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: 3.03). 02/2011; 69(1):80-93; discussion 93-4. DOI: 10.1227/NEU.0b013e318212bb1a
Source: PubMed

ABSTRACT 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.

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    ABSTRACT: Cortical dysplasia (CD) is one of the most impor-tant causes of intractable epilepsy. The precise mechanisms of epileptogenesis in CD are not known. Using CD animal models, we attempted to understand the mechanisms and efficacy of various antiepileptic drugs. In two separate stud-ies, we assessed (1) the effects of levetiracetam (LEV) and vagus nerve stimulation (VNS) on pen-tylenetetrazol (PTZ)–kindled rats, and (2) the effects of LEV and topiramate (TPM) on rats with CD and hyperthermia (HT). In the HT-induced rats with CD study, LEV and TPM decreased both the intensity of seizures and the number of rats with seizure. In these studies, we used immunocy-tochemistry (occludin, glial fibrillary acidic pro-tein [GFAP], and P-glycoprotein [Pgp antibodies] and electron microscopy (EM) (sodium fluores-cein [NaFlu]) and horseradish peroxidase [HRP]) to assess blood–brain barrier (BBB) integrity. Both LEV and TPM protected BBB. In PTZ-kin-dled rats with CD, both LEV and VNS reduced the duration of seizures. Immunocytochemistry and EM revealed no BBB impairment in any of the treatment groups. In a second set of experi-ments, we assessed the relationship between dis-ruption of vascular components and epileptogenesis. Astrocytic albumin uptake in focal epileptogenic lesions with vascular compo-nents suggested that dysfunction of the BBB con-tributes immediately to epileptogenesis, rather than simply resulting from seizure activity. He-mosiderin deposits were seen as potential epilep-togenic triggers in vascular malformations (e.g., cavernomas [CA] or arteriovenous malforma-tions [AVMs] with or without a dysplastic cortical component). However, we found strikingly high accumulation of astrocytic albumin deposits in surgically removed brain parenchyma in the vicin-ity of CAs and AVMs from patients with pharma-coresistant epilepsy, which suggests different pathophysiologic dispersion pathways for hemo-siderin and albumin in vascular lesions. KEY WORDS: Cortical dysplasia, Epilepsy, Blood– brain barrier, Electron microscopy, Immunohisto-chemistry, Lesion with vascular component.
  • Seminars in roentgenology 01/2014; 49(1):99-111. · 0.70 Impact Factor
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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 reports. 12/2013; 74(2):118-122.


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May 23, 2014