henoch-Schonlein purpura and eczema presents to clinic for 6 months of right anterolateral calf pain without a clear injury. He reports constant, dull, aching pain, worse with dorsiflexion and resisted plantar flexion. He notes associated pitting edema, dry leathery skin, hypopigmentation, and hyperesthesia that began 3-4 months ago. He has stopped jujitsu due to symptoms. Tib-fib xrays and venous duplex were negative. He tried acetaminophen, ibuprofen, physical therapy, topical clobetasol, and oral prednisone with short-term improvement. PHYSICAL EXAMINATION: Skin of the anterolateral calf is indurated with hair loss, a leathery appearance, and areas of depigmentation. The distal lateral calf is warm and erythematous, with swelling posterior to the lateral malleolus. Tinel’s sign is negative at the fibular head. Pulses are normal bilaterally with ankle plantar and dorsiflexion. Ankle ROM is full. Light touch sensation is intact in L2-S2 dermatomes and strength is 5/5 in lower extremities. DIFFERENTIAL DIAGNOSIS: Complex regional pain syndrome, Cellulitis, Scleroderma, Eosinophilic fasciitis, Chronic exertional compartment syndrome, Vascular insufficiency TEST AND RESULTS: Lab work: inflammatory markers and rheumatologic labs negative except for elevated CK (356) of unknown significance. EMG/NCS: low amplitude right vs left sural sensory nerve suggesting sural neuropathy although within normal limits; no fibular neuropathy or radiculopathy. MRI right leg: nonspecific skin thickening of anterolateral shin with fascial edema and mild fibularis longus myositis. Skin biopsy: linear morphea versus eosinophilic fasciitis FINAL WORKING DIAGNOSIS: Segmental Linear Morphea (localized scleroderma) TREATMENT AND OUTCOMES: Dermatology referral led to biopsy; subsequently, treatment with PO methotrexate (MTX), high dose IV methylprednisolone for three cycles, and topical clobetasol ointment BID. UVA1 phototherapy was also started due to extensive disease and ankle and knee joint involvement. Subjective improvement in ROM, skin stiffness, and strength per patient after 2 cycles of methylprednisolone. Switched to SQ MTX for better absorption and lower cost. Patient continues to improve as he remains on the above treatment protocol.

Can Cobalamin prevent Oxaliplatin induced peripheral neuropathy?

Background and objectives:Peripheral neuropathy induced by oxaliplatin is one of the main reasons for discontinuing chemotherapy. In this article, we evaluated the role of vitamin B12 in the prevention of oxaliplatin-induced peripheral neuropathy. Methods: A prospective randomized interventional study was done from 1st January 2018 to 30th De- cember 2018, in which patients who were diagnosed with gastrointestinal cancer in Rizgary and Nanakali teaching hospitals that have been scheduled to receive oxaliplatin-based regimen were enrolled. Patients were divided into two groups: control group received chemotherapy only and prophylaxis group received chemotherapy with vitamin B12; each group included fifteen patients with no significant differences between the groups regarding age and gender. The prophylaxis group received vitamin B12 injection in scheduled periods. All Patients received at least a cumulative dose of 500 mg/m2 of oxaliplatin. Patients were evaluated by nerve conduction study, B12 level, and other laboratory tests. Results: Twenty-one patients completed the study. There was a significant decrease in the serum vitamin B12 level (601.84±398.43 to 363±337.31) post-chemotherapy among the control group. Among the prophylaxis group, the mean value of serum vitamin B12 increased significantly after chemotherapy. To summarize, there was a significant decrease in the amplitude of nerve conduction study in the control group as compared to the prophylaxis group espe- cially in left (11.85±6.84 to 8.14±5.36) and right (14.01±6.05 to 9.52±6.08) Sural nerves. Conclusions:Vitamin B12 injection had an important role in the prevention of development of chronic oxaliplatin-induced peripheral neuropathy.

Habituation of the Interlimb Reflex (ILR) Over the Biceps Brachii Muscle After Electrical Stimuli Over the Sural Nerve.

Up to now relatively little is known about interlimb reflexes (ILR). Especially it is not well known whether ILR may habituate or not to subsequent stimuli. The main aim of the present investigation was to explore the short term habituation behavior of ILR. The electromyogram was recorded over the tonically active biceps brachii (BB) muscle in 11 healthy subjects contralateral and ipsilateral to supramaximum electrical stimuli (9–12 mA) that were delivered at 1.0 and 0.4 Hz over the left sural nerve. In addition, a selective averaging method was used to investigate the influence of preceding stimuli on the ILR. Thus, 30 blocks of 3 subsequent stimuli were used. All 1st ILR of each block were averaged together. Averages were also obtained for 2nd and 3rd ILR. While ILR amplitudes gained significantly both ipsilateral and contralateral to the stimulus (p < 0.05) after train stimuli as compared with single stimuli, ILR amplitudes showed a significant decrease at 1.0 Hz versus 0.4 Hz stimuli. ILR amplitudes decreased significantly after the 2nd and 3rd stimulus relative to the 1st (p < 0.05). ILR can be recorded bilaterally remote from the stimulus site. Furthermore, ILR show clear short term habituation behavior.

P87-T Rapid recovery of motor and sensory conduction block in multifocal motor neuropathy

Background Multifocal motor neuropathy (MMN) almost purely involves motor nerve. About 20% MMN patients develop minor sensory symptoms in the course of disease. Material and method We reported a 62-year-old male who developed a slowly progressive asymmetrical limb weakness for five years. Motor nerve conduction studies showed definite CB in left median and ulnar nerves, and probable CB in right tibial nerve. Although the patient complained of no sensory symptom, sensory never conduction studies showed absent sensory nerve action potential (SNAP) for bilateral medial plantar and fibular nerves, left sural nerve and reduced amplitude for left median, ulnar and radial nerves. Conduction velocities were otherwise normal. One month after receiving intravenous immunoglobulin (IVIg), his weakness alleviated apparently. A substantial increase in motor amplitude recorded with stimulation at the PF indicated a partial reversal of CB. The SNAP amplitude of left median, ulnar and radial nerves increased more than 50% and the return of bilateral fibular nerve potentials provided evidence of reversible conduction failure in sensory nerves. We reviewed related literature for this performance. Result Three previously published studies reported such a decrease of SNAP amplitude in MMN patients. Such features suggest a more prominent axonal damage more than demyelination. The hyperpolarization of axolemma, resulting from axonal Na+/K+ pump inhibition at the lesion site and overactivity at the adjacent site may constitutes the prominent mechanism of CB. Conclusion Amplitude reduction of SNAP combined with motor CB, which recovered rapidly after IVIg, may suggest axonal damage rather than demyelination.

The nerve conduction study is the key tool for the assessment of a peripheral neuropathy after carbon monoxide intoxication in a young adolescent mimicking a central presentation

Background Peripheral neuropathy after carbon monoxide (CO) intoxication is rarely reported. A peripheral nerve dysfunction mimicking a central presentation has never been reported. Objectives To determine the place of nerve conduction studies (NCS) in the assessment of peripheral neuropathy following CO intoxication. Methods We reported the case of a young patient aged 21 years who was addressed to the electrophysiological department Sahloul to perform NCS one year after a severe CO intoxication. He developed during his hospitalization, a left hemiparesis (lower and upper limbs). The NCS was not performed at this time. The diagnosis was rhabdomyolysis complicated by an acute renal failure due to CO poisoning in a patient with central nervous system complication. Actually the physical examination revealed the left hemiparesis with conserved or even exaggerated reflexes. These clinical features were compatible with a central dysfunction. However, when performing NCS on the left side, sural, superficial peroneal, ulnar, and median sensory nerve action potentials were unobtainable, as well as peroneal and tibial compound muscle action potentials. Such findings evoke a diffuse peripheral neuropathy with axonal dysfunction. This association was not reported after CO intoxication. Results Although demyelinating neuropathy is the mostly common reported form of neuropathy after CO intoxication, axonopathy can also be occurred but needs more times to recover. Rhabdomyolysis and CO itself are the major factors leading to peripheral neuropathy. Conclusion A peripheral neuropathy mimicking a central presentation can occur after CO intoxication. Clinicians should be aware of the major implication of the peripheral nervous system in this context.

Hypertensive Neuropathy: A New Clinical Entity?

Hypertension is a main risk factor for stroke and vascular dementia and may cause important changes to the cerebrovascular tree, turning the brain more susceptible to infarcts, microaneurysms and ischemia. In spite of the well documented influence of hypertension on the brain, data on the sensitivity of peripheral nerves in hypertension is scarce. Our laboratory has been working for decades to help understanding how hypertension affects peripheral nerve morphology and function, using the spontaneously hypertensive rats (SHR) model. Spontaneously hypertensive rats (SHR), first inbred from Wistar Kyoto rats (WKY), are considered a good experimental model of human essential hypertension. The purpose of this study was to investigate the alterations on the morphology and morphometric data on sural, phrenic, vagus and recurrent laryngeal nerves of SHR, previous to the development of hypertension and with well‐established hypertension. Male and female SHR and normotensive WKY rats aged 5, 8 and 20 weeks (N = 6 in each group) were investigated. After arterial pressure and heart rate recordings in anesthetized animals, right and left sural, vagus, phrenic and recurrent laryngeal nerves were removed and prepared for epoxy resin embedding and light microscopy. Morphometric analysis was performed with the aid of computer software, and took into consideration the fascicle area and diameter, as well as myelinated fiber number, density, area and diameter. Nerves from young animals did not show differences between sides and genders. Significant differences were observed for the myelinated fiber number and density, comparing different genders of WKY and SHR in all nerves. Also, significant differences for the morphological (thickening of the endoneural blood vessel walls and lumen reduction) and morphometric (myelinated fibers diameter and G ratio) parameters of myelinated fibers were identified in nerves from adult hypertensive animals. Morphological exam of the myelinated fibers suggested the presence of a neuropathy due to hypertension in both SHR genders. These results indicate that hypertension altered important morphometric parameters related to nerve conduction in hypertensive animals. Moreover the comparison between males and females of WKY and SHR showed that the morphological and morphometric alterations due to hypertension are not gender related. The presence of a so called “hypertensive neuropathy” is documented with endoneural vascular lesions, axonal atrophy and loss of small myelinated fibers.Support or Funding InformationSupport: CNPq, FAPESP and FAEPAThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Contralateral segmental transcutaneous electrical nerve stimulation inhibits nociceptive flexion reflex in healthy participants.

Transcutaneous electrical nerve stimulation (TENS) is a non-invasive treatment to relieve pain. Contralateral TENS (i.e. TENS administered to the contralateral side of a painful body part) is beneficial when TENS cannot be directly applied to pain site, such as in cases of trauma. Although TENS produces segmental analgesia in an ipsilateral limb, it has been unclear whether TENS produces higher analgesic effects in the contralateral segmental area. The aim of the present study was to investigate the analgesic effects of TENS in contralateral segmental or extra-segmental areas on physiological and subjective pain outcomes, using a nociceptive flexion reflex (NFR) method. We randomly allocated 60 healthy participants to three groups: contralateral segmental TENS (CS-TENS); contralateral extra-segmental TENS (CE-TENS); and contralateral placebo TENS (CP-TENS). CS-TENS was applied to right superficial sural nerve and CE-TENS was applied to the right superficial femoral nerve, each for 30minutes. The magnitude of the NFR elicited by electrical stimulation of the left sural nerve was measured at baseline and at three subsequent 10-minute intervals. Subjective pain intensity was measured simultaneously with a visual analogue scale (VAS). At 30min, the NFR magnitude of CS-TENS group was significantly lower than that of the CP-TENS group (p=0.021). There were no significant differences in VAS scores among the groups at any time point. Our findings suggest that CS-TENS inhibited NFR. Although there was no significant between-group difference in subjective pain intensity, factors such as a placebo effect probably impacted it. Our findings provide support for the contralateral approach at stimulation sites when TENS cannot be directly administered to a pain site (e.g. due to disease or trauma).

Evaluation of Nerve Conduction Studies in Lower Limb in Acute Spinal Cord Injury Patients

Background: As the number of patients in spinal cord injury (SCI) is increasing day by day, the nerve conduction studies helps in forecasting functional recovery of patient. Aim and Objectives: The objective of this study was to assess the nerve conduction studies in lower limb in acute SCI patients. Material and Methods: An observational descriptive study was carried out on 35 patients of acute SCI patients who were between the age of 16 and 65 years by using RMS EMG EP Mark-II. Motor and sensory studies were performed on tibial, peroneal and sural nerve respectively. Parameters recorded were latency, amplitude and conduction velocity. Result: Mean latency and mean conduction velocity of tibial nerve (right and left) increase with subsequent follow up but this change were non significant. Increment in mean amplitude of right and left tibial nerve was statistically highly significant (p<0.001, p=0.03 for right, left respectively). Mean latency of right and left peroneal nerve increase in subsequent follow-up but this change is non- significant. Increment in mean conduction velocity and mean amplitude of peroneal nerve was statistically significant (p=0.003, p=0.004) for right and left respectively; p<0.001 for amplitude of peroneal nerve (right and left both). Mean latency of right and left sural nerve was increased in subsequent follow up visits but this change was not significant. Increment in mean conduction velocity and mean amplitude was statistically highly significant (p<0.001) for right and left both of sural nerve. Conclusion: It is concluded from this study is that impact of SCI on latency, amplitude and conduction velocity of tibial, peroneal and sural nerve is very detrimental at onset of injury. But with subsequent follow up it has improved significantly, which can be related with recovery of lower limb.

Clinical characteristics and risk factors of diabetic peripheral neuropathy of type 1 diabetes mellitus patients.

Small nerve fibers are more easily injured than large ones for diabetic peripheral neuropathy (DPN). The study investigated the characteristics and related risk factors of DPN of T1DM patients using nerve conduction velocity and CPT values, which provided evidences for its early diagnosis. 70 T1DM patients and 48 healthy volunteers were included. All subjects accepted nerve conduction velocity and CPT examinations for four limbs. Detailed clinical indicators were recorded. CPT values were compared between TIDM group and control group. The risk factors affecting DPN were further explored. Compared with the control group, CPT values under three frequencies were decreased in T1DM group. The abnormality rate of sural nerves was higher than that of median nerves (P<0.001). Median nerve dysfunction mainly presented as hypoesthesia under 250Hz and 5Hz current stimulus. And sural nerve dysfunction mainly presented as hyperesthesia under three frequencies. Compared with left median nerve, abnormal rate of right median nerve was higher under 2000Hz current stimulus (P=0.035). However, abnormal rate of left sural nerve was higher than that of right side under 250Hz and 5Hz current stimulus (P=0.001, <0.001). Duration, NDS scores and CPT values of right median nerve under 2000Hz current stimulus were independent risk factors of abnormal nerve conduction velocity. The study proved that DPN of T1DM are mainly lower limb-injured., amyelinated and thin myelinated nerve fiber-involved. CPT can be combined with traditional nerve conduction velocity examination, which will help the diagnosis of DPN of T1DM earlier and more comprehensively.