Medical imaging technology has exhibited rapid progress. Various sequences/modalities exist with respect to computed tomography (CT), magnetic resonance imaging (MRI), cerebral angiography and nuclear medicine examinations. In addition, the development of brain functional imaging, including diffusion tensor tractography, functional MRI and computational fluid dynamics studies, is remarkable. Although these different modalities can be fused to perform three-dimensional (3D) visualization, image processing methods continue to have many issues that need be solved.
  In this report, the fundamental knowledge, principles, construction methods, usefulness, problems and future trends of imaging are reviewed based on the experience of 450 examples of neurosurgical simulation using 3D fusion images in our facility.

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  Neuronavigation has become an established technology to provide objective data on localization in 3D space. In the surgery for lesions near the eloquent area, obtaining a functional image including functional magnetic resonance imaging (fMRI) and tractography is important for making presurgical planning. Navigation technology is essential to perform the operation according to the pre-surgical planning. The surgeons, however, must realize that it does not always correlate well with real localization accuracy. Error analysis includes image distortion, fiducial localization error and registration error, which can all be minimized. Brain shift, caused by the loss of cerebrospinal fluid and tumor resection, is a major problem negatively affecting navigation accuracy. Intraoperative imaging to obtain updated anatomic image data overcomes the problem of brain shift, but the equipment is not so easily installed into the operating room. The development of computer technology is expected to solve this problem in the future.
  The following are some perspectives of neuronavigation with the advance of computer technology : The 3D virtual image will be more intuitive to navigate for surgeons. The development of navigation workstations could have the potential to interpret the real surgical view and provide an automated nomenclature of brain structure to surgeons. Robotic systems might facilitate the navigation procedure to enhance the localization accuracy. Networked neuronavigation is a future direction to assist in operations performed at remote hospitals using navigation image software that utilizes network technology. Finally, to improve the navigation procedure amongst the operation team as well as surgeons, environmental navigation could be proposed to monitor the operative staff and to show the optimal arrangement in the operating room.

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  To maintain the quality of life in patients undergoing neurosurgical treatment, it is essential to evaluate brain function pre- and intra- operatively. These evaluations which have been developed with studies in epilepsy are now essential in neurosurgery for brain tumors and vascular diseases. The goal of functional brain mapping followed by real-time function monitoring is to enable safe and effective surgery with better outcomes. Among multiple modern modalities for brain functional evaluations, we should consider each physiological aspect of these methods from a view point of functional recovery or compensation. Clinical usefulness and differences between intraoperative electrical stimulation of the motor cortex and subcortical fibers (i.e., pyramidal tracts) and voluntary movement to preserve affected or unaffected motor function during neurosurgery are also discussed.

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  Dementia is a common disease, affecting 14% of the over 65s with numbers steadily increasing. The recent development of brain imaging techniques have contributed to the better diagnosis of Alzheimer's disease (AD), dementia with Lewy bodies (DLB), vascular dementia (VaD), frontotemporal lobar degeneration (FTLD) and corticobasal degeneration (CBD). Structural imaging, previously used to exclude non-degenerative causes for dementia, is becoming increasingly important in the diagnostic procedure. Atrophy of the hippocampus and entorhinal cortex suggests the presence of AD, and cortical and subcortical infarcts and white matter lesions are characteristic of VaD. Disease-specific patterns of regional hypoperfusion on single-photon emission computed tomography (SPECT) or hypometabolism on positron emission tomography (PET) could further help differentiate degenerative dementia. Newer techniques show great promise to detect the pathological basis of dementia, such as amyloid in AD.
  This review describes the use of these imaging techniques in dementia. Together, these imaging techniques will be useful tools for early diagnosis, disease monitoring, and consequently contribute to developing effective treatments for dementia.

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  Sciatic scoliosis caused by lumbar disc herniation can be improved by discectomy. However, there have been few studies investigating the course of severe sciatic scoliosis after discectomy. Herein, the authors analyze the characteristics of sciatic scoliosis due to lumbar disc herniation and any change in the scoliosis after discectomy and consider the appropriate surgical approach for sciatic scoliosis.
  A retrospective study of 134 patients who underwent discectomy was performed. The preoperative and postoperative L1-5 Cobb angle was measured. The direction of scoliosis, the location of disc herniation, clinical parameters and the postoperative course of the scoliosis were investigated.
  Of the 76 patients, 54 (71%) had a lumbar disc herniation at the convex side of the scoliosis. There was no statistical significance between the location of disc herniation and the direction of scoliosis. In the 36 patients who had a follow-up X-ray in more than 1 year, there was a statistical significance in preoperative Cobb angle between 3-10°group (33 patients) and 10°<group (3 patients) (5.3°, 20.8°. p=0.005). But after the discectomy, the scoliosis improved in two groups and there was no statistical significance in postoperative Cobb angle. Two patients with severe scoliosis of more than 20°also had improvement of their scoliosis from the early period after discectomy.
  These results indicate that the direction of sciatic scoliosis wasn't associated with the location of disc herniation, but was related to the side of disc herniation.
  The authors suggest that discectomy is an appropriate surgical approach for sciatic scoliosis, even if the scoliosis is severe, without spinal fixation.

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  Intracranial hemorrhage is uncommon during pregnancy and the puerperium, but when it occurs, 40% of these cases manifest specific features depending on the individual patient's condition. The aim of this study is to identify the clinical features of intracranial hemorrhage during pregnancy and to present the associated management strategies and outcomes.
  We present our experience with 5 cases of pregnant women who developed intracranial hemorrhage. Three of them received operations, and the other two were treated with conservation therapy. All of the patients recovered successfully, but one fetus died. Pregnancy induced hypertension (PIH) was the associated factor in three patients and moyamoya disease in one patient. All five patients were in their first pregnancy, and three had hemorrhage during pregnancy and the other two were in the puerperium.
  First-time pregnant woman with PIH or a preexisting cerebrovascular lesion have a high risk of intracerebral hemorrhage during pregnancy and puerperium ; accordingly, an aggressive surgical treatment is indicated. General management using a team approach is also important to manage possible systemic vascular spasm and DIC induced by PIH.

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  Wyburn-Mason syndrome is a rare syndrome associated with multiple arteriovenous malformations (AVMs) involving the orbit, brain and face. We report a case of this rare syndrome with subarachnoid hemorrhage. A 25-year-old man had been diagnosed with cerebral AVM on magnetic resonance imaging and was observed for 3 years. After he developed headaches and vomiting, computed tomography (CT) showed subarachnoid hemorrhage with intraventricular hemorrhage on admission. Cerebral angiography showed a large AVM (diameter, 6.5 cm) involving the basal ganglia and orbit on the left side. Three-dimensional (3D) rotational angiography clarified three aneurysms on the feeder vessels : a distal medial striate artery aneurysm ; a distal anterior choroidal artery aneurysm ; and a paraclinoid internal carotid artery aneurysm. From the perspective of bleeding distribution on CT, the distal anterior choroidal artery aneurysm was suspected to have ruptured. Coil embolization was performed for this aneurysm on day 7, with additional embolization for the remaining two aneurysms on day 17. Postoperative course was uneventful. He achieved complete recovery and resumed his previous life. Target embolization may be a useful treatment option for extensive, deep-seated AVMs such as in Wyburn-Mason syndrome.

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  The epidemiology of idiopathic intracranial internal carotid artery dissection is unclear and there are few reports on stent placement for these lesions. A 54-year-old male was admitted to our hospital with gait disturbance following severe throbbing retrobulbar pain for two days. He was unconscious with slight left hemiparesis. Magnetic resonance imaging (MRI) showed a fresh cerebral infarction in the right temporal lobe. Digital subtraction angiography revealed severe stenosis of the internal carotid artery at the petrous portion ; therefore, we diagnosed the condition as idiopathic carotid artery dissection. The fluctuation of the consciousness level indicated a hemodynamic disorder ; therefore reconstruction of the blood flow was attempted by stent placement. Emergency stent placement with a PALMAZ^TM Genesis^TM stent (Cordis^® Johnson & Johnson, Miami, FL, USA) and PRECISE^® PRO RX^® Carotid Stent System (Cordis^® Johnson & Johnson, Miami, FL, USA) achieved favorable dilatation of the stenosis followed by almost complete remission of the symptoms. Idiopathic internal carotid artery dissection can be successfully treated with stent placement ; however, several difficulties concerning the technique and instruments need to be overcome to achieve safer intervention. Headache accompanied by a focal cerebral ischemic sign permit definite diagnosis of this condition ; therefore, an accurate and exact history of the present illness is very important for early application of the most appropriate therapy.

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