Practice guideline summary: Use of fMRI in the presurgical evaluation of patients with epilepsy

Abstract

Objective: To assess the diagnostic accuracy and prognostic value of functional MRI (fMRI) in determining lateralization and predicting postsurgical language and memory outcomes.Methods: An 11-member panel evaluated and rated available evidence according to the 2004 American Academy of Neurology process. At least 2 panelists reviewed the full text of 172 articles and selected 37 for data extraction. Case reports, reports with ,15 cases, metaanalyses, and editorials were excluded. Results and recommendations:The use of fMRI may be considered an option for lateralizing language functions in place of intracarotid amobarbital procedure (IAP) in patients with medial temporal lobe epilepsy (MTLE; Level C), temporal epilepsy in general (Level C), or extratemporal epilepsy (Level C). For patients with temporal neocortical epilepsy or temporal tumors, the evidence is insufficient (Level U). fMRI may be considered to predict postsurgical language deficits after anterior temporal lobe resection (Level C). The use of fMRI may be considered for lateralizing memory functions in place of IAP in patients with MTLE (Level C) but is of unclear utility in other epilepsy types (Level U). fMRI of verbal memory or language encoding should be considered for predicting verbal memory outcome (Level B). fMRI using nonverbal memory encoding may be considered for predicting visuospatial memory outcomes (Level C). Presurgical fMRI could be an adequate alternative to IAP memory testing for predicting verbal memory outcome (Level C). Clinicians should carefully advise patients of the risks and benefits of fMRI vs IAP during discussions concerning choice of specific modality in each case. Neurology ® 2017;88:395-402 GLOSSARY AAN 5 American Academy of Neurology; ATL 5 anterior temporal lobe; fMRI 5 functional MRI; IAP 5 intracarotid amobarbital procedure; LI 5 laterality index; MTL 5 medial temporal lobe; MTLE 5 medial temporal lobe epilepsy; ROI 5 region of interest; TLE 5 temporal lobe epilepsy.This article summarizes an American Academy of Neurology (AAN) guideline on use of functional MRI (fMRI) for presurgical mapping in epilepsy. Additional information is provided in the complete guideline, available as a data supplement at Neurology.org. Appendices e-1 through e-5, available in the complete guideline, tables e-1 and e-2, and references e1-e16, cited here, are available at Neurology.org.The choice of performing intracarotid amobarbital procedure (IAP) or fMRI for presurgical language and memory assessment depends on multiple factors that need to be taken into account when selecting the study. fMRI is properly described as an image acquisition technique that has come to mean imaging brain activity. fMRI results may depend on, for example, scanner strength, analysis methods, type of task contrast used, patient compliance and cooperation with the tasks, or medications administered at the time of the procedure; neither selection of fMRI tasks nor data processing methods have been universally standardized.1-4 Nonetheless, standard prac...

Presurgical language fMRI: Technical practices in epilepsy surgical planning

“…Some of the best‐studied tasks were identified in a recent, exhaustive review of the evidence supporting the use of language fMRI for the American Academy of Neurology Practice Parameters (Szaflarski et al, 2017). An approach approximating the approach validated by Binder et al (Sabsevitz et al, 2003), which uses a semantic decision task paired with an active control and uses a laterality index in analysis (whole‐brain or regional), was reported by up to 7% of programs.…”

“…Each of the best‐validated approaches (Szaflarski et al, 2017) is used by fewer than 10% of programs. As with clinicians, analysts report that their maps are frequently used to guide surgical margins to preserve language function (59% of sites).…”

“…Conversely, it is also frequently seen as opposing standardization, objectivity, and the research method. Note, however, that the best validation studies to date do actually use a highly standardized approach (Bonelli et al, 2012; Janecek et al, 2013; Szaflarski et al, 2017). As in a more comprehensive survey of clinicians' experience of clinical language fMRI (Benjamin et al, 2018), analysts frequently (46%) report that language laterality judged by fMRI has disagreed with that yielded by other methods in at least some instances.…”

Presurgical language fMRI: Clinical practices and patient outcomes in epilepsy surgical planning

“…The evidence supporting fMRI's validity was recently outlined [Szaflarski et al, 2017], with the conclusion that language fMRI is a valid alternative to Wada testing in most patients. One approach to incorporating fMRI in clinical decision making developed by Swanson and colleagues is shown in Figure 1 [Swanson et al, 2015].…”

“…Importantly, fMRI is not validated for comprehensive language mapping to tailor surgical margins and avoid post-surgical language decline [Giussani et al, 2010; Szaflarski et al, 2017]. Clinical guidelines for fMRI use are available within radiology [American College of Radiology, 2014] and neuropsychology [Bobholz et al, 2004].…”