In order to prevent recurrent stroke, antiplatelet is administered to patients with non-cardioembolic stroke, and warfarin is given to those with cardioembolic stroke. In stroke patients with nonvalvular atrial fibrillation, PT-INR should be kept between 2.0 and 3.0 when patients are under 70 years old, and between 1.6 and 2.6 when they are 70 years old or more. Thrombo-embolic events may happen when we withdraw antithrombotic agents for surgery, but bleeding becomes a big issue when we continue them. As for tooth extraction and cataract surgery, antithrombotic agents should be continued. However, it is usually discontinued at major surgery or endoscopic surgery. Alternative therapy with heparin is acceptable for patients with high risk factors of thrombo-embolic events when atithrombotic agents are discontinued. Because, alternative therapy can not remove all risks of thrombo-embolic evetns, informed consent is required when antithrombotic agents are discontinued. When severe hemorrhagic complications happen in patients using warfarin, the increased PT-INR can be reversed immediately by intravenous administration of prothrombin complex concentrate.

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In order to preserve function of the brain and cranial nerves, various methods of intraoperative electrophysiological monitoring have been widely used in the field of neurosurgery. Recently brain functions such as motor, sensory, speech, visual or auditory function can be monitored as well as cranial nerve functions. In this manuscript, basic details such as type of recording electrodes, artifact measuring, filters, and anesthesia are discussed. Methods of somatosensory evoked potentials (SEP) elicited by electrical stimulation of the median nerve and posterior tibial nerve, motor evoked potentials (MEP) elicited by cortical and transcranial stimulation, and visual evoked potentials (VEP) are demonstrated. Finally, pitfall cases who underwent intraoperative monitoring with SEP, MEP and VEP are presented with some considerations.

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Deep brain stimulation (DBS) was firstly introduced into movement disorder treatment as a substitute for the classical lesioning method previously employed in stereotactic and functional neurosurgery. Today, DBS has become a standard treatment of choice for essential tremor and for advanced Parkinson disease with motor fluctuation. For essential tremor, the thalamus (Vim: nucleus ventralis intermedius) is employed as a target and for advanced Parkinson disease, thalamus, globus pallidus pars medialis, and subthalamic nucleus. Quite recently, the pedunclopontine nucleus is also considered as a target for some Parkinson disease patients who are refractory to subthalamic DBS. The indication has also extended to several other movement disorders where no alternative and effective treatment is available, namely, several types of generalized and focal dystonia, chorea, and tics. Several other indications for DBS are currently under investigation, such as epilepsy, obsessive-compulsive disorders, and depression. The effect of DBS with high frequency stimulation mimics focal lesioning of the target. However, its mechanism of action seems more complex, and needs to yet be investigated for future wide indication.

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Selecting the best surgical approach, either anterior or posterior, has been controversial in the management of degenerative cervical spine disorders. We usually selected anterior decompression and fusion if the neural compression was limited to one or two disc levels. Posterior decompression by laminoplasty was selected if the patients showed multiple compression at or more than three levels or significant compression by the yellow ligament. In this article, we reviewed our surgical series including cervical spondylosis (263 patients) and OPLL (91 patients) between 1996 and 2007. The purpose of this study is to discuss complications and problems in each approach, and to provide information for selecting the appropriate surgical approach in cervical spondylosis. A total of 227 patients were treated with anterior decompression and fusion, while 127 patients underwent bilateral open-door laminopalsty. The number of the patients showing postoperative upper limb symptoms was smaller in the anterior group than the posterior group (4 patients, 1.8% and 6 patients, 4.7%). The number of reoperations was larger in the anterior group than the posterior group (10 patients, 4.4% and 3 patients, 1.9%). The laminoplasty patients showed a significantly reduced range of neck motion by 11 degrees at follow-up. The literature review revealed several advantages and shortcomings in each approach that should be understood. Meticulous decompression procedures and fusion techniques will be needed for the anterior approach. Postoperative axial symptoms should be considered when the posterior approach is conducted. The appropriate surgical approach for each patient should be determined considering multiple factors such as the longitudinal extent of spinal cord compression, compression by the posterior elements such as the yellow ligament, the presence of kyphotic alignment and general condition.

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The standard endovascular treatment for cerebral aneurysms is endosaccular COIL embolization (coiling) and parent artery occlusion with internal trapping. The ISAT study on the treatment of ruptured aneurysms demonstrated the superiority of coiling over clipping in 2002. Small aneurysms with a small neck (4mm or less, 50% or less of dome size) and a dome of 10mm or less in size are good for coiling. Aneurysms larger than 11mm in size tend to be recanalized after long-term follow-up. Partially thrombosed aneurysms should not be treated with coils. The SAPPHIRE study proved that carotid artery stenting (CAS) in high-risk patients was not inferior to carotid endarterectomy. The treatment indication in Japan is carotid stenosis with 50% or more in symptomatic high-risk patients, and 80% or more in asymptomatic high-risk patients. CAS is a less invasive technique for carotid revascularization. Thromboembolic complications due to plaque debris, however, must be overcome.

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In patients with hemifacial spasm, stimulation of the zygomatic branch or the marginal mandibular branch of the facial nerve elicits abnormal muscle responses (AMRs) in the mentalis muscle or orbicularis oculi muscle respectively, although these muscles are normally innervated by the the marginal mandibular branch and zygomatic branch, respectively. The AMRs are specific for patients with hemifacial spasm and are called "exaggerated F waves". The F wave that is observed in the mentalis muscle following marginal mandibular branch stimulation is a small recurrent discharge, which antidromically propagates to the facial motor nucleus and returns orthodromically down the same axon. The F wave is enhanced on the spasm side, which means that the excitability of the facial motor nucleus increases in patients with hemifacial spasm. This concept is important for considering the clinical course of patients with hemifacial spasm before and after microvascular decompression surgery.

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Object: Intraoperative transcranial motor-evoked potential (TCMEP) monitorings are widely performed during neurosurgical operations. Alarm points for TCMEP were examined in our series. Methods: TCMEP monitorings were performed during 300 neurosurgical operations. Transcranial stimulations at 100〜600V were delivered by screw electrodes placed in the scalp and electromyographic responses were recorded with surface electrodes on the affected muscles. To exclude the effects of muscle relaxants on TCMEP, compound muscle action potential (CMAP) by supra-maximum stimulation of the peripheral nerve immediately after transcranial stimulation was recorded in 266 operations. Among these 266 patients, 241 patients including 77 cerebral aneurysms, 94 spinal operations, 26 brain tumors, 26 extracranial-intracranial bypass operations, 15 carotid endoarterectomies, 2 intracerebral hematomas, and a arterio-venous malformation, had no preoperative motor palsy. Results: Among 229 patients who had had no preoperative and postoperative definitive motor palsy, the amplitudes of TCMEP compensated by CMAP after peripheral nerve stimulation decreased less than 20% in 4 patients, thus the specificity was 98.3%. Two false negative findings were recognized in 12 patients who had had postoperative newly progressed motor palsy and the sensitivity was 83.3%. Although the threshold for postoperative motor palsy is 80% compensated relative amplitude reduction in both brain tumor and spinal surgery, the alarm point for the operator is considered to be a 70% reduction in all neurological surgery including aneurismal surgeries. Conclusions: Intraoperative TCMEP monitoring is a significantly reliable method to prevent postoperative motor palsy in cranial surgery. A seventy percent reduction of the compensated amplitude is considered to be the alarm point in all neurological surgeries.

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