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ABSTRACT: The purpose of this study was to investigate the connectivity from the negative motor area and to elucidate the mechanism of negative motor phenomena. We report the results of cortico-cortical evoked potentials (CCEPs) by electrical stimulation of the primary motor area (MI), primary sensory area (SI), primary (PNMA) and supplementary negative motor area (SNMA) in eight epilepsy patients who underwent intracranial electrode placement. Alternating 1-Hz electrical stimuli were delivered to MI (six patients), SI (five), PNMA (six) and SNMA (two). CCEPs were recorded by averaging electrocorticograms time-locked to the stimuli. Stimulation of MI, SI and PNMA induced CCEP responses in the premotor area (PM), pre- and postcentral gyri, posterior parietal cortex and the temporo-parietal junction. Upon SNMA stimulation, CCEP responses were detected in the prefrontal cortex, PM, pre- and postcentral gyri, supplementary motor area (SMA) and preSMA. Compared with stimulation of SI and MI, PNMA stimulation revealed a broader distribution of CCEP responses in the frontal or parietal association cortex, indicating the importance of the fronto-parietal network associated with a higher level of motor control. We concluded that these connections are associated with motor control and that the negative motor phenomenon results from impairment of the organization of movements.
Cortex 09/2012; · 6.08 Impact Factor
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Rei Enatsu,
Yuichi Kubota,
Yosuke Kakisaka,
Juan Bulacio,
Zhe Piao, Timothy O'Connor,
Karl Horning,
John Mosher,
Richard C Burgess,
William Bingaman,
Dileep R Nair
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ABSTRACT: OBJECTIVE: To investigate the connectivity associated with the reorganized language network in patients with temporal lobe epilepsy (TLE) using cortico-cortical evoked potential (CCEP), which reveals the brain networks. METHODS: Six patients with intractable TLE who underwent chronic intracranial electrode placement and revealed an atypical distribution of posterior language areas (Wernicke's areas) were studied. Alternating 1Hz electrical stimuli were delivered to the anterior language areas (Broca's areas). CCEPs were recorded by averaging electrocorticograms time-locked to stimuli from the subdural electrodes. Thereafter, the posterior language areas identified by the electrical cortical mapping and CCEP distributions were compared by calculating the root mean square of CCEP responses. RESULTS: CCEP responses were observed in various areas within the temporal, temporo-parietal or temporo-occipital area. The correlation between CCEP distributions and posterior language areas revealed two patterns. In two patients, the posterior language areas were located within CCEP distribution, but out of the maximum responses in the temporal lobe. On the other hand, parts of the language areas were outside CCEP-positive areas in four patients. CONCLUSION: Our results suggest that language reorganization might be associated with a functional shift from the termination of anterior-posterior language connection to the surrounding cortices. It should be noted that language areas can be identified outside the anterior-posterior language connection.
Epilepsy research 07/2012; · 2.48 Impact Factor
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ABSTRACT: To better understand the process of ictal propagation in epilepsy by using cortico-cortical evoked potential (CCEP), which reveals the brain networks.
Intracranial EEG recordings of 11 seizures from 11 patients with pharmacoresistant focal epilepsy were studied to identify the propagation sites and times. Six patients had a history of secondary generalization (Gen (+) group) and five patients did not (Gen (-) group). Thereafter repetitive 1Hz bipolar electrical stimuli were applied to the ictal onset zones and CCEPs were recorded by averaging electrocorticograms.
The propagation of contiguous spread was significantly faster than non-contiguous spread (p=0.033). In four patients, CCEP amplitudes were significantly larger in the ictal propagation area than out of the propagation area. However, the distribution of CCEP responses was not necessarily consistent with the ictal propagation area as a whole. Furthermore, the ictal propagation areas out of CCEP-positive areas were significantly broader in Gen (+) group than Gen (-) group (p=0.017).
The present findings suggest that contiguous spread is faster than non-contiguous spread, which can be explained by the enhancement of excitability around the ictal onset area. Furthermore, there is a group of fibers that is "closed" during the seizures and secondary generalization might be more associated with the impairment of cortical inhibition over the broad cortical area rather than direct connection.
Epilepsy research 03/2012; 101(1-2):76-87. · 2.48 Impact Factor
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ABSTRACT: To better understand pathological neuronal excitation in epilepsy by comparing cortico-cortical evoked potential (CCEP) responses in regions with different ictal onset patterns: focal paroxysmal fast (PF) and repetitive spiking (RS).
Fourteen patients undergoing invasive monitoring (six patients with PF and eight with RS) were studied with CCEPs. A repetitive 1 Hz bipolar electrical stimulus was applied to both the ictal onset region (iCCEP) and to a control region (nCCEP) and CCEPs were recorded from the surrounding electrodes. The two groups were compared by subtracting the amplitude of nCCEP from that of iCCEP (CCEP(ictal-control)) at each stimulus intensity, and then normalizing the amplitudes of iCCEP at maximum stimulus intensity by dividing by nCCEP (CCEP(ictal/control)).
The CCEP response to stimulation in the ictal onset region was significantly larger than to control stimulation for both ictal patterns (paroxysmal fast: P=0.02, repetitive spiking: P<0.01), with repetitive spiking group amplitudes higher than the paroxysmal fast group (CCEP(ictal-control): P<0.01 and CCEP(ictal/control): P=0.04).
Pro-epileptic excitability is more accentuated in regions showing an ictal repetitive spiking pattern than a paroxysmal fast pattern.
These findings confirm in a new way that cortical excitability varies depending on the ictal onset pattern.
Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 07/2011; 123(2):252-60. · 3.12 Impact Factor
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ABSTRACT: Extraoperative electrical stimulation is frequently used to identify eloquent areas in patients with pharmacoresistant epilepsy who undergo subdural grid evaluation for epilepsy surgery. Oral automatisms elicited by cortical stimulation have been described in the mesial temporal lobe, but also in the mesial frontal lobe, particularly the cingulate gyrus. However oral automatisms attributed to stimulation in the superior frontal gyrus without afterdischarges have never been reported. Herein we present two patients with right frontal lobe epilepsy with oral automatisms induced by electrical stimulation of the right mesial superior frontal gyrus.
Epilepsia 02/2009; 50(6):1620-3. · 3.96 Impact Factor
