P238 Homonymous Ib inhibition during remote muscle contraction

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Abstracts / Clinical Neurophysiology 128 (2017) e178–e303

with maximal power. ESI was performed using a distributed linear inverse solution and an individual head model. The solution point with maximal average power in the band of interest was selected as the source of focal slowing (ESI-FS). Finally, we computed the Euclidian distance between the ESI-FS and the nearest solution point included in the resection with a 5 mm margin. Results: In 11/16 (69%), ESI of focal slowing (ESI-FS) was inside the margins of resection. The remaining 5/16 cases had distances <15 mm. Discussion and Conclusions: These findings suggest that a ‘‘nonepileptiform” activity, such as focal slowing, could help to localize the epileptogenic zone. ESI-FS may aid presurgical lateralization in patients without focal interictal spikes improving the identification of possible good candidate for surgical treatment. Significance: The study provides a new quantitative marker of brain dysfunction in children, with a potential application to other neurological disorders, using a non-invasive tool as hdEEG.

Keywords: Focal slowing, Drug-resistant epilepsy doi:10.1016/j.clinph.2017.07.243

P236 Electrophysiological assessment of Guillain–Barre subtypes in a sample of IRAQI children—Lamees Al-Najafi 1, Safaa Ali 2, Najeeb Mohammed 1 (1 Baghdad College of Medicine, Department of Physiology, Baghdad, Iraq, 2 College of Medicine, University of Al mustansiriyah, Department of Physiology, Baghdad, Iraq) Objectives: Assess the role of neurophysiological study (EMG and NCS) in the diagnosis of Guillain-Barre syndrome subtypes in children and estimate the frequency of subtypes whether demyelinating or axonal. Methods: Two study groups of either sex were involved, (thirty) Guillain-Barre patients with different ages and (thirty) healthy subjects matched for age and gender served as control group. Each subject submitted to sensory and motor nerve conduction study (NCS) and electromyography (EMG) of both upper and lower limbs. Results: Results revealed that (80%), (16.7%), (3.3%) of children had acute inflammatory demyelinating polyneuropathy (AIDP), acute motor axonal neuropathy (AMAN) and acute motor sensory axonal neuropathy (AMSAN) respectively. The H-reflex was absent in (73.3%) of patients. Discussion: In this study AIDP was the most frequent type of GBS followed by AMAN then AMSAN, similarly a study from Iran reported that AIDP was the most frequent type among children, suggesting that; the incidence of AIDP in GBS differs geographically. H-reflex was absent in the majority (73.3%) of children, and this was lower than Gordon P.2001 where the absence of H-reflex was 97%, because of early time of examination. Conclusion: Acute inflammatory demyelinating polyneuropathy (AIDP) is the most frequent subtype of GBS, the change in sensory and motor NCS parameters was higher in lower limbs than upper limbs. Proximal segments are more vulnerable to demyelination rather than intermediate or distal nerve segments. Significance: The subtype differentiation is essential for the neurologist and the patient’s parents in identifying the recovery period. Keywords: GBS, NCS, AIDP doi:10.1016/j.clinph.2017.07.244

P237 Axonal excitability findings in type 1 diabetes mellitus – Median nerve versus tibial nerve comparison—Pinar Gencpinar 1, Gamze Celmeli 2, Abir Alaamel 3, Gizem Kızılay 3, Özgür Duman 4, Senay Haspolat 4, Hilmi Uysal 3,* (1 Izmir Katip Celebi University, Pediatric Neurology, Izmir, Turkey, 2 Akdeniz University, Pediatric Endocrinology, Antalya, Turkey, 3 Akdeniz University, Neurology, Antalya, Turkey, 4 Akdeniz University, Pediatric Neurology, Antalya, Turkey) Objective: Length dependent peripheral neuropathy is the most common complication of diabetes mellitus (DM). As no curative treatment for diabetic polyneuropathy (DMP) is available, its prevention and early detection is very important. Axonal excitability is defined as the capability of nodal and paranodal pathological changes in DMP. The aim of present study was to determine alterations in axonal excitability findings in tibial nerve by comparing median nerve axonal excitability findings in Type 1 DMP. Methods: The total 284 patients, who were followed up for Type 1 DM according to criteria of American Diabetes Association, were screened in this study. Six DMP patients, 10 random nonpolyneuropathy cases and 14 healthy control subjects were examined by threshold tracking method (TROND protokol) from median and tibial nerve. Results: Even if there is not prominent difference in median nerve axonal excitability studies in PNP and DM patients there was prominent pathological findings in tibial nerve. The strength–duration time constant was significantly longer in DPN Type 1 patients than in normal patients. Supernormality was significantly smaller in DPN patients. Threshold electrotonus studies showed abnormalities in patients with DPN that smaller threshold changes by long depolarizing and hyperpolarizing conditioning current named as ‘‘fanning-in”. Conclusion: This study confirms that there was significantly alteration in axonal excitability findings in DMP in tibial nerve. Comparisons median and tibial nerve axonal excitability findings have potential to show the length dependent polyneuropathic pathological status in axonal excitability studies. Keywords: Lenght dependent, Type 1 diabetes, Axonal excitability doi:10.1016/j.clinph.2017.07.245

Poster I. – Functional connectivity P238 Homonymous Ib inhibition during remote muscle contraction—Miklos Lukacs (Semmelweis Health Center and Teaching Hospital, Neurology, Miskolc, Hungary) Objective: Conflicting theoretical models exist regarding the mechanism related to the ability of the Jendrassek maneuvre to reinforce reflex parameters. Our objective was to investigate if eventually inhibition of the spinal Ib motoneurone during remote muscle contraction would contribute to H-reflex enhancement. Method: Soleus H-reflex from 26 healthy subjects was evoked on both sides by stimulating the tibial nerve at rest and during bilateral vigorous hadgrip. This procedure was repeated using paired stimulation at interstimulus intervals ranging from 2 ms to 15 ms. Mean conditioned H-wave amplitude expressed as a percentage of its unconditioned value (H-ratio) evoked during handgrip was compared with the H-ratio obtained at the same interstimulus interval at rest.

Abstracts / Clinical Neurophysiology 128 (2017) e178–e303

Results: The size of H-reflex evoked during handgrip was significantly higher then of that evoked at rest. The H-ratio value plotted against the interstimulus interval showed both at rest and during handgrip a similar decrease that was maximal at 5 ms and lasted less than 10 ms. Discussion: The size of the conditioned H-reflex is determined by the balance between test Ia excitation and Ib inhibition elicited by the conditioning stimulus. According to our results the interneurones intercalated in pathways from Ib afferents retain their inhibitory effect on the alpha motoneurone during remote muscle contraction. Conclusion: H-reflex enhancement during Jendrassek maneuvre is not due to inhibition of Ib interneurones. Significance: Further studies are needed in order to test the role of other spinal circuits or descending drives that produce subthreshold excitation of alpha motoneurones by remote muscle contraction. Keywords: H-reflex, Jendrassek maneuvre, Ib interneurone doi:10.1016/j.clinph.2017.07.246

P239 Muscle contraction does not always trigger the appearance of motor evoked potential polyphasia in healthy individuals— Stefani Stefani 1, Eleftherios Papathanasiou 2, Ioanna Kousiappa 3, Savvas Papacostas 2 (1 The Cyprus School of Molecular Medicine, Clinical Neurophysiology, Nicosia, Cyprus, 2 The Cyprus Institute of Neurology and Genetics, Clinical Neurophysiology, Nicosia, Cyprus, 3 The Cyprus Institute of Neurology and Genetics, Department of Neuroscience, Nicosia, Cyprus) Objective: Motor evoked potentials (MEP) using magnetic stimulation are a non-invasive method that assesses the integrity of the central motor pathway. A phase is a part of the motor unit action potential that falls between two baseline crossings. Previous studies suggest that voluntary muscle contraction increases the appearance of MEP polyphasia. In this study we examined healthy individuals with the use of MEP, in order to evaluate the probability of polyphasia appearance during both muscle contraction and relaxation. Methods: Thirty normal volunteers were studied with the use of MEP in two different stages; contracted and relaxed. Both stages were examined with the use of the circular coil and the contracted stage was also examined with the butterfly coil. With the circular coil, both upper and lower limbs were examined and with the butterfly coil only the upper limbs. The muscles examined were the abductor digiti minimi and the tibialis anterior. Results: Only four individuals (13.3%) were found to have polyphasia during the contracted state in the upper limbs using the butterfly coil and two additional individuals (6.7%) with the use of the circular coil during contraction of the tibialis anterior. Conclusion: No significant correlation was found between the voluntary contraction of target muscles and the appearance of polyphasia in the MEP. Significance: Our findings contradict the existing notion that voluntary muscle contraction increases the appearance of MEP polyphasia. Discussion: Future work examining both stages of all limbs with the butterfly coil may give more answers concerning polyphasia and coil choice. Keywords: Polyphasia, Motor evoked potential, Contraction doi:10.1016/j.clinph.2017.07.247

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P240 Gender differences in resting state functional brain networks—Francesca Miraglia 1, Fabrizio Vecchio 1, Paolo Maria Rossini 2 (1 IRCCS San Raffaele Pisana, Brain Connectivity Laboratory, Rome, Italy, 2 Università Cattolica del Sacro Cuore, Department of Neurology, Rome, Italy) Objectives: Aim of this study was to verify whether the topological organization of human brain functional networks is different for males and females in resting state EEGs. Methods: Undirected and weighted brain networks were computed by eLORETA lagged linear connectivity in 130 subjects (59 males and 71 females) within each hemisphere and in four resting state networks (Attentional Network (AN), Frontal Network (FN), Sensorimotor Network (SN), Default Mode Network (DMN)). Results: We found that small-world (SW) architecture in the left hemisphere Frontal network presented differences in both delta and alpha band, in particular lower values in delta and higher in alpha 2 in males respect to females while in the right hemisphere differences were found in lower values of SW in males respect to females in gamma Attentional, delta Sensorimotor and delta and gamma DMNs. Discussion: Gender small-worldness differences in some of resting state networks indicated that there are specific brain differences in the EEG rhythms when the brain is in the resting-state condition. Significance: The findings are consistent with the gender differences in behavioral and cognitive domains and might improve our understanding of the gender differences from the perspective of brain functions. Conclusions: An intriguing future studies direction will be to reveal the association between gender specific brain connectivity patterns and gender-related differences of various brain diseases. Keywords: Gender, Small world, EEG doi:10.1016/j.clinph.2017.07.248

P241 Insula connectivity during wakefulness and sleep studied through single pulse electrical stimulation during seeg recordings—Anca Adriana Arbune 1, Ioana Mindruta 1, Mihai Maliia 1, Irina Popa 1, Cristian Donos 2, Sabina Ene 2, Jean Ciurea 3, Andrei Barborica 2 (1 University Emergency Hospital, Neurology, Bucharest, Romania, 2 University of Bucharest, Department of Electricity and Magnetism, Solid-State Physics, and Biophysics, Bucharest, Romania, 3 Bagdasar-Arseni Emergency Hospital, Neurosurgery, Bucharest, Romania) Objective: We aim to study the connections of the posterior insula (pI) and anterior insula (aI) through cortico-cortical evoked potentials (CCEP) by single pulse electrical stimulation (SPES). Method: We performed SPES stimulation protocol in a group of 8 refractory epilepsy patients presurgically explored with intracerebral depth electrodes, out of which 6 were operated on and are currently seizure-free. We selected the early responses (ER) obtained from contacts of 24 electrodes that were included in the anterior and posterior insula, when this structure was outside the seizure onset zone (SOZ). Responses were analyzed in terms of amplitude variations during wakefulness and sleep. Effective connectivity betweeen cortical was calculated based on the measured CCEPs. Results: The ER amplitudes by SPES stimulation in the insula during wakefulness compared to sleep showed statistically significant (p < 0:05) differences in 6 patients. There are constant connections between aI and pI. We identified connectivity of the pI with language-related brain stuctures during wakefulness, and with the