Erb's Point Research Articles

Mucopolysaccharidosis Type I (Hurler – Scheie Syndrome): Case Report

Background. Mucopolysaccharidosis type I (MPS I) is an inherited disease caused by pathogenic variants in the IDUA gene, which encodes the lysosomal enzyme alpha-L-iduronidase. This clinical case demonstrates the importance of diagnosing rare diseases when patients have phenotypic features indicating hereditary pathology presence. Phenotype changes can be so-called “red flag” that helps specialists suspect and diagnose lysosomal storage diseases. Clinical case description. The patient was observed with delayed psychomotor development; she also had hepatomegaly and on auscultation of the heart there was a functional systolic murmur above the apex and in the Botkin–Erb point on heart auscultation. Coarse “garholoid” facial features attracted attention at external examination: large nose, wide sunken nose bridge, macroglossia, thick lips, synophrysis, scaphocephaly, wide chest, and flat-valgus feet. Echocardiography has revealed mitral valve insufficiency and hardened valve leaflets. Ophthalmologist examination: hypermetropic astigmatism. Psychiatrist examination: mental and speech development delay. Enzymatic diagnostics: significant decrease in alpha-Liduronidase activity. No further examinations were carried out due to the onset of the COVID-19 epidemic and parents' doubts about the diagnosis. The patient was readmitted to the hospital at the age of 6 years due to aggravation of her condition. A molecular genetic study has revealed two pathogenic variants in the IDUA gene. Diagnosis of MPS I was established according to the clinical data, results of biochemical and molecular genetic studies. Conclusion. This clinical case demonstrates the classic course of MPS I with typical phenotypic signs and lesions in various organs and systems. The presented case demonstrates the importance of professional vigilance among doctors of various specialties regarding orphan diseases.

The difference in nerve ultrasound and motor nerve conduction studies between autoimmune nodopathy and chronic inflammatory demyelinating polyneuropathy.

Nerve enlargement has been described in autoimmune nodopathy and chronic inflammatory demyelinating polyneuropathy (CIDP). However, comparisons of the distribution of enlargement between autoimmune nodopathy and CIDP have not been well characterized. To fill this gap, we explored differences in the ultrasonographic and electrophysiological features between autoimmune nodopathy and CIDP. Between March 2015 and June 2023, patients fulfilling diagnostic criteria for CIDP were enrolled; among them, those with positive antibodies against nodal-paranodal cell-adhesion molecules were distinguished as autoimmune nodopathy. Nerve ultrasound and nerve conduction studies (NCS) were performed. Overall, 114 CIDP patients and 13 patients with autoimmune nodopathy were recruited. Cross-sectional areas (CSA) at all sites were larger in patients with CIDP and autoimmune nodopathy than in healthy controls. CSAs at the roots and trunks of the brachial plexus were significantly larger in patients with anti-neurofascin-155 (NF155), anti-contactin-1 (CNTN1), and anti-contactin-associated protein 1 (CASPR1) antibodies than in CIDP patients. The patients with anti-NF186 antibody did not have enlargement in the brachial plexus. NCS showed more frequent probable conduction block at Erb's point in autoimmune nodopathy than in CIDP (61.9% vs. 36.6% for median nerve, 52.4% vs. 39.5% for ulnar nerve). Markedly prolonged distal motor latencies were also present in autoimmune nodopathy. Patients with autoimmune nodopathies had distinct distributions of peripheral nerve enlargement revealed by ultrasound, as well as distinct NCS patterns, which were different from CIDP. This suggests the potential utility of nerve ultrasound and NCS to supplement clinical characteristics for distinguishing nodopathies from CIDP.

Brachial Plexus Injury Influences Efferent Transmission on More than Just the Symptomatic Side, as Verified with Clinical Neurophysiology Methods Using Magnetic and Electrical Stimulation.

The variety of sources of brachial plexus injuries (BPIs) and the severity and similarity of their clinical symptoms with those of other injuries make their differential diagnosis difficult. Enriching their diagnosis with objective high-sensitivity diagnostics such as clinical neurophysiology may lead to satisfactory treatment results, and magnetic stimulation (MEP) might be an advantageous addition to the diagnostic standard of electrical stimulation used in electroneurography (ENG). The asymptomatic side in BPI cases sometimes shows only subclinical neurological deficits; this study aimed to clarify the validity and utility of using MEP vs. ENG to detect neural conduction abnormalities. Twenty patients with a BPI and twenty healthy volunteers with matching demographic and anthropometric characteristics were stimulated at their Erb's point in order to record the potentials evoked using magnetic and electrical stimuli to evaluate their peripheral motor neural transmission in their axillar, musculocutaneous, radial, and ulnar nerves. MEP was also used to verify the neural transmission in participants' cervical roots following transvertebral stimulations, checking the compatibility and repeatability of the evoked potential recordings. The clinical assessment resulted in an average muscle strength of 3-1 (with a mean of 2.2), analgesia that mainly manifested in the C5-C7 spinal dermatomes, and a pain evaluation of 6-4 (mean of 5.4) on the symptomatic side using the Visual Analog Scale, with no pathological symptoms on the contralateral side. A comparison of the recorded potentials evoked with magnetic versus electrical stimuli revealed that the MEP amplitudes were usually higher, at p = 0.04-0.03, in most of the healthy volunteers' recorded muscles than in those of the group of BPI patients, whose recordings showed that their CMAP and MEP amplitude values were lower on their more symptomatic than asymptomatic sides, at p = 0.04-0.009. In recordings following musculocutaneous and radial nerve electrical stimulation and ulnar nerve magnetic stimulation at Erb's point, the values of the latencies were also longer on the patient's asymptomatic side compared to those in the control group. The above outcomes prove the mixed axonal and demyelination natures of brachial plexus injuries. They indicate that different types of traumatic BPIs also involve the clinically asymptomatic side. Cases with predominantly median nerve lesions were detected in sensory nerve conduction studies (SNCSs). In 16 patients, electromyography revealed neurogenic damage to the deltoid and biceps muscles, with an active denervation process at work. The predominance of C5 and C6 brachial plexus injuries in the cervical root and upper/middle trunk of patients with BPI has been confirmed. A probable explanation for the bilateral symptoms of dysfunction detected via clinical neurophysiology methods in the examined BPI patients, who showed primarily unilateral damage, maybe the reaction of their internal neural spinal center's organization. Even when subclinical, this may explain the poor BPI treatment outcomes that sometimes occur following long-term physical therapy or surgical treatment.

Health Monitoring via Heart, Breath, and Korotkoff Sounds by Wearable Piezoelectret Patches.

Real-time monitoring of vital sounds from cardiovascular and respiratory systems via wearable devices together with modern data analysis schemes have the potential to reveal a variety of health conditions. Here, a flexible piezoelectret sensing system is developed to examine audio physiological signals in an unobtrusive manner, including heart, Korotkoff, and breath sounds. A customized electromagnetic shielding structure is designed for precision and high-fidelity measurements and several unique physiological sound patterns related to clinical applications are collected and analyzed. At the left chest location for the heart sounds, the S1 and S2 segments related to cardiac systole and diastole conditions, respectively, are successfully extracted and analyzed with good consistency from those of a commercial medical device. At the upper arm location, recorded Korotkoff sounds are used to characterize the systolic and diastolic blood pressure without a doctor or prior calibration. An Omron blood pressure monitor is used to validate these results. The breath sound detections from the lung/ trachea region are achieved a signal-to-noise ration comparable to those of a medical recorder, BIOPAC, with pattern classification capabilities for the diagnosis of viable respiratory diseases. Finally, a 6×6 sensor array is used to record heart sounds at different locations of the chest area simultaneously, including the Aortic, Pulmonic, Erb's point, Tricuspid, and Mitral regions in the form of mixed data resulting from the physiological activities of four heart valves. These signals are then separated by the independent component analysis algorithm and individual heart sound components from specific heart valves can reveal their instantaneous behaviors for the accurate diagnosis of heart diseases. The combination of these demonstrations illustrate a new class of wearable healthcare detection system for potentially advanced diagnostic schemes.

Features of damage to the conductive structures of the nervous system in patients with vibration disease, burdened with diabetes mellitus and metabolic syndrome

Introduction. Of interest are the processes developing in vibration disease (VD) in combination with metabolic syndrome (MS) or diabetes mellitus (DM), combined forms of diseases worsen their course and prognosis.
 The study aims to assess the features of the state of central afferent conductive structures and peripheral nerves in patients with vibration disease, burdened with diabetes mellitus or metabolic syndrome.
 Materials and methods. The scientists have examined 155 workers with VD — group one with an established diagnosis of VD (86 people); group two — with VD combined with DM (30 people); group three — with VD burdened with MS (39 people). The authors have conducted the electroneuromyographic examination and registration of somatosensory evoked potentials, with stimulation of the median nerve in the wrist. Abduction points — Erb point, cervical spinal cord, from the scalp of the projection area of the precentral gyrus. The researchers have applied multivariate discriminant analysis from the STATISTICA — version 6 application software package of StatSoft Inc (USA).
 Results. With VD complicated by MS, changes were in the distal part of the motor axons, with VD burdened with DM, the amplitude of the motor component of the median and tibial nerves decreased, the speed of the pulse in the proximal part of the median nerve. Somatosensory evoked potentials in VD in combination with MS revealed an increase in latency of N13 and N20. The duration of N13-N18, N13-N20, latency N18, N20, N30 increased in the case of WB, burdened with DM.
 Limitations. The limitation of the study is the use of unrelated samples for statistical analysis. The study of the state of central and peripheral conductive structures in connected samples should be considered evidence-based: metabolic syndrome and further — diabetes mellitus.
 Conclusion. The patterns of peripheral nerve damage in VD associated with exposure to general and local vibration, burdened with DM or MS, were disorders of afferent axons of the upper and lower extremities, as well as changes in the distal parts of the motor component of the tibial and median nerves. The features of the peripheral nerve states in VD, burdened with DM, were the complex involvement of the motor component in the pathological process, characterized by changes in the amplitude, pulse transit time at the level of the terminal unmyelinated fibers of the median and tibial nerves and changes in the proximal part of the median nerve. In VD complicated by MS, pathological changes were characteristic of the distal part of the motor axons. The patterns of afferent conductive structures lesion in VD, burdened with DM or MS, consisted in a violation of the activity of neurons of the cervical spinal cord and the somatosensory cortex. The peculiarity of the state of the central afferent conducting structures in VD, burdened with DM, was the slowing down of the afferent excitation wave in the area of thalamic structures to the somatosensory zone of the cortex, a violation of the conduction from the trunk to the cortical projections of the somatosensory zone. In case of VD, complicated by MS — the time of the afferent excitation wave at the level of the cervical spine and the somatosensory cortex.
 Ethics. Conclusion of the MEC of the Federal State Budgetary Scientific Institution "East Siberian Institute of Medical and Environmental Research" No. 32 dated 09.10.2019.

The Great Auricular Nerve Trigger Site: Anatomy, Compression Point Topography, and Treatment Options for Headache Pain.

Peripheral nerve decompression surgery can effectively address headache pain caused by compression of peripheral nerves of the head and neck. Despite decompression of known trigger sites, there are a subset of patients with trigger sites centered over the postauricular area coursing. The authors hypothesize that these patients experience primary or residual pain caused by compression of the great auricular nerve. Anatomical dissections were carried out on 16 formalin-fixed cadaveric heads. Possible points of compression along fascia, muscle, and parotid gland were identified. Ultrasound technology was used to confirm these anatomical findings in a living volunteer. The authors' findings demonstrate that the possible points of compression for the great auricular nerve are at Erb's point (point 1), at the anterior border of the sternocleidomastoid muscle in the dense connective tissue before entry into the parotid gland (point 2), and within its intraparotid course (point 3). The mean topographic measurements were as follows: Erb's point to the mastoid process at 7.32 cm/7.35 (right/left), Erb's point to the angle of the mandible at 6.04 cm/5.89 cm (right/left), and the posterior aspect of the sternocleidomastoid muscle to the mastoid process at 3.88 cm/4.43 cm (right/left). All three possible points of compression could be identified using ultrasound. This study identified three possible points of compression of the great auricular nerve that could be decompressed with peripheral nerve decompression surgery: Erb's point (point 1), at the anterior border of the sternocleidomastoid muscle (point 2), and within its intraparotid course (point 3).

Preoperative electrophysiologic assessment of C5-innervated muscles in predicting C5 palsy after posterior cervical decompression.

To investigate the feasibility of both needle electromyography (EMG) and proximal nerve conduction studies (NCS) in predicting C5 palsy after posterior cervical decompression. This study included 192 patients with cervical myelopathy undergoing laminoplasty or laminectomy. Preoperatively, all patients accepted bilateral needle EMG detection and proximal NCS that consisted of supramaximally stimulating Erb's point and recording compound muscle action potential (CMAP) from bilateral deltoid. In the present study, 11 (11/192, 5.7%) patients developed unilateral C5 palsy after operation, and more patients with C5 palsy showed abnormal spontaneous activity in C5-innervated muscles compared to those without C5 palsy (8/11 vs. 16/181, p < 0.05). The sensitivity and specificity of spontaneous activity in C5-innervated muscles in predicting postoperative C5 palsy were 72.7% and 91.2%, respectively. Furthermore, there were significant left-to-right differences of deltoid CMAP amplitudes between the patients with and without C5 palsy (p < 0.05), and this measurement was also demonstrated to be useful for distinguishing patients with C5 palsy from cases without C5 palsy by receiver operating characteristic (ROC) curve analysis (cut-off value: 2.1mV, sensitivity: 63.6%; specificity: 95.0%). In addition, the sensitivity and specificity of a series application of these two measurements were 63.6% and 100.0%, respectively. The findings of this study support the hypothesis that pre-existing progressive C5 root injury may be a risk factor for C5 palsy after posterior cervical decompression. Clinically, the estimation of NCS and needle EMG in C5-innervated muscles may provide additional useful information for predicting C5 palsy after cervical spinal surgery. Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

Cutaneous Vasculitis and Generalized Lymphadenopathy Associated with Extended-Spectrum Beta-Lactamase (ESBL)-Producing Escherichia coli Endocarditis: A Rare Case Report.

IntroductionInfective endocarditis (IE) has been known as the great imitator due to variable clinical manifestation, making its diagnosis challenging. A missed diagnosis could lead to inappropriate therapy. We presented a rare case of blood culture-negative infective endocarditis (BCNIE) due to extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli manifest with cutaneous vasculitis and generalized lymphadenopathy. We highlighted its diagnostic challenge and management.Case Illustration and DiscussionA 36-year-old male with known asymptomatic ruptured sinus of Valsalva (SOV) presented with fever of unknown origin for six months, fatigue, weight loss with a history of multiple hospitalizations. The physical examination revealed a continuous murmur at Erb's point, cutaneous vasculitis, and bilateral inguinal lymphadenopathy. The laboratory result was leukocytosis and elevated C-Reactive Protein (CRP). Generalized lymphadenopathy was detected from the thorax and abdominal Computed Tomography (CT) Scans. Positive Anti Nuclear Antibody (ANA) Indirect Immunofluorescence (IF) speckled pattern led us to consider an autoimmune as the etiology, but we still considered IE as a differential diagnosis due to history of structural heart disease. Detection of multiple tiny oscillating masses at the tricuspid valve from the echocardiogram and cardiac CT led to possible IE diagnosis. Negative three consecutive blood cultures led the diagnosis to BCNIE. Surgery was performed to evacuate the vegetations, repair the SOV, and tricuspid valve replacement with a bioprosthetic valve. These results in improvement of the patient’s condition. ESBL-producing Escherichia coli yielded in tissue culture made the diagnosis of IE became definite.ConclusionESBL-producing Escherichia coli should be considered as the etiology of BCNIE. Cutaneous vasculitis and generalized lymphadenopathy as a manifestation of IE could lead to diagnostic confusion. A thorough investigation will help clinician to avoid delay or inappropriate treatment that could be detrimental for the patient.

Peripheral, synaptic and central neuronal transmission is affected in type 1 diabetes

AimsWe hypothesized that adults with type 1 diabetes and severe polyneuropathy have alterations in neuronal transmission at different anatomical levels. The aims were to investigate upstream sensory neuronal activation in terms of peripheral, spinal, precortical, and cortical transmission. Methods48 participants with type-1 diabetes and polyneuropathy, and 21 age-matched healthy participants were included. Electrophysiological median nerve recordings were used to analyze peripheral transmission at Erb's point (P9-N11); spinal evoked potentials at Cv7 (P11-N14); subcortical evoked potentials at Oz (N14-P18); early cortical evoked potentials at CP5 (N20-P22); late cortical evoked potentials at C1 (N60-P80) and estimated cortical inter-peak latencies as measures of central conduction time. ResultsIn comparison to healthy, the presence of diabetes prolonged peripheral transmission at P9 and N11 (+0.49 ms, p = .000; +0.47 ms, p = .04, respectively), early cortical evoked potentials at CP5: N20 (+2.41 ms, p = .003) and P22 (+5.88 ms, p = .001) and cortical potentials at C1: N60 (+39.08 ms, p = .001) and P80 (+54.55 ms, p = .000) and central conduction time.Decreased amplitudes were shown peripherally (−2.13 μV, p = .000), spinally (−0.57 μV, p = .005) and pre-cortically (−0.22 μV, p = .004).In both healthy and people with diabetes increased central conduction time were associated with decreased parasympathetic tone (ρ = −0.52, p = .027; ρ = −0.35, p = .047, respectively). ConclusionNeuronal afferent transmission and brain responses were significantly impaired in diabetes and the presence of prolonged central conduction time is indicative of severe extensive neuronal damage.Trial registry number: EUDRA CT: 2013-004375-12; clinicaltrials.gov: NCT02138045.

Comparison of MRI and motor evoked potential with triple stimulation technique for the detection of brachial plexus abnormalities in multifocal motor neuropathy.

Conduction blocks (CB) are the diagnostic hallmark of multifocal motor neuropathy (MMN). Conventional nerve conduction studies cannot detect CB above Erb's point. Our purpose was to compare the performance of the motor evoked potential with triple stimulation technique (MEP-TST) and MRI in the detection of abnormalities of the brachial plexus. Examinations were performed on 26 patients with MMN (11 definite, 6 probable, 9 possible), of whom 7 had no CB. MEP-TST detected proximal CB in 19/26 patients. Plexus MRI showed T2 hyperintensity in 18/26 patients, with nerve enlargement in 14/18. A combination of both techniques increased the detection rate of brachial plexus abnormalities to 96% of patients (25/26). MEP-TST and MRI have high sensitivities for detecting brachial plexus abnormalities. A combination of the two techniques increases the detection rate of supportive criteria for the diagnosis of MMN.

Modified ischaemic nerve block of the forearm: use for the induction of cortical plasticity in distal hand muscles.

Ischaemic nerve block (INB) of the forearm rapidly reduces somatosensory input to a part of the body, which leads to the functional reorganization of the temporarily deafferented primary motor cortex (M1). We applied a novel modified INB (mINB) to the forearm, maintaining mean blood pressure, to assess cortical plasticity in the primary somatosensory cortex (S1) and the M1 regions associated with small hand muscles. S1 excitability was measured by median nerve somatosensory-evoked potentials (SEPs), while M1 excitability was evaluated by motor-evoked potentials (MEPS), using transcranial magnetic stimulation. The finding that S1 excitability increased and M1 excitability decreased after the mINB was removed reflects the differential short-term cortical plasticity of the S1 and M1 regions. These opposite effects observed for the S1 and M1 regions following the mINB may indicate a possible intra-hemispheric interaction between the S1 and M1 regions. Ischaemic nerve block (INB) causes short-term sensory deprivation, leading to functional reorganization in the deafferented motor cortex (M1). We used a modified INB (mINB) to evaluate cortical plasticity in the somatosensory cortex (S1) and M1 region associated with small hand muscles, because INB strongly inhibits muscles distal to the tourniquet. Thirty-three healthy adults participated in different combinations of four experiments. A pneumatic tourniquet was placed just below the right elbow and inflated to induce a mINB. We recorded the median nerve somatosensory- and motor-evoked potentials (SEPs and MEPs) before, during and after mINB placement and assessed spinal cord excitability using F-wave measurements. SEPs at Erb's point (N9) were abolished during the mINB; those at cortical N20 were suppressed. After removing the mINB, N20 amplitudes increased significantly, while those at N9 did not fully recover. P14 amplitudes after tourniquet deflation immediately recovered to baseline levels. M1-MEP amplitudes decreased during the mINB, and Erb-MEPs were suppressed. After the mINB was removed, M1-MEPs remained suppressed, while Erb-MEPs fully recovered. F-waves were not affected by the intervention. Therefore, sensory, but not motor, nerve function was affected by the mINB. S1 excitability was enhanced after the mINB was removed, indicating that S1 and M1 excitability were modulated in opposing directions after deflation. These after-effects may reflect isolated effects or interactions between the S1 and M1 regions. Our findings may facilitate improved understanding of the sensorimotor modulations that occur distal to the tourniquet due to temporal deafferentation and lead to development of novel neuromodulation protocols.

Diagnosis and treatment response in the asymmetric variant of chronic inflammatory demyelinating polyneuropathy.

The objectives were to (a) assess the diagnostic value of testing clinically affected and unaffected limbs with nerve conduction studies (NCS) in patients with the asymmetric chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) variant and to define the most useful strategy for diagnosis, and (b) describe treatment response and long-term outcome. We performed a retrospective study and included patients with a multifocal distribution of symptoms and signs, who met the probable or definite EFNS/PNS diagnostic categories for CIDP. We included 34 patients and 32 NCS datasets were available. Of these 32 patients, 25 (78%) met the electrodiagnostic criteria for definite or probable CIDP and seven (22%) for possible CIDP. Patients fulfilling the possible electrodiagnostic criteria and a supportive criterion were considered as probable CIDP. NCS of the clinically affected forearm and leg led to a probable or definite diagnosis in 13 patients (41%). Measuring both arms up to Erb's point led to a probable or definite diagnosis in 25 patients (78%), after which NCS of both legs did not contribute to additional probable or definite diagnoses. In total, 30% of patients treated with dexamethasone and 94% of patients treated with intravenous immunoglobulins (IVIg) responded. IVIg withdrawal attempts were successful in 21% of patients. After measuring the clinically affected arm up to Erb's point, NCS of the unaffected arm to Erb's point has the highest additional diagnostic yield in patients with asymmetric CIDP. Patients seem to respond better to IVIg than to corticosteroids and long-term treatment is often required, although IVIg withdrawal was successful in 21%.

P53-T Evaluation of atypical chronic autoimmune inflammatory polyneuropathies - clinical and neurophysiological comparison

Background Chronic autoimmune inflammatory polyneuropathies (CAIP) is a group of rare and potentially treatable conditions that are often underdiagnosed due to non-compatibility with recognized diagnostic criteria that might be partially related to incomplete neurophysiological investigation or lack of follow-up. Methods Case series study of 4 CAIP patients with atypical clinical and/or neurophysiological features. Results Case 1. 10 year history of distal weakness in upper extremities (UE), NCS – diffuse conduction slowing with conduction block (CB) and marked sensory involvement. Improvement with IVIG. Case 2. Slow progression of asymmetrical weakness in distal UE and right lower extremity (LE), NCS – axonal loss with CB in all extremities. No response to glucocorticoids, improvement on IVIG. Case 3. Progressive weakness in distal UE with marked sensory involvement and diffuse severe fasciculations, 1st ENMG – no CB, slight axonal loss with demyelination not below 75% of lower normal, slight sensory impairment, with diffuse fasciculations. Follow up ENMG – 1 definitive CB, 2 probable CB (1 in Erb point), with significant demyelination and sensory impairment in UE. Slight improvement with glucocorticoids. Case 4. Progressive asymmetrical tetraparesis LE > UE, with sensory signs proximally in LE and distally in UE and LE. NCS – axonal loss with conduction slowing not below 75% normal range, no CB, no increase in distal latencies, significant sensory nerve involvement. No improvement on IVIG, marked response to glucocorticoids. Conclusions NCS should be comprehensive, including proximal stimulations. Follow-up ENMG studies and immunomodulatory treatment should be considered in all patients with suspected CAIP.

Detection of axillary nerve multisegment motor nerve conduction using magnetic stimulation

Objective: To establish a method for detecting multi-segmental motor nerve conduction of axillary nerve using magnetic stimulation technique, and to preliminarily discuss its clinical application value. Methods: From April 2017 to February 2018, 80 healthy volunteers, 40 male and 40 female, were included and divided into five groups according to age and gender (groupⅠwere <35 years old; groupⅡwere 35-44 years old; group Ⅲ were 45-54 years old; groups Ⅳ were 55-64 years old; groups Ⅴ aged 65-74). Axillary nerve recording electrodes were placed in the deltoid muscle belly, reference electrode was placed in the deltoid muscle check point. Using the magnetic stimulation coil, stimulation was released at spots which were, respectively, 2 fingers from the lateral side of subscapular fossa, 2 fingers from the lateral side of infraclavicular fossae, and Erb's point. The latency, amplitude, detection distance (stimulation to recording electrode) were recorded at each spot, and the height and arm length were also measured. Results: The detection rate of axillary nerve waveform in healthy volunteers was 97.2%. There were no statistically significant differences in latency and amplitude in the different sides, gender (P>0.05).The latency corresponding to different detection distances was compared, and the difference was statistically significant (P<0.05).Height and arm length in different age groups were significantly increased in groupsⅠ, Ⅱ and Ⅲ compared with groups Ⅳ and Ⅴ, with statistical significance (P<0.05). When compared among different age groups, the latency and amplitude of group Ⅳand Ⅴ (more than 55 years old and over) were significantly prolonged and decreased, with statistically significant differences (P<0.05). Conclusions: The method of detecting multi-segmental magnetic stimulation of axillary nerve is stable and the result is reliable, which makes the evaluation of the proximal nerve of upper limbs be possible. However, the biological effects of age on nerve conduction should be carefully considered.

CSM 2019 American Academy of Sports Physical Therapy Poster Presentations (Abstracts SPO1–SPO132)

CSM 2019 American Academy of Sports Physical Therapy Poster Presentations (Abstracts SPO1–SPO132)

Auf den Spuren des Erb’schen Auskultationspunkts: Rätsel gelöst

"Erb's point" is the fifth point of auscultation for the heart exam, located in the third intercostal space close to the sternum. It has sometimes been attributed to famous German neurologist Wilhelm Heinrich Erb (1840 - 1921), but without historical evidence. Erb's focus on neurology suggested that the auscultation point may have been confused with other points in the neck named after Erb. As Erb was a specialist for neurological manifestations of syphilis, we speculated that the heart murmur of aortic incompetence produced by syphilitic aortitis, best heard at Erb's point, linked Erb's name to the auscultation point. However, we eventually found a publication by an American physician who visited Erb's lectures in Heidelberg and reported that Erb explicitly introduced this "fifth point" in his case presentations in the late 1890 s. After all, Erb was chair of general medicine, with the first German chair of neurology only being established in 1919.

Diagnosing chronic inflammatory demyelinating polyradiculoneuropathy with triple stimulation technique.

To assess the value of triple stimulation technique (TST) for diagnose of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Seven clinically suspected CIDP patients who did not fulfill EFNS/PNS electrodiagnostic criteria for demyelinating neuropathy were enrolled in our study. Routine nerve conduction studies, lumbar puncture, spinal cord magnetic resonance imaging and TST were detected. The patients were being treated with oral prednisone starting at 1mg/kg daily. The overall disability sum score was performed to evaluate the effect of corticosteroids. Twenty-eight motor nerves were tested with TST, two conduction blocks (CBs) were detected between the root emergence and the Erb point in six patients respectively and one CB was detected in one patient. Symptoms of all seven patients improved after treatment with oral prednisone. TST can detect CBs located between the root emergence and the Erb point. TST is useful for early diagnosis of CIDP.

Estimation of voluntary elicited motor neuron discharge using a peripheral nerve collision technique at different contraction strengths

ObjectiveTo estimate non-invasively the amount, recruitment pattern and discharge frequency of spinal motor neurons (MN) at contraction strength >20% of maximal voluntary contraction (MVC) of small hand muscles. MethodsA peripheral collision technique was used and consisted of supramaximal electrical stimuli at Erb's point and at the wrist, synchronizing descending volleys of action potential during voluntary isometric contractions of the abductor digiti minimi muscle at 20–80% of MVC strength and 1–8 s of contraction duration. Responses of 13 healthy volunteers were quantified and analysed using a recently described model of MN behaviour. ResultsA linear relationship between MN discharge and force generation was noticed with R2 = 0.996, and was confirmed using the simulation results (R2 = 0.997) for contraction durations up to 8 s. For each investigated force level, discharge frequency and recruitment pattern were calculated for individual MN. ConclusionsUsing this method, MN discharge properties during voluntary activity can be estimated non-invasively. SignificanceThis method provides new opportunities for the non-invasive study of MN behaviour, and could be expanded to patients with conduction failure and during fatigue.

Abnormal cortical brain integration of somatosensory afferents in ALS

ObjectivesInfraclinical sensory alterations have been reported at early stages of amyotrophic lateral sclerosis (ALS). While previous studies mainly focused on early somatosensory evoked potentials (SEPs), late SEPs, which reflect on cortical pathways involved in cognitive-motor functions, are relatively underinvestigated. Early and late SEPs were compared to assess their alterations in ALS. MethodsMedian and ulnar nerves were electrically stimulated at the wrist, at 9 times the perceptual threshold, in 21 ALS patients without clinical evidence of sensory deficits, and 21 age- and gender-matched controls. SEPs were recorded at the Erb point using surface electrodes and using a needle inserted in the scalp, in front of the primary somatosensory area (with reference electrode on the ear lobe). ResultsCompared to controls, ALS patients showed comparable peripheral (N9) and early cortical component (N20, P25, N30) reductions, while the late cortical components (N60, P100) were more depressed than the early ones. ConclusionsThe peripheral sensory alteration likely contributed to late SEP depression to a lesser extent than that of early SEPs. SignificanceLate SEPs may provide new insights on abnormal cortical excitability affecting brain areas involved in cognitive-motor functions.

The effect of shoulder position on motor evoked and maximal muscle compound action potentials of the biceps brachii.

The purpose of the study was to assess the effect of shoulder position, 0° versus 90° shoulder flexion, on stimulation intensity and maximal muscle compound action potentials (Mmax) and motor evoked potentials (MEP) of the biceps brachii during both rest and 10% maximum voluntary contraction (MVC). Nine participants completed two experimental sessions with four conditions. During each condition, transcranial magnetic (TMS) and Erb's point stimulation were used to elicit MEPs and Mmax, respectively. During rest, the TMS intensity to elicit a MEP response (p<0.001), was significantly lower by 28.6±6.8%, in the 90° compared to the 0° position, but the stimulation intensity to elicit a Mmax was not different. MEP (p<0.001) and Mmax (p<0.001) amplitudes were significantly higher by 212.4±43.3% and 86.5±38.0%, respectively in the 90° compared to the 0° position. During 10% MVC the Mmax stimulation intensity (p=0.022), but not TMS intensity, was significantly lower by 7.4±3.8% in the 90° compared to the 0° position. Mmax (p<0.001) amplitudes were significantly higher by 92.2±20.2% in the 90° compared to the 0° position whereas MEP (p<0.001) amplitudes were significantly lower by 24.5±6.0% in the 90° compared to the 0° position. In conclusion, TMS intensity and Mmax intensity were both shoulder-position and state-dependent, whereas MEP and Mmax amplitudes were only shoulder position-dependent.