Abstract
Background: Neurosurgical intervention often requires pre-surgical or intra-operative planning/mapping techniques that are invasive. For example, prior to temporal lobectomy for intractable epilepsy, patients often undergo a WADA test which involves anesthetizing one hemisphere of the brain at a time to localize memory and language functions. For other neurosurgical cases, electrophysiological intra-operative mapping of the cortex is often used during tumor resections proximal to eloquent cortex, or for localization of specific cortex (i.e., motor) when placing neurostimulators (e.g., for pain management). Less common, but emerging as a noninvasive planning tool, fMRI was designated in three CPT codes for pre-surgical planning purposes. Here, we examined the effectiveness of fMRI and DTI by comparing fMRI data to WADA test results (for epilepsy patients) and electrophysiological recordings (for tumor resections and motor cortex stimulator placement). We also examine the utility of DTI in the context of surgical intervention.
Methods: We examined 8 intractable temporal lobe epilepsy (TLE) patients (5 males, 3 females; 6 left TLE, 2 right TLE) who underwent both WADA testing and fMRI language mapping for pre-surgical planning purposes, 1 tumor resection case in which the tumor was near the motor cortex and intra-operative electrophysiological mapping was employed, and 1 motor cortex neurostimulator case in which electrophysiological mapping was performed. All patients were enrolled in IRB-approved studies. FMRI data (language or motor) was obtained prior to surgical intervention and maps were used intra-operatively using BrainLab.
Results: In all 8 epilepsy cases, language mapping data was concordant between fMRI and WADA test results. However, fMRI mapping allowed for discrete, focal localization of regions involved in language processes whereas WADA testing only delineated hemispheric dominance. In the tumor resection case, fMRI data was consistent with electrophysiological recordings obtained intra-operatively. Finally, fMRI data was used as the primary localization technique for the motor cortex neurostimulator, and confirmed with electrophysiological recordings.
Conclusions: Here, we demonstrate the effectiveness of fMRI as a powerful pre-surgical planning tool that has the potential to replace invasive and costly conventional methods. FMRI maps can easily be uploaded and used intra-operatively during stereotactic neurosurgery for accurate localization of complex brain functions.
- Received May 27, 2010.
- Accepted May 27, 2010.
