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Michael J. Schlosser, Marie Luby, Dennis D. Spencer, Issam A. Awad and Gregory McCarthy

The authors have previously described a functional magnetic resonance (fMR) imaging procedure for the localization of auditory comprehension in which focal activation of posterior temporal and inferior frontal regions of the left hemisphere was reliably demonstrated. Because this past study was conducted in neurologically normal volunteers, it was not possible to determine whether the activated regions were critical to the performance of language tasks; that is, whether the fMR imaging activations provided a rate measure of language processing. A direct comparison of fMR imaging language activation with cortical stimulation must be completed before the tool can be used with confidence in presurgical planning.

Here the authors report a series of 33 consecutive patients who underwent dominant hemisphere resection in which fMR image mapping of auditory comprehension was performed at the Yale neurosurgical program.

In 23 of the 33 patients reliable fMR imaging activation was shown. In 16 of these 23 patients language mapping was performed using either intra- or extraoperative cortical stimulation. Cortical stimulation failed to localize language areas in two of the 16 patients. Electrical stimulation that was performed in close proximity to the fMR image activations interfered with auditory comprehension, object naming, or speech production in 12 of the remaining 14 patients. Five of the 10 cases in which evocation reliable fMR imaging activation failed were attributable to technical problems and/or patient head movement.

Cortical stimulation results and fMR imaging findings were consistent in all but two patients. However, the spatial extent of the activation produced by fMR imaging and the spatial extent of stimulation-induced language disruption that was caused by direct cortical stimulation did not always correspond. Problems in defining the extent of activation by both methods are discussed.

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Michael J. Schlosser, Marie Luby, Dennis D. Spencer, Issam A. Awad and Gregory McCarthy

Object. The authors previously described a functional magnetic resonance (fMR) imaging task for the localization of auditory comprehension in which focal activation of posterior temporal and inferior frontal regions of the left hemisphere was reliably demonstrated. Because this study was conducted in neurologically normal volunteers, it was not possible to determine whether the activated regions were critical to the performance of language tasks; that is, whether the fMR imaging activations provided a valid measure of language processing. A direct comparison of fMR imaging language activation with cortical stimulation must be completed before it can be used with confidence in presurgical planning, and this comparison is performed in the present study.

Methods. The authors report on a series of 33 consecutive patients who underwent dominant hemisphere resection and in whom fMR imaging mapping of auditory comprehension was performed at the Yale neurosurgical program.

In 23 of the 33 patients fMR imaging activation was consistent with the typical results obtained in normal participants in the earlier study. In 16 of these 23 patients language mapping was performed using either intra- or extraoperative cortical stimulation. Cortical stimulation failed to localize language areas in two of the 16 patients. Electrical stimulation that was performed in proximity to the fMR image activations interfered with auditory comprehension, object naming, or speech production in 12 of the remaining 14 patients. Five of the 10 cases in which evocation of reliable fMR imaging activation failed were attributable to technical problems and/or patient head movement.

Conclusions. Cortical stimulation results and fMR imaging findings were consistent in all but two patients. However, the spatial extent of the activation produced by fMR imaging and the spatial extent of stimulation-induced language disruption that was caused by direct cortical stimulation did not always correspond. Problems in defining the extent of activation by both methods are discussed.

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Alexandre C. Carpentier, R. Todd Constable, Michael J. Schlosser, Alain de Lotbinière, Joseph M. Piepmeier, Dennis D. Spencer and Issam A. Awad

Object. Functional magnetic resonance (fMR) imaging of the motor cortex is a potentially powerful tool in the preoperative planning of surgical procedures in and around the rolandic region. Little is known about the patterns of fMR imaging activation associated with various pathological lesions in that region or their relation to motor skills before surgical intervention.

Methods. Twenty-two control volunteers and 44 patients whose pathologies included arteriovenous malformations (AVMs; 16 patients), congenital cortical abnormalities (11 patients), and tumors (17 patients) were studied using fMR imaging and a hand motor task paradigm. Activation maps were constructed for each participant, and changes in position or amplitude of the motor activation on the lesion side were compared with the activation pattern obtained in the contralateral hemisphere. A classification scheme of plasticity (Grades 1–6) based on interhemispheric pixel asymmetry and displacement of activation was used to compare maps between patients, and relative to hand motor dexterity and/or weakness.

There was 89.4% interobserver agreement on classification of patterns of fMR imaging activation. Displacement of activation by mass effect was more likely with tumors. Cortical malformations offer a much higher functional reorganization than AVMs or tumors. High-grade plasticity is recruited to compensate for severe motor impairment.

Conclusions. Pattern modification of fMR imaging activation can be systematized in a classification of motor cortex plasticity. This classification has shown good correlation among grading, brain lesions, and motor skills. This proposal of a classification scheme, in addition to facilitating data collection and processing from different institutions, is well suited for comparing risks associated with surgical intervention and patterns of functional recovery in relation to preoperative fMR imaging categorization. Such studies are underway at the authors' institution.