bluuebunny/crossref_metadata_2025 huggingface dataset:
Deep brain stimulation for the treatment of parkinsonian, essential, and poststroke tremor: a suitable stimulation method and changes in effective stimulation intensity
Authors: Yamamoto Takamitsu , Katayama Yoichi , Kano Toshikazu , Kobayashi Kazutaka , Oshima Hideki , Fukaya Chikashi
Published: May 2009

Object. The tremor-suppression effect resulting from long-term stimulation of the thalamic nucleus ventralis intermedius (Vim) and the nucleus ventralis oralis posterior (Vop) was examined in the treatment of parkinsonian, essential, and poststroke tremor.

Methods. After identifying the accurate anterior border of the nucleus ventrocaudalis (Vc), deep brain stimulation (DBS) electrodes with four contacts were inserted into the Vim—Vop region at an angle of between 40 and 50° from the horizontal plane of the anterior commissure—posterior commissure line. Two distal contacts were placed on the Vim side and two proximal contacts on the Vop side. The best sites of stimulation and parameters of bipolar stimulation were selected in each case and follow-up examinations were conducted for at least 2 years.

In all 15 cases of parkinsonian tremor (18 sides) and in 14 of 15 cases of essential tremor (24 of 25 sides), cathodal stimulation of the Vim side with anodal stimulation of the Vop side was determined to be the best choice to suppress the tremor. In poststroke tremor, however, six of 12 cases (six of 12 sides) were selected for cathodal stimulation of the Vop side with anodal stimulation of the Vim side. The average stimulation intensity 1 month after initiation of DBS was 1.61 V in cases of parkinsonian tremor, 1.99 V in cases of essential tremor, and 2.39 V in cases of poststroke tremor. A comparison of stimulation intensities required at 1 and 24 months after initiation of DBS revealed that the lowest effective stimulation intensity increased 24.2% in cases of parkinsonian tremor, 21% in cases of poststroke tremor, and 46.9% in cases of essential tremor. Suppression of tremor was achieved in all cases (42 cases, 55 sides) during a period of 2 years. Nevertheless, two cases of poststroke tremor required dual-lead stimulation at the unilateral Vim—Vop region from the start of DBS, and two cases of essential tremor and one case of poststroke tremor required a stimulation intensity that was high enough to evoke unpleasant paresthesia and slight motor contraction during the follow-up period.

Conclusions. Effective stimulation sites and stimulation intensities differ in different kinds of tremor; Vim and Vop stimulation is necessary in many cases. Interactions of the Vim and Vop under the control of interconnected areas of the motor circuitry may play an important role in both the development and DBS-induced suppression of tremor.
Malignant progression in meningioma: documentation of a series and analysis of cytogenetic findings
Authors: Al-Mefty Ossama , Kadri Paulo A. S. , Pravdenkova Svetlana , Sawyer Jeffrey R. , Stangeby Colin , Husain Muhammad
Published: May 2009

Object.The malignant progression of benign tumors is well documented in gliomas and other systemic lesions. It is also well known that some meningiomas become progressively aggressive despite their original benign status. The theory of clonal evolution is widely believed to explain malignant progression in meningioma; however, the data used to explain stepwise progression have typically been derived from the cytogenetic analysis of different types of tumors of different grades and in different patients. In this study, the authors examined the data obtained in a group of patients with meningiomas that showed clear histopathological progression toward a higher grade of malignancy and then analyzed the underlying cytogenetic findings.

Methods.Among 175 patients with recurrent meningiomas, 11 tumors showed a histopathological progression toward a higher grade that was associated with an aggressive clinical course. Six tumors progressed to malignancy and five to the atypical category over a period averaging 112 months. Tests for MIB-1 and p53 and cytogenetic studies with the fluorescence in situ hybridization (FISH) method were performed in successive specimens obtained in four patients.

The MIB-1 value increased in subsequent samples of tumors. Cytogenetic analysis with FISH showed deletions of 22, 1p, and 14q. In all but one case, these aberrations were also present in the previous specimen despite its lower hispathological grade.

Conclusions.The authors documented the progression of meningiomas from benign to a higher histological grade. These tumors were associated with a complex karyotype that was present ab initio in a histologically lower-grade tumor, contradicting the stepwise clonal evolution model. Although it was limited to the tested probes, the FISH method appears to be more accurate than the standard cytogenetic one in detecting these alterations. Tumors that present with complex genetic alterations, even those with a benign histological grade, are potentially aggressive and require closer follow up.
Endoscope-assisted microsurgical resection of epidermoid tumors of the cerebellopontine angle
Authors: Schroeder Henry W. S. , Oertel Joachim , Gaab Michael R.
Published: May 2009

Object. Epidermoid tumors located in the cerebellopontine angle (CPA) are challenging lesions because they grow along the subarachnoid spaces around delicate neurovascular structures and often extend into the middle cranial fossa. The purpose of this study was to determine the value of endoscopic assistance in the microsurgical resection of these lesions, in which total removal is the therapy of choice.

Methods. Eight patients harboring an epidermoid tumor of the CPA were treated using an endoscope-assisted microsurgical technique. A retrosigmoid suboccipital approach was used in five patients and a pterional transsylvian approach was chosen in the other three. In four patients the lesion was resected microsurgically and the endoscope was used repeatedly to verify complete tumor removal, whereas most of the tumor mass was removed with the aid of an operating microscope in the other four. Tumor parts extending into other cranial compartments that were not visible through the microscope were removed under endoscopic view by using rigid rod-lens scopes with 30 and 70° angles of view.

All epidermoids were completely evacuated and the membranes were widely resected. Large tumors occupying both the middle and posterior cranial fossa were removed through a single small opening without enlarging the craniotomy. Permanent hearing loss and permanent hypacusis were observed in one patient each. One patient with facial and one with abducent nerve palsy recovered within 6 and 4 months, respectively. A transient weakness of the chewing muscles was encountered in one patient. Postoperative magnetic resonance imaging revealed no residual tumor in any patient. To date no recurrences have been observed (follow up range 12–98 months).

Conclusions. The endoscope-assisted microsurgical technique enables safe removal even when tumor parts are not visible in a straight line. Tumor extensions into adjacent cranial compartments can be removed with the same approach without retracting neurovascular structures or enlarging the craniotomy.
Primary hypophysitis: a single-center experience in 16 cases
Authors: Leung Gilberto K. K. , Lopes Maria-Beatriz S. , Thorner Michael O. , Vance Mary Lee , Laws Edward R.
Published: May 2009

Object.The authors review their experience in the treatment of 16 patients with primary hypophysitis.

Methods.A retrospective study was undertaken to review cases of primary hypophysitis. The mean age of the patients was 47 years and there was an equal distribution of sexes. Recent pregnancy and underlying autoimmunity were noted in 50% of the patients. Two patients had undergone previous transsphenoidal operations at other centers, one for prolactinoma and another for hypophysitis. Headache, anterior pituitary deficiency, and suprasellar mass lesions were the most common presenting features. The initial presumptive diagnosis was pituitary adenoma in six patients (37.5%) and inflammatory hypophysitis in 10 (62.5%). Five patients received initial medical therapy for hypophysitis; although three (60%) responded satisfactorily, two (40%) did not and later underwent surgery.

Altogether 13 patients (81.2%) underwent transsphenoidal surgery. The histological diagnoses were lymphocytic hypophysitis in 10 (76.9%) and granulomatous hypophysitis in three (23.1%) of the surgically treated patients. A coexistent Rathke cleft cyst was noted in one patient. There was no death in this series. One patient experienced postoperative cerebrospinal fluid leakage and meningitis. One patient had bilateral internal carotid artery occlusion secondary to inflammatory involvement of the cavernous sinuses and arteritis. This patient recovered and is capable of independent functional activities.

Conclusions.All surgical patients experienced improvement in their headache and/or visual field defects and none had visual deterioration. None of the patients experienced any improvement in endocrine function and all required long-term hormone replacement. Transsphenoidal surgery was a safe and effective treatment especially for visual and pressure symptoms. A postoperative recurrence developed in two patients (15.4%) and the treatment modalities included steroid therapy, repeated surgery, and radiosurgery.
Quantification of in vivo Photofrin uptake by human pituitary adenoma tissue
Authors: Igbaseimokumo Usiakimi
Published: May 2009

Object. Photofrin is widely distributed in the body after intravenous injection. This study was designed to quantify the preferential uptake of Photofrin by pituitary adenoma tissue for intraoperative photodynamic therapy.

Methods. Eight patients (seven men) with recurrent pituitary adenomas who had undergone previous surgery and radiation therapy were recruited for a Phase I/II feasibility study of the application of photodynamic therapy to pituitary tumors. Photofrin was administered intravenously at a dose of 2 mg/kg body weight 48 hours before repeated transsphenoidal hypophysectomy was performed. At the time of the operation, pituitary adenoma tissue, muscle, fat, skin, and plasma were obtained for measurement of Photofrin content by fluorometric assay.

The mean Photofrin level in pituitary adenoma tissue was 6.87 ng/mg (95% confidence interval [CI] 3.99–9.75), which was significantly higher than the uptake by skeletal muscle (2.24 ng/mg, 95% CI 1.28–3.2; p = 0.008), or fat (2.54 ng/mg, 95% CI 0.66–4.42; p = 0.007). Nevertheless, the mean drug concentration in pituitary adenoma tissue was not significantly different from the level in plasma (7.65 µg/ml, 95% CI 5.38–9.90; p = 0.558). Skin specimens were available in four patients, and these showed a mean uptake of 2.19 ng/mg.

Conclusions. Photofrin is preferentially retained by pituitary adenoma tissue to levels both adequate for intraoperative photodynamic therapy and approximately 50% higher than those reported for gliomas.
Seprafilm superior to Gore-Tex in the prevention of peridural fibrosis
Authors: Topsakal Cahide , Akpolat Nusret , Erol Fatih Serhat , Ozveren Mehmet Faik , Akdemir Ismail , Kaplan Metin , Tiftikci Murat , Kilic Nermin
Published: May 2009

Object.This is an investigation into the effects of two barrier membranes in the prevention of peridural fibrosis in an animal model.

Methods.Seprafilm or Gore-Tex was applied to a laminectomy defect overlying the dura mater in rats separated into treatment groups. A third group of rats underwent laminectomy only and served as controls. Two months postoperatively a histological study was performed to compare the amount of scar tissue in each group.

The gross dissection demonstrated that both membranes created a controlled dissection plane, facilitated access to the epidural space, and provided a reduction in the amount of tissue adhering to the dura mater. Statistically, Seprafilm was superior to Gore-Tex in preventing peridural fibrosis (p < 0.05).

Conclusions.Seprafilm can prevent peridural fibrosis better than Gore-Tex and can be used in humans in spinal surgery.
Blood—brain barrier opened by stimulation of the parasympathetic sphenopalatine ganglion: a new method for macromolecule delivery to the brain
Authors: Yarnitsky David , Gross Yossi , Lorian Adi , Shalev Alon , Lamensdorf Itschak , Bornstein Rinat , Shorer Shy , Mayevsky Avraham , Patel Kaushik P. , Abbott N. Joan , Mayhan William G.
Published: May 2009

Object. Drug delivery across the blood—brain barrier remains a significant challenge. Based on earlier findings, the authors hypothesized that parasympathetic innervation of the brain vasculature could be used to augment drug delivery to the brain.

Methods. Using a craniotomy—cerebrospinal fluid superfusate paradigm in rats with an intravenous injection of tracer the authors demonstrated that stimulation of the postganglionic parasympathetic fibers of the sphenopalatine ganglion (SPG) increased the concentration of fluorescein isothiocyanate—dextran (4–250 kD) in the superfusate by two- to sixfold. A histological examination indicated the presence of dextran in the parenchyma. In another experiment the amount of Evans blue dye in the brain following SPG activation was similarly significantly elevated. The chemotherapeutic agents anti-HER2 monoclonal antibody and etoposide were also delivered to the brain and reached therapeutic concentrations. Brain homeostasis was not disturbed by this procedure; a measurement of nicotinamide adenine dinucleotide reduction did not show a decrease in the tissue metabolic state and brain water content did not increase significantly.

Conclusions. Sphenopalatine ganglion activation demonstrates a promising potential for clinical use in the delivery of small and large molecules to the brain.
Influence of oxygen therapy on glucose—lactate metabolism after diffuse brain injury
Authors: Reinert Michael , Schaller Benoit , Widmer Hans Rudolf , Seiler Rolf , Bullock Ross
Published: May 2009

Object. Severe traumatic brain injury (TBI) imposes a huge metabolic load on brain tissue, which can be summarized initially as a state of hypermetabolism and hyperglycolysis. In experiments O2 consumption has been shown to increase early after trauma, especially in the presence of high lactate levels and forced O2 availability. In recent clinical studies the effect of increasing O2 availability on brain metabolism has been analyzed. By their nature, however, clinical trauma models suffer from a heterogeneous injury distribution. The aim of this study was to analyze, in a standardized diffuse brain injury model, the effect of increasing the fraction of inspired O2 on brain glucose and lactate levels, and to compare this effect with the metabolism of the noninjured sham-operated brain.

Methods. A diffuse severe TBI model developed by Foda and Maramarou, et al., in which a 420-g weight is dropped from a height of 2 m was used in this study. Forty-one male Wistar rats each weighing approximately 300 g were included. Anesthesized rats were monitored by placing a femoral arterial line for blood pressure and blood was drawn for a blood gas analysis. Two time periods were defined: Period A was defined as preinjury and Period B as postinjury. During Period B two levels of fraction of inspired oxygen (FiO2) were studied: air (FiO2 0.21) and oxygen (FiO2 1). Four groups were studied including sham-operated animals: air-air-sham (AAS); air-O2-sham (AOS); air-air-trauma (AAT); and air-O2-trauma (AOT). In six rats the effect of increasing the FiO2 on serum glucose and lactate was analyzed.

During Period B lactate values in the brain determined using microdialysis were significantly lower (p < 0.05) in the AOT group than in the AAT group and glucose values in the brain determined using microdialysis were significantly higher (p < 0.04). No differences were demonstrated in the other groups. Increasing the FiO2 had no significant effect on the serum levels of glucose and lactate.

Conclusions. Increasing the FiO2 influences dialysate glucose and lactate levels in injured brain tissue. Using an FiO2 of 1 influences brain metabolism in such a way that lactate is significantly reduced and glucose significantly increased. No changes in dialysate glucose and lactate values were found in the noninjured brain.
Functional role of the Na+/H+ exchanger in the regulation of cerebral arteriolar tone in rats
Authors: Saesue Prajak , Horiuchi Tetsuyoshi , Goto Tetsuya , Tanaka Yuichiro , Hongo Kazuhiro
Published: May 2009

Object. In vascular smooth-muscle cells, the Na+/H+ exchanger (NHE) is involved in the regulation of [Na+]i, pHi through [H+], and cell volume. Recently, investigations have determined that this exchanger contributes to ischemia and reperfusion injury in coronary circulation. Nonetheless, there is limited information on this glycoprotein in cerebral circulation, especially microcirculation. Thus, the authors in the present study examined the role of NHE in the regulation of cerebral arteriolar tone and its related mechanisms in vitro.

Methods. The internal diameter of isolated pressurized intracerebral arterioles in rats was monitored with the aid of a microscope. To examine the basal activity of NHE two kinds of Na+/H+ exchange inhibitors (FR183998 and 5-[N,N-hexamethylene] amiloride) were administered in the arterioles. Furthermore the authors studied the effects of nitric oxide (NO) synthase inhibitor (NG methyl-l-arginine), Na+/K+—adenosine triphosphatase (NKA) inhibitor (ouabain), and the Na+/Ca++ exchange inhibitor (SEA0400) on the vascular response induced by either of the Na+/H+ exchange inhibitors.

Both of the Na+/H+ exchange inhibitors constricted the arteriole. Subsequent application of NO synthase inhibitor further decreased the diameter of the arterioles. The Na+/H+ exchange inhibitor—induced constriction was completely abolished in the presence of ouabain and SEA0400.

Conclusions. The NHE is active in the basal condition and regulates cerebral arteriolar tone through NKA and the Na+/Ca++ exchanger. Endogenous NO is not related to the activity of NHE in basal conditions.
Intracerebral pneumatocele presenting after air travel
Authors: Mahabir Raman C. , Szymczak Artur , Sutherland Garnette R.
Published: May 2009

✓ In this report the authors discuss a patient who experienced symptoms of an acute right frontal, intraparenchymal pneumatocele while on an airplane descending to an international airport. This rare complication of an ethmoid sinus osteoma that eroded upward through the dura mater is described along with a literature review. A persistent headache and inappropriate behavior consistent with a frontal lobe syndrome brought the patient to clinical and imaging evaluation, which revealed a large right frontal lobe pneumatocele and an associated ethmoid sinus osteoma extending upward into the frontal lobe. Through a right frontal craniotomy, the air cavity was evacuated, the osteoma partially excised, and the dural defect closed using a vascularized pericranial flap. Postoperatively, the patient made an unremarkable recovery. For patients with air sinus osteomas extending into the cranial cavity, air travel or other barotrauma may result in a life-threatening tension pneumatocele.
Striatal hyperintensity on T1-weighted magnetic resonance images and high-density signal on computerized tomography scans obtained in patients with hyperglycemia and no involuntary movement
Authors: Sorimachi Takatoshi , Fujii Yukihiko , Tsuchiya Naoto , Saito Masatsune
Published: May 2009

✓ The authors report on two patients in whom an increased signal on T1-weighted magnetic resonance images and a high-density signal on computerized tomography scans of the striatum were demonstrated, both of which were associated with nonketotic hyperglycemia. Involuntary movements, which have been present in all previously reported cases, were not observed in either patient at any time during the entire course of illness. One patient displayed hemiparesis, whereas the other had dementia, gait disturbance, and urinary incontinence. Clinical and radiological abnormalities improved on control of blood glucose levels. Invasive studies, including biopsy procedures, should be avoided on encountering this disease given the good prognosis that results from simple medical treatment.
Surgical repair of brachial plexus injury: a multinational survey of experienced peripheral nerve surgeons
Authors: Belzberg Allan J. , Dorsi Michael J. , Storm Phillip B. , Moriarity John L.
Published: May 2009

Object.Brachial plexus injuries (BPIs) are often devastating events that lead to upper-extremity paralysis, rendering the limb a painful extraneous appendage. Fortunately, there are several nerve repair techniques that provide restoration of some function. Although there is general agreement in the medical community concerning which patients may benefit from surgical intervention, the actual repair technique for a given lesion is less clear. The authors sought to identify and better define areas of agreement and disagreement among experienced peripheral nerve surgeons as to the management of BPIs.

Methods.The authors developed a detailed survey in two parts: one part addressing general issues related to BPI and the other presenting four clinical cases. The survey was mailed to 126 experienced peripheral nerve physicians and 49 (39%) participated in the study. The respondents represent 22 different countries and multiple surgical subspecialties. They performed a mean of 33 brachial plexus reconstructions annually. Areas of significant disagreement included the timing and indications for surgical intervention in birth-related palsy, treatment of neuroma-in-continuity, the best transfers to achieve elbow flexion and shoulder abduction, the use of intra- or extraplexal donors for motor neurotization, and the use of distal or proximal coaptation during nerve transfer.

Conclusions.Experienced peripheral nerve surgeons disagree in important ways as to the management of BPI. The decisions made by the various treating physicians underscore the many areas of disagreement regarding the treatment of BPI, including the diagnostic approach to defining the injury, timing of and indications for surgical intervention in birth-related palsy, the treatment of neuroma-in-continuity, the choice of nerve transfers to achieve elbow flexion and shoulder abduction, the use of intra- or extraplexal donors for neurotization, and the use of distal or proximal coaptation during nerve transfer.
Quantitative analysis of radioisotope cisternography in the diagnosis of intracranial hypotension
Authors: Moriyama Eiji , Ogawa Tomoyuki , Nishida Ayumi , Ishikawa Shinichi , Beck Hiroichi
Published: May 2009

Object. The authors attempted a quantitative analysis of conventional radioisotope cisternography for the purpose of more accurate diagnosis of intracranial hypotension.

Methods. Fifty-seven patients suspected of having intracranial hypotension underwent radioisotope cisternography. Whole-body images were obtained 2.5, 6, and 24 hours after intrathecal injection of 111In—diethylenetriamine pentaacetic acid. Radioactivity in the cerebrospinal fluid (CSF) space was counted during scanning, and radioisotope clearance was studied. Direct signs of radioisotope leakage into the spinal epidural space were found in 25 patients. Most leaks were located in the lumbosacral region. Analysis of the radioisotope clearance curve revealed two different patterns. In patients without a radiographically demonstrated radioisotope leak, absolutely exponential curves were observed (R2 > 0.99). The activity of the radioisotope decreased at a rate of e−0.03 to e−0.107 (mean ± standard deviation, e−0.056 ± 0.018; 32 patients). Clearance in patients with an overt radioisotope leak was not a simple exponential curve; it could be divided into an early rapid phase and a late slow phase. The clearance rate during the first 6 hours was e−0.219 ± 0.127 (25 patients) and e−0.076 ± 0.021 thereafter. The authors speculated that the early escape of undiluted radioisotope solution through an aberrant CSF outlet, such as a traumatic spinal dural tear, was responsible for this phenomenon.

Conclusions. The quantitative analysis featured in this study seems to be useful in the diagnosis of intracranial hypotension. A small CSF leak below the limit of radioisotope cisternography resolution might be detected using this technique.
Risk of persistent cranial nerve injury after carotid endarterectomy
Authors: Cunningham Edwin J. , Bond Rick , Mayberg Marc R. , Warlow Charles P. , Rothwell Peter M.
Published: May 2009

Object. Cranial nerve injuries, particularly motor nerve injuries, following carotid endarterectomy (CEA) can be disabling and therefore patients should be given reliable information about the risks of sustaining such injuries. The reported frequency of cranial nerve injury in the published literature ranges from 3 to 23%, and there have been few series in which patients were routinely examined before and after surgery by a neurologist.

Methods. The authors investigated the risk of cranial nerve injuries in patients who underwent CEA in the European Carotid Surgery Trial (ECST), the largest series of patients undergoing CEA in which neurological assessment was performed before and after surgery. Cranial nerve injury was assessed and recorded in every patient and persisting deficits were identified on follow-up examination at 4 months and 1 year after randomization. Risk factors for cranial nerve injury were examined by performing univariate and multivariate analyses. There were 88 motor cranial nerve injuries among the 1739 patients undergoing CEA (5.1% of patients; 95% confidence interval [CI] 4.1–6.2). In 23 patients, the deficit had resolved by hospital discharge, leaving 3.7% of patients (95% CI 2.9–4.7) with a residual cranial nerve injury: 27 hypoglossal, 17 marginal mandibular, 17 recurrent laryngeal, one accessory nerve, and three Horner syndrome. In only nine patients (0.5%; 95% CI 0.24–0.98) the deficit was still present at the 4-month follow-up examination; however, none of the persisting deficits resolved during the subsequent follow up. Only duration of operation longer than 2 hours was independently associated with an increased risk of cranial nerve injury (hazard ratio 1.56, p < 0.0001).

Conclusions. The risk of motor cranial nerve injury persisting beyond hospital discharge after CEA is approximately 4%. The vast majority of neurological deficits resolve over the next few months, however, and permanent deficits are rare. Nevertheless, the risk of cranial nerve injury should be communicated to patients before they undergo surgery.
Variability of intraoperative electrocortical stimulation mapping parameters across and within individuals
Authors: Pouratian Nader , Cannestra Andrew F. , Bookheimer Susan Y. , Martin Neil A. , Toga Arthur W.
Published: May 2009

Object. Electrocortical stimulation mapping is regarded as the gold standard of intraoperative mapping for predicting functional outcomes. Nevertheless, methodologies across institutions are inconsistent. Although many vary and maximize stimulation currents at each cortical site, some use a single current level to map the entire exposed cortex. The former comes at the cost of possibly inducing additional afterdischarge activity. The authors retrospectively reviewed their experience with intraoperative electrocortical stimulation mapping to characterize variability of both mapping and afterdischarge thresholds.

Methods. Seventeen patients satisfied the study inclusion criteria. Significant variability in mapping thresholds was identified within individuals and across the patient population. Moreover, a statistically significant difference in mapping thresholds was demonstrated between the frontal and parietal/temporal lobes (p = 0.007, one-way analysis of variance). The authors report a surprisingly high incidence of afterdischarge during mapping, wide variability in afterdischarge thresholds within individuals and across the study population, and mapping thresholds regularly exceeding afterdischarge thresholds in neighboring cortex. Differences in afterdischarge thresholds across lobes only approached significance (p = 0.086).

Conclusions. To maximize identification of eloquent cortices in some clinical situations, it may be advantageous to maximize currents at each cortical site regardless of adjacent afterdischarge threshold rather than to map the entire exposed cortex at a single current level. Moreover, the current findings highlight the need for electrocorticography during electrocortical stimulation mapping, both to identify when afterdischarges occur and to verify stimulation by recording stimulation artifacts. The advantages and limitations of maximizing currents at each cortical site as well as mapping at a single current level are discussed.
Neurotransmitter release from high-frequency stimulation of the subthalamic nucleus
Authors: Lee Kendall H. , Chang Su-Youne , Roberts David W. , Kim Uhnoh
Published: May 2009

Object. High-frequency stimulation (HFS) delivered through implanted electrodes in the subthalamic nucleus (STN) has become an established treatment for Parkinson disease (PD). The precise mechanism of action of deep brain stimulation (DBS) in the STN is unknown, however. In the present study, the authors tested the hypothesis that HFS within the STN changes neuronal action potential firing rates during the stimulation period by modifying neurotransmitter release.

Methods. Intracellular electrophysiological recordings were obtained using sharp electrodes in rat STN neurons in an in vitro slice preparation. A concentric bipolar stimulating electrode was placed in the STN slice, and electrical stimulation (pulse width 50–100 µsec, duration 100–2000 µsec, amplitude 10–500 µA, and frequency 10–200 Hz) was delivered while simultaneously obtaining intracellular recordings from an STN neuron.

High-frequency stimulation of the STN either generated excitatory postsynaptic potentials (EPSPs) and increased the action potential frequency or it generated inhibitory postsynaptic potentials and decreased the action potential frequency of neurons within the STN. These effects were blocked after antagonists to glutamate and γ-aminobutyric acid were applied to the tissue slice, indicating that HFS resulted in the release of neurotransmitters. Intracellular recordings from substantia nigra pars compacta (SNc) dopaminergic neurons during HFS of the STN revealed increased generation of EPSPs and increased frequency of action potentials in SNc neurons.

Conclusions. During HFS of STN neurons the mechanism of DBS may involve the release of neurotransmitters rather than the primary electrogenic inhibition of neurons.
Diagnosis of Erdheim—Chester disease by using computerized tomography—guided stereotactic biopsy of a caudate lesion
Authors: Tashjian Vartan , Doppenberg Egon M. R. , Lyders Eric , Broaddus William C. , Pavot Pierre , Tye Gary , Liu Amon Y. , Perez Juan , Ghatak Nitya
Published: May 2009

✓ The authors present the case of a 27-year-old woman with Erdheim-Chester disease (ECD) and extensive intracranial involvement, in whom the initial diagnosis of ECD was established based on computerized tomography (CT)—guided stereotactic biopsy of a caudate lesion. Erdheim—Chester disease is a rare non-Langerhans cell histiocytosis of unknown origin that is clinically characterized by bone pain, diabetes insipidus, and exophthalmos. The radiological hallmarks of the disease include symmetrical sclerosis of the long bones with epiphysial sparing and increased tracer uptake in lesions seen on scintigraphic imaging. Erdheim—Chester disease is characterized histologically by the presence of infiltrating lipid-laden histiocytes that commonly involve the retroperitoneum, orbits, skin, pericardium, lungs, and long bones. Although the occurrence of diabetes insipidus often precedes the diagnosis of ECD by more than a decade in most patients, magnetic resonance imaging— and CT-documented central nervous system involvement is exceedingly rare. In the setting of neurological involvement, neurosurgical biopsy has been reported seven times in the literature, with only one of these biopsies being the basis for the initial diagnosis of the disease. The authors' case represents only the second time the disease has been diagnosed by means of neurosurgical biopsy, highlighting the diagnostic difficulties that patients with EDC present. Skeletal radiographs were confirmatory in this case and this modality should be emphasized as the simplest and most direct route to the diagnosis. The degree of neurological involvement further distinguishes the case presented from prior reports in the literature. The multiple bilateral intraaxial lesions were intensely enhancing on contrast CT scans, distributed infra- and supratentorially, involving both white and gray matter, and associated with diffuse cerebral edema. The case presented is also remarkable by virtue of the symmetrical involvement of the caudate nuclei, representing the first such example documented in the literature. The diagnosis, treatment, and outcome in this patient are discussed, and a review of the literature is presented.
Harvey W. Cushing and cerebrovascular surgery: Part I, aneurysms
Authors: Cohen-Gadol Aaron A. , Spencer Dennis D.
Published: May 2009

✓ The development of surgical techniques for the treatment of intracranial aneurysms has paralleled the evolution of the specialty of neurological surgery. During the Cushing era, intracranial aneurysms were considered inoperable and only ligation of the carotid artery was performed. Cushing understood the limitations of this approach and advised the need for a more thorough understanding of aneurysm pathology before further consideration could be given to the surgical treatment of cerebral aneurysms. Despite his focus on brain tumors, Cushing's contributions to the discipline of neurovascular surgery are of great importance. With the assistance of Sir Charles Symonds, Cushing described the syndrome of subarachnoid hemorrhage. He considered inserting muscle strips into cerebral aneurysms to promote aneurysm sac thrombosis and designed the “silver clip,” which was modified by McKenzie and later used by Dandy to clip the first intracranial aneurysm. Cushing was the first surgeon to wrap aneurysms in muscle fragments to prevent recurrent hemorrhage. He established the foundation on which pioneers such as Norman Dott and Walter Dandy launched the modern era of neurovascular surgery.
Harvey W. Cushing and cerebrovascular surgery: Part II, vascular malformations
Authors: Cohen-Gadol Aaron A. , Spencer Dennis D.
Published: May 2009

✓ The surgical treatment of cerebrovascular malformations intrigued early neurosurgeons. Cushing defined vascular malformations as tumors arising from cerebral blood vessels. He successfully resected the first arteriovenous malformation 3 years after it had been irradiated. In the absence of angiography, the pathoanatomy of these lesions remained elusive and early techniques such as cortical vein ligation proved catastrophic. Cushing demonstrated the favorable results of radiation treatments on vascular malformations and advocated decompressive craniectomy followed by radiotherapy. He ligated cortical feeding vessels and external carotid arteries with an improved understanding of the angioarchitecture of vascular malformations. He stressed the importance of preoperative diagnosis because the radical resection of nonirradiated vascular malformations challenged the limitations of the available neurosurgical armamentarium.
Radiosurgery and radiotherapy: observations and clarifications
Authors: Kondziolka Douglas , Lunsford L. Dade , Loeffler Jay S. , Friedman William A.
Published: May 2009

Object. Radiosurgery and radiation therapy represent important but unique treatment paradigms for patients with certain neoplasms, vascular lesions, or functional disorders. The authors discuss their differences.

Methods. Reviewing the authors' experiences shows how the roles of these approaches vary just as their techniques differ. The distinct differences include the method of target localization (intraoperative compared with pretreatment) and irradiation (focused compared with wide-field), their radiobiology (effects of a single high-dose compared with multiple fractions), the physicians and other health personnel involved in the conduct of these procedures (surgical team compared with radiation team), and the expectations that follow treatment. During the last decade, considerable confusion has grown regarding nomenclature, requisite physician training, and the roles of the physician and surgeon. Ten years ago, two task forces on radiosurgery were created by national organizations in neurosurgery and radiation oncology to address these issues of procedural conduct and quality-assurance requirements. At the present time these guidelines are widely ignored. Currently, many patients, payers, and regulatory agencies are bewildered. What are the differences among stereotactic radiosurgery, fractionated radiation therapy, and stereotactic radiation therapy? Radiosurgery is to radiation therapy as microsurgery is to “microtherapy.”

Conclusions. In this report the authors discuss terminology, training, and physician roles in this expanding field.
Postoperative evaluation of microsurgical resection for cavernous malformations of the brainstem
Authors: Kikuta Ken-ichiro , Nozaki Kazuhiko , Takahashi Jun A. , Miyamoto Susumu , Kikuchi Haruhiko , Hashimoto Nobuo
Published: May 2009

Object. The aim of this study was to propose criteria to determine whether complete resection of cavernous malformations in the brainstem had been achieved.

Methods. The authors retrospectively analyzed data in 10 patients harboring a single cavernous malformation who had presented with hemorrhagic symptoms and had been followed up for longer than 2 years postsurgery. The study population consisted of five male and five female patients ranging in age from 13 to 57 years (mean 36.8 years). When preoperative magnetic resonance (MR) images demonstrated the lesion as a homogeneous hyperintense mass, the surgery was defined as complete or incomplete based on intraoperative findings. When preoperative MR images revealed other findings, complete resection was determined according to whether postoperative MR imaging results demonstrated lesions distinct from the peripheral hemosiderin rim. Among the 13 operations in this series, nine resulted in complete resection and were associated with no postoperative clinical relapse of hemorrhage, whereas four operations resulted in incomplete resection and were correlated with postoperative recurrent hemorrhage. The seven patients in whom the outcome of the initial operation was complete demonstrated good neurological recovery in the long-term follow-up period, whereas the three patients in whom the outcome of the initial surgery was judged to be incomplete showed inadequate neurological recovery due to recurrent hemorrhage.

Conclusions. The criteria proposed in this study to evaluate surgical treatment may be a reliable means of predicting the recurrence of hemorrhage postoperatively.
Craniotomy for supratentorial brain tumors: risk factors for brain swelling after opening the dura mater
Authors: Rasmussen Mads , Bundgaard Helle , Cold Georg Emil
Published: May 2009

Object. Cerebral swelling often occurs during craniotomy for cerebral tumors. The primary aim in this study was to determine risk factors (intracranial pressure [ICP], patient characteristics, histopathological features, neuroimaging characteristics, anesthetic regimen, and perioperative physiological data) predictive of brain swelling through the dural opening. As a secondary aim the authors attempted to define subdural ICP thresholds associated with brain swelling.

Methods. The study population consisted of 692 patients (mean age 50 ± 15 years) scheduled for elective craniotomy for supratentorial brain tumors. Brain swelling through the dural opening was estimated according to a four-point scale. The patients were dichotomized as those without cerebral swelling (that is, brain below the dura mater [59 patients] or brain at the level of the dura mater [386 patients]) and those with cerebral swelling (that is, moderate brain swelling [205 patients] or pronounced brain swelling [42 patients]). Logistic regression analysis was used to identify subdural ICP (odds ratio [OR] 1.9, 95% confidence interval [CI] 1.72–2.1, p < 0.0001), midline shift (OR 1.06, 95% CI 1.02–1.11, p = 0.008), a diagnosis of glioblastoma multiforme (OR 2.1, 95% CI 1.01–4.3, p = 0.047), and metastasis (OR 2.9, 95% CI 1.3–6.9, p = 0.01) as independent risk factors of intraoperative brain swelling. Thresholds for ICP associated with brain swelling were defined as follows: at an ICP less than 5 mm Hg, brain swelling rarely occurred (5% probability); at an ICP greater than 13 mm Hg, brain swelling occurred with 95% probability; and at an ICP greater than 26 mm Hg, severe brain swelling occurred with 95% probability.

Conclusions. Subdural ICP is the strongest predictor of intraoperative brain swelling. It is possible to define thresholds of cerebral swelling and the authors recommend subdural ICP measurement as a tool to initiate preventive measures to reduce ICP before opening the dura mater.
Acute alterations in microvascular basal lamina after subarachnoid hemorrhage
Authors: Sehba Fatima A. , Mostafa Gulam , Knopman Jared , Friedrich Victor , Bederson Joshua B.
Published: May 2009

Object. Aneurysmal subarachnoid hemorrhage (SAH) causes acute and delayed ischemic brain injuries. The mechanisms of acute ischemic injury following SAH are poorly understood, although an acute increase in microvascular permeability has been noted. The integrity of cerebral microvessels is maintained in part by components of basal lamina: collagen IV, elastin, lamina, and so forth. Destruction of basal lamina components by collagenases and matrix metalloproteinases (MMPs), especially MMP-9, has been known to occur in other ischemic models. The authors assessed the integrity of cerebral microvasculature after acute SAH by examining collagen IV and MMP-9 levels and collagenase activity in the microvessels.

Methods. Subarachnoid hemorrhage was induced in rats through endovascular perforation of the intracranial bifurcation of the internal carotid artery. Animals were killed 10 minutes to 48 hours after SAH or sham operation (time-matched controls). Levels of collagen IV and MMP-9 were studied in the microvasculature by performing immunoperoxidase and immunofluorescence staining, and collagenase activity was assessed by in situ zymography.

Little change occurred in collagen IV and MMP-9 immunostaining or collagenase activity at 10 minutes or 1 hour after SAH. Starting 3 hours after SAH, collagen IV immunostaining was reduced or eliminated along segments of microvessels whereas MMP-9 staining was segmentally increased. These effects reached a maximum at 6 hours and returned toward those values in sham-operated controls at 48 hours.

Conclusions. Results of this study demonstrated an acute loss of collagen IV from the cerebral microvasculature after SAH and indicated that MMP-9 contributes to this event. The loss of collagen IV might contribute to the known failure of the blood—brain barrier after SAH.
Effects of arterial geometry on aneurysm growth: three-dimensional computational fluid dynamics study
Authors: Hoi Yiemeng , Meng Hui , Woodward Scott H. , Bendok Bernard R. , Hanel Ricardo A. , Guterman Lee R. , Hopkins L. Nelson
Published: May 2009

Object. Few researchers have quantified the role of arterial geometry in the pathogenesis of saccular cerebral aneurysms. The authors investigated the effects of parent artery geometry on aneurysm hemodynamics and assessed the implications relative to aneurysm growth and treatment effectiveness.

Methods. The hemodynamics of three-dimensional saccular aneurysms arising from the lateral wall of arteries with varying arterial curves (starting with a straight vessel model) and neck sizes were studied using a computational fluid dynamics analysis. The effects of these geometric parameters on hemodynamic parameters, including flow velocity, aneurysm wall shear stress (WSS), and area of elevated WSS during the cardiac cycle (time-dependent impact zone), were quantified. Unlike simulations involving aneurysms located on straight arteries, blood flow inertia (centrifugal effects) rather than viscous diffusion was the predominant force driving blood into aneurysm sacs on curved arteries. As the degree of arterial curvature increased, flow impingement on the distal side of the neck intensified, leading to elevations in the WSS and enlargement of the impact zone at the distal side of the aneurysm neck.

Conclusions. Based on these simulations the authors postulate that lateral saccular aneurysms located on more curved arteries are subjected to higher hemodynamic stresses. Saccular aneurysms with wider necks have larger impact zones. The large impact zone at the distal side of the aneurysm neck correlates well with other findings, implicating this zone as the most likely site of aneurysm growth or regrowth of treated lesions. To protect against high hemodynamic stresses, protection of the distal side of the aneurysm neck from flow impingement is critical.
Deep brain stimulation of the ventral caudate nucleus in the treatment of obsessive—compulsive disorder and major depression
Authors: Aouizerate Bruno , Cuny Emmanuel , Martin-Guehl Corinne , Guehl Dominique , Amieva Helene , Benazzouz Abdelhamid , Fabrigoule Colette , Allard Michele , Rougier Alain , Bioulac Bernard , Tignol Jean , Burbaud Pierre
Published: May 2009

✓ Obsessive—compulsive disorder (OCD) is an anxiety disorder associated with recurrent intrusive thoughts and repetitive behaviors. Although conventional pharmacological and/or psychological treatments are well established and effective in treating OCD, symptoms remain unchanged in up to 30% of patients. Deep brain stimulation (DBS) of the anterior limb of the internal capsule has recently been proposed as a possible therapeutic alternative in treatment-resistant OCD. In the present study, the authors tested the hypothesis that DBS of the ventral caudate nucleus might be effective in a patient with intractable severe OCD and concomitant major depression. Psychiatric assessment included the Yale—Brown Obsessive Compulsive Scale (Y-BOCS), the Hamilton Depression Rating Scale (HDRS), the Hamilton Anxiety Rating Scale (HARS), and the Global Assessment of Functioning (GAF) Scale for determining the symptom severity of OCD, depression, and anxiety as well as the quality of pychosocial and occupational functioning, respectively. Neuropsychological assessment consisted of a wide range of tests primarily exploring memory and executive functions. Deep brain stimulation of the ventral caudate nucleus markedly improved symptoms of depression and anxiety until their remission, which was achieved at 6 months after the start of stimulation (HDRS ≤ 7 and HARS ≤ 10). Remission of OCD (Y-BOCS < 16) was also delayed after 12 or 15 months of DBS. The level of functioning pursuant to the GAF scale progressively increased during the 15-month follow-up period. No neuropsychological deterioration was observed, indicating that DBS of the ventral caudate nucleus could be a promising strategy in the treatment of refractory cases of both OCD and major depression.