Surface cortical cerebral blood flow monitoring and single photon emission computed tomography: prognostic factors for selecting temporal lobectomy candidates

Weinand, Martin E.; Carter, L. Philip

doi:10.1016/s1059-1311(05)80163-3

Cited by 16 publications

(6 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While the IAT has remained the 'gold standard' for evaluating the functional integrity of mTL structures in preparation for ATL, newly emerging technologies, such as PET and functional MRI (fMRI) hold the promise of providing less invasive methods of assessment with potentially higher spatial resolution for detecting functional deficits. Asymmetries in functional activation within the mTL using event-related potentials (ERPs), SPECT 19,20 , and PET 21-23 also appear to be predictive of post-operative seizure control. In comparison with PET, however, the newly emerging technology of fMRI may provide a more widely available and potentially more cost-effective method of measuring functional brain activity.…”

Section: Introductionmentioning

confidence: 99%

Functional MRI and the Wada test provide complementary information for predicting post-operative seizure control

Killgore¹,

Glosser²,

Casasanto³

et al. 1999

Seizure

View full text Add to dashboard Cite

Prediction of post-surgical seizure relief and potential cognitive deficits secondary to anterior temporal lobectomy (ATL) are important to pre-surgical planning. Although the intracarotid amobarbital test (IAT) is predictive of post-ATL seizure outcome, development of non-invasive and more precise means for determining post-ATL seizure relief are needed. We previously reported on a technique utilizing functional MRI (fMRI) to evaluate the relative functional adequacy of mesial temporal lobe structures in preparation for ATL. In the present study, we report follow-up outcome data on eight temporal lobe epilepsy (TLE) patients 1-year post-ATL who were evaluated pre-surgically using IAT and fMRI. Functional memory lateralization using fMRI predicted post-ATL seizure outcome as effectively as the IAT. In general, asymmetry of functional mTL activation favouring the non-epileptic hemisphere was associated with seizure-free status at 1-year follow-up. Moreover, when combined, fMRI and IAT provided complementary data that resulted in improved prediction of post-operative seizure control compared with either procedure alone.

show abstract

Section: Introductionmentioning

confidence: 99%

Functional MRI and the Wada test provide complementary information for predicting post-operative seizure control

Killgore¹,

Glosser²,

Casasanto³

et al. 1999

Seizure

View full text Add to dashboard Cite

show abstract

“…If prospective studies clearly demonstrate that resection in a region of fMRI activation results in a decrement in memory performance, fMRI data might further be used in planning specific resections in individual cases to avoid postsurgical amnesia. Because memory function is subserved by the same brain regions that typically harbor the seizure focus itself, memory‐activation patterns observed with fMRI also may contribute to seizure lateralization and to prediction of seizure‐free outcome from temporal lobectomy, as has been demonstrated for the memory portion of the Wada test (84,85) and interictal metabolic imaging (86,87).…”

Section: Mapping Episodic Memory Systemsmentioning

confidence: 98%

Functional MRI in Epilepsy

Binder¹,

Achten²,

Constable³

et al. 2002

Epilepsia

View full text Add to dashboard Cite

The discovery of blood oxygenation level-dependent (BOLD) contrast in magnetic resonance imaging (MRI) created exciting prospects for advancing our knowledge about the neural organization of cognitive operations in the brain and for improving on available techniques for functional mapping in neurologic patients (1). We present here a brief review of functional MRI (fMRI) methods and applications, with emphasis on identification of motor, language, and memory systems that are at risk in patients treated surgically for intractable epilepsy. FMRI DATA AND IMAGE ANALYSISThe most commonly used contrast mechanism employed in fMRI is BOLD contrast (1). BOLD contrast is dependent on changes in blood flow and so is not a direct measure of neural activity. The physiologic basis of BOLD contrast was actually identified in the 1980s by positron emission tomography (PET) researchers (2). After initiation of a functional activation task, those areas of the brain that are actively engaged by the task experience a local increase in cerebral blood flow. The magnitude of the blood flow increase exceeds the associated increase in local cerebral oxygen consumption. This leads to a spatially localized increase in the ratio of oxyhemoglobin to deoxyhemoglobin when compared with that in the nonactive state. Oxyhemoglobin is diamagnetic (i.e., its effect on T 2 -relaxation rate is fairly negligible), whereas deoxyhemoglobin is paramagnetic (i.e., it accelerates the rate of T 2 relaxation) (3). This, therefore, provides a link between physiologic events that occur during mental activation and localized changes in signal intensity that are detectable by MRI. The magnitude of the activationdependent change in MR signal, however, is quite modest. Activation tasks that produce a quite vigorous response, such as sensorimotor stimulation or visual stimulation via flashing lights, produce only a 1-5% change in signal at 1.5 Tesla. Regional changes in blood flow require several seconds to develop, making the temporal resolution of fMRI relatively coarse compared with underlying neural activity.The method by which a functional activation map is derived from an fMRI examination is driven in large part by the quite modest activation signal observed with the BOLD contrast mechanism. During fMRI, the subject performs an activation task while a series of MR images sensitized to BOLD contrast is acquired over time (Fig.

show abstract

“…Asymmetric sclerosis and volume loss in TLE can be detected with good sensitivity and specificity using structural MRI (20, 23, 58, 135). Positron emission tomography (PET) may reveal interictal MTL hypometabolism and associated hypoperfusion in patients with TLE (86, 123, 139). The memory portion of the Wada test, which assesses episodic encoding during unilateral cerebral anesthesia, can detect asymmetric dysfunction of the MTL, which can be used to infer the laterality of a seizure focus (1, 61, 81, 85, 102).…”

Section: Uses For Functional Imaging Of Memory Systemsmentioning

confidence: 99%

“…In addition to assisting in seizure focus identification, asymmetry of activation might be useful for predicting seizure outcome after anterior temporal lobe (ATL) surgery. When functional asymmetry consistent with the side of seizure focus is demonstrated on PET or on the Wada memory test, for example, seizure control is better than when no asymmetry or reversed asymmetry is observed (75, 84, 86, 102, 124, 139). Although several fMRI studies suggest that MTL activation asymmetry may be correlated with side of seizure focus and seizure outcome in TLE (46, 60, 66, 108), sample sizes in these studies have been small, and no studies have yet examined whether fMRI contributes additional predictive value beyond ictal EEG, ictal semiology, and structural MRI.…”

Section: Uses For Functional Imaging Of Memory Systemsmentioning

confidence: 99%

Preoperative Prediction of Verbal Episodic Memory Outcome Using fMRI

Binder

2011

Neurosurgery Clinics of North America

View full text Add to dashboard Cite

Interest in functional imaging of memory systems stems from two clinical problems. The first of these is localization of seizure foci in temporal lobe epilepsy (TLE). TLE often arises from the medial temporal lobe (MTL) (4,31,134), and structural and functional abnormalities in the MTL can provide important evidence regarding seizure localization. Asymmetric sclerosis and volume loss in TLE can be detected with good sensitivity and specificity using structural MRI (20,23,58,135). Positron emission tomography (PET) may reveal interictal MTL hypometabolism and associated hypoperfusion in patients with TLE (86,123,139). The memory portion of the Wada test, which assesses episodic encoding during unilateral cerebral anesthesia, can detect asymmetric dysfunction of the MTL, which can be used to infer the laterality of a seizure focus (1,61,81,85,102). One potential application of fMRI, therefore, is to provide evidence about seizure focus laterality by measuring asymmetry of activation in the MTL. In addition to assisting in seizure focus identification, asymmetry of activation might be useful for predicting seizure outcome after anterior temporal lobe (ATL) surgery. When functional asymmetry consistent with the side of seizure focus is demonstrated on PET or on the Wada memory test, for example, seizure control is better than when no asymmetry or reversed asymmetry is observed (75,84,86,102,124,139). Although several fMRI studies suggest that MTL activation asymmetry may be correlated with side of seizure focus and seizure outcome in TLE (46,60,66,108), sample sizes in these studies have been small, and no studies have yet examined whether fMRI contributes additional predictive value beyond ictal EEG, ictal semiology, and structural MRI.The present chapter focuses on an equally important neurosurgical problem for which functional imaging may have a role. Temporal lobe epilepsy surgery typically involves removal of much of the anterior MTL, including portions of the hippocampus and parahippocampus, which are known to be critical for encoding and retrieval of long-term episodic memories (127). Verbal episodic memory decline after left ATL resection is a consistent finding in group studies and is observed in 30-60% of such patients © 2010 Elsevier Inc. All rights reserved.Corresponding Author: Dr. Jeffrey R. Binder Department of Neurology, Medical College of Wisconsin 9200 W. Wisconsin Ave. Milwaukee, Wisconsin 53226 USA jbinder@mcw.edu . Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author ManuscriptNeurosurg Clin N Am. Author manuscript; available in PMC 20...

show abstract

Surface cortical cerebral blood flow monitoring and single photon emission computed tomography: prognostic factors for selecting temporal lobectomy candidates

Cited by 16 publications

References 8 publications

Functional MRI and the Wada test provide complementary information for predicting post-operative seizure control

Functional MRI and the Wada test provide complementary information for predicting post-operative seizure control

Functional MRI in Epilepsy

Preoperative Prediction of Verbal Episodic Memory Outcome Using fMRI

Contact Info

Product

Resources

About