• Journal of Korean Neurosurgical Society
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• v.47 no.2
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• pp.148-150
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• 2010

Osteolipoma is an ossified lipoma with distinct components of fat and bone. We present a case of interhemispheric osteolipoma associated with total agenesis of the corpus callosum. A 20-year-old man complained of severe headache, nausea and vomiting. Brain computed tomography showed a low-density mass in an interhemispheric fissure, with high T1 and T2 magnetic resonance signals compatible with fat. The mass measured $4.9\;{\times}\;2.9\;cm$ in size and showed peripheral calcifications. There was another small piece of same signal mass within the lateral ventricular choroid plexus. The interhemispheric lesion was removed by an interhemispheric approach. Osteolipoma is rare in interhemispheric region, however, it should be a differential diagnosis of lesions with fat intensity mass and calcifications.

• Journal of Korean Neurosurgical Society
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• v.64 no.4
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• pp.524-533
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• 2021

Objective : When treating high-positioned anterior communicating artery (ACoA) aneurysms, pterional-transsylvian and interhemispheric approaches are both viable options, yet comparative studies of these two surgical approaches are rare. Accordingly, this retrospective study investigated the surgical results of both approaches. Methods : Twenty-four patients underwent a pterional approach (n=11) or interhemispheric approach (n=13), including a unilateral low anterior interhemispheric approach or bifrontal interhemispheric approach, for high-positioned ACoA aneurysms with an aneurysm dome height >15 mm and aneurysm neck height >10 mm both measured from the level of the anterior clinoid process. The clinical and radiological data were reviewed to investigate the surgical results and risk factors of incomplete clipping. Results : The pterional patient group showed a significantly higher incidence of incomplete clipping than the interhemispheric patient group (p=0.031). Four patients (36.4%) who underwent a pterional approach showed a postclipping aneurysm remnant, whereas all the patients who experienced an interhemispheric approach showed complete clipping. In one case, the aneurysm remnant was obliterated by coiling, while follow-up of the other three cases showed the remnants remained limited to the aneurysm base. A multivariate analysis revealed that a pterional approach for a large aneurysm with a diameter >8 mm presented a statistically significant risk factor for incomplete clipping. Conclusion : For high-positioned ACoA aneurysms with a dome height >15 mm and neck height >10 mm above the level of the anterior clinoid process, a large aneurysm with a diameter >8 mm can be clipped more completely via an interhemispheric approach than via a pterional approach.

• Journal of Korean Neurosurgical Society
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• v.60 no.2
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• pp.250-256
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• 2017

Objective : Cases of a ruptured pericallosal artery aneurysm with a high risk of intraoperative premature rupture and technical difficulties for proximal vascular control require a technique for the early and safe establishment of proximal vascular control. Methods : A combined pterional or subfrontal approach exposes the bilateral A1 segments or the origin of the ipsilateral A2 segment of the anterior cerebral artery (ACA) for proximal vascular control. Proximal control far from the ruptured aneurysm facilitates tentative clipping of the rupture point of the aneurysm without a catastrophic premature rupture. The proximal control is then switched to the pericallosal artery just proximal to the aneurysm and its intermittent clipping facilitates complete aneurysm dissection and neck clipping. Results : Three such cases are reported : a ruptured pericallosal artery aneurysm with a contained leak of the contrast from the proximal side of the aneurysm, a low-lying ruptured pericallosal artery aneurysm with irregularities on its proximal wall, and a multilobulated ruptured pericallosal artery aneurysm with the parasagittal bridging veins hindering surgical access to the proximal parent artery. In each case, the proposed combined pterional-interhemispheric or subfrontal-interhemispheric approach was successfully performed to establish proximal vascular control far from the ruptured aneurysm and facilitated aneurysm clipping via the interhemispheric approach. Conclusion : When using an anterior interhemispheric approach for a ruptured pericallosal artery aneurysm with a high risk of premature rupture, a pterional or subfrontal approach can be combined to establish early proximal vascular control at the bilateral A1 segments or the origin of the A2 segment.

• Journal of Korean Neurosurgical Society
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• v.30 no.sup2
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• pp.197-202
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• 2001

Objective : The purpose of this study is to evaluate and compare surgical results of pterional(fronto-temporal) approach and interhemispheric approach for the high positioned anterior communicating artery aneurysm with our surgical experience. Methods : During the period between May 1990 and May 2001, 263 anterior communicating aneurysms were treated at the department of neurosurgery of Dong-A university hospital. Among them, 175 patients were operated by same operator. Thirty six out of the 175 cases were high positioned anterior communicating artery aneurysms located more than 15mm above the anterior clinoid process. Results : Pterional approaches were applied in 32 cases and interhemispheric approaches were applied in 4 cases of total 36 cases of the high positioned anterior communicating artery aneurysms. The 32 cases of pterional approach resulted in Good Recovery 20/32(63%), Moderate Disability 6/32(19%), Severe Disability 4/32(12%) and Dead 2/32(6%), and 4 cases of interhemispheric approach resulted in GR 3/4(75%) and MD 1/4(25%). Relatively, pterional approach showed poorer result on high positioned anterior communicating artery aneurysm located more than 19mm above the anterior clinoid process with GR 5/13(39%), MD 3/13(23%), SD 3/13(23%) and Dead 2/13(15%). Conclusion : Interhemispheric approach is preferable to pterional approach for certain cases of high positioned anterior communicating artery aneurysm located more than 19 mm above the anterior clinoid process because it provides adequate orientation to the regional anatomy, less retraction of frontal lobe and preservation of the olfactory tract and gyrus rectus without any surgical complications.

• The Korean Journal of Physiology and Pharmacology
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• v.8 no.3
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• pp.129-132
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• 2004

Single unit responses of the ventral posterior medial (VPM) thalamic neurons to stimulation were monitored in anesthetized rats during activation of contralateral primary somatosensory (SI) cortex by GABA antagonist. The temporal changes of afferent sensory transmission were quantitatively analyzed by poststimulus time histogram (PSTH). Mainly, afferent sensory transmission to VPM thalamus was facilitated (15 neurons of total 23) by GABA antagonist (bicuculline) applied to contralateral cortex, while 7 neurons were suppressed. However, when ipsilateral cortex was inactivated by GABA agonist, musimol, there was significant suppression of afferent sensory transmission of VPM thalamus. This suppressed responsiveness by ipsilateral musimol was not affected by bicuculline applied to contralateral cortex. These results suggest that afferent transmission to VPM thalamus may be subjected to the interhemispheric modulation via ipsilateral cortex during inactivation of GABAergic neurons in contralateral SI cortex.

• Journal of Korean Neurosurgical Society
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• v.40 no.1
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• pp.6-10
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• 2006

Objective : The purpose of this study is to evaluate the surgical outcomes of bifrontal interhemispheric[BIH] approach and compare them to those of the pterional approach for the treatment of craniopharyngioma. Methods : Seventeen patients had their first operation for the resection of craniopharyngiomas between 2000 and 2004 at our medical center. Eleven patients who had the pterional approach and 6 with the BIH approach were enrolled. The age range at the time of surgery was 5 to 80 years [mean age 35.6 years old]. The presenting symptoms were visual disturbance increased intracranial pressure in 5 patients. Results : The tumors were totally removed in 3 [27 %] and subtotally in 8 [73 %] patients with the pterional approach. Total tumor removal was achieved in 5 out of 6 [83%] patients by the BIH approach, except improved in 4 [36 %] patients treated with the pterional approach and in all patients treated by the BIH approach. Conclusion : The BIH approach for craniopharyngioma surgery may be an effective and safe approach for tumors that extend outside of the sellar-suprasellar region with acceptable outcomes.

• Korean Journal of Cognitive Science
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• v.17 no.1
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• pp.29-52
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• 2006

There has been a claim that Interaction between the cerebral hemispheres could reduce the effect interfering information (Weissman & Banich, 1999). We ran three experiments to show that between-hemisphere separation of target and distractor could be more effective for reducing interference than Interaction between the hemispheres. In experiment 1, a colored box and a rotor name were presented to a single or to separate hemispheres. In experiment 2 and 3, a colored circle (distractor) was presented along with a colored box and a color name which was always printed in black. In experiment 3, a peripheral cue was presented either to the target location(66.7%) or to the distractor location(33.3%) Immediately before the presentation of stimuli. In all experiments, the participants were asked to deride whether the moaning of the color matched the rotor of the box, Ignoring the printed rotor of the word(Exp. 1), or the color of the circle(Exp. 2 & 3). There were three renditions of distractor (congruent, incongruent, and neutral) and two conditions of matching (between- and within-hemisphere matching). If interhemispheric interaction were effective for interference reduction, there should be a decrease in the interference in the between-hemisphere compared to the within-hemisphere matching condition. The results showed that there was no difference in the interference between the two matching conditions in Exp 1. In Exp 2 and in the target-cue renditions of Exp. 3, the amount of interference in the between-hemisphere condition was greater than that in the within-hemisphere condition. These findings are consistent with what we have previously reported (Sohn et al., 1996, Sohn & Lee, 2003). However, when the distractor was precued in Exp. 3, the amount of interference did not differ between the two marching conditions. These results suggest that between-hemisphere separation of target and distractor can be more effective for reducing response interference than interhemispheric communication. It implies a possible role of an interhemispheric shielding mechanism (Merola & Liederman, 1985) to prevent the transfer of task-irrelevant, harmful information across the hemispheres.

• Journal of Korean Neurosurgical Society
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• v.30 no.sup2
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• pp.337-339
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• 2001

The development of completely new intracranial aneurysms after previous successfully treated aneurysm is uncommon. A 50-year-old female presented with a case of multiple de novo aneurysm which were an aneurysm of right ophthalmic segment of internal carotid artery and an aneurysm of right A1 artery, 6 years after the clipping of an aneurysm of right posterior communicating artery. She had no history of hypertension, cigarette smoking and use of oral contraceptives, and had no evidence of genetic disorder. The laboratory findings were normal. All de novo aneurysms were clipped by basal anterior interhemispheric approach in one stage due to the direction of the aneurysm of the ophthalmic segment of the internal carotid artery.

• Sleep Medicine and Psychophysiology
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• v.8 no.2
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• pp.121-128
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• 2001

Objectives: In narcoleptic patients diagnosed with ICSD (international classification of sleep disorders, 1990) criteria, nocturnal polysomnography, and MSLT (multiple sleep latency test), we tried to find characteristic features of quantitative electroencephalography (QEEG) in a wakeful state. Methods: We compared eight drug-free narcoleptic patients with sex- and age-matched normal controls, using computerized electroencephalographic mapping technique and spectral analysis. Absolute power, relative power, interhemispheric asymmetry, interhemispheric and intrahemispheric coherence, and mean frequency in each frequency band (delta, theta, alpha and beta) were measured and analyzed. Results: Compared with normal controls, narcoleptic patients showed decrease in monopolar interhemispheric coherence of alpha frequency bands in occipital ($O_1/O_2$), parietal ($P_3/P_4$), and temporal ($T_5/T_6$) areas and beta frequency band in the occipital ($O_1/O_2$) area. Monopolar intrahemispheric coherences of alpha frequency bands in left hemispheric areas ($T_3/T_5$, $C_3/P_3$ & $F_3/O_1$) decreased. Decrease of monopolar interhemispheric asymmetry of delta frequency band in the occipital ($O_1/O_2$) area was also noted. The monopolar absolute powers of beta frequency bands decreased in occipital ($O_2,\;O_z$) areas. Conclusion: Decreases in coherences of narcoleptic patients compared with normal controls may indicate fewer posterior neocortical interhemispheric neuronal connections, and fewer left intrahemispheric neuronal connections than normal controls in a wakeful state. Therefore, we suggest that abnormal neurophysiological sites of narcolepsy may involve complex areas such as neocortex and subcortex as well as the brainstem.

• Journal of Korean Neurosurgical Society
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• v.30 no.12
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• pp.1361-1368
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• 2001

Objective : "Paraclinoid" aneurysms include those aneurysms arising from the internal carotid artery between the site of emergence of the carotid artery from the roof of the cavernous sinus and the origin of the posterior communicating artery. The authors reviewed and analysed the results of surgical approaches to paraclinoid aneurysms treated with transcranial surgery and endovascular surgery. Methods : Between January 1998 and May 1999, 14 patients were treated surgically through ipsilateral and contralateral pterional approaches, and anterior interhemispheric approach, and endovascular surgery for paraclinoid aneurysms. All transcranial approaches were performed by same surgeon. The medical records, neuroimaging studies and videotapes which had been recorded operations were reviewed retrospectively. Results : Twelve patients presented with subarachnoid hemorrhage and ICH. Nine of fourteen patients had multiple aneurysms. Thirteen cases were small and one was a large aneurysm. Six patients were treated through ipsilateral approaches, six contralateral pterional approaches, one anterior interhemispheric approach and one primarily by GDC embolization. All aneurysms treated through contralateral approaches were multiple aneurysms. Neck clipping was performed in 9(69.2%) of the thirteen aneurysms, wrapping in four cases, among them three cases were followed by GDC embolization. The surgical outcomes were : Glasgow Outcome Scale(GOS) I 71.4%, GOS II 21.4% and GOS V 7.1%. Conclusion : The surgical approaches to paraclinoid aneurysms should be chosen after careful anatomical evaluation of aneurysm and its neighboring structures. 3D-CT angiography and/or the raw data of MR angiography were useful. This study supports the usefulness of the contralateral approach to paraclinoid aneurysm associated with multiple aneurysms, unruptured and small aneurysms whose dome projecting medially, superiorly and dorsally. The determination of contralateral approach to small and medially projecting paraclinoid aneurysm may be stressful to operator, thus we believe anterior interhemispheric approach is better alternated. Also we recommend the endovascular surgery after reinforcement of aneurym neck and dome in the case with difficulty in clipping.