bluuebunny/crossref_metadata_2025 huggingface dataset:
Bone regeneration at rabbit skull defects treated with transforming growth factor—β1 incorporated into hydrogels with different levels of biodegradability
Authors: Hong Liu , Tabata Yasuhiko , Miyamoto Susumu , Yamamoto Masaya , Yamada Keisuke , Hashimoto Nobuo , Ikada Yoshito
Published: May 2009

Object. Skull bone regeneration induced by transforming growth factor—β1 (TGFβ1)—containing gelatin hydrogels (TGFβ1-hydrogels) was investigated using a rabbit skull defect model. Different strengths of TGFβ1 were examined and compared: different TGFβ1 doses in gelatin hydrogels with a fixed water content, different water contents in gelatin hydrogels with a fixed TGFβ1 dose, and TGFβ1 in solution form. In addition, regenerated skull bone was observed over long time periods after treatment.

Methods. Soft x-ray, dual energy x-ray absorptometry, and histological studies were performed to assess the time course of bone regeneration at a 6-mm-diameter skull defect in rabbits after treatment with TGFβ1-hydrogels or other agents. The influence of TGFβ1 dose and hydrogel water content on skull bone regeneration by TGFβ1-hydrogels was evaluated. Gelatin hydrogels with a water content of 95 wt% that incorporated at least 0.1 µg of TGFβ1 induced significant bone regeneration at the rabbit skull defect site 6 weeks after treatment, whereas TGFβ1 in solution form was ineffective, regardless of dose. The in vivo degradability of the hydrogels, which varied according to water content, played an important role in skull bone regeneration induced by TGFβ1-hydrogels. In our hydrogel system, TGFβ1 is released from hydrogels as a result of hydrogel degradation. When the hydrogel degrades too quickly, it does not retain TGFβ1 or prevent ingrowth of soft tissues at the skull defect site and does not induce bone regeneration at the skull defect. It is likely that hydrogel that degrades too slowly physically impedes formation of new bone at the skull defect. Following treatment with 0.1-µg TGFβ1-hydrogel (95 wt%), newly formed bone remained at the defect site without being resorbed 6 and 12 months later. The histological structure of the newly formed bone was similar to that of normal skull bone. Overgrowth of regenerated bone and tissue reaction were not observed after treatment with TGFβ1-hydrogels.

Conclusions. A TGFβ1-hydrogel with appropriate biodegradability will function not only as a release matrix for the TGFβ1, but also as a space provider for bone regeneration. The TGFβ1-hydrogel is a promising surgical tool for skull defect repair and skull base reconstruction.
Early aneurysm recurrence after technically satisfactory Guglielmi detachable coil therapy: is early surveillance needed?
Authors: Makoui A. Shahram , Smith Donald A. , Evans Avery J. , Cahill David W.
Published: May 2009

✓ Guglielmi detachable coil (GDC) therapy was initially intended as a treatment for select patients harboring aneurysms deemed to be at high risk for clip ligation. As experience with the technique has grown, many centers are now offering GDC therapy as a primary treatment to patients who are also good surgical candidates. The authors report a case in which a ruptured anterior communicating artery aneurysm recurred within 2 weeks of a technically satisfactory GDC procedure. The patient subsequently underwent successful surgery for clip ligation of the lesion. This is the earliest reported recurrence of an aneurysm after angiographically confirmed successful GDC therapy and underscores the need for performing early control angiography in patients undergoing this procedure.
Stereotactic pallidotomy performed without using microelectrode guidance in patients with Parkinson's disease: surgical technique and 2-year results
Authors: Eskandar Emad N. , Shinobu Leslie A. , Penney John B. , Cosgrove G. Rees , Counihan Timothy J.
Published: May 2009

Object. Pallidotomy for the treatment of medically refractory Parkinson's disease (PD) has enjoyed renewed popularity. However, the optimal surgical technique, lesion location, and long-term effectiveness of pallidotomy remain subjects of debate. In this article the authors describe their surgical technique for performing pallidotomy without using microelectrode guidance, and the clinical and radiological results of this procedure.

Methods. Patients were evaluated preoperatively by using a battery of validated clinical rating scales and magnetic resonance (MR) imaging of the brain. Individuals with severe treatment-refractory idiopathic PD who were believed to be good candidates for surgery underwent computerized tomography scanning— and MR imaging—guided stereotactic pallidotomy. Intraoperative macrostimulation was used to optimize lesion placement and to avoid injury to nearby structures. Lesion location and size were calculated from MR imaging sequences of the brain obtained within the first 24 hours after surgery and again 3 months later. Clinical examinations were conducted at 1.5, 3, 6, 12, and 24 months after surgery.

Seventy-five patients (mean age 61 years, range 38–79 years) underwent unilateral pallidotomy. Significant improvements were observed in the “off” period scores for the activities of daily living portion of the Unified Parkinson's Disease Rating Scale (UPDRS), the UPDRS motor scores, total “on” time, levodopa-induced dyskinesias, and contralateral tremor. These improvements were maintained 24 months postoperatively. The mean lesion volume measured on the immediate postoperative MR image was 73 ± 5.4 mm3. Radiological analysis suggests that initial lesion volume does not predict outcome. The only permanent major complication was a single visual field defect.

Conclusions. Pallidotomy performed without using microelectrode guidance is a safe and effective treatment for selected patients with medically refractory PD.
Prevention of subdural fluid collections following transcortical intraventricular and/or paraventricular procedures by using fibrin adhesive
Authors: Al-Yamany Mahmoud , Del Maestro Rolando F.
Published: May 2009

Object. Subdural fluid collections following transcortical intraventricular and/or paraventricular neurosurgical procedures for tumors are common and can be difficult to treat. The authors prospectively studied the efficacy of a fibrin adhesive (Tisseel) in closing cortical and ependymal defects following intraventricular and/or paraventricular lesion resection and in preventing the development of subdural fluid collections.

Methods. Twenty-five patients who underwent 29 transcortical approaches for the resection of intraventricular and/or paraventricular lesions were studied. No patient developed a symptomatic subdural fluid collection and no new seizure or progression of a preexisting seizure disorder was encountered during a median follow-up time of 29 months (range 1–57 months). The incidence of preoperative hydrocephalus was 72% and four (22%) of these patients required postoperative shunt placement.

Conclusions. The use of a fibrin adhesive to seal cortical and ependymal defects after transcortical procedures appears to prevent the development of subdural fluid collections.
Long-term follow-up study of chronic globus pallidus internus stimulation for posttraumatic hemidystonia
Authors: Loher Thomas J. , Hasdemir Mustafa G. , Burgunder Jean-Marc , Krauss Joachim K.
Published: May 2009

✓ The authors report the first case of chronic globus pallidus internus (GPi) stimulation for treatment of medically intractable hemidystonia for which long-term follow-up data are available. The patient had developed left-sided low-frequency tremor and hemidystonia after a severe head trauma sustained at 15 years of age. He experienced relief of the tremor but not of the hemidystonia after a thalamotomy was performed in the right hemisphere 3 years postinjury. When the patient was 24 years old, the authors performed a magnetic resonance-guided stereotactic implantation of a monopolar electrode in the right-sided posteroventral GPi. Chronic deep brain stimulation resulted in remarkable improvement of dystonia-associated pain, phasic dystonic movements, and dystonic posture, which was accompanied by functional gain. Postoperative improvement was sustained after 4 years of follow up. Chronic GPi stimulation appears to be a valuable treatment option for posttraumatic dystonia.
Interdural origin of the ophthalmic artery at the dural ring of the internal carotid artery
Authors: Kyoshima Kazuhiko , Oikawa Susumu , Kobayashi Shigeaki
Published: May 2009

✓ The authors report two cases in which the ophthalmic artery (OA) originated from the interdural portion of the internal carotid artery at the carotid dural ring and coursed within the dura. This configuration was observed during surgeries performed in 82 cases of juxta—dural ring aneurysms.

In surgery for such an aneurysm, if the OA is not seen intradurally, an attempt should be made to find this kind of variation by using a Doppler flowmeter before sectioning the dural ring.
Benign aqueductal cyst causing bilateral internuclear ophthalmoplegia after external ventricular drainage
Authors: Shin Masahiro , Nishihara Tetsuhiro , Iai Shigeo , Eguchi Tsuneyoshi
Published: May 2009

✓ The introduction of magnetic resonance (MR) imaging to the field of neuroimaging has allowed detection of various lesions that cause aqueductal stenosis. The authors report the case of a 3-year-old boy in whom a benign ventricular cyst developed in the aqueduct. The patient became drowsy after having complained of headache and vomiting; MR imaging revealed mild triventricular dilation and a normal-sized fourth ventricle. Repeated MR imaging performed 1 week later revealed an aqueductal cyst that had markedly enlarged during the intervening period. An external ventricular drainage system was installed, but recovery of consciousness in the child was unsatisfactory and a new bilateral internuclear ophthalmoplegia developed. Fenestration of the cyst wall and placement of a ventriculocisternostomy in the third ventricle were performed simultaneously by using a flexible neuroendoscope. By 2 weeks postsurgery, the patient's neurological symptoms had completely resolved. This case illustrates that simple rerouting of ventricular cerebrospinal fluid (CSF) can aggravate the symptoms of this rare lesion by causing severe compression of periaqueductal structures by a cyst that maintains a high intracystic pressure. Endoscopic surgery was an excellent choice of treatment to achieve both cyst fenestration and normalization of intracranial CSF pressure by creating a ventriculocisternostomy.
Correspondence between functional magnetic resonance imaging somatotopy and individual brain anatomy of the central region: comparison with intraoperative stimulation in patients with brain tumors
Authors: Lehéricy Stéphane , Duffau Hugues , Cornu Philippe , Capelle Laurent , Pidoux Bernard , Carpentier Alexandre , Auliac Stéphanie , Clemenceau Stèphane , Sichez Jean-Pierre , Bitar Ahmed , Valery Charles-Ambroise , Van Effenterre Remy , Faillot Thierry , Srour Abbas , Fohanno Denis , Philippon Jacques , Le Bihan Denis , Marsault Claude
Published: May 2009

Object. The goal of this study was to determine the somatotopical structure—function relationships of the primary motor cortex in individual patients by using functional magnetic resonance (fMR) imaging. This was done to assess whether there is a displacement of functional areas compared with anatomical landmarks in patients harboring brain tumors close to the central region, and to validate these findings with intraoperative cortical stimulation.

Methods. One hundred twenty hemispheres in 60 patients were studied by obtaining blood oxygen level—dependent fMR images in patients while they performed movements of the foot, hand, and face on both sides. There was a good correspondence between anatomical landmarks in the deep portion of the central sulcus on axial slices and the somatotopical organization of primary motor areas. Pixels activated during hand movements were centered on a small characteristic digitation; those activated during movements in the face and foot areas were located in the lower portion of the central sulcus (lateral to the hand area) and around the termination of the central sulcus, respectively. In diseased hemispheres, signal-intensity changes were still observed in the projection of the expected anatomical area. The fMR imaging data mapped intraoperative electrical stimulation in 92% of positive sites.

Conclusions. There was a high correspondence between the somatotopical anatomy and function in the central sulcus, which was similar in normal and diseased hemispheres. The fMR imaging and electrical stimulation data were highly concordant. These findings may enable the neurosurgeon to locate primary motor areas more easily during surgery.
Bilateral subthalamic stimulation for Parkinson's disease by using three-dimensional stereotactic magnetic resonance imaging and electrophysiological guidance
Authors: Bejjani Boulos-Paul , Dormont Didier , Pidoux Bernard , Yelnik Jérôme , Damier Philippe , Arnulf Isabelle , Bonnet Anne-Marie , Marsault Claude , Agid Yves , Philippon Jacques , Cornu Philippe
Published: May 2009

Object. Several methods are used for stereotactically guided implantation of electrodes into the subthalamic nucleus (STN) for continuous high-frequency stimulation in the treatment of Parkinson's disease (PD). The authors present a stereotactic magnetic resonance (MR) method relying on three-dimensional (3D) T1-weighted images for surgical planning and multiplanar T2-weighted images for direct visualization of the STN, coupled with electrophysiological recording and stimulation guidance.

Methods. Twelve patients with advanced PD were enrolled in this study of bilateral STN implantation. Both STNs were visible as 3D ovoid biconvex hypointense structures located in the upper mesencephalon. The coordinates of the centers of the STNs were determined with reference to the patient's anterior commissure—posterior commissure line by using a new landmark, the anterior border of the red nucleus. Electrophysiological monitoring through five parallel tracks was performed simultaneously to define the functional target accurately.

Microelectrode recording identified high-frequency, spontaneous, movement-related activity and tremor-related cells within the STNs. Acute STN macrostimulation improved contralateral rigidity and akinesia, suppressed tremor when present, and could induce dyskinesias. The central track, which was directed at the predetermined target by using MR imaging, was selected for implantation of 19 of 24 electrodes. No surgical complications were noted.

Conclusions. At evaluation 6 months after surgery, continuous STN stimulation was shown to have improved parkinsonian motor disability by 64% and 78% in the “off” and “on” medication states, respectively. Antiparkinsonian drug treatment was reduced by 70% in 10 patients and withdrawn in two patients. The severity of levodopainduced dyskinesias was reduced by 83% and motor fluctuations by 88%. Continuous high-frequency stimulation of the STN applied through electrodes implanted with the aid of 3D MR imaging and electrophysiological guidance is a safe and effective therapy for patients suffering from severe, advanced levodopa-responsive PD.
Pretreatment with continuous-wave ultraviolet irradiation to prevent the development of delayed vasospasm in the rabbit common carotid artery model
Authors: Nakai Kanji , Morimoto Yuji , Wada Kojiro , Nawashiro Hiroshi , Shima Katsuji , Kikuchi Makoto
Published: May 2009

Object. Ultraviolet (UV) light irradiation can lead to immunomodulation. The purpose of this study was to determine the preventive effect of UV light on cerebral vasospasm by using a rabbit common carotid artery (CCA) model.

Methods. Rabbit CCAs were constricted for a long period by application of autologous blood within a silicon sheath. Before immersion in blood, the CCAs were adventitiously exposed to UV light emitted from a helium—cadmium laser (wavelength 325 nm) yielding an irradiation energy of 10 mJ/mm2. The occurrence of vasospasm was evaluated using angiography 48 hours after blood exposure in this model.

The UV light treatment significantly reduced the degree of vasospasm. Compared with luminal diameters measured on Day 0, prior to treatment, the luminal diameters of UV light—treated arteries (six animals) decreased by only 6%, whereas that of the sham-treated arteries (eight animals) significantly decreased by 26% (p < 0.001). Histological examination of UV light—treated CCAs revealed no endothelial damage and extended smooth-muscle cells, in which some fragmented nuclei were confirmed by terminal deoxynucleotidyl transferase—mediated deoxyuridine triphosphate nick-end labeling. Twenty-eight days after blood exposure, examination of UV light—treated CCAs revealed only myointimal proliferation, similar to that of the sham-treated CCAs.

Conclusions. These results are the first to provide evidence of a prophylactic effect of UV light on vasospasm and are suggestive of involvement of apoptosis in the mechanism of this effect.
Right temporal lobe glioblastoma presenting in the left orbit
Authors: Kros Johan M. , van den Berge Herbert , Tanghe Hervé L. J. , Bakker Stef L. M.
Published: May 2009

✓ Dissemination of gliomas outside the central nervous system without preceding neurosurgery is a rare phenomenon. Glial neoplasms presenting as bone lesions are even more rare. A case of glioblastoma multiforme (GBM) with initial presentation in the orbit following a single generalized seizure is described. Signs of intracranial hypertension resulted from subarachnoid tumor invasion. The patient was treated with whole-dose radiation therapy but survived for only 6 months following the initial presentation. An autopsy revealed a right temporal GBM with extensive subarachnoid spread and invasion in the left orbit and skull base. The literature on dissemination of primary tumors of the brain is reviewed.
Malignant transformation of a dysembryoplastic neuroepithelial tumor
Authors: Hammond Robert R. , Duggal Neil , Woulfe John M. J. , Girvin John P.
Published: May 2009

✓ A 29-year-old man presented in 1984 with a recent onset of partial seizures marked by speech arrest. Electroencephalography identified a left frontotemporal dysrhythmia. Computerized tomography (CT) scanning revealed a superficial hypodense nonenhancing lesion in the midleft frontal convexity, with some remodeling of the overlying skull. The patient was transferred to the London Health Sciences Centre for subtotal resection of what was diagnosed as a “fibrillary astrocytoma (microcystic).” He received no chemotherapy or radiation therapy and remained well for 11 years.

The patient presented again in late 1995 with progressive seizure activity. Both CT and magnetic resonance imaging demonstrated a recurrent enhancing partly cystic lesion. A Grade IV astrocytoma was resected, and within the malignant tumor was a superficial area reminiscent of a dysembryoplastic neuroepithelial tumor (DNT). Data on the lesion that had been resected in 1984 were reviewed, and in retrospect the lesion was identified as a DNT of the complex form. It was bordered by cortical dysplasia and contained glial nodules, in addition to the specific glioneuronal element. The glial nodules were significant for moderate pleomorphism and rare mitotic figures. The Ki67 labeling index averaged 0.3% in the glial nodules and up to 4% focally. Cells were rarely Ki67 positive within the glioneuronal component. This case is the first documented example of malignant transformation of a DNT. It serves as a warning of the potential for malignant transformation in this entity, which has been traditionally accepted as benign. This warning may be especially warranted when confronted with complex forms of DNT. The completeness of resection in the benign state is of paramount importance.
Gamma surgery for intracranial metastases from renal cell carcinoma
Authors: Payne Bryan Rankin , Prasad Dheerendra , Szeifert György , Steiner Melita , Steiner Ladislau
Published: May 2009

Object. The goal of this study was to evaluate the effectiveness and limitations of gamma surgery (GS) in the treatment of renal cell carcinoma that has metastasized to the brain.

Methods. The authors performed a retrospective analysis of a consecutive series of 21 patients with 37 metastatic brain deposits from renal cell carcinoma who were treated with GS at the University of Virginia from 1990 to 1999.

Clinical data were available in all patients. No patient died of progression of intracranial disease or deteriorated neurologically following GS. Eight patients clinically improved. Follow-up imaging studies were available for 23 tumors in 12 patients. Nine patients did not undergo follow-up imaging. One patient lived 17 months and succumbed to systemic disease; no brain imaging was performed in this case. Another patient refused further imaging and lived 7 months. Seven patients lived up to 4 months after the procedure; however, their physicians did not require these patients to undergo follow-up imaging examinations because of their general conditions—all had systemic progression of disease. Of the 23 tumors that were observed posttreatment, one remained unchanged in volume, 16 decreased in volume, and six disappeared. No tumor progressed at any time, and there were no radiation-induced changes on follow-up imaging an average of 21 months after GS (range 3–63 months).

Conclusions. Gamma surgery provides an alternative to surgical resection of metastatic brain deposits from renal cell carcinoma. Neurological side effects were seen in only one case; freedom from progression of disease was achieved in all cases.
Incidence and clinical features of asymptomatic meningiomas
Authors: Kuratsu Jun-ichi , Kochi Masato , Ushio Yukitaka
Published: May 2009

Object. The increased use of computerized tomography (CT) and magnetic resonance (MR) technology has led to an increase in the detection of asymptomatic meningiomas, although the surgical indication for these tumors remains undetermined. The authors investigated the incidence of asymptomatic meningiomas and their clinical features.

Methods. An epidemiological survey was conducted of primary intracranial tumors diagnosed in Kumamoto Prefecture between 1989 and 1996. Follow-up neuroradiological imaging and clinical studies for asymptomatic meningiomas were performed.

Primary intracranial tumors were diagnosed in 1563 residents. Of these lesions, 504 (32.2%) were meningiomas, and of these meningiomas 196 (38.9%) were asymptomatic. The incidence of asymptomatic meningiomas was significantly higher in individuals older than 70 years of age. Furthermore, the incidence of asymptomatic meningiomas was significantly higher in female than in male patients. Of the asymptomatic meningiomas in 196 patients, 87 (44.4%) were surgically removed, whereas 109 (55.6%) were treated conservatively. Of these conservatively treated patients, 63 received follow-up care for more than 1 year. In 20 of these 63 cases, the tumors increased in size over the 27.8-month average follow-up period (range 12–87 months), whereas in the other 43 cases, the tumor size did not increase during a 36.6-month average follow-up period (range 12–96 months). There was no significant difference with respect to age, tumor size, and male/female ratio between the patient group in which the tumor size increased and the group in which it did not increase during the follow-up period. Asymptomatic meningiomas that evidenced calcification on CT scans and/or hypointensity on T2-weighted MR images appear to have a slower growth rate.

Conclusions. Among patients older than age 70 years who underwent operation for asymptomatic meningioma, the neurological morbidity rate was 23.3%; it was 3.5% among younger patients. This indicates that the advisability of surgery in elderly patients with asymptomatic meningiomas must be considered very carefully.
Bleeding risk of cerebral vascular malformations in hereditary hemorrhagic telangiectasia
Authors: Willemse Ronald B. , Mager Johannes J. , Westermann Cornelius J. J. , Overtoom Timotheus T. C. , Mauser Henk , Wolbers John G.
Published: May 2009

Object. Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal-dominant vascular dysplasia with a high prevalence of cerebrovascular malformations (CVMs), mostly manifested as arteriovenous malformations (AVMs). The natural history and bleeding risk of these CVMs is unknown. The authors investigated the risk of bleeding in conjunction with clinical and radiological features in patients with HHT and proven CVMs.

Methods. Intravenous digital subtraction (DS) angiography was used to screen 196 patients with HHT for the presence of CVMs. Patients with abnormal results on DS angiography were asked to undergo a conventional cerebral angiographic study. All patients with a proven CVM were assessed by a neurologist. The bleeding risk was retrospectively and prospectively calculated for patients with AVMs only, as well as for the whole cohort of patients with CVMs.

Twenty-four patients (12.2%; 16 female and eight male), aged 14 to 66 years (mean 35.4 years) with one or more CVMs were identified. Fifteen patients (62.5%) had a CVM and a pulmonary AVM. Eleven patients (45.8%) exhibited no neurological signs of their CVM; six (25%) had headache or migraine; four (16.7%) had seizures; and three (12.5%) had an intracranial hemorrhage. Twenty-two patients had at least one AVM (with a total of 28 AVMs), whereas two patients only had telangiectases. Twenty-seven AVMs were small (96%), 36% were located in eloquent areas of the brain, and 82% had superficial venous drainage. One third of the patients had multiple CVMs. The bleeding risk for patients with at least one AVM ranged from 0.41 to 0.72% per year, and for the whole cohort the range was 0.38 to 0.69% per year. Calculation of the bleeding risk as determined by lesion-years ranged from 0.36 to 0.56% per year for patients with AVMs and from 0.27 to 0.46% per year for all patients with CVMs.

Conclusions. Patients with HHT have a high risk of harboring a CVM, especially in the presence of a pulmonary AVM. These CVMs are mostly low-grade AVMs (Spetzler—Martin Grade I or II), are frequently multiple, and have a lower risk of bleeding than that associated with sporadic AVMs. Female patients are more often affected than male patients. The inherent low sensitivity of DS angiography screening for CVMs may yield false negative results.
Evaluation of a method for noninvasive intracranial pressure assessment during infusion studies in patients with hydrocephalus
Authors: Schmidt Bernhard , Czosnyka Marek , Schwarze Jens Jürgen , Sander Dirk , Gerstner Werner , Lumenta Christianto Benjamin , Klingelhöfer Jürgen
Published: May 2009

Object. A mathematical model previously introduced by the authors allowed noninvasive intracranial pressure (nICP) assessment. In the present study the authors investigated this model as an aid in predicting the time course of raised ICP during infusion tests in patients with hydrocephalus and its suitability for estimating the resistance to outflow of cerebrospinal fluid (Rcsf).

Methods. Twenty-one patients with hydrocephalus were studied. The nICP was calculated from the arterial blood pressure (ABP) waveform by using a linear signal transformation, which was dynamically modified by the relationship between ABP and cerebral blood flow velocity. This model was verified by comparison of nICP with “real” ICP measured during lumbar infusion tests. In all simulations, parallel increases in real ICP and nICP were evident. The simulated Rcsf was computed using nICP and then compared with Rcsf computed from real ICP. The mean absolute error between real and simulated Rcsf was 4.1 ± 2.2 mm Hg minute/ml. By the construction of simulations specific to different subtypes of hydrocephalus arising from various causes, the mean error decreased to 2.7 ± 1.7 mm Hg minute/ml, whereas the correlation between real and simulated Rcsf increased from R = 0.73 to R = 0.89 (p < 0.001).

Conclusions. The validity of the mathematical model was confirmed in this study. The creation of type-specific simulations resulted in substantial improvements in the accuracy of ICP assessment. Improvement strategies could be important because of a potential clinical benefit from this method.
Efficacy of the Ghajar Guide revisited: a prospective study
Authors: O'Leary Shaun T. , Kole Max K. , Hoover Devon A. , Hysell Steven E. , Thomas Ajith , Shaffrey Christopher I.
Published: May 2009

Object. The goal of this study was to compare the freehand technique of catheter placement using external landmarks with the technique of using the Ghajar Guide for this procedure. The placement of a ventricular catheter can be a lifesaving procedure, and it is commonly performed by all neurosurgeons. Various methods have been described to cannulate the ventricular system, including the modified Friedman tunnel technique in which a soft polymeric tube is inserted through a burr hole. Paramore, et al., have noted that two thirds of noninfectious complications have been related to incorrect positioning of the catheter.

Methods. Forty-nine consecutive patients were randomized between either freehand or Ghajar Guide—assisted catheter placement. The target was the foramen of Monro, and the course was through the anterior horn of the lateral ventricle approximately 10 cm above the nasion, 3 cm from the midline, to a depth of 5.5 cm from the inner table of the skull. In all cases, the number of passes was recorded for successful cannulation, and pre- and postplacement computerized tomography scans were obtained. Calculations were performed to determine the bicaudate index and the distance from the catheter tip to the target point.

Conclusions. Successful cannulation was achieved using either technique; however, the catheters placed using the Ghajar Guide were closer to the target.
Thymidine kinase activation of ganciclovir in recurrent malignant gliomas: a gene-marking and neuropathological study
Authors: Harsh Griffith R. , Deisboeck Thomas S. , Louis David N. , Hilton John , Colvin Michael , Silver Jonathan S. , Qureshi Nazer H. , Kracher Jean , Finkelstein Diane , Chiocca Ennino A. , Hochberg Fred H.
Published: May 2009

Object. The gene therapy paradigm of intratumoral activation of ganciclovir (GCV) following transduction of tumor cells by retroviral vectors bearing the thymidine kinase (tk) gene has produced dramatic remissions of malignant gliomas in animal models. In human trials, although the technique has been deemed safe, little antitumor effect has been demonstrated. To evaluate the basis of this inefficacy in human gliomas, the authors conducted a gene-marking trial involving neuropathological and biochemical studies of treated tumor specimens.

Methods. Five patients with malignant recurrent gliomas underwent stereotactic biopsy sampling and intratumoral implantation procedures with three aliquots of 106 vector-producing cells (VPCs) in columns. After 5 days, the tumor was resected and the tumor bed reimplanted with VPCs, and a course of GCV was given. Patients received clinical and radiological follow up for 6 months. Tumor specimens were analyzed neuropathologically and for tk gene expression by anti-TK immunohistochemistry and TK enzymatic activity.

Four patients tolerated the treatment well but experienced tumor progression. The other developed an abscess after the second operation and died. Increased TK enzymatic activity was demonstrated in the one tumor specimen analyzed. Immunohistochemical evidence of tk gene expression was limited to VPCs. Transduction of tumor cells was not seen. Viable tumor cells were seen near VPCs containing TK. The lymphocytic immune response was mild.

Conclusions. Except for the risk of infection inherent in reoperation, this tk—GCV paradigm was both feasible and safe. Pathological studies indicated that limited dissemination of VPCs and vector from the infusion site and failure to transduce tumor cells with the tk gene are major barriers to efficacy.
Quantitative description of the far-lateral transcondylar transtubercular approach to the foramen magnum and clivus
Authors: Spektor Sergey , Anderson Gregory J. , McMenomey Sean O. , Horgan Michael A. , Kellogg Jordi X. , Delashaw Johnny B.
Published: May 2009

Object. The purpose of this study was to evaluate the far-lateral transcondylar transtubercular approach (complete FLA) based on quantitative measurements of the exposure of the foramen magnum and petroclival area obtained after each successive step of this approach.

Methods. The complete FLA was reproduced in eight specially prepared cadaveric heads (a total of 15 sides). The approach was divided into six steps: 1) C-1 hemilaminectomy and suboccipital craniectomy with unroofing of the sigmoid sinus (basic FLA); 2) partial resection of the occipital condyle (up to the hypoglossal canal); 3) removal of the jugular tuberculum; 4) mastoidectomy (limited to the labyrinth and the fallopian canal) and retraction of the sigmoid sinus; 5) resection of the lateral mass of C-1 with mobilization of the vertebral artery; and 6) resection of the remaining portion of the occipital condyle. After each successive step, a standard set of measurements was obtained using a frameless stereotactic device. The measurements were used to estimate two parameters: the size of the exposed petroclival area and the size of a spatial cone directed toward the anterior rim of the foramen magnum, which depicts the amount of surgical freedom available for manipulation of instruments.

The initial basic FLA provided exposure of only 21 ± 6% of the petroclival area that was exposed with the full, six-step maximally aggressive (complete) FLA. Likewise, only 18 ± 9% of the final surgical freedom was obtained after the basic FLA was performed. Each subsequent step of the approach increased both petroclival exposure and surgical freedom. The most dramatic increase in petroclival exposure was noted after removal of the jugular tuberculum (71 ± 12% of final exposure), whereas the least improvement in exposure occurred after the final step, which consisted of total condyle resection.

Conclusions. The complete FLA provides wide and sufficient exposure of the foramen magnum and lower to middle clivus. The complete FLA consists of several steps, each of which contributes to increasing petroclival exposure and surgical freedom. However, the FLA may be limited to the less aggressive steps, while still achieving significant exposure and surgical freedom. The choice of complete or basic FLA thus depends on the underlying pathological condition and the degree of exposure required for effective surgical treatment.
Telomerase activity and expression of the telomerase catalytic subunit, hTERT, in meningioma progression
Authors: Simon Matthias , Park Tjoung-Won , Leuenroth Sven , Hans Volkmar H. J. , Löning Thomas , Schramm Johannes
Published: May 2009

Object. In recent reports, 6 to 19% of meningiomas have been classified as atypical or anaplastic/malignant. Some atypical and anaplastic meningiomas appear to arise from benign tumors by progression. Telomerase activation has recently been associated with malignant progression of human tumors. The authors have investigated a series of benign, atypical, and anaplastic/malignant meningiomas for telomerase activity and expression of the telomerase catalytic subunit human telomerase reverse transcriptase (hTERT).

Methods. A quantitative telomeric repeat amplification protocol was used to detect telomerase enzyme activity in seven (21%) of 34 benign, but in nine (75%) of 12 atypical and in seven (100%) of seven anaplastic/malignant meningiomas. Very high levels of telomerase activity were observed only in highly aggressive tumors. Messenger (m)RNA expression of the catalytic subunit hTERT was found in 11 (33%) of 33 benign, 12 (92%) of 13 atypical, and all seven anaplastic/malignant tumors. All telomerase-positive lesions were also positive for hTERT mRNA, whereas no telomerase activity was detected in six (21%) of 29 hTERT-positive tumors. This indicates that upregulation of hTERT is the rate-limiting step for telomerase activation in the majority of meningiomas. Expression of telomerase and hTERT was seen in all four tumors with gross brain invasion. All recurrent tumors or meningiomas recurring during follow up expressed hTERT.

Conclusions. The results are consistent with a role for telomerase activation during the development of malignancy in meningiomas. Hence, expression of telomerase activity and hTERT might prove to be potentially useful markers for the evaluation of these tumors.
Adult choroid plexus papilloma of the posterior fossa mimicking a hemangioblastoma
Authors: García-Valtuille Roberto , Abascal Faustino , García-Valtuille Ana I. , Pinto J. Ignacio , Cerezal Luis , Sanz Felipe , Trigueros Felipe , Mazorra Francisco
Published: May 2009

✓ The authors report a case of cystic choroid plexus papilloma that originated in the posterior fossa. No connection with the ventricular system was found intraoperatively. Magnetic resonance (MR) and computerized tomography imaging did not furnish a diagnosis, but findings of pathological examinations were consistent with those of choroid plexus papilloma. The authors describe the different appearances of the tumor on MR images and discuss the differential diagnosis with other tumors of the posterior fossa.
Mathematical theory of stereotactic coordinate transformation: elimination of rotational targeting error by addition of a third reference point
Authors: Taub Ethan
Published: May 2009

✓ All frame-based stereotactic procedures require localization of an anatomical target within the coordinate system of the stereotactic frame. If the target is defined by its coordinates given in a stereotactic atlas (indirect localization), the neurosurgeon faces the mathematical task of transforming atlas coordinates into frame coordinates. In the method usually used, the frame coordinates of two reference points (the anterior and posterior commissures) are obtained from computerized tomography or magnetic resonance images, and serve as the basis for the coordinate transformation. This two-point algorithm relies on the additional assumption that the frame sits on the patient's head without exhibiting roll, that is, rotation about the anteroposterior axis (y axis). Usually this assumption is nearly, but not exactly, correct. An amount of roll as small as 3° can cause a targeting error on the order of 1 mm when a two-point algorithm is used. This potential source of error can be eliminated by using a new method of coordinate transformation, the derivation of which is mathematically reported in this article. The new method requires a third reference point located in the midsagittal plane, in addition to the two commissural reference points.
Imaging correlates of successful endoscopic third ventriculostomy
Authors: Kulkarni Abhaya V. , Drake James M. , Armstrong Derek C. , Dirks Peter B.
Published: May 2009

Object. The goal of this study was to determine and compare imaging correlates in pediatric patients who underwent successful or failed endoscopic third ventriculostomies (ETVs). To this end, the authors measured ventricular size changes and the presence of cerebrospinal fluid (CSF) flow void in both groups of children following ETV.

Methods. Images obtained in children with hydrocephalus immediately before and at least 30 days after having undergone ETV were reviewed by four independent observers (two blinded and two nonblinded). Each observer independently measured the frontal and occipital horn ratio ([FOR], a reliable and valid measure of ventricular size) and provided a subjective assessment of the presence of a flow void at the ETV site, the degree of periventricular edema, and the amount of CSF over the cerebral hemispheres.

There were 29 children whose mean age was 6.6 years at the time of ETV and who had a mean postoperative follow-up period lasting 1.6 years. Postoperatively, the mean reduction in ventricular size (as measured using the FOR) was 7% (95% confidence interval [CI] 3–11%) in cases that were deemed failures (eight patients) and 16% (95% CI 12–20%) in clinically successful cases (21 patients). This reduction was significantly greater in cases of clinical success compared with those that were deemed failures (p = 0.03, t-test). There were no substantial differences between blinded and nonblinded assessments. Flow void was present in 94% of successes and absent in 75% of failures (p = 0.01, Fisher's exact test). The other subjective assessments were not significantly different between the groups of successes and failures.

Conclusions. Ventricular size appears to be somewhat reduced in both groups of patients who underwent clinically successful and failed ETV; however, the reduction is significantly greater among clinically successful cases. The presence of a flow void also appears to correlate with clinical success and its absence with clinical failure.
Asymptomatic Chiari Type I malformations identified on magnetic resonance imaging
Authors: Meadows Jeffery , Kraut Michael , Guarnieri Michael , Haroun Raymond I. , Carson Benjamin S.
Published: May 2009

Object. Chiari Type I malformation (CMI) is a congenital disorder recognized by caudal displacement of the cerebellar tonsils through the foramen magnum and into the cervical canal. Frequently, associated findings include abnormalities of nearby bony and neural elements as well as syringomyelia. Cerebellar tonsillar ectopia is generally considered pathological when greater than 5 mm below the foramen magnum. However, asymptomatic tonsillar ectopia is an increasingly recognized phenomenon, the significance of which is poorly understood.

Methods. The authors retrospectively reviewed the records of all brain magnetic resonance (MR) images obtained at our hospital over a 43-month period in an attempt to ascertain the relative prevalence and MR imaging characteristics of asymptomatic CMIs. Of 22,591 patients who underwent MR imaging of the head and cervical spine, 175 were found to have CMIs with tonsillar herniation extending more than 5 mm below the foramen magnum. Of these, 25 (14%) were found to be clinically asymptomatic. The average extent of ectopia in this population was 11.4 ± 4.86 mm, and was significantly associated with a smaller cisterna magna. Syringomyelia and osseous anomalies were found in only one asymptomatic patient.

Conclusions. The authors suggest that the isolated finding of tonsillar herniation is of limited prognostic utility and must be considered in the context of all available clinical and radiographic data. Strategies for treating patients with asymptomatic CMIs are discussed.
Preoperative embolization of cerebral arteriovenous malformations with silk sutures: analysis and clinical correlation of complications revealed on computerized tomography scanning
Authors: Song Joon K. , Eskridge Joseph M. , Chung Eun-Chul , Blake Lindsey C. , Elliott J. Paul , Finch Lisa , Niakan Cyrus , Maravilla Kenneth R. , Winn H. Richard
Published: May 2009

Object. The aim of this study was to determine the incidence and clinical significance of complications related to preoperative embolization of cerebral arteriovenous malformations (AVMs) with silk sutures as documented on postprocedure computerized tomography (CT) scans.

Methods. The CT scans were obtained within 12 to 24 hours after 221 (96%) of 230 consecutive embolizations in 70 patients. These CT scans were evaluated for the presence of ischemia, infarction, hemorrhage, or contrast agent extravasation. Adverse patient outcomes were determined after each embolization and were correlated with CT findings. New abnormalities demonstrated on CT scans were also correlated with the Spetzler—Martin AVM grade, degree of arteriovenous shunting, and location. New abnormalities, the majority of them infarcts, resulted from 29 (13%) of 221 embolization procedures. In 11 (38%) of 29 cases of new CT findings, patients were asymptomatic, including 10 with new infarcts on CT scans. New neurological deficits occurred in 20 (8.7%) of 230 total embolization procedures in 19 patients, including one death. Permanent deficits occurred in nine patients (3.9% per embolization procedure, 12.8% per patient). Of the patients with new neurological deficits, 18 (90%) of 20 embolization procedures resulted in new abnormalities on CT scans. Two patients with new transient neurological deficits had no new findings on CT scans. Spetzler—Martin grade, AVM location, degree of arteriovenous shunting, and higher numbers of procedures were not statistically associated with a higher incidence of abnormalities on CT scans or new permanent neurological deficits.

Conclusions. Silk sutures are an effective and relatively safe embolic agent. After brain AVM embolization with silk sutures, new abnormalities were found on CT scans obtained in one of eight procedures. When a new CT finding occurred, the patient had roughly equal chances of having no new symptoms, having new transient neurological deficits, or having new permanent neurological deficits.
Adverse effects of limited hypotensive anesthesia on the outcome of patients with subarachnoid hemorrhage
Authors: Chang Han Soo , Hongo Kazuhiro , Nakagawa Hiroshi
Published: May 2009

Object. This study was aimed at clarifying the effect of intraoperative hypotensive anesthesia on the outcome of early surgery in patients with subarachnoid hemorrhage (SAH) caused by saccular cerebral aneurysms. Other factors were also screened for possible effects on the outcome.

Methods. Hospital charts in 84 consecutive patients with SAH who underwent aneurysm clipping by Day 4 were examined. Possible factors affecting the outcome were analyzed using multiple logistic regression with the dichotomous Glasgow Outcome Scale score as the outcome variable. The relationship between the intraoperative hypotension and the occurrence and severity of vasospasm was studied using both single- and multivariate analyses.

Conclusions. Intraoperative hypotension had a significantly adverse effect on the outcome of SAH. Hypotension was also related to more frequent and severe manifestations of vasospasm. A long-lasting effect of brain retraction is possibly the cause of this phenomenon. The data contained in this study preclude the use of intraoperative hypo- tension even in a limited form.
Long survival and therapeutic responses in patient histologically disparate high-grade gliomas demonstrating chromosome 1p loss
Authors: Ino Yasushi , Zlatescu Magdalena C. , Sasaki Hikaru , Macdonald David R. , Stemmer-Rachamimov Anat O. , Jhung Sarah , Ramsay David A. , von Deimling Andreas , Louis David N. , Cairncross J. Gregory
Published: May 2009

Object. Allelic loss of chromosome 1p is a powerful predictor of tumor chemosensitivity and prolonged survival in patients with anaplastic oligodendrogliomas. Chromosome 1p loss also occurs in astrocytic and oligoastrocytic gliomas, although less commonly than in pure oligodendroglial tumors. This observation raises the possibility investigated in this study that chromosome 1p loss might also provide prognostic information for patients with high-grade gliomas with astrocytic components.

Methods. The authors report on seven patients with high-grade gliomas composed of either pure astrocytic or mixed astrocytic-oligodendroglial phenotypes, who had remarkable neuroradiological responses to therapy or unexpectedly long survivals. All of the tumors from these seven patients demonstrated chromosome 1p loss, whereas other genetic alterations characteristic of high-grade gliomas (p53 gene mutations, EGFR gene amplification, chromosome 10 loss, chromosome 19q loss, or CDKN2A/p16 deletions) were only found in occasional cases. The authors also assessed the frequency of chromosome 1p loss in a series of anonymous high-grade astrocytoma samples obtained from a tumor bank and demonstrate that this genetic change is uncommon, occurring in only 10% of cases.

Conclusions. Although any prognostic importance of chromosome 1p loss in astrocytic or mixed astrocytic—oligodendroglial gliomas can only be determined in larger and prospective series, these findings raise the possibility that some high-grade gliomas with chromosome 1p loss, in addition to pure anaplastic oligodendrogliomas, may follow a more favorable clinical course.