bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microsurgical anatomy of the great cerebral vein of Galen and its tributaries
Authors: Chaynes Patrick 
Published: May 2009

Object. The deep cerebral veins may pose a major obstacle in operative approaches to deep-seated lesions, especially in the pineal region where multiple veins converge on the great cerebral vein of Galen. Because undesirable sequelae may occur from such surgery, the number of veins and branches to be sacrificed during these approaches should kept to a minimum. The purpose of this study was to examine venous drainage into the vein of Galen with a view to surgical approaches. If a vein hampering surgical access must be sacrificed, it can therefore be selected according to the smallest draining territory.
Methods. The deep cerebral veins and their surrounding neural structures were examined in 50 cerebral hemispheres from 25 adult cadavers in which the arteries and veins had been perfused with red and blue silicone, respectively. Special consideration was given to the size and location of drainage of the vein of Galen and its tributaries.
Conclusions. When a surgeon approaches the pineal region, several veins may hamper the access route. From posterior to anterior, these include the following: the superior vermian and the precentral or superior cerebellar veins, which drain into the posteroinferior aspect of the vein of Galen; and the tectal and pineal veins, which drain into its anterosuperior aspect. The internal occipital vein is the main vessel draining into the lateral aspect of the vein of Galen. It may be joined by the posterior pericallosal vein, and in that case has an extensive territory. To avoid intraoperative venous infarction, it is important to use angiography to determine the venous organization before surgery and to estimate the permeability and size of the branches of the deep venous system.
Inhibition of DNA repair for sensitizing resistant glioma cells to temozolomide
Authors: Kanzawa Takao , Bedwell Joshua , Kondo Yasuko , Kondo Seiji , Germano Isabelle M. 
Published: May 2009

Object. Temozolomide (TMZ) is a DNA alkylating agent currently used as adjuvant treatment for anaplastic astrocytomas. Its use in managing glioblastoma multiforme has been halted because of the lack of therapeutic effects due to cell resistance. Note that O6-alkylguanine—DNA alkyltranferase (AGT) is a DNA repair enzyme that limits the efficacy of TMZ. In this study the authors investigated the ability of O6-benzylguanine (BG), an AGT inhibitor, to sensitize a glioblastoma cell line resistant to TMZ.
Methods. The effects of TMZ alone (100 µg) and after exposure to BG (50 µg) were assessed in two glioblastoma cell lines, U373-MG and T98G, respectively, sensitive and resistant to TMZ. Cell viability was assessed using trypan blue; cell cycle analysis by fluorescence-activated cell sorter; and apoptosis and autophagy by terminal deoxynucleotidyl transferase—mediated deoxyuridine triphosphate nick-end labeling (TUNEL) and acridine orange staining, respectively. Furthermore, the involvement of an autophagy marker, microtubule-associated light chain 3 (LC3), was assessed. Temozolomide suppressed the growth of and caused cell cycle arrest in the G2—M phase of U373-MG cells but not T98G cells. Exposure to BG prior to TMZ resulted in a significant decrease in cell viability as well as cell cycle arrest in the G2—M phase in T98G cells (p < 0.05). Although apoptosis was not detected on TUNEL staining, programmed cell death Type II (autophagy) was detected after exposure to BG and TMZ in T98G cells.
Conclusions. These results indicate that inhibition of AGT by BG can render previously resistant glioma cells sensitive to TMZ treatment. The mechanism of cell demise following BG-TMZ treatment seems to be autophagy and not apoptosis. Combination therapy involving TMZ and an AGT inhibitor may be an effective strategy to treat resistant gliomas.
Repetitive transcranial magnetic stimulation for protection against delayed neuronal death induced by transient ischemia
Authors: Fujiki Minoru , Kobayashi Hidenori , Abe Tatsuya , Kamida Tohru 
Published: May 2009

Object. Data in the present study demonstrate that repetitive transcranial magnetic stimulation (rTMS) induces ischemic tolerance against delayed neuronal death (DND) of hippocampal neurons following an otherwise lethal ischemic insult.
Methods. Various regimens of rTMS were delivered to adult gerbils at various times prior to an episode of ischemia induced by transient (5-minute) bilateral common carotid artery (CCA) occlusion. The extent of DND in the CA1 region of the hippocampus was assessed quantitatively 7 days after the transient ischemic episode.
When rTMS was delivered 2 to 5 days prior to bilateral CCA occlusion, DND was substantially attenuated; delivery of rTMS 12 to 24 hours prior to occlusion induced partial tolerance. In the group of animals that had received stimulation 2 days prior to occlusion, neuron density in the CA1 sector was significantly higher (three gerbils, 210.33, 86.01% of normal) than in the group that experienced ischemia only (three gerbils, 10.66, 4.36% of normal). A similar degree of neuron sparing occurred when stimulation was delivered 3, 4, or 5 days prior to occlusion. Note that rTMS was effective when it was delivered at frequencies of 25 and 50 Hz. Stimulation at 25 Hz for 128 seconds (3200 pulses) was more effective than stimulation at 50 Hz for 64 seconds (3200 pulses) or 128 seconds (6400 pulses), however.
Conclusions. Noninvasive rTMS represents an important tool for exploring the mechanisms of ischemic tolerance and preventing ischemic neuronal damage.
Surgical innovation or surgical evolution: an ethical and practical guide to handling novel neurosurgical procedures
Authors: Bernstein Mark , Bampoe Joseph 
Published: May 2009

Object. Surgical innovation is an important driver of improvements in technique and technology, which ultimately translates into improvements in patients' outcomes. Nevertheless, patients may face new risks of morbidity and mortality when surgical innovation is used, and well-intentioned surgical “experimentation” on patients must be regulated and monitored. In this paper the authors examine the challenges of defining surgical innovation and briefly review the literature on this challenging subject.
Methods. Using examples from the field of neurosurgery and in part from the personal experience of the senior author, the authors develop a model of levels of experimental acuity of surgical procedures and offer recommendations on how these procedures would best be regulated.
Conclusions. The authors propose guidelines for determining the need for regulation of innovation. The potential role of institutional review boards in this process is highlighted.
The multichannel auditory brainstem implant: how many electrodes make sense?
Authors: Kuchta Johannes , Otto Steven R. , Shannon Robert V. , Hitselberger William E. , Brackmann Derald E. 
Published: May 2009

Object. Development of multichannel auditory brainstem implant (ABI) systems has been based in part on the assumption that audiological outcome can be optimized by increasing the number of available electrodes. In this paper the authors critically analyze this assumption on the basis of a retrospective clinical study performed using the Nucleus 22 ABI surface electrode array.
Methods. The perceptual performances of 61 patients with neurofibromatosis Type 2 were tested approximately 6 weeks after an eight-electrode ABI had been implanted. Of eight implanted electrodes 5.57 ± 2.57 (mean ± standard deviation [SD] provided auditory sensations when stimulated. Electrodes were deactivated when stimulation resulted in significant nonauditory side effects or no auditory sensation at all, and also when they failed to provide distinctive pitch sensations. The mean (± SD) scores for patients with ABIs were the following: sound-only consonant recognition, 20.4 ± 14.3 (range 0–65%); vowel recognition, 28.8 ± 18% (range 0–67%); Monosyllable Trochee Spondee (MTS) word recognition 41.1 ± 25.3% (range 0–100%); and sentence recognition, 5.3 ± 11.4% (range 0–64%). Performance in patients in whom between one and three electrodes provided auditory sensation was significantly poorer than that in patients with between four and eight functional electrodes in the vowel, MTS word, and City University of New York (CUNY) sentence recognition tests. The correlation between performance and electrode number did not reach the 0.05 level of significance with respect to the sound effect, consonant, and MTS stress-pattern recognition tests, probably because a satisfactory performance in these tests can be obtained only with temporal cues, that is, without any information about the frequency of the sounds. In the MTS word and the CUNY sentence recognition tests, performance was optimal in the patients with eight functional electrodes. Although all top performers had more than three functional auditory electrodes, no further improvement (asymptotic performance) was seen in those with five or more active electrodes in the consonant, vowel, and sound effect recognition tests.
Conclusions. A minimum of three spectral channels, programmed in the appropriate individual tonotopic order seem to be required for satisfactory speech recognition in most patients with ABI. Due to the limited access to the tonotopic frequency gradient of the cochlear nucleus with surface stimulation, patients with ABI do not receive a wide range of spectral cues (frequency information) with multielectrode (> 5) surface arrays.
Surgical treatment of symptomatic Rathke cleft cysts: clinical features and results with special attention to recurrence
Authors: Kim Jeong Eun , Kim Jeong Hoon , Kim Oh Lyong , Paek Sun Ha , Kim Dong Gyu , Chi Je G. , Jung Hee-Won 
Published: May 2009

Object. Rathke cleft cysts (RCCs) are rarely symptomatic. The purpose of this study was to clarify the clinical, neuroimaging, surgical, and pathological features of symptomatic RCCs with special attention to their recurrence.
Methods. This retrospective study involved 53 patients with pathologically confirmed symptomatic RCCs. There were 28 female and 25 male patients, ranging in age from 11 to 68 years (mean 37 years). Common clinical presentations included headache, visual impairment, and endocrine disturbance. The most common endocrine disturbances were hyperprolactinemia and diabetes insipidus. Most of these improved or were resolved after surgery, with the exception of diabetes insipidus and panhypopituitarism. The cysts were intrasellar with suprasellar extension in 33 patients, and ranged in size from 5 to 40 mm (mean 17 mm). In the 50 magnetic resonance (MR) images that were reviewed, the signal intensities were quite variable. Fourteen MR images demonstrated enhancement after an injection of Gd. Intraoperatively, the cyst contents were found to be yellowish (18 patients [37%]) and mucoid (25 patients [51%]). Pathological examinations revealed a pseudostratified columnar epithelium in 26 patients (49%). Abundant squamous metaplasia and a stratified squamous epithelium were also found in 12 patients (23%). Follow-up MR images revealed cyst recurrences that required a repeated operation in six patients. Statistically significant risk factors for a recurrence included enhancement of the lesion on MR images (p = 0.017), the extent of cyst removal (p = 0.012), and the presence of squamous epithelium (p = 0.008).
Conclusions. Rathke cleft cysts are associated with a variety of clinical presentations and sometimes confusing intraoperative and pathological findings. Close postoperative observation with neuroimaging and neuroophthalmological assessment is necessary, especially after a partial removal, as in cases with squamous metaplasia.
Serial evaluation of axonal function in patients with brain death by using anisotropic diffusion-weighted magnetic resonance imaging
Authors: Watanabe Toru , Honda Yoshiho , Fujii Yukihiko , Koyama Miyako , Tanaka Ryuichi 
Published: May 2009

Object. The purposes of this study were to evaluate the serial changes in diffusion anisotropy of the brain, probably reflecting axonal function in brain-dead patients, and thus to explore the possibility of quantitatively estimating the risk of brain death.
Methods. Ten patients suffering from stroke with or without impending brain death and 10 healthy volunteers were studied using three-dimensional anisotropy contrast (3DAC) magnetic resonance (MR) axonography with the aid of a 1.5-tesla MR imaging system. To detect changes in the diffusion anisotropy of neural bundles, the corticospinal tract was evaluated.
Diffusion anisotropy of short axonal fibers decreased immediately after apparent brain death. Whereas the trichromatic coefficients of the corticospinal tract greatly diminished between 6 and 12 hours after apparent brain death, the coefficients of the corpus callosum and the optic radiation decreased in less time, that is, between 1 and 6 hours. The coefficients of these three bundles turned isotropic between 24 and 44 hours after apparent brain death.
Conclusions. Results of 3DAC MR axonography revealed that diffusion anisotropy of neural bundles diminished between 1 and 12 hours after the onset of apparent brain death, probably depending on the length of the bundles, and disappeared between 24 and 44 hours after the onset of brain death, which might reflect dynamic changes of axonal structure and indirectly herald axonal dysfunction. These findings seem to be greatly helpful in establishing an appropriate method to estimate the risk of brain death quantitatively and in forming the basis of future definitions of brain death.
Cystic glioblastoma multiforme: survival outcomes in 22 cases
Authors: Maldaun Marcos V. C. , Suki Dima , Lang Frederick F. , Prabhu Sujit , Shi Weiming , Fuller Gregory N. , Wildrick David M. , Sawaya Raymond 
Published: May 2009

Object. The goal of this study was to determine whether the presence of a large tumor cyst was associated with improved outcome in patients undergoing surgery for newly diagnosed glioblastomas multiforme (GBMs) by comparing these patients with a matched cohort of patients with noncystic GBMs in clinical features, tumor imaging characteristics, survival, and time to tumor recurrence after surgery.
Methods. A retrospective analysis was conducted in 22 patients by using imaging information and chart reviews of operative reports of GBMs with large cysts (≥ 50% of tumor volume) at The University of Texas M. D. Anderson Cancer Center between 1993 and 2002. Clinical and neurosurgical outcomes and recurrence rates were studied. A statistical comparison was made with a matching cohort of 22 patients with noncystic GBMs.
No significant differences in clinical variables were found between the cohort with cystic GBMs and the matched cohort with noncystic GBMs. To avoid bias in preoperative assessment of tumor volume, the tumor burden was compared in patients whose tumors had cysts (excluding the cystic mass) and in patients whose tumors did not contain cysts. There was no statistically significant difference between the two groups (p = 0.8). In patients with cystic GBMs the median survival time after surgery was 18.2 months (95% confidence interval [CI] 11.9–24.5 months) and at 2 years 43% of the patients were still alive. In comparison, in patients with noncystic GBMs, the median survival time was 14.3 months (95% CI 12.1–16.4 months) and only 16% of patients were alive at 2 years. The median time to tumor recurrence was 7.6 months (95% CI 0.01–18 months) in patients harboring cystic GBMs and 4.2 months (95% CI 1.8–6.6 months) in the matched cohort (log-rank test, p = 0.04). In the cystic GBM group, no recurrence was observed in 53% of patients at 6 months, 45% at 1 year, and 38% at 2 years after surgery, whereas the corresponding numbers for the noncystic group were 36, 14, and 9%, respectively.
Conclusions. The results indicate that patients harboring a GBM that contains a large cyst survive longer and have a longer time to recurrence than those who lack such a cyst. This is the first such observation in the literature.
Proliferation, migration, and differentiation of human neural stem/progenitor cells after transplantation into a rat model of traumatic brain injury
Authors: Wennersten André , Meijer Xia , Holmin Staffan , Wahlberg Lars , Mathiesen Tiit 
Published: May 2009

Object. Cultures containing human neural stem and progenitor cells (neurospheres) have the capacity to proliferate and differentiate into the major phenotypes of the adult brain. These properties make them candidates for therapeutic transplantation in cases of neurological diseases that involve cell loss. In this study, long-term cultured and cryopreserved cells were transplanted into the traumatically injured rat brain to evaluate the potential for human neural stem/progenitor cells to survive and differentiate following traumatic injury.
Methods. Neural stem/progenitor cell cultures were established from 10-week-old human forebrain. Immunosuppressed adult rats received a unilateral parietal cortical contusion injury, which was delivered using the weight-drop method. Immediately following the injury, these animals received transplants of neural stem/progenitor cells, which were placed close to the site of injury. Two or 6 weeks after the procedure, these animals were killed and their brains were examined by immunohistochemical analysis.
At both 2 and 6 weeks postoperatively, the transplanted human cells were found in the perilesional zone, hippocampus, corpus callosum, and ipsilateral subependymal zone of the rats. Compared with the 2-week time point, an increased number of HuN-positive cells was observed at 6 weeks. In addition, at 6 weeks post—injury/transplantation, the cells were noted to cross the midline to the contralateral corpus callosum and into the contralateral cortex. Double labeling demonstrated neuronal and astrocytic, but not oligodendrocytic differentiation. Moreover, the cortex appeared to provide an environment that was less hospitable to neuronal differentiation than the hippocampus.
Conclusions. This study shows that expandable human neural stem/progenitor cells survive transplantation, and migrate, differentiate, and proliferate in the injured brain. These cells could potentially be developed for transplantation therapy in cases of traumatic brain injury.
Proximal occlusion of the middle cerebral artery in C57Black6 mice: relationship of patency of the posterior communicating artery, infarct evolution, and animal survival
Authors: Furuya Kazuhide , Kawahara Nobutaka , Kawai Kensuke , Toyoda Tomikatsu , Maeda Keiichiro , Kirino Takaaki 
Published: May 2009

Object. The intraluminal suture model for focal cerebral ischemia is increasingly used, but not without problems. It causes hypothalamic injury, subarachnoid hemorrhage, and inadvertent premature reperfusion. The patency of the posterior communicating artery (PCoA) potentially affects the size of the infarct. In addition, survival at 1 week is unstable. The authors operated on C57Black6 mice to produce proximal middle cerebral artery occlusion (MCAO) so that drawbacks with the suture model could be circumvented.
Methods. The MCA segment just proximal to the olfactory branch was occluded either permanently or temporarily. After 1 hour of MCAO the infarct volume was significantly smaller than that found after 2 hours or in instances of permanent MCAO. The differences were assessed at 24 hours and 7 days after surgery (p < 0.05 and p < 0.001, respectively). The patency of the PCoA, as visualized using carbon black solution, did not correlate with the infarct size. Neurologically, the 1- and 2-hour MCAO groups displayed significantly less severe deficits than the permanent MCAO group on Days 1, 4, and 7 (p < 0.005 and p < 0.01, respectively). Although the infarct size, neurological deficits, and body weight loss were more severe in the permanent MCAO group, the survival rate at Day 7 was 80%.
Conclusions. This model provides not only a robust infarct size (which is not affected by the patency of the PCoA), but also a better survival rate.
Cerebrovascular stereolithographic biomodeling for aneurysm surgery
Authors: Wurm Gabriele , Tomancok Berndt , Pogady Peter , Holl Kurt , Trenkler Johannes 
Published: May 2009

✓ Stereolithographic (SL) biomodeling is a new technology that allows three-dimensional (3D) imaging data to be used in the manufacture of accurate solid plastic replicas of anatomical structures. The authors describe their experience with a patient series in which this relatively new visualization method was used in surgery for cerebral aneurysms.
Using the rapid prototyping technology of stereolithography, 13 solid anatomical biomodels of cerebral aneurysms with parent and surrounding vessels were manufactured based on 3D computerized tomography scans (three cases) or 3D rotational angiography (10 cases). The biomodels were used for diagnosis, operative planning, surgical simulation, instruction for less experienced neurosurgeons, and patient education. The correspondence between the biomodel and the intraoperative findings was verified in every case by comparison with the intraoperative video. The utility of the biomodels was judged by three experienced and two less experienced neurosurgeons specializing in microsurgery.
A prospective comparison of SL biomodels with intraoperative findings proved that the biomodels replicated the anatomical structures precisely. Even the first models, which were rather rough, corresponded to the intraoperative findings. Advances in imaging resolution and postprocessing methods helped overcome the initial limitations of the image threshold. The major advantage of this technology is that the surgeon can closely study complex cerebrovascular anatomy from any perspective by using a haptic, “real reality” biomodel, which can be held, allowing simulation of intraoperative situations and anticipation of surgical challenges. One drawback of SL biomodeling is the time it takes for the model to be manufactured and delivered. Another is that the synthetic resin of the biomodel is too rigid to use in dissecting exercises. Further development and refinement of the method is necessary before the model can demonstrate a mural thrombus or calcification or the relationship of the aneurysm to nonvascular structures.
This series of 3D SL biomodels demonstrates the feasibility and clinical utility of this new visualization medium for cerebrovascular surgery. This medium, which elicits the intuitive imagination of the surgeon, can be effectively added to conventional imaging techniques. Overcoming the present limitations posed by material properties, visualization of intramural particularities, and representation of the relationship of the lesion to parenchymal and skeletal structures are the focus in an ongoing trial.