Electromagnetic methods are the most important diagnostic tools in the presurgical evaluation of medically intractable epilepsy. Localization of the source of the epileptic discharge is essential, in the presence or absence of structural lesions. Scalp electroencephalography (EEG), intracranial EEG and magnetoencephalography provide temporal resolutions of millisecond-order that are adequate to evaluate the physiology of the disease. The advantages and limitations of these electromagnetic methods are based on the following characteristics: 1) space-sampling and sensor position; 2) time-sampling and measurement time; 3) effect of ambient- and brain-noises and; 4) source localization methods. Combined and complementary use of these electromagnetic methods can provide the information essential for the surgical treatment of epilepsy.

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In this review article, the author summarizes the present status of auditory brainstem implant (ABI), comparing it to cochlear implant (CI). CI restores hearing by stimulating the cochlea for patients whose deafness has been caused by inner ear disease; ABI does it by stimulating the cochlear nucleus of the brainstem for those deaf due to bilateral cochlear nerve dysfunction. In the world, up until now, more than 150 patients, almost all of whom are neurofibromatosis type 2, have undergone ABI and had hearing restored. Hearing performance by ABI, however, is not so good as that by CI. To improve the quality of hearing by ABI, new techniques such as neural response telemetry and depth electrodes are now being introduced.

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The merits of using cell lines as donors for neural grafting are that they are unlimited as donor source theoretically and they can be genetically modified. However, when using cell lines as donors, immunological rejection and tumor formation should be controlled. To overcome these issues, encapsulated cell grafting technique using semipermeable membrane consisted of polymer has been developed. This technique also has safety because the capsule is retrieval after transplantation. In this review, encapsulated cell grafting research using neurotransmitter and/or neurotrophic factor secreting cell lines will be summarized and future perspectives will be performed from the aspects of therapy for neurological disorders.

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Recent clinical studies have demonstrated that deep brain stimulation (DBS) of the subthalamic nucleus (STN) can afford great benefits to the daily living activities of patients with advanced Parkinson's disease (PD). STN-DBS improves the daily living activity and total motor scores on the Unified Parkinson's Disease Rating Scale at off-medication, through improvement of the tremor, rigidity, akinesia, gait disturbance and postural instability subscores. STN-DBS also attenuates pronounced motor fluctuations due to on-off (wearing off) phenomenon at on-medication, through improved motor symptoms during the off-period and prolonged on-period. The dopa dose can be reduced and dopa-induced dyskinesia can be controlled by STN stimulation. The best indication for STN-DBS is currently considered to be dopa-responsive PD which demonstrates 1) marked motor fluctuations due to the on-off phenomenon, 2) dopa-induced dyskinesia or 3) levodopa-intolerance because of various other side effects. In contrast, STN-DBS may not improve the overall daily living activities at all in patients who have become unresponsive to a large-dose levodopa and continuously immobile. Continued use of large-dose levodopa has been suggested to cause various adverse reactions, including dyskinesia, the on-off phenomenon and mental symptoms. STN-DBS can be employed to decrease the cumulative levodopa dose taken by patients over the course of their illness. It appears possible therefore that early initiation of STN-DBS therapy could well alter the course of symptoms of PD. We consider that STN-DBS in less-advanced PD warrants further clinical investigation.

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To determine the surgical indication of supratentorial asymptomatic unruptured cerebral aneurysms (SAUCAs), we investigated the literature regarding the natural history of and surgical result for SAUCAs. We obtained the following results: 1) The annual rupture rate of SAUCAs is estimated at approximately 1 to 2%, except for a very low rupture rate suggested by International Cooperative Study because it seemed to be highly biased regarding patient selection ; 2) Small aneurysms (<5mm) and aneurysms harbored in elderly patients over 70 years of age have a chance of rupture ; 3) Surgical mortality and morbidity is 1% and 4%, respectively, and ; 4) In the present situation, direct surgery should be considered as the primary option of treatment. Based on the above mentioned reasons, surgical indication of SAUCAs is valid on persons who can manage ordinary daily life without severe systemic disease even if they are over 70 years of age, and who present with nongiant aneurysm including small aneurysms (<5mm). On the other hand, in cases of giant aneurysm, the age of the patient should be less than 70.

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1) Adjuvant chemotherpay for high-grade gliomas. The randomized clinical trials BTSG 69-01, 72-01, 75-01 and RTOG7401/ECOG1374 showed radiotherapy plus chemotherapy with nitrosoureas offered a long term survival advantage to patients younger than 60 years old. Combination chemotherapy, such as PCV, gava a survival advantage to patients with anaplastic gliomas in one study and it shouuld be tested furthermore. Intra-artrial chemotherapy with nitrosoureas did not offer a survival advantage. 2) Chemotherapy for anaplastic oligodendroglioma and anaplastic oligoastrocytoma. Combination chemotherapy with PCV was effective in patients with anaplastic oligodendroglioma and anaplastic oligoastrocytoma and it was shown that 1 pLOH was the predictor of chemosensitivity. 3) Drug resistance. The MGMT level in tumor tissue correlated with survival of patients who were treated with BCNU. 4) New drugs. Temozolomide is the most promising drug and a phase II randomized study in patients with glioblastoma at first relapse showed a survival advantage of temozolomide over procarbazine. 5) Future directions. The genetic predictors of chemosensitivity, methods overcoming drug resistance, and drugs with new mechanisms of action such as signal transduction inhibitor and angiogenesis inhibitor are undergoing preclinical and clinical testing.

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Report of Brain Tumor Registry of Japan (1969-1993) 10th Edition was issued as a supplement of Neurologia medico-chirurgica, Vol.40 in January, 2000. More than 80,000 cases of brain tumors were registered by 281 neurosurgical institutes all over Japan. According to the report the frequency of registered cases of gliomas has been decreasing while that of the benign tumors such as meningiomas and pituitary adenomas has been increasing. The frequency of meningiomas was 26% of all the primary brain tumors and that of gliomas was 24%. The five-year survival rates of malignant astrocytomas and glioblastomas were only 23% and 6%, respectively, even for the cases after 1991. Histological diagnosis, mode of surgery, preoperative performance status and age have been considered to be the factors influencing the survival rates of gliomas. The report demonstrated that the more tumors were removed, the longer survival rates were expected for any kind of gliomas. The elder patients over 70 years of age showed poor survival rates. Radiotherapy was beneficial to the longer survival of malignant gliomas but did not always contribute to that of low grade gliomas. These data have not resulted from the controlled studies but they represent the recent standard of neurosurgery in Japan. Precise registration is essential in order to establish the reliability of the registry.

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