bluuebunny/crossref_metadata_2025 huggingface dataset:
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.
Traumatic aneurysm of the supraclinoid internal carotid artery and an associated carotid—cavernous fistula: vascular reconstruction performed using intravascular implantation of stents and coils
Authors: Lee Chang-Young , Yim Man-Bin , Kim Il-Man , Son Eun-Ik , Kim Dong-Won
Published: May 2009

✓ This report documents the treatment of a traumatic aneurysm of the supraclinoid internal carotid artery (ICA) that was associated with a carotid—cavernous fistula (CCF), which appeared following closed head trauma. This life-threatening lesion, which is very rare, required aggressive management achieved using intravascular stents and coils. A 19-year-old man presented with severe traumatic intracerebral and subarachnoid hematoma after he had suffered a severe closed head injury in a motor vehicle accident. Cerebral angiography performed 11 days after the injury demonstrated a traumatic aneurysm and severe narrowing of the right supraclinoid ICA, which was consistent with a dissection-induced stenosis associated with a direct CCF. Both lesions were successfully obliterated with preservation of the parent artery by using stents in conjunction with coils. Follow-up angiography obtained 7 months postoperatively revealed persistent obliteration of the aneurysm and CCF as well as patency of the parent artery. The patient remained asymptomatic during the clinical follow-up period of 14 months. Endovascular treatment involving the use of a stent combined with coils appears to be a feasible, minimally invasive option for treatment of this hard-to-treat lesion.
Endovascular treatment of a transverse—sigmoid sinus aneurysm presenting as pulsatile tinnitus
Authors: Zenteno Marco , Murillo-Bonilla Luis , Martínez Sergio , Arauz Antonio , Pane Carlo , Lee Angel , del Valle Ramiro
Published: May 2009

✓ The authors report on the case of a 38-year-old woman who had experienced incapacitating pulsatile tinnitus in the left ear for 6 months. Angiographic studies revealed a wide-necked venous aneurysm of the left transverse—sigmoid sinus. Solitary stent placement across the aneurysm neck resulted in a slight modification in the lesion's characteristics. A second session, in which embolization with Guglielmi Detachable Coils was performed, resulted in a 100% occlusion of the aneurysm, with patency of the parent vessel and resolution of the tinnitus.
Focal hyperperfusion after superficial temporal artery—middle cerebral artery anastomosis in a patient with moyamoya disease
Authors: Furuya Kazuhide , Kawahara Nobutaka , Morita Akio , Momose Toshimitsu , Aoki Shigeki , Kirino Takaaki
Published: May 2009

✓ Superficial temporal artery—middle cerebral artery (STA—MCA) anastomosis is a standard surgical therapeutic option in patients with moyamoya disease. Most patients experience improvement in their clinical symptoms immediately after surgery. The authors report on the case of a 39-year-old man with moyamoya disease who suffered from temporary and frequent neurological deterioration after undergoing a left STA—MCA anastomosis. Hemodilution and hypervolemia therapies did not improve his course. Technetium-99m hexamethylpropyleneamine oxime single-photon emission tomography scans demonstrated focal intense accumulation of the tracer in the frontal operculum on the side of the surgery. Although diffusion-weighted magnetic resonance (MR) imaging demonstrated no abnormalities except for the postoperative change, perfusion-weighted MR images and MR digital subtraction angiography revealed focal hyperperfusion in the left frontal operculum where the cerebral perfusion reserve was severely disturbed preoperatively. This evidence strongly supports the notion that focal hyperperfusion observed after STA—MCA anastomosis could occur in the poor perfusion reserve area preoperatively and could cause temporary neurological deterioration.
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.
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.
Inverse correlation of epidermal growth factor receptor messenger RNA induction and suppression of anchorage-independent growth by OSI-774, an epidermal growth factor receptor tyrosine kinase inhibitor, in glioblastoma multiforme cell lines
Authors: Halatsch Marc-Eric , Gehrke Esther E. , Vougioukas Vassilios I. , Bötefür Ingolf C. , A.-Borhani Farhad , Efferth Thomas , Gebhart Erich , Domhof Sebastian , Schmidt Ursula , Buchfelder Michael
Published: May 2009

Object.Quantitative and qualitative alterations in the epidermal growth factor receptor (EGFR) commonly occur in many cancers in humans, including malignant gliomas. The aim of the current study was to evaluate molecular and cellular effects of OSI-774, a novel EGFR tyrosine kinase inhibitor, on nine glioblastoma multiforme (GBM) cell lines.

Methods.The effects of OSI-774 on expression ofEGFRmessenger (m)RNA and protein, proliferation, anchorage-independent growth, and apoptosis were examined using semiquantitative reverse transcription—polymerase chain reaction, immunocytochemical analysis, Coulter counting, soft agar cloning, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling/fluorescence-activated cell sorting, respectively. Allp53genes were completely and bidirectionally sequenced.

Suppression of anchorage-independent growth by OSI-774 was inversely correlated to the induction ofEGFRmRNA during relative serum starvation (r = −0.74) and was unrelated top53status. Overall, suppression of anchorage-independent growth was a considerably stronger effect of OSI-774 than inhibition of proliferation. The extent of OSI-774—induced apoptosis positively correlated with both proliferation and anchorage-independent growth of GBM cell lines (r = 0.75 and 0.79, respectively). In a single cell line derived from a secondary GBM, exposure to concentrations of greater than or equal to 1 Émol/L resulted in a substantial net cell loss during proliferation studies.

Conclusions.The induction ofEGFRmRNA may constitute a cellular mechanism to counteract the inhibitory effect of OSI-774 on the anchorage-independent growth of GBM cells. In contrast, no considerable correlation could be established between baseline expression levels of EGFR (both mRNA and protein) in GBM cell lines and their biological response to OSI-774. The OSI-774 induced greater (p53-independent) apoptosis in more malignant GBM phenotypes and may be a promising therapeutic agent against secondary GBM.
Magnetic and electrical stimulation of the auditory cortex for intractable tinnitus
Authors: De Ridder Dirk , De Mulder Gert , Walsh Vincent , Muggleton Neil , Sunaert Stefan , Møller Aage
Published: May 2009

✓ Tinnitus is a distressing symptom that affects up to 15% of the population for whom no satisfactory treatment exists. The authors present a novel surgical approach for the treatment of intractable tinnitus, based on cortical stimulation of the auditory cortex.

Tinnitus can be considered an auditory phantom phenomenon similar to deafferentation pain, which is observed in the somatosensory system. Tinnitus is accompanied by a change in the tonotopic map of the auditory cortex. Furthermore, there is a highly positive association between the subjective intensity of the tinnitus and the amount of shift in tinnitus frequency in the auditory cortex, that is, the amount of cortical reorganization. This cortical reorganization can be demonstrated by functional magnetic resonance (fMR) imaging.

Transcranial magnetic stimulation (TMS) is a noninvasive method of activating or deactivating focal areas of the human brain. Linked to a navigation system that is guided by fMR images of the auditory system, TMS can suppress areas of cortical plasticity. If it is successful in suppressing a patient's tinnitus, this focal and temporary effect can be perpetualized by implanting a cortical electrode.

A neuronavigation-based auditory fMR imaging-guided TMS session was performed in a patient who suffered from tinnitus due to a cochlear nerve lesion. Complete suppression of the tinnitus was obtained. At a later time an extradural electrode was implanted with the guidance of auditory fMR imaging navigation. Postoperatively, the patient's tinnitus disappeared and remains absent 10 months later.

Focal extradural electrical stimulation of the primary auditory cortex at the area of cortical plasticity is capable of suppressing contralateral tinnitus completely. Transcranial magnetic stimulation may be an ideal method for noninvasive studies of surgical candidates in whom stimulating electrodes might be implanted for tinnitus suppression.