Epilepsy surgery has become one alternative in treating medically irremediable epilepsies. This was achieved partially due to the development of diagnostic techniques for foci. To establish some standard guide lines, we studied the current status of the presurgical focus diagnostic protocol in the Japanese institutes where specialized epilepsy surgeries are performed. Since 2001 till 2005, the annual number of epilepsy surgeries was counted as 489, 620, 600, 553, and 595, respectively. In 2005, three institutes recorded more than 60 surgeries each. The distribution of foci was as Follows; medial temporal 46%, lateral temporal 11%, and frontal 23%. Interictal SPECT was carried out in more than 80% of thge cases. MEG was performed in about 50% of the cases, whereas this rate was more than 80% for parietal and occipital foci. Ictal SPECT was performed in about 50% of neocortical cases but in only 10% of MTLE cases. This reflects the difficuty of this method in practice. Ictal EEG was considered to be a gold standard for focus diagnosis and it was performed in more than 80% of all cases. In contrast, intracranial EEG was used in about 40% of MTL cases and about 80% of neocortical foci cases. This implies that many "skip" cases were found in MTLE because focus the diagnosis is easier here than in other locations. Subdural electrodes were used in most of the neocortical foci cases, because of the need for focus diagnosis and functional mapping using electrical stimulation at the same time. Postsurgical outcome was good (Class I+II: 90%) for medial temporal foci cases, whereas it was less than 80% for neocortical foci cases. These results are considered to be comparable to those reported in the US. Several representative cases were demonstrated to delinate the methodologies used.

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The main goal of the presurgical evaluation is to presume the epileptogenic zone, which is defined as the cortical area capable of generating seizures, and whose removal or disconnection will result in seizure freedom. Intracranial EEG plays an important role in localizing the epileptogenic zone though, it should be integrated with other diagnostic techniques such as semiological analysis, neuroimaging and neuropsychological test to presume the zone as precisely as possible. Intraoperative electrocorticography (ECoG) can define the location and extent of interictal epileptiform activities. Although this technique can be utilized easily without huge equipment, one should keep in mind that the region displaying the active interictal epileptiform activities is not necessarily coterminous with the epileptogenic zone. Intraoperative ECoG may contribute to epilepsy-oriented lesional surgery. Chronic intracranial electroencephalography(EEG) serves a specific need only in the context of a specific question. It should not be used in fishing expedition. Such questions as laterality of mesial temporal lobe epilepsy, extent of the epileptogenic zone surrounding the epileptogenic lesion, spatial relationship between the presumed epileptogenic zone and the functionally indispensable area, etc. must be defined before the invasive study is considered. Although chronic invasive monitoring has advantage of being able to analyze patient's habitual seizures, the relative significance of cortical area where the seizures arise must be weighted carefully.

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Corpus callosotomy for medically intractable epilepsies was initially performed to prevent secondarily seizure generalization through the corpus callosum in 1940, but surgical experiences indicated that this procedure was also effective for generalized epilepsies. Corpus callosotomy has been extensively used in the past 30 years. Results to date suggest that patients with secondarily generalized epilepsy with atonic, tonic, tonic-clonic seizure appear to respond well, while patients with complex partial seizures have less favorable results except for those with frontal lobe epilepsy. However, several issues remain controversial : the criteria of patient selection, the timing of the surgery, the extent of division, and the significance of postoperative EEG changes. We reviewed the developments of corpus callosotomy and its surgical indication, and discussed the seizure control mechanisms of the corpus callosum.

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Hemispherectomy and its modifications are the most effective treatment for intractable epilepsy with hemispheric foci. In this article, those procedures were historically overviewed, and then the anatomical background and surgical techniques of the latest modification, hemispherotomy, were illustrated along with our refinements. The major anatomical components to be disconnected in hemispherotomy are the corpus callosum and the projection fibers. For each, we compared the approaches we adopted. The interhemispheric callosotomy enabled more reliable disconnection of the callosal fibers than transventricular callosotomy and was especially advantageous for anomalous and asymmetric callosum frequently found in hemimegalencephaly. Transopercular disconnection of the projection fibers overcame the problems encountered in peninsular disconnection but resulted in a higher occurrence of impaired CSF circulation. Reviewing these results we recently adopted vertical hemispherotomy for use with our modification.

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Vagus nerve stimulation (VNS) is an efficient and well-tolerated adjunct therapy for drug-resistant epilepsy. The system is comprised of an implantable, programmable pulse generator and a helical bipolar electrode, which continuously delivers an intermittent current to the midcervical portion of the left vagus nerve. Although the mechanisms of action are still under discussion, VNS likely exerts its effect by attenuating excitatory activity while augmenting inhibitory activity in wide cortical areas. VNS has been approved for the treatment of intractable epilepsy all over the world. Because Japan essentially remains the single country where VNS is not approved for clinical use, there are major barriers to providing this treatment to patients with drug-resistant epilepsy in whom resective surgery is not indicated or who did not achieve satisfactory seizure control. The author advocates that proposals for the approval of VNS be considered by the associated academic societies.

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Intraoperative electrophysiological monitoring became popular over time and is now indispensable for neurosurgical operations. Neuroimaging techniques such as functional MRI (fMRI) and magnetoencephalography (MEG) have recently become available in the clinical scene. We describe the clinical usefulness and pitfalls of the recent neuroimaging and electrophysiological techniques and emphasize the reliability of multi-modality integration to visualize the anatomical-functional relationships between lesions and eloquent brain areas. "Functional neuronavigation" with multi-modality integration is novel and useful for maximal resection of brain lesions, sparing the eloquent function and allowing the restoration of the damaged neuronal functions.

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Purpose: Our aim was to determine whether CT angiography (CTA) is suitable for the evaluation of patency and in-stent restenoses in small vessel stents for intracranial angioplasty. Methods: From June, 2000 to February, 2006, 26 patients received stent-assisted angioplasty for intracranial atherosclerotic lesions. The procedure was successfully performed in all patients. Multi plannar reconstruction (MPR) was evaluated for image quality on three groups with I-E (Internal-External diameter) ratios, as follows: Group A=I-E ratio>0.5 (Possible to evaluate stent lumen, high certainty), Group B=0.31≦I-E ratio≦0.5 (Possible to evaluate stent lumen, low certainty), Group C=I-E ratio≦0.31 (Uninterpretable). We examined the possibility of evaluating the stent lumen, maching the identity with the angiographical findings, and finding a predictor of favorable CTA findings. Result: CTA was performed in 19 patients. It was possible to evaluate the visible stent lumen in 14 patients (73.7%); 10 patients comprised group A, 4 patients group B, 5 patients group C. Nine patients were evaluated with both CTA and angiography after the stenting. CTA findings were identical with angiographical findings in 8 of 9 patients. Stent diameter was associated with CTA findings, all of the patients who received 4.0 mm stents were in group A. Conclusion: The stent lumen may be visualized and evaluated in most stents using CTA, but tend to only be interpretable in the small vessels.

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Isolated cortical vein thrombosis (ICVT) occurs very rarely. In a 32-year-old woman with symptoms of increased intracranial pressure, both acute and subacute intracerebral hematoma were demonstrated by computed tomography (CT) and magnetic resonance imaging (MRI). Cerebral angiography suggested thrombosis of the superficial middle cerebral vein, which was confirmed during surgery and by pathologic examination. We carried out a review of pertinent literature concerning ICVT.

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