bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transcranial electrical stimulation through screw electrodes for intraoperative monitoring of motor evoked potentials
Authors: Watanabe Katsushige , Watanabe Takashi , Takahashi Akio , Saito Nobuhito , Hirato Masafumi , Sasaki Tomio 
Published: May 2009

✓ The feasibility of high-frequency transcranial electrical stimulation (TES) through screw electrodes placed in the skull was investigated for use in intraoperative monitoring of the motor pathways in patients who are in a state of general anesthesia during cerebral and spinal operations.
Motor evoked potentials (MEPs) were elicited by TES with a train of five square-wave pulses (duration 400 µsec, intensity ≤ 200 mA, frequency 500 Hz) delivered through metal screw electrodes placed in the outer table of the skull over the primary motor cortex in 42 patients. Myogenic MEPs to anodal stimulation were recorded from the abductor pollicis brevis (APB) and tibialis anterior (TA) muscles. The mean threshold stimulation intensity was 48 ± 17 mA for the APB muscles, and 112 ± 35 mA for the TA muscles. The electrodes were firmly fixed at the site and were not dislodged by surgical manipulation throughout the operation. No adverse reactions attributable to the TES were observed.
Passing current through the screw electrodes stimulates the motor cortex more effectively than conventional methods of TES. The method is safe and inexpensive, and it is convenient for intraoperative monitoring of motor pathways.
Intraoperative subcortical stimulation mapping for hemispheric perirolandic gliomas located within or adjacent to the descending motor pathways: evaluation of morbidity and assessment of functional outcome in 294 patients
Authors: Keles G. Evren , Lundin David A. , Lamborn Kathleen R. , Chang Edward F. , Ojemann George , Berger Mitchel S. 
Published: May 2009

Object. Intraoperative stimulation mapping of subcortical white matter tracts during the resection of gliomas has become a valuable surgical adjunct that is used to reduce morbidity associated with tumor removal. The purpose of this retrospective analysis was to assess the morbidity and functional outcome associated with this method, thus allowing the surgeon to predict the likelihood of causing a temporary or permanent motor deficit.
Methods. In this study, the authors report their experience with intraoperative stimulation mapping to locate subcortical motor pathways in 294 patients who underwent surgery for hemispheric gliomas within or adjacent to the rolandic cortex. Data were collected regarding intraoperative cortical and subcortical stimulation mapping results, along with the patient's neurological status pre- and postoperatively. For patients in whom an additional motor deficit occurred postoperatively, its evolution was examined.
Of 294 patients, an additional postoperative motor deficit occurred in 60 (20.4%). Of those 60, 23 (38%) recovered to their preoperative baseline status within the 1st postoperative week. Another 12 (20%) recovered from their postoperative motor deficit by the end of the 4th postoperative week, and 11 more recovered to their baseline status by the end of the 3rd postoperative month. Thus, 46 (76.7%) of 60 patients with postoperative motor deficits regained their baseline function within the first 90 days after surgery. The remaining 14 patients (4.8% of the entire study population of 294) had a persistent motor deficit after 3 months. Patients whose subcortical pathways were identified with stimulation mapping were more prone to develop an additional (temporary or permanent) motor deficit than those in whom subcortical pathways could not be identified (27.5% compared with 13.1%, p = 0.003). This was also true when additional (permanent) motor deficits lasted more than 3 months (7.4% when subcortical pathways were found, compared with 2.1% when they were not found; p = 0.041).
Conclusions. In patients with gliomas that are located within or adjacent to the rolandic cortex and, thus, the descending motor tracts, stimulation mapping of subcortical pathways enables the surgeon to identify these descending motor pathways during tumor removal and to achieve an acceptable rate of permanent morbidity in these high-risk functional areas.
Monitoring of motor evoked potentials compared with somatosensory evoked potentials and microvascular Doppler ultrasonography in cerebral aneurysm surgery
Authors: Neuloh Georg , Schramm Johannes 
Published: May 2009

Object. The aims of this study were to compare the efficiency of motor evoked potentials (MEPs), somatosensory evoked potentials (SSEPs), and microvascular Doppler ultrasonography (MDU) in the detection of impending motor impairment from subcortical ischemia in aneurysm surgery; to determine their sensitivity for specific intraoperative events; and to compare their impact on the surgical strategy used.
Methods. Motor evoked potentials, SSEPs, and MDU were monitored during 100 operations for 129 aneurysms in 95 patients. Intraoperative events, monitoring results, and clinical outcome were correlated in a prospective observational design.
Motor evoked potentials indicated inadequate temporary clipping, inadvertent occlusion, inadequate retraction, vasospasm, or compromise to perforating vessels in 21 of 33 instances and deteriorated despite stable SSEPs in 18 cases. Microvascular Doppler ultrasonography revealed inadvertent vessel occlusion in eight of 10 cases and insufficient clipping in four of four cases. Stable evoked potentials (EPs) allowed safe, permanent vessel occlusion or narrowing despite reduced flow on MDU in five cases. Two patients sustained permanent and 10 showed transient new weakness, which had been detected by SSEPs in two of 12 patients and MEPs in 10 of 11 monitored cases. The surgical strategy was directly altered in 33 instances: by MEPs in 16, SSEPs in four, and MDU in 13.
Conclusions. Monitoring of MEPs is superior to SSEP monitoring and MDU in detecting motor impairment, particularly that from subcortical ischemia. Microvascular Doppler ultrasonography is superior to EP monitoring in detecting inadvertent vessel occlusion, but cannot assess remote collateral flow. Motor evoked potentials are most sensitive to all other intraoperative conditions and have a direct influence on the course of surgery in the majority of events. A controlled study design is required to confirm the positive effect of monitoring on clinical outcome in aneurysm surgery.
Efficacy of multiple intraarterial papaverine infusions for improvement in cerebral circulation time in patients with recurrent cerebral vasospasm
Authors: Liu James K. , Tenner Michael S. , Gottfried Oren N. , Stevens Edwin A. , Rosenow Joshua M. , Madan Neel , Macdonald Joel D. , Kestle John R. W. , Couldwell William T. 
Published: May 2009

Object. Cerebral vasospasm that is caused by aneurysmal subarachnoid hemorrhage and that is refractory to maximal medical management can be treated with selective intraarterial papaverine infusions. The effects of single papaverine treatments on cerebral circulation time are well known. The purpose of this study was to assess the efficacy of multiple, repeated papaverine infusions on the cerebral circulation time in patients with recurrent vasospasm.
Methods. A retrospective study was conducted in 17 patients who received multiple intraarterial papaverine infusions in 91 carotid artery (CA) territories for the treatment of cerebral vasospasm. Cerebral circulation times were measured from the first angiographic image, in which peak contrast was seen above the supraclinoid internal CA, to the peak filling of cortical veins. Glasgow Outcome Scale (GOS) scores assessed 12 months after discharge were reviewed. Cerebral circulation times in 16 CA territories were measured in a control group of 11 patients.
Seventeen patients received a total of 91 papaverine treatments. Prolonged cerebral circulation times improved after 90 (99%) of 91 papaverine treatments. The prepapaverine mean cerebral circulation time was 6.54 seconds (range 3.35–27 seconds) and the immediate postpapaverine mean cerebral circulation time was 4.19 seconds (range 2.1–12.6 seconds), an overall mean decrease of 2.35 seconds (36%, p < 0.001). Recurrent vasospasm reflected by prolonged cerebral circulation times continued to improve with subsequent papaverine infusions. Repeated infusions were just as successful quantitatively as the primary treatment (mean change 2.06 seconds). The mean cerebral circulation time in the control group was 5.21 seconds (range 4–6.8 seconds). In five patients a dramatic reversal of low-attenuation changes was detected on computerized tomography scans. The mean GOS score at 12 months after discharge was 3.4.
Conclusions. The preliminary results indicate that multiple intraarterial papaverine treatments consistently improve cerebral circulation times, even with repeated infusions in cases of recurrent vasospasm.
Gamma knife surgery for treatment of residual nonfunctioning pituitary adenomas after surgical debulking
Authors: Losa Marco , Valle Micol , Mortini Pietro , Franzin Alberto , Passano Camillo Ferrari da , Cenzato Marco , Bianchi Stefania , Picozzi Piero , Giovanelli Massimo 
Published: May 2009

Object. Radiation therapy diminishes the risk of recurrence of incompletely removed nonfunctioning pituitary adenoma (NPA). The authors evaluated the efficacy and safety of gamma knife surgery (GKS) in patients with residual NPA following surgical debulking of the tumor.
Methods. Fifty-four patients, 26 men and 28 women, ranging in age from 29 to 72 years underwent gamma knife treatment. Baseline and follow-up studies involved magnetic resonance imaging, hormone evaluation, and neuroophthalmological examination 6 and 12 months after GKS and at yearly intervals thereafter. The mean follow up after GKS was 41.1 ± 3.1 months. Two of 52 patients undergoing follow up had a recurrence 40 and 49 months after GKS. In both of these patients the treated lesion had reduced in size, but a new lesion appeared in the contralateral side of the sella turcica. The recurrence-free interval at 5 years was 88.2% (95% confidence interval 72.6–100%). Tumor volume decreased from a baseline value of 2.3 ± 0.2 to 1.7 ± 0.2 cm3 at the last follow up (p < 0.001). Twenty-two patients (42.3%) had a 20% or greater reduction in tumor volume. The administered radiation dose had been significantly higher in patients who experienced tumor reduction. Visual function and motility did not deteriorate in any patient. New cases of hypogonadism, hypothyroidism, and hypoadrenalism occurred in 12.5, 8.6, and 2.3%, respectively, of assessable patients at risk.
Conclusions. Gamma knife surgery was effective in controlling the growth of residual NPA after previously performed maximal surgical debulking. The major advantage of GKS compared with fractionated radiotherapy seems to be a lower risk of side effects, especially a lower risk of hypopituitarism.
Multimodality image-guided surgery for the treatment of medically refractory epilepsy
Authors: Murphy Michael A. , O'Brien Terence J. , Morris Kevin , Cook Mark J. 
Published: May 2009

Object. The aim of this study was to review seizure outcome, imaging modalities used, and complications following surgery in patients with epilepsy who had undergone multimodality image-guided surgery at our institution.
Methods. Data from patients with epilepsy who had undergone surgery between April 1999 and October 2001 were reviewed. During this time period, 116 operations were performed in 109 patients with medically refractory epilepsy. Among these patients, 22 were selected to undergo multimodality image-guided surgery primarily on the basis of whether they had no lesion visible on conventional magnetic resonance (MR) imaging sequences, multiple lesions, or one very large lesion that could not be completely resected without the risk of significant postoperative morbidity. A fourth group of patients in whom there was a single lesion in the eloquent cortex, a location associated with a significant risk of postoperative morbidity, was also included in the analysis. This latter group was assessed with the aid of intracranial grid electrodes that were coregistered to the MR image and were used intraoperatively to minimize electrode position error. Other imaging modalities used included positron emission tomography (PET), fluid-attenuated inversion recovery (FLAIR) MR imaging, and subtracted ictal–interictal single-photon positron emission computerized tomography (SPECT) coregistered with MR imaging (SISCOM). After coregistration, images were then downloaded onto an image-guided surgical system and the epileptogenic area was then resected.
The mean patient age was 33 years (range 17–46 years), and there was a mean follow up of 27 months (range 14–41 months). Multimodality coregistrations used were as follows: nine PET scans, seven subdural electrode grids, four SISCOM studies, one FLAIR MR image, and one combined PET/subdural grid. Seizure outcome was excellent in 17 patients (77%) and not excellent in five (23%), or favorable in 19 (86%) and unfavorable in three (14%). Six patients (27%) had a transient neurological deficit, one patient (5%) a permanent major deficit, and three patients (15%) a permanent minor deficit. Five patients (24%) had a transient psychiatric problem postoperatively.
Conclusions. Multimodality image-guided surgery offers a new perspective in surgery for epilepsy. Functional imaging modalities previously lateralized and often localized a seizure focus, but did not provide enough anatomical information to resect the epileptogenic zone confidently and safely. The coregistration of these modalities to a volumetric MR image and their incorporation into an image-guided system has allowed surgeons to offer surgery to patients who may not previously have been considered eligible, with outcomes comparable to those in patients with more straightforward lesional epilepsy.
Adding or repositioning intracranial electrodes during presurgical assessment of neocortical epilepsy: electrographic seizure pattern and surgical outcome
Authors: LEE Sang Kun , Kim Kwang-ki , Nam Hyunwoo , Oh Jong Bai , Yun Chang Ho , Chung Chun-Kee 
Published: May 2009

Object. The aim of this study was to investigate changes in electroencephalography (EEG) patterns obtained from added or repositioned electrodes after those initially implanted had failed to indicate the true local ictal onset zone. The authors focused on the following matters: rationale for adding or repositioning electrodes, topographic and frequency characteristics of ictal onset before and after adding or repositioning electrodes, the effect of the procedures, and the relationship between changes in intracranial EEG onset patterns and surgical outcomes.
Methods. Of 183 patients with intracranial recordings, 18 experienced repositioning of existing or implanting of additional electrodes 7 or 10 days later. All patients underwent resection and were followed up for more than 1 year. In particular, the relationship between surgical outcome and distribution/frequency of intracranial seizure onset was analyzed. Results of noninvasive presurgical evaluations in patients who had undergone single and double invasive studies were also evaluated.
By adding or repositioning electrodes, a new ictal onset zone was revealed in 13 patients. In another four, the second evaluation led to a change in defining the resection margin. Ictal onset in the partially sampled area, simultaneous or independent onset in two separate areas, and onset in the distal end of the electrode strip or grid were common reasons for failing to localize the ictal onset zone during the initial evaluation. Seven of 11 patients who were ultimately found to have a focal ictal onset zone on the second evaluation became seizure free after the operation. Only one of six patients with a regional ictal onset zone identified on the second evaluation became seizure free. There was no relationship between the frequency of the ictal rhythm and surgical outcome. Note, however, that surgical outcome was more favorable in patients who had undergone a single invasive study than in those who had undergone double invasive studies. The patients who needed a second evaluation had less localizing information and less concordant results on presurgical evaluations. When comparing nonlesional cases, surgical outcomes were not significantly different among patients with a single invasive study and those with double invasive studies. No additional morbidity or death occurred during the second study.
Conclusions. The addition or reposition of intracranial electrodes with a short-term interval should be considered in selected patients. Spatial restriction of the ictal onset rhythm identified on repeated evaluation is the most important predictor of a good surgical outcome.
Endolymphatic sac tumors in von Hippel—Lindau disease
Authors: Choo Daniel , Shotland Lawrence , Mastroianni Maryann , Glenn Gladys , Waes Carter van , Linehan W. Marston , Oldfield Edward H. 
Published: May 2009

Object. Von Hippel—Lindau (VHL) disease is a hereditary multiple-neoplasia syndrome mapping to chromosome 3p25–26. Endolymphatic sac (ELS) tumors have been identified as a neoplastic manifestation of VHL disease. The purpose of this study was to evaluate comprehensively the natural history of inner ear disease in a large population of patients with confirmed or suspected VHL disease and to correlate the clinical features with the VHL genotype.
Methods. The authors collated and analyzed clinical and genotypic data obtained in patients enrolled in an Institutional Review Board—approved protocol in which families and individuals affected by VHL disease were studied. These data included results from multidisciplinary history workups and physical examinations, imaging studies, and a battery of audiological tests.
One hundred seventy-five patients were enrolled in the study, 129 with confirmed VHL disease and 46 of their family members in whom test results for VHL disease were negative and who served as controls. Twenty-one patients had ELS tumors that were evident on magnetic resonance images; three of them had bilateral ELS lesions. Hearing loss, often sudden in onset and severe to profound in nature, vestibulopathy, aural fullness, and tinnitus represented the primary symptoms of ELS tumor. Distinct patterns of auditory and vestibular dysfunction occurred at different stages of the disease. Phenotypic data showed that 17 of 21 patients with ELS tumors did not have pheochromocytomas, whereas all had VHL disease affecting the kidney, all but two had VHL disease affecting the central nervous system, and all but one had disease affecting the pancreas. Genotyping revealed 10 rearrangements (partial deletions), eight single bp substitutions, and one 3-bp insertion. Although there was no difference in the incidence of hearing loss between populations, symptoms of imbalance and aural fullness were more common in patients with VHL disease but without imaging evidence of ELS tumor than they were in family members who did not have VHL disease (p < 0.01).
Conclusions. Endolymphatic sac tumors are frequently associated with VHL disease. Symptoms of disequilibrium or aural fullness in patients with VHL disease may be an early indication of endolymphatic dysfunction. Patients with VHL disease provide a unique opportunity to examine the effects of specific gene mutations and a discrete neoplastic process on the human inner ear. The study of ELS tumors in this group also provides a pathological model of ELS function and supplies evidence for a role of the ELS in clinical Ménière-like disease(s).
Endolymphatic sac tumors in patients with and without von Hippel—Lindau disease: the role of genetic mutation, von Hippel—Lindau protein, and hypoxia inducible factor-1α expression
Authors: Jensen Randy L. , Gillespie David , House Paul , Layfield Lester , Shelton Clough 
Published: May 2009

Object. Endolymphatic sac (ELS) tumors are low-grade malignancies of the temporal bone that are associated with von Hippel—Lindau (VHL) disease but can also occur sporadically. The VHL gene product VHL protein is important in the regulation of hypoxia inducible factor (HIF)-1α, which controls expression of molecules that are important in angiogenesis and cell metabolism. In this study the authors examine the role of VHL and HIF-1 in ELS tumors.
Methods. The ELS tumors from three patients were examined using the following method: DNA from tumor tissue was isolated, amplified by polymerase chain reaction and the VHL gene sequence was compared with the known wild-type sequence. Loss of heterozygosity (LOH) studies were performed to confirm the sequencing data. Immunohistochemical evaluation for VHL, HIF-1α, vascular endothelial growth factor (VEGF), and carbonic anhydrase IX (CA IX) was performed. Snap-frozen tumor tissue was examined using Western blot and HIF-1 immunoassays for HIF-1α and VHL expression.
Two patients had sporadic ELS tumors and the other one suffered from VHL disease. Results of VHL gene sequencing were normal in the tissue derived from the sporadic ELS tumors. The ELS tumor, pheochromocytoma, and spinal hemangioblastoma were heterozygous for the same C-to-A transversion found in the germline carried by the patient with VHL disease. No LOH was detected in the tumor tissue obtained in the patient with VHL disease. Expression of HIF-1α, VEGF, and CA IX evaluated using immunohistochemical studies was elevated in the VHL-associated tumors. Nevertheless, Western blots and immunoassays for HIF-1α did not show elevated expression in these tumors.
Conclusions. The sporadic and VHL disease—associated ELS tumors in this study had normal VHL-mediated HIF-1 regulation. This is a result of normal VHL gene expression in the case of the sporadic ELS tumor. In the VHL-associated ELS tumor, this is due to one normal copy of the VHL gene and adequate VHL gene expression.
Comparison of waterjet dissection and ultrasonic aspiration: an in vivo study in the rabbit brain
Authors: Oertel Joachim , Gaab Michael Robert , Pillich Dirk-Thomas , Schroeder Henry W. S. , Warzok Rolf , Piek Jürgen 
Published: May 2009

Object.The waterjet method of dissection has been shown to enable the precise dissection of the parenchyma vessels while preserving blood in cadaveric pig brains. The waterjet device has also been applied clinically to treat various diseases and disorders without complications. Evidence still remains to be gathered as to how the instrument performs in reducing surgical trauma, intraoperative blood loss, and postsurgical brain edema. In the present study the authors investigate these parameters in a comparison between waterjet dissection and ultrasonic aspiration in the rabbit brain in vivo.Methods.Thirty-one rabbits received identical bilateral frontal corticotomies, which were created using the waterjet device or an ultrasonic aspirator. The animals were killed 1, 3, or 7 days, or 6 weeks after surgery and their brains were processed for immunohistological analysis. Blood vessel preservation, intraoperative hemorrhage, postsurgical brain edema, and posttraumatic microglial and astoglial reactions were evaluated. Only in animals subjected to waterjet dissection were preserved vessels observed within the corticotomies. In addition, less intraoperative bleeding occurred in animals in which the waterjet was used. The microglial reaction was significantly reduced by waterjet dissection compared with ultrasonic aspiration; however, no difference in edema formation or astrocytic reactivity was observed.Conclusions.These results demonstrate that waterjet dissection appears to be less traumatic than ultrasonic aspiration with respect to intraoperative hemorrhage and postoperative microglial reactivity in the rabbit model. Nevertheless, no difference in edema formation could be demonstrated. It remains to be proven that the observed differences are of clinical relevance.