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Analysis of Clinical Utility of Functional MRI in Neurosurgical Decision-Making in Focal Epilepsy

Published online by Cambridge University Press:  05 November 2024

Christopher O’Grady  and
Antonina Omisade Open the ORCID record for Antonina Omisade [Opens in a new window]
Christopher O’Grady
Affiliation:
Dahousie University Medical School, Halifax, NS, Canada
Antonina Omisade*
Affiliation:
Nova Scotia Health, Halifax, NS, Canada Department of Psychology & Neuroscience, Dalhousie University, Halifax, Canada
*
Corresponding author: Antonina Omisade; Email: [email protected]
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Abstract

Background:

Functional MRI (fMRI) has proven valuable in presurgical planning for people with brain tumors. However, it is underutilized for patients with epilepsy, likely due to less data on its added clinical value in this population. We reviewed clinical fMRI referrals at the QEII Health Sciences Center (Halifax, Nova Scotia) to determine the impact of fMRI on surgical planning for patients with epilepsy. We focused on reasons for fMRI referrals, findings and clinical decisions based on fMRI findings, as well as postoperative cognitive outcomes.

Methods:

We conducted a retrospective chart review of patients who underwent fMRI between June 2015 and March 2021.

Results:

Language lateralization represented the primary indication for fMRI (100%), with 7.7% of patients also referred for motor and sensory mapping. Language dominance on the side of resection was observed in 12.8% of patients; in 20.5%, activation was adjacent to the proposed resection site. In 18% of patients, fMRI provided an indication for further invasive testing due to the risk of significant cognitive morbidity (e.g., anterograde amnesia). Further invasive testing was avoided based on fMRI findings in 69.2% of patients. Cognitive outcomes based on combined neuropsychological findings and fMRI-determined language dominance were variable.

Conclusion:

fMRI in epilepsy was most often required to identify hemispheric language dominance. Although fMRI-determined language dominance was not directly predictive of cognitive outcomes, it helped identify patients at low risk of catastrophic cognitive morbidity and those at high risk who required additional invasive testing.

Résumé

RÉSUMÉ

Analyse de l’utilité clinique de l’IRM fonctionnelle dans les cas d’épilepsie focale en ce qui concerne les prises de décision relatives à la neurochirurgie.

Contexte :

L’imagerie par résonance magnétique fonctionnelle (IRMf) se révèle particulièrement utile en phase préopératoire chez les personnes souffrant d’une tumeur cérébrale. Toutefois, cette technique est sous-utilisée chez les patients atteints d’épilepsie, probablement en raison d’une collecte moindre de données sur la valeur clinique ajoutée de l’examen dans cette population. Aussi avons-nous procédé à une analyse clinique des demandes d’IRMf au QEII Health Sciences Center (Halifax, Nouvelle-Écosse) dans le but de déterminer l’incidence de cet examen sur la planification chirurgicale dans les cas d’épilepsie. Ont été retenus les motifs des demandes d’IRMf, les constatations et les décisions cliniques fondées sur les résultats de l’examen ainsi que les résultats cognitifs postopératoires.

Méthode :

Il s’agit d’une étude rétrospective de dossiers de patients qui ont subi une IRMf entre juin 2015 et mars 2021.

Résultats :

La latéralisation du langage constituait le principal motif des demandes d’IRMf (100 %), auquel s’ajoutait une cartographie motrice et sensorielle dans 7,7 % des cas. La zone de domination du langage était du côté de la résection chez 12,8 % des patients, et l’activation, adjacente au siège proposé de résection dans 20,5 % de l’échantillon. Dans 18 % des cas, l’IRMf a fourni des indications d’autres examens effractifs en raison de risques d’une morbidité cognitive grave (p. ex. l’amnésie antérograde). Par contre, les résultats de l’IRMf ont permis d’éviter des examens exploratoires effractifs additionnels chez 69,2 % des patients. Les résultats cognitifs fondés sur l’association d’observations neuropsychologiques et de la zone de domination du langage déterminée par l’IRMf se sont révélés variables.

Conclusion :

Les demandes d’IRMf visaient principalement à déterminer la domination hémisphérique du langage dans les cas d’épilepsie. Bien que la détermination de la latéralité du langage par l’IRMf n’ait pas été associée à une valeur prévisionnelle directe quant aux résultats cliniques, elle a néanmoins permis de repérer les patients à faible risque de morbidité cognitive catastrophique et ceux à risque élevé chez qui d’autres examens effractifs s’imposaient.

Keywords

Epilepsy surgeryfunctional MRIneuropsychologyneuroimagingneurosurgery
Type
Original Article
Information
Canadian Journal of Neurological Sciences , First View , pp. 1 - 6
Copyright
© The Author(s), 2024. Published by Cambridge University Press on behalf of Canadian Neurological Sciences Federation

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