bluuebunny/crossref_metadata_2025 huggingface dataset:
Sexual Differentiation of the Zebra Finch Song System
Authors: WADE JULI , ARNOLD ARTHUR P.
Published: August 2004

Abstract: The song system of zebra finches (Taeniopygia gutatta) is highly sexually dimorphic. Only males sing, and the brain regions and muscles controlling song are much larger in males than in females. Development of the song system is highly sensitive to steroid hormones. However, unlike similar sexually dimorphic systems in other animal models, masculinization of song system structure and function is most likely not induced by testosterone secreted from the testes. Instead, sex‐specific development of the neural song system appears to be regulated by factors intrinsic to the brain, probably by the expression of sex chromosome gene(s) that influence the levels of estradiol synthesized in the brain and/or the responses of brain tissue to estradiol. However, the existing data are complex and in some cases contradictory. More work is required to identify the critical genes and their relationships with steroid hormones.
Synaptic and Molecular Mechanisms Regulating Plasticity during Early Learning
Authors: NORDEEN KATHY W. , NORDEEN ERNEST J.
Published: August 2004

Abstract: Many behaviors are learned most easily during a discrete developmental period, and it is generally agreed that these “sensitive periods” for learning reflect the developmental regulation of molecular or synaptic properties that underlie experience‐dependent changes in neural organization and function. Avian song learning provides one example of such temporally restricted learning, and several features of this behavior and its underlying neural circuitry make it a powerful model for studying how early experience sculpts neural and behavioral organization. Here we describe evidence that within the basal ganglia‐thalamocortical loop implicated in vocal learning, song acquisition engages N‐methyl‐d‐aspartate receptors (NMDARs), as well as signal transduction cascades strongly implicated in other instances of learning. Furthermore, NMDAR phenotype changes in parallel with developmental and seasonal periods for vocal plasticity. We also review recent studies in the avian song system that challenge the popular notion that sensitive periods for learning reflect developmental changes in the NMDAR that alter thresholds for synaptic plasticity.
Neuron Addition and Loss in the Song System: Regulation and Function
Authors: WILBRECHT LINDA , KIRN JOHN R.
Published: August 2004

Abstract: Neurons continue to be produced and replaced throughout life in songbirds. Proliferation in the walls of the lateral ventricles gives rise to neurons that migrate long distances to populate many diverse telencephalic regions, including nuclei dedicated to the perception and production of song, a learned behavior. Many projection neurons are incorporated into the efferent motor pathway for song control. Replacement of these neurons is regulated, in part, by neuron death. Underlying mechanisms include gonadal steroids and BDNF, but are likely to involve other trophic factors as well. The functional significance of neuronal replacement remains unclear. However, recent experiments suggest a link between cell turnover and one or more specific attributes of song learning and production. Several hypotheses are critically examined, including the possibility that neuronal replacement provides motor flexibility to allow for error correction—a capacity needed for juvenile and adult song learning, but also likely to be important for the maintenance of song stereotypy. We highlight important gaps in our knowledge and discuss future directions that may bring us closer to solving the riddle of why neurons are produced and replaced in adulthood.
Hormone‐Dependent Neural Plasticity in the Juvenile and Adult Song System: What Makes a Successful Male?
Authors: GAHR MANFRED
Published: August 2004

Abstract: The sexual quality of adult song is the result of genetic and epigenetic mechanisms shaping the neural song system throughout life. Genetic brain‐intrinsic mechanisms determine the neuron pools that develop into forebrain song control areas independent of gonadal steroid hormones, androgens and estrogens. One fate of these neurons is the potential to express sex steroid receptors, such as androgen and estrogen receptors. Genetic brain‐intrinsic mechanisms, too, determine the activity of hypothalamic‐pituitary‐gonad (HPG) axis, i.e., the working range and responsiveness of HPG axis to produce gonadal hormones. The epigenetic action of gonadal steroid hormones (androgens and estrogens) on determined vocal neurons is required to maintain and increase the pool of determined vocal neurons and to complete the connections of the vocal system, i.e., to make it function motorically. The subsequent influence of environmental information, including both external (socio‐sexual and physical) and internal (body physiology) signals, specify the further neural phenotype of vocal areas either through acting on the HPG axis and differential release of gonadal hormones or through non‐gonadal hormone systems, both of which have target neurons in the functional vocal system. Despite the clear evidence of hormone dependency of the development of both the adult song phenotype and song system phenotype, their causal relation is complex.
The Road We Travelled: Discovery, Choreography, and Significance of Brain Replaceable Neurons
Authors: NOTTEBOHM FERNANDO
Published: August 2004

Abstract: Neurons are constantly added to the telencephalon of songbirds. In the high vocal center (HVC), where this has been studied, new neurons replace older ones that died. Peaks in replacement are seasonal and affect some neuronal classes but not others. Peaks in replacement coincide with peaks in information acquisition. The new neurons are produced by division of cells in the wall of the lateral ventricle. Where studied closely, the neuronal stem cells proved to be radial glia. Life expectancy of the new neurons ranges from weeks to months. New neuron survival is regulated by vacancies, hormones, and activity. The immediate agent of new neuron survival is, in some cases, brain‐derived neurotrophic factor (BDNF). The effect of BDNF is maximal 14‐20 days after the cells are born, when they are establishing their connections. These observations are now being extended to other vertebrates and may apply, to varying degrees, to all of them. The function of neuronal replacement in healthy adult brain remains unclear. If synaptic number and efficacy sufficed as mechanisms for long‐term memory storage and could be adjusted again and again to incorporate new memories, then neuronal replacement would seem unnecessary. Since it occurs, it seems reasonable to suppose that replacement serves to maintain learning potential in a way that could not be done just by synaptic change. Long‐term memories may be encoded by long‐term changes in gene expression akin to a last step in cell differentiation. If so, neuronal replacement may be the adult brain's way of striking a balance between limited memory space and the need to acquire new memories. The testing of this hypothesis remains in the future. This chapter tells how neuronal replacement was discovered in the adult songbird brain.
Birdsong and Singing Behavior
Authors: WILLIAMS HEATHER
Published: August 2004

Abstract:Birdsong provides neuroscientists with a uniquely powerful model for studying imitative vocal learning in a system where the brain structures responsible for song learning and production are well known. The 4,500+ species of songbirds provide a remarkable diversity of songs with a variety of tonal, structural, and learning characteristics, but most studies of the neural bases of learning have concentrated on two domesticated species, the canary and the zebra finch. Important differences in the songs of these two species provide useful properties for comparative studies, which could be expanded by using other species that demonstrate mimicry or action‐based learning. Although the primary goal of most studies of the neural bases of song has been to define the mechanisms responsible for imitative learning during development, studies of adult crystallized song are important for two reasons. First, they define the endpoint of learning, and second, adult song shows interesting forms of variability in its performance. The degree of adult song variability itself varies among individuals and is influenced by the sources from which the song was learned, how the song was assembled during learning, behavioral responses of adult listeners, and levels of circulating sex steroids. In addition, song may be associated with coordinated visual displays, which also contribute to its communicative function. Thus the study of crystallized adult song is likely to provide insights into the neural control of facultative behavior as well as into the important question of how imitative learning takes place.
Hormonal Modulation of Singing: Hormonal Modulation of the Songbird Brain and Singing Behavior
Authors: HARDING CHERYL F.
Published: August 2004

Abstract: During the past three decades research on the hormonal control of singing has fundamentally altered our basic concepts about how hormones modulate brain function and activate behavior. Exciting discoveries first documented in songbird brains have since been documented in a wide variety of vertebrate species, including humans. Circulating hormones organize sexual dimorphisms in brain structure during development, activate changes in brain structure during adulthood, and modulate the addition of new neurons in the adult brain. The brain has proved to be the primary source of estrogens in general circulation in adult male finches. Studies of the hormonal modulation of singing are complicated by multiple sites of hormone production, multiple sites of hormone action, hormone metabolism by different tissues, the involvement of a variety of hormones, and the effects of social context. This chapter provides a brief review of these topics, as well as a brief overview of techniques used to study endocrine mechanisms controlling behavior.
Where Is the Bird?
Authors: DEVOOGD TIMOTHY J.
Published: August 2004

Abstract: Patterns of song perception, learning, and expression differ across species, sexes, and individuals. We can understand the neurobiology of song better by paying attention to these differences. I focus selectively on a few of the studies done in my lab over in recent years to illustrate this.
Bird Calls: Their Potential for Behavioral Neurobiology
Authors: MARLER PETER
Published: August 2004

Abstract: Birdsongs are always part of larger set of sound signals. Every bird uses a repertoire of calls for communication. Calls are shorter and simpler than songs, with a much larger range of functions. Whereas songs are specialized for application in reproduction and territoriality, calls also serve such functions as signaling about food, maintaining social cohesion, contact calls, synchronizing and coordinating flight, and the resolution of aggressive and sexual conflicts. Alarm calls of various kinds are a major component, including distress, mobbing, and hawk alarm calls. Call repertoires vary greatly in size, up to 20 or so distinct call types. Rough estimates for songbirds range between 5 and 10, but some birds, especially galliforms, may have twice as many. Call usage is often sexually dimorphic and commonly varies seasonally and with physiological state. Most calls appear to be innate, but more and more examples of developmental plasticity in bird calls are emerging. Some display well‐defined local dialects. A case is made for the value to avian behavioral neurobiology of including bird calls in studies of the psychophysics and sensory physiology of signal perception. They may also help to extend the range of neurobiological investigations of the song system to include circuitry controlling such functionally related behaviors as aggression and reproduction.
Using Learned Calls to Study Sensory‐Motor Integration in Songbirds
Authors: VICARIO DAVID S.
Published: August 2004

Abstract: Communicating songbirds produce calls as well as song and some of these are learned. One of these—the long call in zebra finches—is used by both sexes in similar behavioral contexts, but is learned in males and not in females. The male long call includes learned spectral and temporal features. In several studies, the learned long call has been used as a tool to study sensory‐motor integration and vocal learning in a way that complements the use of song. Lesion studies showed that production of the male‐typical call features requires an intact nucleus RA, the sexually dimorphic source of the telencephalic projection to brainstem vocal effectors. Behavioral studies that quantified zebra finch calling in response to long call playbacks showed that intact adult males have a categorical preference, absent in females, for the long calls of females over those of males. By using synthetic call stimuli, it was found that males use both spectral and temporal information to classify long call stimuli by gender, but that females use only temporal information. In juvenile males, the emergence of categorical preference occurs during the same period when RA matures anatomically (40‐50 days) and the first male‐typical vocalizations are produced. Adult males with RA lesions lost the categorical preference for female long calls, suggesting that RA could also play a role in long call discrimination. Preliminary analysis of recordings from neurons in NCM—a telencephalic auditory area (see Mello and colleagues, this volume)—suggests a pattern of responses to the spectral features of synthetic call stimuli that parallels the behavioral responses they elicit.
Multimodality Treatment of Giant Intracranial Arteriovenous Malformations
Authors: Chang Steven D. , Marcellus Mary L. , Marks Michael P. , Levy Richard P. , Do Huy M. , Steinberg Gary K.
Published: August 2004

OBJECTIVE

Giant arteriovenous malformations (AVMs) (i.e., those greater than 6 cm at maximum diameter) are difficult to treat and often carry higher treatment morbidity and mortality rates than do smaller AVMs. In this study, we reviewed the treatment, angiographic results, and clinical outcomes in 53 patients with giant AVMs who were treated at Stanford between 1987 and 2001.

METHODS

The patients selected included 20 males (38%) and 33 females (62%). Their presenting symptoms were hemorrhage (n = 20; 38%), seizures (n = 18; 34%), headaches (n = 8; 15%), and progressive neurological deficits (n = 7; 13%). One patient was in Spetzler-Martin Grade III, 9 were in Spetzler-Martin Grade IV, and 43 were in Spetzler-Martin Grade V. The mean AVM size was 6.8 cm (range, 6–15 cm). AVM venous drainage was superficial (n = 7), deep (n = 20), or both (n = 26). At presentation, 31 patients (58%) were graded in excellent neurological condition, 17 were graded good (32%), and 5 were graded poor (9%).

RESULTS

The patients were treated with surgery (n = 27; 51%), embolization (n = 52; 98%), and/or radiosurgery (n = 47; 89%). Most patients received multimodality treatment with embolization followed by surgery (n = 5), embolization followed by radiosurgery (n = 23), or embolization, radiosurgery, and surgery (n = 23). Nineteen patients (36%) were completely cured of their giant AVMs, 90% obliteration was achieved in 4 patients (8%), less than 90% obliteration was achieved in 29 patients (55%) who had residual AVMs even after multimodality therapy, and 1 patient was lost to follow-up. Of the 33 patients who either completed treatment or were alive more than 3 years after undergoing their most recent radiosurgery, 19 patients (58%) were cured of their AVMs. The long-term treatment-related morbidity rate was 15%. The clinical results after mean follow-up of 37 months were 27 excellent (51%), 15 good (28%), 3 poor (6%), and 8 dead (15%).

CONCLUSION

The results in this series of patients with giant AVMs, which represents the largest series reported to date, suggest that selected symptomatic patients with giant AVMs can be treated successfully with good outcomes and acceptable risk. Multimodality treatment is usually necessary to achieve AVM obliteration.
Embolization of Spinal Cord Arteriovenous Shunts: Morphological and Clinical Follow-up and Results—Review of 69 Consecutive Cases
Authors: Rodesch Georges , Hurth Michel , Ducot Beatrice , Alvarez Hortensia , David Philippe , Tadie Marc , Lasjaunias Pierre
Published: August 2004

OBJECTIVE

We sought to analyze the results of embolization in patients with intradural spinal cord arteriovenous shunts.

METHODS

The clinical and radiological files of 69 of a population of 155 patients treated with embolization between 1981 and 1999 were reviewed retrospectively. The patients' clinical status was evaluated according to Karnofsky Performance Scale score. Twenty-one (14%) of 155 patients were treated surgically because they were thought to be poor candidates for embolization. Twenty-four (15%) of 155 patients were considered untreatable with surgery or embolization; in these patients, follow-up was proposed, but only 8 of them were followed appropriately and remained stable after the first consultation. Forty-one (26%) of 155 patients consulted our group, but no follow-up could be obtained. In 69 (45%) of 155 patients, comprising 20 children and 49 adults, endovascular treatment was performed with the patients under general anesthesia and without provocative tests, mainly with acrylic glue, in 99% of these patients.

RESULTS

The mean number of diagnostic and therapeutic sessions was 3.5 per patient, and the mean number of pure therapeutic sessions was 1.5 per patient. Follow-up ranged between 6 months and 18 years (mean, 5.6 yr). In 16% of patients, anatomic obliteration of spinal cord arteriovenous shunts was obtained. Embolization reduced more than 50% of the spinal cord arteriovenous shunts in 86% of cases. No recanalization was noted on follow-up angiograms. Good clinical outcomes were obtained in 83% of the patients: 15% of them were asymptomatic, 43% were improved, and 25% were stable. In 4% of patients, embolization failed to stabilize the disease. Transient deficits were seen after embolization in 14% of the patients, and permanent severe complications occurred in 4% of the patients (Karnofsky Performance Scale score ≤70). Mild worsening was seen in 9% of the patients (Karnofsky Performance Scale score, 80). No bleeding or rebleeding was seen after endovascular treatment was considered to have been completed.

CONCLUSION

This study proves that embolization with acrylic glue is a therapeutic option that compares favorably with surgery or embolization with other agents (particles, coils, or balloons). It offers stable long-term clinical results, despite not necessarily achieving total cure. Studies of larger series with longer follow-up are necessary to confirm these encouraging therapeutic data.
Image-guided Craniotomy for Cerebral Metastases: Techniques and Outcomes
Authors: Tan Tze-Ching , Black Peter McL.
Published: August 2004

OBJECTIVE

The purpose of the present study was to analyze the outcomes after craniotomies for brain metastases in a modern series using image-guided technologies either in the regular operating room or in the intraoperative magnetic resonance imaging unit.

METHODS

Neurosurgical outcomes were analyzed for 49 patients who underwent 55 image-guided craniotomies for excision of brain metastases during a 5-year period. Tumors were located in critical and noncritical function regions of the brain. A total of 23 craniotomies for tumors in critical brain were performed using intravenous sedation anesthesia; craniotomies for noncritical function brain regions were completed under general anesthesia. The patients were also divided into Radiation Therapy Oncology Group recursive partitioning analysis (RPA) classes on the basis of age, Karnofsky Performance Scale scores, state of primary disease, and presence or absence of extracranial metastases.

RESULTS

There was no perioperative mortality. Gross total resection, as verified by postoperative contrast-enhanced computed tomography or magnetic resonance imaging, was achieved in 96% of patients. The median anesthesia time was 4.25 hours, and the median length of hospital stay was 3 days. In 51 symptomatic cases, there was complete resolution of symptoms in 70% (n = 36), improvement in 14% (n = 7), and no change in 12% (n = 6) postoperatively. No patient who was neurologically intact preoperatively deteriorated after surgery, and 93% of patients maintained or improved their functional status. Only two patients (3.6%) with significant preoperative deficits had increased long-term deficits postoperatively. The mean follow-up was 1 year, and the local recurrence rate was 16%. The median survival of the entire group was 16.23 months (17.5 mo in RPA Class I, 22.9 mo in RPA Class II, and 9.8 mo in RPA Class III).

CONCLUSION

Gross total resection of brain metastases, including those involving critical function areas, can be safely achieved with a low morbidity rate using contemporary image-guided systems. RPA Class I and II patients with controlled primary disease benefit from aggressive treatment by surgery and radiation.
Endovascular Treatment for Dural Arteriovenous Fistulae of the Superior Petrosal Sinus
Authors: Ng Perry P. , Halbach Van V. , Quinn Roswell , Balousek Peter , Caragine Louis P. , Dowd Christopher F. , Higashida Randall T. , Wilson Charles
Published: August 2004

OBJECTIVE

To determine the usefulness of endovascular embolization for treatment of dural arteriovenous fistulae of the superior petrosal sinus.

METHODS

We performed a retrospective review of 18 patients treated during a 16-year period. Transarterial and/or transvenous embolizations were performed as a preoperative adjunct or definitive therapy. Clinical follow-up status was supplemented by telephone interviews to determine Glasgow Outcome Scale scores.

RESULTS

Fourteen patients (78%) were treated with a combination of endovascular therapy and open surgery, and 4 were treated by embolization alone (22%). Angiographic cure was achieved in all patients (100%). Thirty-day morbidity and mortality were 11 and 0%, respectively. The mean follow-up period was 5.4 years. At the latest follow-up examination, all patients had returned to independent clinical status (Glasgow Outcome Scale scores of 1 or 2).

CONCLUSION

Endovascular treatment of dural arteriovenous fistulae of the superior petrosal sinus can result in cure when access to the site of the fistula can be achieved. Preoperative embolization is a safe and effective adjunct to minimize bleeding during open neurosurgery.
Gamma Knife Irradiation Increases Cerebral Endothelial Expression of Intercellular Adhesion Molecule 1 and E-selectin
Authors: Sharp Christopher D. , Jawahar Ajay , Warren April C. , Elrod John W. , Nanda Anil , Alexander J. Steven
Published: August 2004

OBJECTIVE

Alterations in multiple functions of the microvasculature occur in response to gamma irradiation and are thought to contribute to radiation-induced end organ damage by inducing inflammatory responses, particularly leukocyte infiltration into the affected area. Endothelial cell adhesion molecules (ECAMs) mediate leukocyte adhesion and migration. Here, we validate a method to study the effect of Leksell gamma knife stereotactic radiosurgery on the expression of ECAMs on human cerebral endothelium at 0, 24, 48, and 72 hours after irradiation.

METHODS

A human brain endothelial cell line (IHEC) was cultured on 12-mm coverslips and subjected to 50 Gy of collimated gamma irradiation with the Leksell gamma knife (Elekta Instruments, Inc., Atlanta, GA). Lactate dehydrogenase release was measured at 24, 48, and 72 hours after irradiation and caspase-3 at 24, 48, 72, 96, and 120 hours. ECAM expression was measured at postirradiation intervals of 0, 24, 48, and 72 hours by cell enzyme-linked immunoabsorbent assay. We used a cell irradiator composed of two chambers. The upper chamber holds the coverslips firmly in place while they are immersed in media. The lower chamber is connected to a peristaltic pump, which pumps water into the chamber and maintains the media in the upper chamber at 37°C through convection.

RESULTS

None of the ECAMs tested was significantly elevated compared with the control basally. Twenty-four hours after irradiation, intercellular adhesion molecule 1 was significantly elevated on brain endothelial cells but there was no significant elevation of E-selectin. Vascular cell adhesion molecule 1 was increased slightly but not significantly and decreased at 48 hours. At 72 hours, E-selectin expression was significantly increased; intercellular adhesion molecule 1 and vascular cell adhesion molecule 1 were not altered relative to sham controls.

CONCLUSION

Increased ECAM expression and lactate dehydrogenase release support the idea that the cerebral microvasculature undergoes an inflammatory response after Leksell gamma knife stereotactic radiosurgery.
Role of the Zygomaticofacial Foramen in the Orbitozygomatic Craniotomy: Anatomic Report
Authors: Martins Carolina , Li Xiaoyong , Rhoton Albert L.
Published: August 2004

OBJECTIVE

Elevation of the lateral orbital rim and zygomatic arch during an orbitozygomatic craniotomy requires a bone cut across the zygoma, which commonly extends into the lateral edge of the inferior orbital fissure. The zygomaticofacial foramen has been identified as a superficial landmark for the cut that extends into the inferior orbital fissure. This study examined the usefulness of the zygomaticofacial foramen during orbitozygomatic craniotomy.

METHODS

One-hundred two dry hemicrania were used in this study. The zygomaticofacial foramen was considered to be related to the inferior orbital fissure when it was located on the zygoma in the area between lines extending in the medial-to-lateral direction along the long axis of the fissure and crossing the anterior and posterior ends of the lateral edge of the fissure.

RESULTS

The zygomaticofacial foramen varied from being absent to representing as many as four small openings. A single foramen was observed in one-half of the specimens. Of the 115 zygomaticofacial foramina, 93 were related to the inferior orbital fissure. Among the 51 specimens with a single foramen, 49 foramina met the criteria for being related to the inferior orbital fissure; in those cases, there would have been no difference in the amount of bone resected using the inferior orbital fissure or the zygomaticofacial foramen as the landmark for the zygomatic cut.

CONCLUSION

The zygomaticofacial foramen was a reliable landmark for locating the inferior orbital fissure and making the cut across the zygoma in only 50% of the specimens.
Cerebral Vasospasm after Subarachnoid Hemorrhage: Putative Role of Inflammation
Authors: Dumont Aaron S. , Dumont Randall J. , Chow Michael M. , Lin Chi-lung , Calisaneller Tarkan , Ley Klaus F. , Kassell Neal F. , Lee Kevin S.
Published: August 2004

CEREBRAL VASOSPASM IS a common, formidable, and potentially devastating complication in patients who have sustained subarachnoid hemorrhage (SAH). Despite intensive research efforts, cerebral vasospasm remains incompletely understood from both the pathogenic and therapeutic perspectives. At present, no consistently efficacious and ubiquitously applied preventive and therapeutic measures are available in clinical practice. Recently, convincing data have implicated a role of inflammation in the development and maintenance of cerebral vasospasm. A burgeoning (although incomplete) body of evidence suggests that various constituents of the inflammatory response, including adhesion molecules, cytokines, leukocytes, immunoglobulins, and complement, may be critical in the pathogenesis of cerebral vasospasm. Recent studies attempting to dissect the cellular and molecular basis of the inflammatory response accompanying SAH and cerebral vasospasm have provided a promising groundwork for future studies. It is plausible that the inflammatory response may indeed represent a critical common pathway in the pathogenesis of cerebral vasospasm pursuant to SAH. Investigations into the nature of the inflammatory response accompanying SAH are needed to elucidate the precise role(s) of inflammatory events in SAH-induced pathologies.
Trigeminal Neuralgia in a Patient with a Dural Arteriovenous Fistula in Meckel's Cave: Case Report
Authors: Du Rose , Binder Devin K. , Halbach Van , Fischbein Nancy , Barbaro Nicholas M.
Published: August 2004

OBJECTIVE AND IMPORTANCE

Trigeminal neuralgia is often the result of vascular compression at the root entry zone of the trigeminal nerve. We report a case of trigeminal neuralgia in a patient with a dural arteriovenous fistula in Meckel's cave. Endovascular closure of the fistula resulted in elimination of the patient's pain at the gasserian ganglion level.

CLINICAL PRESENTATION

A 77-year-old woman was referred for treatment of trigeminal neuralgia after failed conservative treatment, including multiple gasserian ganglion blocks. Magnetic resonance imaging of the brain suggested a vascular lesion, and cerebral angiography demonstrated a dural arteriovenous fistula in Meckel's cave.

INTERVENTION

Endovascular coil embolization was performed, with obliteration of the dural arteriovenous fistula and resolution of facial pain but with decreased sensation in the face.

CONCLUSION

Trigeminal neuralgia may be associated with complex vascular lesions around the base of the brain and along the course of the trigeminal nerve. The evaluation of patients with trigeminal neuralgia should include high-quality, thin-section, magnetic resonance imaging scans, to exclude the possibility of vascular lesions and other structural lesions. In particular, patients who are being evaluated for surgical treatment of trigeminal neuralgia should undergo magnetic resonance imaging, with a focus on the course of the trigeminal nerve.
Postoperative Hyperperfusion in a Patient with a Dural Arteriovenous Fistula with Retrograde Leptomeningeal Venous Drainage: Case Report
Authors: Kai Yutaka , Hamada Jun-ichiro , Morioka Motohiro , Yano Shigetoshi , Mizuno Takamasa , Ushio Yukitaka
Published: August 2004

OBJECTIVE AND IMPORTANCE

Hyperperfusion has been reported after carotid endarterectomy or stenting for stenosis of the internal carotid artery. Because few reports have examined postoperative hyperperfusion after treatment for dural arteriovenous fistulae (DAVFs), we present a case describing a patient who manifested this clinical entity.

CLINICAL PRESENTATION

The patient was a 63-year-old man with a DAVF in the left transverse sigmoid sinus with retrograde leptomeningeal venous drainage. He experienced slowly progressive disorientation lasting for several months. Preoperative single-photon emission computed tomography with 123I-labeled N-isopropyl-p-iodoamphetamine revealed an area of hyperintensity on T2-weighted magnetic resonance imaging (MRI) scans that coincided with the hypoperfusion area; it was not increased after acetazolamide challenge. Complete DAVF obliteration was achieved by embolization, then sinus isolation. After treatment, he experienced frequent generalized convulsions that were terminated by 2-day barbiturate therapy.

INTERVENTION

On T2-weighted MRI scans obtained 3 days after surgery, the hyperintense area not only persisted but had expanded to the left parietal lobe. Moreover, a subcortical hyperintense lesion was recognized on T1-weighted MRI scans; this was considered to reflect cortical laminar necrosis. Single-photon emission computed tomography revealed hyperperfusion in the left parietal lobe; it changed to hypoperfusion a month after treatment.

CONCLUSION

In patients with DAVFs with preoperative findings of marked low perfusion and a poor perfusion reserve, postoperative study may reveal hyperperfusion on single-photon emission computed tomography or cortical laminar necrosis on MRI. This may be evidence of severe perfusion disturbance as a result of venous infarction. In these patients, careful blood pressure control and early treatment of seizures are important after DAVF treatment.
Proton Magnetic Resonance Spectroscopic Imaging Can Predict Length of Survival in Patients with Supratentorial Gliomas
Authors: Kuznetsov Yevgeniy E. , Caramanos Zografos , Antel Samson B. , Preul Mark C. , Leblanc Richard , Villemure Jean-Guy , Pokrupa Ronald , Olivier Andre , Sadikot Abbas , Arnold Douglas L.
Published: August 2004

OBJECTIVE

We compared the ability of proton magnetic resonance spectroscopic imaging (1H-MRSI) measures with that of standard clinicopathological measures to predict length of survival in patients with supratentorial gliomas.

METHODS

We developed two sets of leave-one-out logistic regression models based on either 1) intratumoral 1H-MRSI features, including maximum values of a) choline and b) lactate-lipid, c) number of 1H-MRSI voxels with low N-acetyl group values, and d) number of 1H-MRSI voxels with high lactate-lipid values, all (a–d) of which were normalized to creatine in normal-appearing brain, or 2) standard clinicopathological features, including a) tumor histopathological grade, b) patient age, c) performance of surgical debulking, and d) tumor diagnosis (i.e., oligodendroglioma, astrocytoma). We assessed the accuracy of these two models in predicting patient survival for 6, 12, 24, and 48 months by performing receiver operating characteristic curve analysis. Cox proportional hazards analysis was performed to assess the extent to which patient survival could be explained by the above predictors. We then performed a series of leave-one-out linear multiple regression analyses to determine how well patient survival could be predicted in a continuous fashion.

RESULTS

The results of using the models based on 1H-MRSI and clinicopathological features were equally good, accounting for 81 and 64% of the variability (r2) in patients' actual survival durations. All features except number of 1H-MRSI voxels with lactate-lipid/creatine values of at least 1 were significant predictors of survival in the 1H-MRSI model. Two features (tumor grade and debulking) were found to be significant predictors in the clinicopathological model. Survival as a continuous variable was predicted accurately on the basis of the 1H-MRSI data (r = 0.77, P < 0.001; median prediction error, 1.7 mo).

CONCLUSION

Our results suggest that appropriate analysis of 1H-MRSI data can predict survival in patients with supratentorial gliomas at least as accurately as data derived from more invasive clinicopathological features.
Recurrence of Olfactory Groove Meningiomas
Authors: Obeid Fayez , Al-Mefty Ossama
Published: August 2004

OBJECTIVE

Despite apparent gross total resection, olfactory groove meningiomas have a high rate of late recurrence (average, 23%). In this retrospective study, we confirmed that the sites of these recurrences are the cranial base and paranasal sinuses. We postulated that these recurrences stem from conservative handling of the underlying invaded bone. Therefore, we analyzed patient outcomes according to the radicality of surgical resection.

METHODS

Fifteen consecutive patients with a diagnosis of olfactory groove meningioma were treated surgically between 1992 and 2001 (nine new cases, six recurrent). Only patients with benign meningiomas were included; atypical and malignant meningiomas were excluded. Surgical resection included the dura and drilling of the underlying bone and resection of involved mucosa. We reviewed each patient's clinical records, radiological studies, sites of recurrence, grade of previous resection, and complications.

RESULTS

Olfactory groove meningiomas invaded the underlying bone in 13 cases. All patients with recurrence had previously undergone a surgical resection corresponding only to Simpson Grade 2, which does not include the removal of underlying invaded bone. The sites of recurrence were in the cranial base or adjacent paranasal sinuses. The time to recurrence varied from 1 to 12 years (average, 7 yr; mean, 8 yr). Three patients had undergone one previous resection, two had undergone two previous resections, and one had undergone four previous operations. The ethmoid sinus was involved in all cases of recurrence, either with the sphenoid sinus or with an intracranial recurrence. Thirteen patients underwent complete resection of underlying bone and the invaded paranasal sinuses, then reconstruction of the anterior fossa. No patient died. There were three instances of cerebrospinal fluid leakage (one requiring operative repair), one case of delayed worsening vision after initial improvement, and two cases of transient cranial nerve palsy (Cranial Nerves III and IV). There was no recurrence at follow-up (average, 3.7 yr; range, 1–7.3 yr).

CONCLUSION

The cranial base and paranasal sinuses are sites of predilection for recurrence of olfactory groove meningiomas. Recurrence is the result of a direct extension attributable to incomplete resection of involved bone and regrowth at the edge of a previous surgical field. Extensive resection of all suspicious underlying bone is a complement to radical removal of these lesions. Reconstruction with a vascularized pericranial flap to prevent cerebrospinal fluid leakage is crucial.
Characteristics of Distal Posteroinferior Cerebellar Artery Aneurysms
Authors: Horiuchi Tetsuyoshi , Tanaka Yuichiro , Hongo Kazuhiro , Nitta Junpei , Kusano Yoshikazu , Kobayashi Shigeaki
Published: August 2004

OBJECTIVE

Distal posteroinferior cerebellar artery (PICA) aneurysms are rare and have not been well investigated previously. We report our series of 24 patients with 27 distal PICA aneurysms.

METHODS

All patients with distal PICA aneurysms that were surgically treated at Shinshu University Hospital and its affiliated hospitals between 1983 and 2001 were reviewed retrospectively. Data relating to clinical, radiological, and intraoperative findings were analyzed.

RESULTS

In our series, distal PICA aneurysms reached an incidence of 0.28 and 0.38% of all intracranial aneurysms and ruptured aneurysms, respectively. There were 23 ruptured and 4 unruptured distal PICA aneurysms. Of these, 74.1% were saccular, 7.4% fusiform, and 18.5% dissecting aneurysms. Primarily the telovelotonsillar segment of the PICA was affected. Usually, the surgical outcome was favorable and was influenced by the obstructive hydrocephalus and the preoperative grade. It was sometimes difficult to detect the ruptured distal PICA aneurysm on the initial angiogram, and an extracranial origin of the PICA was sometimes observed.

CONCLUSION

This review summarizes the presentation and outcome of a large series of 24 patients with 27 distal PICA aneurysms, and we conclude that distal PICA aneurysms are benign entities compared with vertebral artery-PICA aneurysms. Characteristics that should be considered in the treatment of distal PICA aneurysms are discussed.
Epithelioid Ependymoma: A New Variant of Ependymoma: Report of Three Cases
Authors: Kleinman George M. , Zagzag David , Miller Douglas C.
Published: August 2004

OBJECTIVE

To describe the pathological features of three very similar and unusual primary central nervous system tumors that are not readily recognized as conventional ependymomas but which, by ultrastructural examination, have an ependymomatous character.

METHODS

Three distinctive tumors were found in a review of our files for cases of ependymoma. In each case, hematoxylin and eosin-stained sections were reviewed, and immunostains for epithelial membrane antigen, cytokeratin, vimentin, and glial fibrillary acidic protein were performed on formalin-fixed, paraffin-embedded sections. Electron microscopy was performed in each case.

RESULTS

The tumors had a diffuse myxoid background, often containing tightly clustered cells that mimicked multinucleated giant cells, but lacking perivascular pseudorosettes or central lumen rosettes. Glial fibrillary acidic protein and vimentin immunostains did not reveal perivascular processes. Epithelial membrane antigen immunostains showed a dot-like cytoplasmic immunoreactivity in some cell clusters in two of the three cases. Cytokeratin was negative in all three cases. However, ultrastructurally, the cells of each tumor had extensive surface microvilli; the giant cell-like clusters had cells with extensive close appositions, some junctions, and, in two cases, lumina with microvilli. Two of the patients were adults (both with temporal lobe tumors), and one patient was 13 years old and had a cervical spinal cord intramedullary tumor. Each tumor was sharply circumscribed from adjacent central nervous system tissue but was not encapsulated. One of the cases in an adult was mitotically highly active; this tumor recurred locally 4 years after initial gross total excision.

CONCLUSION

These tumors are unusual variants of ependymoma. This pattern of ependymoma is sufficiently distinctive to be recognized in hematoxylin and eosin stains once the architecture of the epithelioid clusters is appreciated.
The Predictive Value of Sympathetic Block for the Success of Spinal Cord Stimulation
Authors: Hord E. Daniela , Cohen Steven P. , Cosgrove G. Rees , Ahmed Shihab U. , Vallejo Ricardo , Chang Yuchiao , Stojanovic Milan P.
Published: August 2004

OBJECTIVE

The purpose of this study was to assess the predictive value of response to sympathetic blockade (SB) on the success rate of spinal cord stimulation (SCS) in patients with complex regional pain syndrome.

METHODS

We performed a retrospective study on 23 patients with complex regional pain syndrome who underwent both SB and subsequent SCS trials in the past 3 years at the Massachusetts General Hospital Pain Center, Boston, MA, and Walter Reed Army Medical Center, Washington, DC. Fifteen of these patients underwent permanent placement of an SCS device, and pain relief at 1- and 9-month follow-up was recorded.

RESULTS

Among the 23 patients included in the study, those having transient pain relief with SB were more likely to have a positive SCS trial: all 13 with positive SB had good pain relief during the trial, compared with only 3 of the 10 with negative SB (100% versus 30%, P < 0.001). Among the 10 patients with negative SB, 7 noted poor pain relief during the trial despite adequate coverage, and they did not undergo placement of a permanent device. Among the patients who underwent permanent placement of an SCS device, those who received good pain relief with SB were more likely to have greater than 50% pain relief at 1-month follow-up (100% versus 33%, P = 0.029) and 9-month follow-up (87.5% versus 33.3%, P = 0.15).

CONCLUSION

We conclude that patients with good response to SB before SCS are more likely to have a positive response during their SCS trial and long-term pain relief after placement of permanent SCS device.
Recurrence of a Vertebral Artery Dissecting Pseudoaneurysm after Successful Stent-supported Coil Embolization: Case Report
Authors: MacKay Christopher I. , Han Patrick P. , Albuquerque Felipe C. , McDougall Cameron G.
Published: August 2004

OBJECTIVE AND IMPORTANCE

Dissecting aneurysms of the intracranial vertebral artery are increasingly recognized as a cause of subarachnoid hemorrhage. We present a case involving technical success of the stent-supported coil embolization but with recurrence of the dissecting pseudoaneurysm of the intracranial vertebral artery. The implications for the endovascular management of ruptured dissecting pseudoaneurysms of the intracranial vertebral artery are discussed.

CLINICAL PRESENTATION

A 36-year-old man with a remote history of head injury had recovered functionally to the point of independent living. He experienced the spontaneous onset of severe head and neck pain, which progressed rapidly to obtundation. A computed tomographic scan of the head revealed subarachnoid hemorrhage centered in the posterior fossa. The patient underwent cerebral angiography, which revealed dilation of the distal left vertebral artery consistent with a dissecting pseudoaneurysm.

INTERVENTION

Transfemoral access was achieved under general anesthesia, and two overlapping stents (3 mm in diameter and 14 mm long) were placed to cover the entire dissected segment. Follow-up angiography of the left vertebral artery showed the placement of the stents across the neck of the aneurysm; coil placement was satisfactory, with no residual aneurysm filling. Approximately 6 weeks after the patient's initial presentation, he developed the sudden onset of severe neck pain. A computed tomographic scan showed no subarachnoid hemorrhage, but computed tomographic angiography revealed that the previously treated left vertebral artery aneurysm had recurred. Angiography confirmed a recurrent pseudoaneurysm around the previously placed Guglielmi detachable coils. A test balloon occlusion was performed for 30 minutes. The patient's neurological examination was stable throughout the test occlusion period. Guglielmi detachable coil embolization of the left vertebral artery was then performed, sacrificing the artery at the level of the dissection. After the procedure was completed, no new neurological deficits occurred. On the second day after the procedure, the patient was discharged from the hospital. He was alert, oriented, and able to walk.

CONCLUSION

We appreciate the value of preserving a parent vessel when a dissecting pseudoaneurysm of the intracranial vertebral artery ruptures in patients with inadequate collateral blood flow, in patients with disease involving the contralateral vertebral artery, or in patients with both. However, our case represents a cautionary note that patients treated in this fashion require close clinical follow-up. We suggest that parent vessel occlusion be considered the first option for treatment in patients who will tolerate sacrifice of the parent vessel along its diseased segment. In the future, covered stent technology may resolve this dilemma for many of these patients.
Presacral Arteriovenous Fistula: Case Report
Authors: Kähärä Veikko , Lehto Ulla , Sajanti Juha
Published: August 2004

OBJECTIVE AND IMPORTANCE

We describe a case of arteriovenous fistula in front of the sacrum. Drainage induced epidural venous dilation in the sacral spinal canal. The fistula was embolized endoarterially with n-butyl-2-cyanoacrylate via its iliac arterial feeders. In follow-up digital subtraction angiography 1 month later, the fistula was found to be totally closed. The patient was followed up clinically for 2.5 years. She has remained symptom-free.

CLINICAL PRESENTATION

A previously healthy 43-year-old woman presented with severe gluteal and perineal pain and a local sensation of hyperesthesia. The primary computed tomographic scan of the lumbosacral spine was normal, and emergency laparoscopy showed no signs of any pathological lesions. Magnetic resonance imaging discovered an unidentified mass in the sacral spinal canal, and the patient was hospitalized for neurosurgery. However, surgery on this mass had to be discontinued because of profuse bleeding, and the patient was referred for angiography.

INTERVENTION

Diagnostic catheter angiography revealed a high-flow arteriovenous fistula anterior to the sacrum, and the mass detected earlier by magnetic resonance imaging seemed to be a dilated epidural vein draining the fistula. The feeders of the fistula originated in both internal iliac arteries, and the fistula was occluded via these arteries in two angiographic sessions.

CONCLUSION

A paraspinal arteriovenous fistula may have venous drainage through the epidural venous plexus, and the ectatic veins may induce radicular symptomology. To the best of our knowledge, a paraspinal fistula at such a presacral location has not been documented previously. An unidentified mass in the sacral spinal canal should be suspected of being a dilated vascular structure. Prompt angiographic examinations with an option for embolization should be performed, and open surgical intervention should be avoided.