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Intracarotid Amobarbital Procedure (intracarotid + amobarbital_procedure)

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Medical Sciences	100%

Selected Abstracts

Unilateral Intracarotid Amobarbital Procedure for Language Lateralization

EPILEPSIA, Issue 11 2005
Jörg Wellmer
Summary:,Purpose: The determination of language dominance as part of the presurgical workup of patients with pharmacoresistant epilepsies has experienced fundamental changes. With the introduction of noninvasive functional magnetic resonance imaging (fMRI), the number of patients receiving intracarotid amobarbital procedures (IAPs) for assessment of language dominance has decreased considerably. However, recent studies show that because of methodologic limitations of fMRI, IAP remains an important tool for language lateralization. The current study examines whether unilateral instead of bilateral IAP is an adequate way to apply IAP with reduced invasiveness. Methods: We retrospectively examine the predictive value of unilateral IAP for the results of bilateral IAP based on a sample of 75 patients with various types of language dominance. Target parameters are the prediction of the language-dominant hemisphere and the identification of patients with atypical language dominance. For language assessment based on unilateral IAP, we introduce the measure hemispheric language capacity (HLC). Results: Unilateral IAP performed on the side of intended surgery quantifies language capacity contralateral to the intended surgery. It detects atypical (bilateral or right) language dominance in the majority of patients. Experience with a separate series of 107 patients requiring presurgical language lateralization shows that in >80%, bilateral IAPs are redundant. Conclusions: Unilateral IAP is principally sufficient for language lateralization in the presurgical evaluation of patients with pharmacoresistant epilepsies. Necessity of bilateral IAP is restricted to few indications (e.g., callosotomy). In times of noninvasive language lateralization, we propose unilateral IAP as the method of choice for the verification of doubtful (bilateral) fMRI activation patterns. [source]

Removing Eye-movement Artifacts from the EEG during the Intracarotid Amobarbital Procedure

EPILEPSIA, Issue 3 2005
Weidong Zhou
Summary:,Purpose: The EEG is often recorded during the intracarotid amobarbital procedure (IAP) to help in the assessment of the spatial extent and the duration of the effect of the drug. In scalp recordings, the EEG is always heavily contaminated with eye movement artifacts as the patient actively performs visual tasks. Methods: Independent component analysis (ICA) is a new technique for blind source separation. In this study, we separated the EEG data recorded during the IAP into independent components using ICA. The EEG signal was reconstructed by excluding the components related to eye movement and eye blinks. Results: EEGs from 10 IAP tests were analyzed. The experimental results indicate that ICA is very efficient at subtracting eye-movement artifacts, while retaining the EEG slow waves and making their interpretation easier. Conclusions: ICA appears to be a generally applicable and effective method for removing ocular artifacts from EEG recordings during IAP, although slow waves and ocular artifacts share similar frequency distributions. [source]

Distributed source modeling of language with magnetoencephalography: Application to patients with intractable epilepsy

EPILEPSIA, Issue 10 2009
Carrie R. McDonald
Summary Purpose:, To examine distributed patterns of language processing in healthy controls and patients with epilepsy using magnetoencephalography (MEG), and to evaluate the concordance between laterality of distributed MEG sources and language laterality as determined by the intracarotid amobarbital procedure (IAP). Methods:, MEG was performed in 10 healthy controls using an anatomically constrained, noise-normalized distributed source solution (dynamic statistical parametric map, dSPM). Distributed source modeling of language was then applied to eight patients with intractable epilepsy. Average source strengths within temporoparietal and frontal lobe regions of interest (ROIs) were calculated, and the laterality of activity within ROIs during discrete time windows was compared to results from the IAP. Results:, In healthy controls, dSPM revealed activity in visual cortex bilaterally from ,80 to 120 ms in response to novel words and sensory control stimuli (i.e., false fonts). Activity then spread to fusiform cortex ,160,200 ms, and was dominated by left hemisphere activity in response to novel words. From ,240 to 450 ms, novel words produced activity that was left-lateralized in frontal and temporal lobe regions, including anterior and inferior temporal, temporal pole, and pars opercularis, as well as bilaterally in posterior superior temporal cortex. Analysis of patient data with dSPM demonstrated that from 350 to 450 ms, laterality of temporoparietal sources agreed with the IAP 75% of the time, whereas laterality of frontal MEG sources agreed with the IAP in all eight patients. Discussion:, Our results reveal that dSPM can unveil the timing and spatial extent of language processes in patients with epilepsy and may enhance knowledge of language lateralization and localization for use in preoperative planning. [source]

Removing Eye-movement Artifacts from the EEG during the Intracarotid Amobarbital Procedure

Contralateral EEG Slowing and Amobarbital Distribution in Wada Test: An Intracarotid SPECT Study

EPILEPSIA, Issue 2 2000
Seung Bong Hong
Summary: Purpose: To relate the occurrence of contralateral electroencephalogram slowing (CES) to amobarbital distribution, we performed electroencephalogram (EEG) monitoring and intracarotid single photon emission computed tomography (SPECT) during an intracarotid amobarbital procedure (IAP). Methods: IAP was performed on 22 patients with temporal lobe epilepsy. CES was defined as the occurrence of significant EEG slowing on the contralateral hemisphere (>50% of the ipsilateral hemisphere slowing) after amobarbital injection. To map the distribution of the amobarbital, we injected a mixture of amobarbital and 99m technetium-ethylcysteinate dimer (99m Tc-ECD) into the internal carotid artery and performed a brain SPECT 2 h later. In the SPECT images, regions of interest were determined by ipsilateral and contralateral anterior cerebral artery territories (iACA, cACA), ipsilateral and contralateral middle cerebral artery territories (iMCA, cMCA), and ipsilateral and contralateral posterior cerebral artery territories (iPCA, cPCA), as well as ipsilateral and contralateral anterior and posterior mesial temporal regions (iAMT, cAMT, iPMT, cPMT). The perfusion of amobarbital was interpreted visually in each region. Results: Amobarbital was distributed in the iMCA in all the patients; in the iACA in 20 (90.9%) patients; in the iAMT in 14 (63.5%); and in the iPCA and iPMT in only two (9.1%). CES was observed in 13 (59.1%) patients. Cross-perfusion of amobarbital in limited areas of the cACA were observed in only four of 13 patients. Wada retention memory scores (WRMS) showed no significant difference between the CES- (n = 9) and CES+ (n = 13) groups. Conclusions: Amobarbital rarely perfused the iPCA territory and the iPMT region and was rarely delivered to the contralat-eral hemisphere. The occurrence of CES was not related to the cross-perfusion of amobarbital. CES appears to be produced by a transient functional disconnection from the ipsilateral hemisphere. [source]

The intracarotid amobarbital or Wada test: unilateral or bilateral?

ACTA NEUROLOGICA SCANDINAVICA, Issue 3 2009
S. G. Uijl
Objective,,, In the Netherlands, presurgical screening for temporal lobe epilepsy (TLE) includes the intracarotid amobarbital procedure (IAP), consisting of two consecutive injections of amobarbital, ipsilateral and contralateral to the epileptic focus. We studied whether a bilateral IAP has added value to a unilateral, ipsilateral IAP. Methods,,, This population-based study included 183 consecutive patients referred for screening for TLE surgery who underwent bilateral IAP. Using multivariable modeling, we assessed the added value of bilateral IAP on the decision for surgery, resection size, amygdalohippocampectomy, post-operative seizure freedom, memory performance, and IQ change. Results,,, Given the results from the unilateral IAP, the bilateral IAP had added prognostic value for postoperative change in verbal memory (P < 0.01) and verbal IQ (P < 0.01), especially if patients had a left-sided focus. In contrast, information provided by the contralateral IAP was not associated with decision-making or surgical strategy. Conclusions,,, A bilateral IAP has added value in predicting post-operative verbal memory and IQ. A bilateral IAP is currently not used to guide surgical strategy, but may be used for this purpose when verbal capacity is of particular concern in patients with a left-sided focus. In other cases, IAP is best performed unilaterally. [source]