In patients with phantom limb, the primary somatosensory cortex may undergo reorganization of receptive field representation (invasion of the phantom limb area by the adjacent area). It has been reported that this reorganization is highly correlated with phantom limb pain and unrelated to the non-painful phantom sensation. These findings led to the hypothesis that restoration of the original cortical organization might diminish phantom limb pain. Similar reorganization of receptive field representation within the thalamic sensory relay nucleus has been shown by microrecordings and microstimulation during surgery for therapeutic electrode implantation. We review the published data and our own experience regarding the effects of neurostimulation therapies on phantom limb pain (spinal cord, thalamic sensory relay nucleus and motor cortex) from a view point that neurostimulation therapies produce their effects through restoration of the original receptive field organization by artificial input to the representation of the phantom limb area. Many phenomena observed during neurostimulation therapies are better explained bv such a hypothesis rather than classic gate control theory.

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The diagnosis of involuntary movements is important in selecting proper therapeutic measures. It is however often difficult because of the complexity of variety of movements. This review deals with their clinical features that help neurosurgeons make precise diagnosis.

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According to the Pcdiatric Brain Tumor Foundation of the United States, brain tumor is becoming tbe leading cause of death in patients below the age of 34 and the mortality rate of brain tumor is the highest among all pediatric cancers. Social recognition for this issue is sadly lacking in our country. Pediatric brain tumors differ from adult brain tumors in several ways. First of all, the histological types of tumors encountered in children are uncommon and various. This variety makes the management strategy complex. The appropriate selection of management including surgery, radiation therapy, and chemotherapy for individual patients is very difficult when concerning their optimal outcomes. Although not well established, chemotherapy may be useful for medullohlastomas, PNETs, germ cell tumors, pilocytic astrocytomas in very young children, etc. In Japan, the medical care system for children with brain tumors who require chemotherapy has been lacking and is far behind that found in Western countries. Cec brain tumors are managed is seriously needed at present.

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There are 3 therapeutic methods for cerebral aneurysms : clipping, endovascular coil embolization, and parent artery occlusion with or without bypass procedures. For lesions such as giant or partially thrombosed aneurysms, which are difficult to treat by a single therapeutic method, the combined use of the 3 methods is required. The therapeutic design for cerebral aneurysms should be decided by the features of the lesion, not by the concept or speciality of the surgeons. In order to devise proper strategy for treating cerebral aneurysms, we should include the clipping technique, the endovascular intervention technique, and the microsurgical anastomosis technique. To perform aneurysmal clipping properly and safely during the operation, surgeons should know the mechanics of the aneurysmal clips. Since the moment of a force is calculated as force by the length of arm, closing force of aneurysmal clips varies by the distance from the blade tips. Width of the opened blade tips are also different between clip brands. Finally, configurations of the clip blade are also different between clip brands. Surgeons should select a proper aneurysmal clip which is suitable for the lesion. Proper therapeutic strategy and knowledge of equipment are key to success in the treatment of cerebral aneurysms.

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Methods of preoperative and periopcrative evaluation for surgical treatment of intractable epilepsy axe described. History taking is the first important approach to recognize characteristics of each patient's epilepsy. In cases witli mesial temporal lobe epilepsy, patients have not infrequently the past history of complicated febrile convulsion in infancy. To diagnose as epilepsy, it is necessary to evaluate neurophysiological testings, I.e. electroencephalogram (EEG) and magneto-encephalogram (MEG) before undertaken neuroradiological imaging. Among non-invasive diagnostic methods, EEC-video monitoring is the most fundamental. We can capture ictal EEG recordings and clinical seizure symptomatology as well as interictal epileptiform discharges in daytime and at night. It is useful to know pathognomonic clinical seizures and lateralizing signs (i.e. gelastic seizures, ipsilateral automatism and contralateral dystonic posturing, etc). The dipole tracing method is useful for identification of epileptic foci from interictal spikes, Neuroradiological examinations are necessary to detect epileptic lesions or foci after combination of CT, MRI, MR spectroscopy, PET. Ictal and inierictal SPECT, and near infrared spectroscopy etc. Volumetry by MR in the amygdala and hippocampus is also useful for the differential diagnosis of mesial from lateral temporal lobe epilepsy and generalized epilepsy. When preoperative workups are discordant, or MRI reveals no organic lesions, intracranial recording is necessary to recognize accurate epileptogenic areas. Electrical cortical stimulation is used to identify eloquent areas associated with individual variations to avoid postsurgical complications. When we can detect epileptic foci and recognize brain functions within and around foci, and remove all of the foci, patients can be seizure-free after resective surgery.

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A retrospective study was designed to examine the operative complications associated with the lumboperitoneal shunl (L-P shunt) for 119 cases of adult communicationg hydrocephalus during the past 19 years. The shunt system was a 3-piece type (lumbar catheter, double chamber flushing device and peritoneal catheter connected by 2 stainless connectors) made from Silastic rubber. CSF flow was controlled by a pressure scnsi-tive-slii valve in the tip of the lumbar catheter. Initial success ratio of the L-P shunt was only 53% (63 cases). Another 56 cases (47%) had a total of 104 shunt-related complications, and needed 82 shunt revisions. The causes of the complications and mul functions were : 33 shunt infections in 21 cases. 10 mechanical problems, such as catheter rupture or migration in 3 cases, 26 problems at the tip of the spinal catheter in 26 cases, 17 problems at the tip of the peritoneal catheter in 15 cases, 4 obstructions due to debris in the shunt system, 2 abortions of the shunt operation due to ifficulty of lumbar catheter placement in 2 cases, 2 acute epidural hematomas in 2 cases, 2 severe pneumoencephalopathies in 2 cases, and unknown causes in 8 cases. Shunt infections were the main causes of the problems that occurred in the early postoperative phase (within 2 weeks). On the other hand, lumbar catheter problems were the main caused in problems occurring in the late postoperative phase (later than 2 months). Shunt infection should be avoided by taking adequate pre- and intraoperative precautions. Catheter disruptions and migrations were unique in this shunl system. These complications should be avoided by careful fixation and connection of the 1 or 2-piece shunt system. During the operation, great care must be paid in order that the catheter does not injure the neural tissue and is not placed in the subdural space but in the subarachnoid space properly, Intraoperative shuntgrams may be useful for the proper placement of the lumbar catheter. However, the obstruction of the lumbar catheter due to late onset inflammation remained unsolved. This study advised us that lumboperitoneal shunt operations should be performed with full comprehension of the unique complications they entail.

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Among the various surgical procedures for treating chronic subdural hematoma (CSDH), burr-hole irrigation with closed-system drainage is now generally accepted as the best treatment method. Lately, it has been reported that patients with postoperative residual subdural air had a high rate of CSDH recurrence. Recently, we have been applying the ncuroendoscopic technique to treat CSDH. A flexible endoscope with small diameter makes it possible to remove the residual air in the cavity safely after evacuating the hematoma. As a result of using this surgical procedure, we could expect a lowering of the recurrence rate of CSDH. Moreover, patients are not bedridden because placing a drain in the hematoma cavity is not required.

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We report a case treated successfully by trapping and a STA-MCA bypass for a giant aneurysm of the extracranial internal carotid artery. An 89-year-old woman had a giant aneurysm in her right extracranial internal carotid artery. Ten days after her admission, the patient required an emergent tracheotomy because of air way obstruction due to the giant aneurysm. After trapping the aneurysm, the STA-MCA bypass was followed by resection of the aneurysmal wall and drainage, which left the aneurysm completely thrombosed and shrunk. Postoperatively, the patient had a good recovery, Extracranial carotid aneurysms are rare. Although treatment strategy and surgical indication for extracranial carotid aneurysms are controversial, symptomatic aneurysms increasing in size should be treated.

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A 51-year-old woman with Marfan syndrome was brought to our hospital as an ambulance emergency suffering from sudden dizziness and dorsalgia. Cerebral computed tomography (CT) images revealed bilateral subarach noid hemorrhage predominant in the peripheries, and CT images of the chest and the abdomen showed Stanford type B aortic dissection. To identify the cause, cerebral angiography was performed from the right brachial artery, but disclosed no aneurysms or dissection of the cerebral arteries. Another cerebral angiography was performed 1 month later, but also found no abnormality. Currently, the patient is doing well under conservative therapy. This is a rare case of subarachnoid hemorrhage and acute aortic dissection both appearing as a consequence of Marfan syndrome. There may be a requirement to check for subarachnoid hemorrhage when a patienl has combination of Marfan syndrome and acute aortic dissection.

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