Image-guided surgery has developed on the basis of navigation-technology born in the late 1980s, enhanced by improvements in various imaging modalities. Intraoperative MRI (iMRI) plays an important role in accurate navigation that is free from the influence of brain shift, allows fine resection control during the tumor surgery, and provides early detection of intraoperative complications. Thus, the role of iMRI is to visualize the intraoperative brain structure and function, namely, to serve as quality assurance (QA) for the neurosurgery. There are increasing number of reports related to iMRI, up to 290 at last count, with at least 200 units installed in ORs throughout the world at present.
  Diffusion tensor imaging (DTI) and tractography enables visualization of the pyramidal tract intraoperatively. High magnetic-field MRI units are capable of conducting DTI to compensate for brain shift during surgery. Lower magnetic-field MRI units, however, are not as powerful. We have developed an advanced imaging technique, “reshape & fuse” in which preoperative images are fused appropriately to deformed intraoperative images using a non-rigid registration algorithm. Using this technique, we were able to successfully estimate the intraoperative shift of the pyramidal tract both toward the inside and outside of the brain.
  Intraoperative hemorrhagic complications can be detected with iMRI, although characterization of the super acute hemorrhage on MRI has not been established yet. We investigated the relationship between blood concentration and MR signals, comparing among the values yielded by T1, T2 and fast FLAIR on various blood concentrations using artificial blood samples. Values of fast FLAIR had the best linearity among the three, suggesting that fast FLAIR is sensitive enough to detect a small amount of blood, and at the same time, able to estimate the concentration of blood in a mixture with CSF. This finding could lead to better visualization of intraoperative super acute hemorrhagic events.
  Expanding iMRI and developing related imaging technologies would contribute greatly to the QA of neurosurgery, pushing forward the frontier for intraoperative visualization of the brain.

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  We developed a novel technique to visualize the electrophysiological phenomenon of high frequency oscillation (HFO) in real time for bed-side use and intraoperative monitoring during awake craniotomy. We investigated four patients with intractable epilepsy and three with brain tumor who underwent lesion resection via awake craniotomy. For data acquisition and processing, we used a 256-channel g.HIamp and MATLAB 2012b. For the bedside HFO mapping, motor and language-related functions were identified and validated by electrocortical stimulation (ECS). During the awake craniotomy, we analyzed the brain oscillation frequency components in real time and used HFO mapping to identify the functional areas. Real-time HFO mapping rapidly indicated the eloquent epicenters of the motor and language functions and significantly shortened the awake craniotomy operation time. This technique makes intraoperative monitoring more reliable, and enabled us to devise rational and objective operation strategies for each patient.

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  Indocyanine green videography is commonly used in the neurosurgical field for intraoperative assessment of vascular flow following clipping of cerebral aneurysms. The indocyanine green videography modality is quick, cost-effective, and safe to use with its integration into the surgical microscope and has become well-established in the field of vascular neurosurgery. However there are few reports of the use of indocyanine green videography for brain tumor surgery. The application of intraoperative indocyanine green videography to brain tumor surgery was reviewed in this section. Hemangioblastoma surgery, glioma surgery, and meningioma surgery were discussed. Vascular flow in the real surgical field was taken into consideration for safety also in the brain tumor surgery.

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  During operative procedure surgeons are obliged to make important clinical decisions constantly. In the past this process was mainly based on the observation of the surgical field and was significantly dependent on the individual experience. Since current clinical data demonstrate profound impact of more aggressive brain tumor resection on patient's prognosis, novel methods for optimization of the surgical decision-making seem necessary. It can be attained by application of the real-time integrated analysis and visualization of the various intraoperative data related to imaging, functional monitoring, and histopathological investigation, which constitutes the basis of the “information-guided surgery” concept opening new perspectives for innovative minimally invasive treatment of the various neurosurgical diseases.
  Integrated analysis of the various intraoperative data from multiple sources may contribute significantly to reliability of surgical decisions and profoundly improve their preciseness. However, this process is rather complex. Technically, there is no straightforward way for judgements on patient response during awake craniotomy, positivity of 5-ALA-induced tissue fluorescence, presence of the navigational error caused by the brain shift, or determination of the threshold of MEP decline. On the other hand, in tumors located within or in close vicinity to eloquent cerebral structures the surgeon frequently encounters a dilemma between anatomical and functional data, which requires prioritizing of the available information during complicated choice between more aggressive tumor resection and preservation of the functionally important neuronal tissue. Availability of the histopathological characteristics of the resected tissue and other kinds of information may be rather helpful for critical surgical decision-making.
  Herein we describe our concept of the information-guided surgery of brain tumors, present the results of its clinical application, and discuss perspectives of its further development in the nearest future.

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  Clipping surgery for cerebral aneurysms occasionally requires transient deflation of the aneurysm to prevent its rupture and to avoid injury to the surrounding tissue structure. Temporary occlusion of the parent artery is an effective method to reduce the pressure of the aneurysm. However, with large aneurysms, blocking the parent artery may not be a suitable alternative. In addition, temporary occlusion may be prohibited by the existence of atherosclerotic changes or perforating branches in the parent artery. Transient cardiac arrest (TCA) induced by adenosine triphosphate (ATP) is an effective alternative in such cases. This method leads to a temporary softening of the aneurysm. Adenosine is a purine nucleoside that suppresses atrioventricular conduction. A bolus dose of ATP causes momentary cardiac arrest. Here, we describe the advantages of inducing TCA to the clipping process.
  Eighty-seven consecutive patients with aneurysms (ruptured aneurysms : 39, unruptured aneurysms : 48) were surgically treated between 2012 and 2013. Of these, seven patients with anterior circulation aneurysms underwent TCA-inclusive surgery. Among them, five had ruptured aneurysms and two had an unruptured aneurysm. Bolus intravenous injection of ATP (10-120 mg) was administered at a dose deemed fit by the anesthesiologist to satisfy the arrest duration requested by the surgeon. Microsurgery was then performed during the short period of cardiac arrest.
  We observed 3-40 seconds of cardiac arrest and noted remarkable softening or collapse of the aneurysms in all cases. In every case, the aneurysms were successfully obliterated without rupture, and the heartbeat recovered spontaneously without any additional intervention. Complications associated with TCA were not observed in any of these patients.
  TCA facilitated safe and quick dissection of the aneurysm and clip application during the clipping operation. This approach is useful when temporary occlusion of the parent artery is difficult. In addition, TCA provides an added advantage of no parent artery injury, which is often associated with its temporary occlusion.
  ATP-induced TCA is a quite useful and safe approach when temporary occlusion of the parent artery is not feasible, although the former requires close monitoring by an experienced anesthesiologist.

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  The outcome of surgical intervention for thoracic degenerative diseases is generally poor compared with that for cervical or lumbar degenerative diseases, especially in patients with lesions ventral to the thoracic spinal cord. Neurological problems due to thoracic degenerative diseases are uncommon ; large case series reports on surgical treatment of these diseases have been rarely reported. The authors retrospectively analyzed the epidemiology, clinical presentations, surgical approaches, and surgical outcomes in 99 consecutive patients with thoracic degenerative diseases who had undergone surgical treatment in a single institution. Neurological symptoms in these patients were caused by ossification of the ligamentum flavum (OLF) (52 patients) ; intervertebral disc herniation (DH) (19) ; ossification of the posterior longitudinal ligament (OPLL) (7) ; both OLF and DH (13) ; both OLF and OPLL (3) ; or spinal canal stenosis without these entities (5). Patients with thoracic OLF had undergone OLF removal via the posterior approach, and those with DH in the cervicothoracic junction had undergone surgical procedures with the conventional anterior approach. Most patients with middle-to-lower thoracic DH had undergone discectomy via the posterolateral approach, and those with thoracic OPLL had undergone OPLL removal via anterior or anterolateral approaches. Surgical outcomes evaluated using the recovery rate of modified Japanese Orthopaedic Association score showed that all diseases had favorable recovery rate. Surgical complications were found in only a limited number of patients. The authors conclude that the surgical approaches adopted were effective and safe in patients with thoracic degenerative diseases.

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  Cerebral vasospasm is a well-documented occurrence of aneurysmal subarachnoid hemorrhage but has not been sufficiently analyzed in cases with arteriovenous malformation. Moreover, cerebral vasospasm following arteriovenous malformation rupture is a rare and critical complication. We describe a case of symptomatic cerebral vasospasm following cerebellar arteriovenous malformation rupture.
  An 8-year-old girl presented with deteriorated consciousness. Computed tomography revealed packed intraventricular and diffuse thin subarachnoid hemorrhages due to cerebellar arteriovenous malformation. Immediate endoscopic evacuation of intraventricular hemorrhage was performed. Subsequently, total arteriovenous malformation resection was achieved surgically after preoperative glue embolization. Twelve days posthemorrhage, cerebral angiogram revealed severe vasospasm at both internal carotid arteries. Although emergency intra-arterial fasudil hydrochloride injection and balloon angioplasty resolved the vasospasm successfully, postoperative magnetic resonance imaging showed bifrontal cerebral infarction.
  The characteristic features of cerebral vasospasm after arteriovenous malformation rupture are discussed. In the present case, packed intraventricular hemorrhage could strongly affect significant vasospasm. Treatment of patients with intraventricular hemorrhage related to arteriovenous malformations should consider the risk of severe delayed vasospasm.

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