The functional role of the uncinate fasciculus is still a matter of debate. We examined 44 patients submitted to awake surgery for removal of a left frontal or temporal glioma. In 18 patients, the removal included the uncinate fasciculus. We compared patients with or without removal on a series of neuropsychological tasks, performed at different time intervals: pre-surgery, in the first week after surgery and 3 months after surgery. Functional magnetic resonance and diffusion tensor imaging, fibre-tracking techniques were performed before surgery. At the last examination, patients with uncinate removal were significantly impaired in naming of famous faces and objects as compared with patients without removal. We further divided patients according to the site of the tumour (either frontal or temporal). At the follow-up, patients with a temporal glioma who underwent uncinate removal had the worst loss of performance in famous face naming. In addition, on the same task, the group with a frontal glioma that underwent resection of the frontal part of the uncinate performed significantly worse than the group with a frontal glioma but without uncinate removal. In conclusion, the resection of the uncinate fasciculus, in its frontal or temporal part, has long-lasting consequences for famous face naming. We suggest that this fibre tract is part of a circuitry involved in the retrieval of word form for proper names. Retrieval of conceptual knowledge was intact.

SEEG is a safe and accurate procedure for the invasive assessment of the epileptogenic zone. Traditional Talairach methodology, implemented by multimodal planning and robot-assisted surgery, allows direct electrical recording from superficial and deep-seated brain structures, providing essential information in the most complex cases of drug-resistant epilepsy.

aBBreViatiONS EEG = electroencephalography; EZ = epileptogenic zone; FCD = focal cortical dysplasia; MTLE = mesial temporal lobe epilepsy; RF-TC = radiofrequency thermocoagulation; SEEG = stereoelectroencephalography. SuBmitted August 28, 2014. accepted December 8, 2014. iNclude wheN citiNg Published online June 19, 2015; DOI: 10.3171/2014.12.JNS141968. diSclOSure Dr. Cardinale is a consultant for Renishaw Mayfield SA, the manufacturer of Neuromate, and a former consultant for Medtronic, the manufacturer of the O-arm device. The other authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. OBJect Radiofrequency thermocoagulation (RF-TC) of presumed epileptogenic lesions and/or structures has gained new popularity as a treatment option for drug-resistant focal epilepsy, mainly in patients with mesial temporal lobe epilepsy. The role of this minimally invasive procedure in more complex cases of drug-resistant epilepsy, which may require intracranial electroencephalographic evaluation, has not been fully assessed. This retrospective study reports on a case series of patients with particularly complex focal epilepsy who underwent stereoelectroencephalography (SEEG) evaluation with stereotactically implanted multicontact intracerebral electrodes for the detailed identification of the epileptogenic zone (EZ) and who received RF-TC in their supposed EZ (according to SEEG findings). methOdS Eighty-nine patients (49 male and 40 female; age range 2-49 years) who underwent SEEG evaluation and subsequent RF-TC of the presumed EZ at the authors' institution between January 2008 and December 2013 were selected. Brain MRI revealed structural abnormalities in 43 cases and no lesions in 46 cases. After SEEG, 67 patients were judged suitable for resective surgery (Group 1), whereas surgery was excluded for 22 patients (Group 2). Thermocoagulation was performed in each of these patients by using the previously implanted multicontact recording electrodes and delivering RF-generated currents to adjacent electrode contacts. reSultS The mean number of TC sites per patient was 10.6 ± 7.2 (range 1-33). Sustained seizure freedom occurred after TC in 16 patients (18.0%) (13 in Group 1 and 3 in Group 2). A sustained worthwhile improvement was reported by 9 additional patients (10.1%) (3 in Group 1 and 6 in Group 2). As a whole, 25 patients (28.1%) exhibited a persistent significant improvement in their seizures. More favorable results were observed in patients with nodular heterotopy (p = 0.0001389), those with a lesion found on MRI (not significant), and those with hippocampal sclerosis (not significant). Other variables significantly correlated to seizure freedom were the patient's age (p = 0.02885) and number of intralesional TC sites (p = 0.0271). The patients in Group 1 who did not benefit at all (21 patients) or who experienced only a transient benefit (30 patients) from TC underwent microsurgical resection of their EZ. Thermocoagulation was followed by se...

Resection of lesions involving motor or language areas or pathways requires the intraoperative identification of functional cortical and subcortical sites for effectively and safe guidance. Diffusion tensor (DT) imaging and fiber tractography are MR imaging techniques based on the concept of anisotropic water diffusion in myelinated fibers, which enable 3D reconstruction and visualization of white matter tracts and provide information about the relationship of these tracts to the tumor mass. The authors routinely used DT imaging fiber tractography to reconstruct various tracts involved in the motor and/or language system in a large series of patients with lesions involving the motor and/or language areas or pathways. The DT imaging fiber tractography data were loaded into the neuronavigational system and combined intraoperatively with those obtained from direct electrical stimulation applied at the subcortical level. In this paper the authors report the results of their experience, describing the findings for each tract and discussing technical aspects of the combined use as well as the pitfalls.

A fine-grained description of the spatiotemporal dynamics of human brain activity is a major goal of neuroscientific research. Limitations in spatial and temporal resolution of available noninvasive recording and imaging techniques have hindered so far the acquisition of precise, comprehensive four-dimensional maps of human neural activity. The present study combines anatomical and functional data from intracerebral recordings of nearly 100 patients, to generate highly resolved four-dimensional maps of human cortical processing of nonpainful somatosensory stimuli. These maps indicate that the human somatosensory system devoted to the hand encompasses a widespread network covering more than 10% of the cortical surface of both hemispheres. This network includes phasic components, centered on primary somatosensory cortex and neighboring motor, premotor, and inferior parietal regions, and tonic components, centered on opercular and insular areas, and involving human parietal rostroventral area and ventral medial-superior-temporal area. The technique described opens new avenues for investigating the neural basis of all levels of cortical processing in humans.A detailed description of the spatiotemporal dynamics of human brain activity is a major goal of neuroscientific research. However, it has been impossible so far to attain both high spatial and temporal resolution using the available noninvasive recording and imaging techniques. Hence, a precise and comprehensive four-dimensional cartography of human neural activity has not yet been obtained. High spatial resolution, provided by neuroimaging techniques such as functional magnetic resonance imaging (fMRI), is crucial for highlighting the topographical organization of specific areas (e.g., somatotopy of sensorimotor areas) as well as identifying the nodes of brain networks endowed with specific functional properties (1). It is not sufficient, however, to know which nodes are active; information is also needed about the local dynamics of the nodes, as well as the relative timing of their activity, to fully understand human brain functions (2, 3). Even if the temporal resolution of electroencephalography (EEG) and magnetoencephalography (MEG) allowed one to observe the intra-and interareal dynamics, to date such recordings remain too poor in localization power (1-2 cm) (3, 4). Combining EEG and fMRI has been suggested as a solution, using EEG to determine the temporal dynamics within and between the areas identified with fMRI (5). However, the disparate nature of the two signals recorded (hemodynamic for fMRI, electrical for EEG) creates discrepancies in the results that prevent precise matching of these methods (3).Invasive intracranial EEG offers a unique opportunity to observe human brain activity with an unparalleled combination of spatial and temporal resolution. Depending on the electrodes used, two kinds of recordings can be made: (i) intraparenchymal recordings, also called stereo-EEG (sEEG) (6), obtained using stereotactically inserted needle-like electrodes...

Rigorous SEEG, thanks to its basic principles and updated technologies, is a safe and accurate method to define the epileptogenic zone by means of stereotactically implanted intracerebral electrodes.

Low-grade gliomas ([LGGs] WHO Grade II) are slow-growing intrinsic cerebral lesions that diffusely infiltrate the brain parenchyma along white matter tracts and almost invariably show a progression toward malignancy. The treatment of these tumors forces the neurosurgeon to face uncommon difficulties and is still a subject of debate. At the authors' institution, resection is the first option in the treatment of LGGs. It requires the combined efforts of a multidisciplinary team of neurosurgeons, neuroradiologists, neuropsychologists, and neurophysiologists, who together contribute to the definition of the location, extension, and extent of functional involvement that a specific lesion has caused in a particular patient. In fact, each tumor induces specific modifications of the brain functional network, with high interindividual variability. This requires that each treatment plan is tailored to the characteristics of the tumor and of the patient. Consequently, surgery is performed according to functional and anatomical boundaries to achieve the maximal resection with maximal functional preservation. The identification of eloquent cerebral areas, which are involved in motor, language, memory, and visuospatial functions and have to be preserved during surgery, is performed through the intraoperative use of brain mapping techniques. The use of these techniques extends surgical indications and improves the extent of resection, while minimizing the postoperative morbidity and safeguarding the patient's quality of life. In this paper the authors present their paradigm for the surgical treatment of LGGs, focusing on the intraoperative neurophysiological monitoring protocol as well as on the brain mapping technique. They briefly discuss the results that have been obtained at their institution since 2005 as well as the main critical points they have encountered when using this approach.

The present study indicates that, at least in a subset of adequately selected patients with PMG-related epilepsy, surgery may provide excellent seizure outcomes. Furthermore, it suggests that surgery is superior to AEDs for achieving seizure freedom in these cases.