Subclinical Abnormal Gyration Pattern, a Potential Anatomic Marker of Epileptogenic Zone in Patients With Magnetic Resonance Imaging-Negative Frontal Lobe Epilepsy

Service de Neurochirurgie Fonctionnelle et Stéréotaxique, CHU Timone, Assistance Publique des Hôpitaux de Marseille, Marseille, France.
Neurosurgery (Impact Factor: 3.62). 02/2011; 69(1):80-93; discussion 93-4. DOI: 10.1227/NEU.0b013e318212bb1a
Source: PubMed


Epilepsy surgery for magnetic resonance imaging (MRI)-negative patients has a less favorable outcome.
Detection of subclinical abnormal gyration (SAG) patterns and their potential contribution to assessment of the topography of the epileptogenic zone (EZ) is addressed in MRI-negative patients with frontal lobe epilepsy.
Between September 1998 and July 2005, 12 MRI-negative frontal lobe epilepsy patients underwent stereoelectroencephalography with postcorticectomy follow-up of longer than 1 year (average, 3.3 years). Original software (BrainVISA/Anatomist, trained on a database of normal volunteers was used to determine which sulci had morphology out of the normal range (SAG). Topography of the EZ, SAG pattern, corticectomy, postoperative seizure control, and histopathology were analyzed.
At last follow-up, 8 of 12 patients (66.7%) were Engel class I (7 IA and 1 IB), 2 class II, and 2 class IV. Small focal cortical dysplasia was histologically diagnosed in 9 of the 12 patients (75%), including 7 of 8 seizure-free patients (87.5%). A SAG pattern was found to be in the EZ area in 9 patients (75%), in the ipsilateral frontal lobe out of the EZ in 2, and limited to the contralateral hemisphere in 1.
SAG patterns appear to be associated with the topography of the EZ in MRI-negative frontal lobe epilepsy and may have a useful role in preoperative assessment. Small focal cortical dysplasia not detected with MRI is often found on histopathological examination, particularly in the depth of the posterior part of the superior frontal sulcus and intermediate frontal sulcus, suggesting a specific developmental critical zone in these locations.


Available from: Olivier Coulon
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    • "Before the implantation of the subdural grid electrodes, volumetric MRI (slice thickness, 2.0 mm; TE, 6.2 milliseconds [ms]; TR, 10.3 ms; flip angle, 8 degrees) was performed on a 3-T Philips ACHIEVA scanner (Philips MRI Equipment, Eindhoven, The Netherlands). Matching of the cortical sulci and gyri was done with Brain VISA software based on T1-weighted MR images.5 6 7 After implantation of the grid, a thin-sliced bone window CT was performed. Both preimplantation MRI and postimplantation CT were incorporated into LGP. "
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    ABSTRACT: Background Leksell GammaPlan (LGP) and SurgiPlan (ELEKTA Instruments AB, Stockholm, Sweden) may be used effectively for the detailed evaluation of regional neuroanatomy before open neurosurgical procedures. We report our initial experience in the cases of cerebral gliomas. Methods LGP v.8.3 was used before the surgical resection of cerebral gliomas for (1) the delineation of subdural grid electrodes and a detailed evaluation of their position relatively to cortical structures, and (2) for the fusion of structural magnetic resonance imaging and diffusion tensor imaging (DTI) for a detailed visualization of the corticospinal tract (CST) and optic radiation. Results Delineation of the subdural grid within LGP in a patient with seizures caused by left parietal glioma permitted a detailed assessment of the location of electrodes relative to the cortical gyri and sulci and significantly facilitated interpretation of brain mapping before tumor resection. In another patient with parieto-occipital glioma, simultaneous three-dimensional visualization of the tumor, CST, and optic radiation with the use of LGP permitted us to perform tumor resection without postoperative neurologic complications. Finally, incorporation of DTI into SurgiPlan resulted in precise planning of stereotactic biopsy for bilateral thalamic glioma. Conclusion The possibility for detailed evaluation of regional neuroanatomy based on various images within LGP and SurgiPlan may facilitate effective and safe surgical management of intracranial gliomas.
    Journal of Neurological Surgery 12/2013; 74(2):118-122. DOI:10.1055/s-0033-1358380 · 0.49 Impact Factor
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    • "Patients with refractory epilepsy due to CD are a challenge for clinicians. There is still a long distance to be covered to achieve complete freedom from seizures (Regis et al., 2011; Chassoux et al., 2012). With the development of neuroimaging technology, the postoperative outcomes convey better results in terms of seizure freedom. "

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    • "FCD II on MRI can be limited to the bottom of a sulcus (Barkovich et al., 1997), with local increased WM signal intensity (Hofman et al., 2011), or form an extensive " transmantle dysplasia " where abnormal signal extends to the margin of the ventricle (Barkovich et al., 1997). Furthermore, in some pathology-proven cases of FCD II, MRI changes are subtle or overlooked (Oster et al., 2012; Regis et al., 2011). These observations suggest that the extent of WM pathology within the spectrum of FCD II lesions is highly variable. "
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    ABSTRACT: Purpose A diagnostic feature of focal cortical dysplasia (FCD) type II on magnetic resonance imaging (MRI) is increased subcortical white matter (WM) signal on T2 sequences corresponding to hypomyelination, the cause of which is unknown. We aimed to quantify WM pathology in FCD type II and any deficiency in the numbers and differentiation of oligodendroglial (OL) cell types within the dysplasia. Methods In 19 cases we defined four regions of interests (ROIs): ROI1 = abnormal WM beneath dysplasia, ROI2 =dysplastic cortex, ROI3 = normal WM, and ROI4 = normal cortex. We quantified axonal and myelin density using immunohistochemistry for neurofilament, myelin basic protein and quantified mature OL with NogoA, cyclic nucleotide 3-phosphodiesterase (CNPase) and OL precursor cell (OPC) densities with platelet derived growth factor receptor (PDGFR)α, β and NG-2 in each region. Key Findings We observed a significant reduction in myelin and axons in the WM beneath dysplasia relative to normal WM and there was a correlation between relative reduction of myelin and neurofilament in each case. OL and OPC were present in the WM beneath dysplasia and although present in lower numbers with most markers, were not significantly different from normal WM. Neurofilament and myelin labeling highlighted disorganized orientation of fibers in dysplastic cortex but there were no significant quantitative differences compared to normal cortex. Clinical correlations showed an association between the severity of reduction of myelin and axons in the WM of FCD and duration of epilepsy. Significance These findings indicate a reduction of myelinated axons in the WM of FCD type II rather than dysmyelination as the primary pathologic process underlying WM abnormalities, possibly influenced by duration of seizures. The range of OPC to OL present in FCD type II does not implicate a primary failure of cell recruitment and differentiation of these cell types in this pathology.
    Epilepsia 03/2013; 54(5). DOI:10.1111/epi.12143 · 4.57 Impact Factor
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