- Email: [email protected]
60. Defective interhemispheric inhibition in focal epilepsies
e338
Abstracts / Clinical Neurophysiology 127 (2016) e323–e341
No difference was found in CSF biomarkers profile within the APOE variants group. Conversely iTBS after effects were significantly reduced in E3 AD in comparison with E4 AD patients. MMSE progression, evaluated as delta between 18-month and baseline MMSE score (delta-MMSE) was higher, although not significantly, for E4 AD patients. Correlation analyses revealed that the individual amount of iTBS induced plasticity did correlate with delta-MMSE and total Tau (t-Tau), showing that a less pronounced LTP-like plasticity and higher t-Tau CSF levels were associated with a higher delta-MMSE. Finally a multivariate analysis showed that APOE polymorphism and LTP-like plasticity, but not t-Tau levels are independently able to predict delta-MMSE in AD patients. These findings demonstrate that cortical plasticity impairment in AD patients is significantly different according to APOE variants. Moreover APOE polymorphism and LTP-like plasticity are both independently associated with clinical progression in AD patients. APOE variants show different level of cortical plasticity and are independently associated with clinical progression in AD patients. doi:10.1016/j.clinph.2016.10.071
60. Defective interhemispheric inhibition in focal epilepsies— G. Strigaro, E. Matino, C. Pizzamiglio, G. Tondo, L. Falletta, P. Barbero, C. Varrasi, R. Cantello (Novara, Italy)
Focal epilepsies (FEs) arise from a lateralized network. In generalized epilepsies (GEs) there is a bilateral network involvement from the outset. The corpus callosum is the anatomical substrate for interhemispheric spread, although its detailed physiological role is uncertain. We used transcranial magnetic stimulation (TMS) to explore the physiology of the corpus callosum in patients with FE and idiopathic GE (IGE), as compared to healthy subjects (HS). We studied 16 patients with FE, 17 with IGE, and 17 HS of similar age and sex. We used TMS to measure the interhemispheric inhibition (IHI) from left-to-right primary motor cortex (M1) and viceversa. A conditioning stimulus (CS) was given to one M1 10 and 50 ms before a test stimulus delivered to the contralateral M1. Statistics was based on ANOVAs. Across HS, IHI was reproducible, since a contralateral CS suppressed MEPs at ISIs of 10 and 50 ms (p < 0.05). Similar effects occurred in IGE patients (p < 0.05). FE patients behaved differently, since IHI was significantly (p < 0.05) reduced bilaterally. In conclusion, FE patients had a bilateral defective inhibitory response. We suggest that it may represent one key factor for the contralateral spread of focal discharges, and seizure generalization. doi:10.1016/j.clinph.2016.10.072
61. Altered recovery from inhibitory repetitive Transcranial Magnetic Stimulation (rTMS) in subjects with photosensitive epilepsy—T. Bocci, M. Caleo, L. Restani, D. Barloscio, L. Parenti, S. Rossi, F. Sartucci (Pisa, Italy, Siena, Italy)
To investigate functional changes underlying photosensitivity, we studied the response of the visual cortex to low-frequency, inhibitory repetitive Transcranial Magnetic Stimulation (rTMS) in patients with photosensitive seizures and healthy volunteers. Visual evoked potentials (VEPs) triggered by grating stimuli of different contrasts were recorded in both hemispheres before and after functional inactivation of the occipital cortex of one side via 0 low-frequency rTMS (0.5 Hz for 20 ). VEPs were recorded before
0
(T0), immediately after (T1) and 45 following the completion of rTMS (T2). Baseline amplitudes of the early VEP components (N1 and P1) were enhanced in photosensitive subjects. At T1, rTMS produced an inhibitory effect on VEPs amplitudes at all contrasts in the targeted side, and a concurrent facilitation of responses in the contralateral hemisphere. While the relative variation with respect to pre-rTMS values was similar in photosensitive patients and controls at T1, robust changes appeared in the recovery phase (T2): visual responses recovered more quickly in the stimulated hemisphere, and disinhibition persisted in the contralateral side of photosensitive subjects. The rapid recovery of excitability and the persistent transcallosal disinhibition following perturbation of cortical activity may play a role in the pathophysiology of photosensitive epilepsy. doi:10.1016/j.clinph.2016.10.073
62. Efficacy of cathodal transcranial direct current stimulation in drug-resistant epilepsy: A proof of principle—G. Assenza, C. Campana, F. Assenza, G. Di Pino, E. Fabrizio, R. Fini, G. Musumeci, M. Tombini, V. Di Lazzaro (Roma, Italy)
It has been proved that Transcranial DCS (tDCS) can modulate cortical excitability, enhancing or decreasing, respectively by anodal or cathodal polarity. The short-term and lasting alterations induced by tDCS are strictly related to the charge density, duration of stimulation and the depth of neuron below the skull. Epilepsy represents a pathophysiological model of unbalanced relation between cortical excitation and inhibition. In this line, tDCS can be exploited to counterbalance the neuronal hyper-excitation through electric neural modulation. This paper aims at providing the efficacy of cathodal tDCS in reducing seizures’ frequency in drug-resistant focal epilepsy. The study was single blind and sham-controlled and compared seizure rate in the 7 days before and after tDCS and after sham in a cross-over design. 9 patients affected by focal resistant epilepsy were enrolled. After tDCS 3 out 9 patients have not any change in seizure rate. 6 patients reduced their seizure frequency >50%. No significant modification were recorded after sham. This study represents the proof that cathodal tDCS may be efficient in reducing seizures’frequency in focal resistant epilepsy. doi:10.1016/j.clinph.2016.10.074
63. Phase dependency of the human primary motor cortex and cholinergic inhibition cancellation during beta tACS—A. Guerra, A. Pogosyan, M. Nowak, H. Tan, F. Ferreri, V. Di Lazzaro, P. Brown (Roma, Italy, Oxford-IK, United Kingdom, Kuopio-FI, Finland)
Growing evidence suggests that human motor cortex has a tendency to resonant activity at about 20 Hz, and therefore stimulation near this frequency can synchronize the activity of neuronal populations. However, do interneuronal circuits contribute to such resonance and if so are they selectively entrained? Is the balance between inhibitory and excitatory interneurons maintained throughout? We investigated how different interneuronal circuits react to exogenously driven rhythmic activities using TMS during transcranial alternating current stimulation (tACS) at motor and non-motor resonance frequencies. We tested different TMS interneuronal protocols and triggered TMS pulses at different phases of tACS. The effect of short-latency afferent inhibition was abolished
Abstracts / Clinical Neurophysiology 127 (2016) e323–e341
No difference was found in CSF biomarkers profile within the APOE variants group. Conversely iTBS after effects were significantly reduced in E3 AD in comparison with E4 AD patients. MMSE progression, evaluated as delta between 18-month and baseline MMSE score (delta-MMSE) was higher, although not significantly, for E4 AD patients. Correlation analyses revealed that the individual amount of iTBS induced plasticity did correlate with delta-MMSE and total Tau (t-Tau), showing that a less pronounced LTP-like plasticity and higher t-Tau CSF levels were associated with a higher delta-MMSE. Finally a multivariate analysis showed that APOE polymorphism and LTP-like plasticity, but not t-Tau levels are independently able to predict delta-MMSE in AD patients. These findings demonstrate that cortical plasticity impairment in AD patients is significantly different according to APOE variants. Moreover APOE polymorphism and LTP-like plasticity are both independently associated with clinical progression in AD patients. APOE variants show different level of cortical plasticity and are independently associated with clinical progression in AD patients. doi:10.1016/j.clinph.2016.10.071
60. Defective interhemispheric inhibition in focal epilepsies— G. Strigaro, E. Matino, C. Pizzamiglio, G. Tondo, L. Falletta, P. Barbero, C. Varrasi, R. Cantello (Novara, Italy)
Focal epilepsies (FEs) arise from a lateralized network. In generalized epilepsies (GEs) there is a bilateral network involvement from the outset. The corpus callosum is the anatomical substrate for interhemispheric spread, although its detailed physiological role is uncertain. We used transcranial magnetic stimulation (TMS) to explore the physiology of the corpus callosum in patients with FE and idiopathic GE (IGE), as compared to healthy subjects (HS). We studied 16 patients with FE, 17 with IGE, and 17 HS of similar age and sex. We used TMS to measure the interhemispheric inhibition (IHI) from left-to-right primary motor cortex (M1) and viceversa. A conditioning stimulus (CS) was given to one M1 10 and 50 ms before a test stimulus delivered to the contralateral M1. Statistics was based on ANOVAs. Across HS, IHI was reproducible, since a contralateral CS suppressed MEPs at ISIs of 10 and 50 ms (p < 0.05). Similar effects occurred in IGE patients (p < 0.05). FE patients behaved differently, since IHI was significantly (p < 0.05) reduced bilaterally. In conclusion, FE patients had a bilateral defective inhibitory response. We suggest that it may represent one key factor for the contralateral spread of focal discharges, and seizure generalization. doi:10.1016/j.clinph.2016.10.072
61. Altered recovery from inhibitory repetitive Transcranial Magnetic Stimulation (rTMS) in subjects with photosensitive epilepsy—T. Bocci, M. Caleo, L. Restani, D. Barloscio, L. Parenti, S. Rossi, F. Sartucci (Pisa, Italy, Siena, Italy)
To investigate functional changes underlying photosensitivity, we studied the response of the visual cortex to low-frequency, inhibitory repetitive Transcranial Magnetic Stimulation (rTMS) in patients with photosensitive seizures and healthy volunteers. Visual evoked potentials (VEPs) triggered by grating stimuli of different contrasts were recorded in both hemispheres before and after functional inactivation of the occipital cortex of one side via 0 low-frequency rTMS (0.5 Hz for 20 ). VEPs were recorded before
0
(T0), immediately after (T1) and 45 following the completion of rTMS (T2). Baseline amplitudes of the early VEP components (N1 and P1) were enhanced in photosensitive subjects. At T1, rTMS produced an inhibitory effect on VEPs amplitudes at all contrasts in the targeted side, and a concurrent facilitation of responses in the contralateral hemisphere. While the relative variation with respect to pre-rTMS values was similar in photosensitive patients and controls at T1, robust changes appeared in the recovery phase (T2): visual responses recovered more quickly in the stimulated hemisphere, and disinhibition persisted in the contralateral side of photosensitive subjects. The rapid recovery of excitability and the persistent transcallosal disinhibition following perturbation of cortical activity may play a role in the pathophysiology of photosensitive epilepsy. doi:10.1016/j.clinph.2016.10.073
62. Efficacy of cathodal transcranial direct current stimulation in drug-resistant epilepsy: A proof of principle—G. Assenza, C. Campana, F. Assenza, G. Di Pino, E. Fabrizio, R. Fini, G. Musumeci, M. Tombini, V. Di Lazzaro (Roma, Italy)
It has been proved that Transcranial DCS (tDCS) can modulate cortical excitability, enhancing or decreasing, respectively by anodal or cathodal polarity. The short-term and lasting alterations induced by tDCS are strictly related to the charge density, duration of stimulation and the depth of neuron below the skull. Epilepsy represents a pathophysiological model of unbalanced relation between cortical excitation and inhibition. In this line, tDCS can be exploited to counterbalance the neuronal hyper-excitation through electric neural modulation. This paper aims at providing the efficacy of cathodal tDCS in reducing seizures’ frequency in drug-resistant focal epilepsy. The study was single blind and sham-controlled and compared seizure rate in the 7 days before and after tDCS and after sham in a cross-over design. 9 patients affected by focal resistant epilepsy were enrolled. After tDCS 3 out 9 patients have not any change in seizure rate. 6 patients reduced their seizure frequency >50%. No significant modification were recorded after sham. This study represents the proof that cathodal tDCS may be efficient in reducing seizures’frequency in focal resistant epilepsy. doi:10.1016/j.clinph.2016.10.074
63. Phase dependency of the human primary motor cortex and cholinergic inhibition cancellation during beta tACS—A. Guerra, A. Pogosyan, M. Nowak, H. Tan, F. Ferreri, V. Di Lazzaro, P. Brown (Roma, Italy, Oxford-IK, United Kingdom, Kuopio-FI, Finland)
Growing evidence suggests that human motor cortex has a tendency to resonant activity at about 20 Hz, and therefore stimulation near this frequency can synchronize the activity of neuronal populations. However, do interneuronal circuits contribute to such resonance and if so are they selectively entrained? Is the balance between inhibitory and excitatory interneurons maintained throughout? We investigated how different interneuronal circuits react to exogenously driven rhythmic activities using TMS during transcranial alternating current stimulation (tACS) at motor and non-motor resonance frequencies. We tested different TMS interneuronal protocols and triggered TMS pulses at different phases of tACS. The effect of short-latency afferent inhibition was abolished