bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abolition of spindle oscillations and 3-Hz absence seizurelike activity in the thalamus by using high-frequency stimulation: potential mechanism of action
Authors: Lee Kendall H. , Hitti Frederick L. , Shalinsky Mark H. , Kim Uhnoh , Leiter James C. , Roberts David W. 
Published: May 2009

Object
The mechanism of action whereby high-frequency stimulation (HFS) in the thalamus ameliorates tremor and epilepsy is unknown. The authors studied the effects of HFS on thalamocortical relay neurons in a ferret in vitro slice preparation to test the hypothesis that HFS abolishes synchronized oscillations by neurotransmitter release.

Methods
Intracellular and extracellular electrophysiological recordings were made in thalamic slices. The neurons in the thalamic slice spontaneously generated spindle oscillations, and treatment with picrotoxin, a γ-aminobutyric acid A receptor antagonist, resulted in 3- to 4-Hz absence seizurelike activity. High-frequency stimulation (stimulation parameters: 10–1000-µA amplitude; 100-µsec pulse width; 100-Hz frequency; 1–60 seconds) was applied using a concentric bipolar stimulating electrode placed adjacent to the recording electrodes.
High-frequency stimulation within the thalamus generated inhibitory and excitatory postsynaptic potentials, membrane depolarization, an increase in action potential firing during the stimulation period, and abolished the spindle oscillations in the thalamocortical relay neurons. High-frequency stimulation applied to 20-µM picrotoxin-treated slices eliminated the 3- to 4-Hz absence seizurelike activity.

Conclusions
High-frequency stimulation eliminates spontaneous spindle oscillations and picrotoxin-induced absence seizurelike activity in thalamic slices by synaptic neurotransmitter release; thus, HFS may abolish synchronous oscillatory activities such as those that generate tremor and seizures. Paradoxically, HFS, which is excitatory, and surgical lesions of the ventrointermedius thalamus, which are presumably inhibitory, both suppress tremors. This paradox is resolved by recognizing that HFS-mediated neurotransmitter release and thalamic surgery both disrupt the circuit generating tremor or seizure, albeit by different mechanisms.
Cerebral acid—base homeostasis after severe traumatic brain injury
Authors: Clausen Tobias , Khaldi Ahmad , Zauner Alois , Reinert Michael , Doppenberg Egon , Menzel Matthias , Soukup Jens , Alves Oscar Luis , Bullock M. Ross 
Published: May 2009

Object. Brain tissue acidosis is known to mediate neuronal death. Therefore the authors measured the main parameters of cerebral acid—base homeostasis, as well as their interrelations, shortly after severe traumatic brain injury (TBI) in humans.
Methods. Brain tissue pH, PCO2, PO2, and/or lactate were measured in 151 patients with severe head injuries, by using a Neurotrend sensor and/or a microdialysis probe. Monitoring was started as soon as possible after the injury and continued for up to 4 days.
During the 1st day following the trauma, the brain tissue pH was significantly lower, compared with later time points, in patients who died or remained in a persistent vegetative state. Six hours after the injury, brain tissue PCO2 was significantly higher in patients with a poor outcome compared with patients with a good outcome. Furthermore, significant elevations in cerebral concentrations of lactate were found during the 1st day after the injury, compared with later time points. These increases in lactate were typically more pronounced in patients with a poor outcome. Similar biochemical changes were observed during later hypoxic events.
Conclusions. Severe human TBI profoundly disturbs cerebral acid—base homeostasis. The observed pH changes persist for the first 24 hours after the trauma. Brain tissue acidosis is associated with increased tissue PCO2 and lactate concentration; these pathobiochemical changes are more severe in patients who remain in a persistent vegetative state or die. Furthermore, increased brain tissue PCO2 (> 60 mm Hg) appears to be a useful clinical indicator of critical cerebral ischemia, especially when accompanied by increased lactate concentrations.
Surgical interventions for traumatic lesions of the brachial plexus: a retrospective study of 134 cases
Authors: Kandenwein Julia A. , Kretschmer Thomas , Engelhardt Martin , Richter Hans-Peter , Antoniadis Gregor 
Published: May 2009

Object.Surgical therapy for traumatic brachial plexus lesions is still a great challenge in the field of peripheral nerve surgery. The aim of this study was to present the results of different surgical interventions in patients with this lesion type.Methods.One hundred thirty-four patients with traumatic brachial plexus lesions underwent surgery between January 1991 and September 1999. In more than 50% of the patients, injury was caused by a motorbike accident. Patients underwent surgery a mean of 6.3 months posttrauma. The following surgical techniques were applied: neurolysis for nerve lesions in continuity (27 cases), grafting for lesions in discontinuity (149 cases), and neurotization for root avulsions (67 cases). Sixty-five patients were evaluated for at least 30 months (mean follow up 42.1 months) after surgery.Function was graded using the Louisiana State University Health Sciences Center classification system. Only 2% of the patients had Grade 3 or better function preoperatively, increasing to 52% postoperatively. The effect of surgical measures on the functional results for different muscles were compared (supra- or infraspinatus, deltoid, biceps, and triceps muscles); the best results were obtained for biceps muscle function (57% of patients with Medical Research Council Grades M3–M5 function). Graft reconstruction yielded a better outcome than neurotization. Surgery within 5 months posttrauma clearly resulted in improved recovery of motor function compared with later interventions. Sural nerve grafts (monofascicular nerves) showed better results.Conclusions.The results of neurosurgical interventions for brachial plexus lesions are satisfactory, especially when the operation is performed between 3 and 6 months after trauma.
Missile-induced complete lesions of the tibial nerve and tibial division of the sciatic nerve: results of 119 repairs
Authors: Roganović Zoran , Pavlićević Goran , Petković Stevan 
Published: May 2009

Object.Very few extensive studies regarding the repair of missile-induced tibial nerve or tibial division complete lesions have been published to date. In this prospective study, the outcomes of such repairs as well as factors influencing them are presented.Methods.Between 1991 and 1994, 119 patients with missile-induced complete lesions of the tibial nerve or tibial division were treated in the neurosurgical department of the Military Medical Academy, Belgrade. After at least 4 years of follow up, the final outcome was defined as poor, insufficient, good, or excellent, based on sensorimotor recovery, electromyoneurography-demonstrated recovery, and patient judgment. Good and excellent outcomes were considered to be successful. The influence of the repair level, length of the defect, and preoperative interval on final outcome was also tested.A successful outcome was obtained in 30.3% of high-level, 50% of intermediate-level, and 85.7% of low-level repairs (p < 0.001). On average, the nerve defect and preoperative interval were significantly shorter in patients with a successful outcome. Significant worsening of the outcome was related to a nerve defect longer than 5 cm and a preoperative interval longer than 4 months. Repair level, preoperative interval, and length of the defect were independent predictors of a successful outcome.Conclusions.A successful outcome is most probable following the low-level repairs, within the first 4 months after injury, and using grafts shorter than 5 cm. Other repairs can also be beneficial in preventing dangerous anesthesia of the sole of the foot and enabling almost normal walking.
Limitations of three-dimensional reconstructed computerized tomography angiography after clip placement for intracranial aneurysms
Authors: Sagara Yoshiko , Kiyosue Hiro , Hori Yuzo , Sainoo Michifumi , Nagatomi Hirofumi , Mori Hiromu 
Published: May 2009

Object. The authors compared the usefulness of three-dimensional (3D) reconstructed computerized tomography (CT) angiography with 3D digital subtraction (DS) angiography in assessing intracranial aneurysms after clip placement. A retrospective review of clinical cases was performed.
Methods. Between May 2001 and May 2003, 17 patients with a total of 20 intracranial aneurysms underwent 3D CT and 3D DS angiography following clip placement. The authors assessed the presence or absence of residual aneurysm necks and stenoocclusive changes in the parent artery and the neighboring artery. The efficacy of CT angiographic visualization was also evaluated.
In 12 of the 20 aneurysms, both 3D modalities similarly demonstrated the residual aneurysm neck and stenoocclusive changes in the parent artery and neighboring artery. Three-dimensional CT angiography failed to demonstrate three of the aneurysms, and the studies were not considered suitable for evaluation because of the presence of metallic artifacts. In the remaining five studies, the 3D CT angiograms did not effectively demonstrate the neighboring and parent arteries. The detectability of residual aneurysm necks was correlated with the clip material and with the number of clips applied.
Conclusions. Three-dimensional DS angiography is still necessary in cases involving multiple clips or with cobalt alloy clips because the clips appear as metal artifacts on 3D CT angiography.
Effect of atorvastatin on spatial memory, neuronal survival, and vascular density in female rats after traumatic brain injury
Authors: Qu Changsheng , Lu Dunyue , Goussev Anton , Schallert Timothy , Mahmood Asim , Chopp Michael 
Published: May 2009

Object. Atorvastatin administered after traumatic brain injury (TBI) induced by controlled cortical impact promotes functional improvement in male rats. Note, however, that parallel studies have not been performed in female rats. Therefore, the authors tested the effect of atorvastatin on TBI in female rats.
Methods. Atorvastatin (1 mg/kg/day) was orally administered for 7 consecutive days in female Wistar rats starting 1 day after TBI; control animals received saline. Modified neurological severity scores, the corner turn test, and the Morris water maze test were used to evaluate functional response to treatment. Rats were killed on Day 15 post-TBI, and brain tissue samples were processed for immunohistochemical staining. Atorvastatin administration after brain injury significantly promoted the restoration of spatial memory but did not reduce sensorimotor functional deficits. Treatment of TBI with atorvastatin increased neuronal survival in the CA3 region and the lesion boundary zone and prevented the loss of neuronal processes of damaged neurons in the hippocampal CA3 region but not in the lesion boundary zone on Day 15 after TBI. The protective effect of atorvastatin on the injured neurons perhaps is mediated by increasing the density of vessels in the lesion boundary zone and the hippocampus after TBI.
Conclusions. These data indicate that atorvastatin is beneficial in the treatment of TBI in female rats, although the effect may differ between sexes.
Secondary ischemia impairing the restoration of ion homeostasis following traumatic brain injury
Authors: Stiefel Michael F. , Tomita Yoshiyuki , Marmarou Anthony 
Published: May 2009

Object. It is well established that posttraumatic secondary ischemia contributes to poor outcome. Ion dysfunction leading to cytotoxic edema is a primary force in the formation of ischemic brain edema and is a principal component of traumatic brain swelling. Because cell swelling is the result of net ion and water movement, it is crucial to have a thorough understanding of these transient phenomena. The purpose of this study was to characterize the effects of secondary ischemia following traumatic brain injury (TBI) on the ability to restore ion homeostasis.
Methods. Twenty-four Sprague—Dawley rats were divided into four groups of six animals each. The rats underwent transient forebrain ischemia via bilateral carotid artery occlusion combined with hypotension: 15 minutes of forebrain ischemia (Group 1); 60 minutes of forebrain ischemia (Group 2); impact acceleration/TBI (Group 3); and impact acceleration/TBI followed by 15 minutes of ischemia (Group 4).
Ischemia resulted in a rapid accumulation of [K+]e: 41.94 ± 13.65 and 66.33 ± 6.63 mM, respectively, in Groups 1 and 2, with a concomitant decrease of [Na+]e: 64 ± 18 mM and 72 ± 11 mM in Groups 1 and 2. Traumatic brain injury resulted in a less severe although identical trend in ion dysfunction ([K+]e 30.42 ± 11.67 mM and [Na+]e 63 ± 33 mM). Secondary ischemia resulted in prolonged and sustained ion dysfunction with a concomitant elevation of intracranial pressure (ICP).
Conclusions. Analysis of these results indicates that ischemia and TBI are sublethal in isolation; however, when TBI is associated with secondary ischemia, ion dysfunction is sustained and is associated with elevated ICP.
Acute obstructive hydrocephalus associated with infratentorial subdural hygromas complicating Chiari malformation Type I decompression
Authors: Marshman Laurence A. G. , Benjamin Jonathan C. , Chawda Sanjiv J. , David Karoly M. 
Published: May 2009

✓ Obstructive hydrocephalus complicating foramen magnum decompression (FMD) for a Chiari malformation (CM) Type I is rare. Two female patients (17 and 55 years old) presented with strain-related headaches. In both cases magnetic resonance (MR) imaging studies confirmed a CM Type I, which was accompanied by syringomyelia in one case. Both patients underwent uncomplicated FMD with good initial recovery. Unfortunately, conditions in both patients deteriorated, with severe headaches occurring between Days 5 and 6 post-FMD. Decreased consciousness occurred in one case. In both patients, computerized tomography scanning demonstrated an acute obstructive hydrocephalus associated with bilateral infratentorial extraaxial fluid collections (EAFCs). In addition, left parafalcine and convexity EAFCs were present in one case. An emergency external ventricular drain was required in one patient, with delayed conversion to a ventriculoperitoneal shunt. Spontaneous resolution occurred in the other patient without neurosurgical intervention. In both cases, MR imaging confirmed that each EAFC was subdural, resembled cerebrospinal fluid (CSF), and had distorted the superior cerebellum anteroinferiorly. Despite upper fourth ventricle/aqueduct compromise in one case, normal aqueduct flow artifacts were apparent on examination. All EAFCs resolved spontaneously.
Obstructive hydrocephalus complicating FMD is rare but invariably associated with infratentorial EAFCs, which were confirmed to be subdural hygromas in this report. The authors assert that hydrocephalus results from upper fourth ventricle/aqueduct compromise as a result of CSF subdural dissection following a pinhole arachnoid tear on durotomy. Because such hygromas spontaneously resolve, permanent shunt insertion should be avoided.
Surgery for primary brain tumors at United States academic training centers: results from the Residency Review Committee for Neurological Surgery
Authors: Jane John A. , Sulton Larry D. , Laws Edward R. 
Published: May 2009

Object. Surgery for primary brain tumors has been an important index of the quality of neurosurgical training programs in the US. The scope of such cases and the proportion of surgeries performed transsphenoidally are an interesting means of tracking the effectiveness of residency education.
Methods. Program Information Forms from the 94 American Council for Graduate Medical Education—approved US neurosurgical residency programs were reviewed for the period between 2000 and 2003. Particular attention was focused on an analysis of the cases requiring craniotomy for primary brain tumor and transsphenoidal surgery.
The mean annual number of primary brain tumor cases per program was 195, with a range from 36 to 724 cases. The proportion of primary brain tumors accessed transsphenoidally was 20%. The mean annual number of transsphenoidal operations performed at academic training centers was 39. A wide range in the frequency of transsphenoidal cases from one program to another was also noted. Almost one third of training centers performed fewer than 20 transsphenoidal operations annually and 80% performed fewer than 50.
Conclusions. Most neurosurgical training programs provide residents with excellent experience in craniotomy for primary brain tumors. Practice with transsphenoidal surgery, however, is less well represented and tends to be clustered at several active centers. The implications for neurosurgical education are significant.
Extracranial—intracranial bypass in the treatment of occlusive cerebrovascular disease and intracranial aneurysms in the United States between 1992 and 2001: a population-based study
Authors: Amin-Hanjani Sepideh , Butler William E. , Ogilvy Christopher S. , Carter Bob S. , Barker Fred G. 
Published: May 2009

Object. The authors assessed the results of extracranial—intracranial (EC—IC) bypass surgery in the treatment of occlusive cerebrovascular disease and intracranial aneurysms in the US between 1992 and 2001 by using population-based methods.
Methods. This is a retrospective cohort study based on data from the Nationwide Inpatient Sample (Healthcare Cost and Utilization Project, Agency for Healthcare Research and Quality, Rockville, MD). Five hundred fifty-eight operations were performed at 158 hospitals by 115 identified surgeons. The indications for surgery were cerebral ischemia in 74% of the operations (2.4% mortality rate), unruptured aneurysms in 19% of the operations (7.7% mortality rate), and ruptured aneurysms in 7% of the operations (21% mortality rate). Overall, 4.6% of the patients died and 4.7% of the patients were discharged to long-term facilities, 16.4% to short-term facilities, and 74.2% to their homes. The annual number of admissions in the US increased from 190 per year (1992–1996) to 360 per year (1997–2001), whereas the mortality rates increased from 2.8% (1992–1996) to 5.7% (1997–2001).
The median annual number of procedures was three per hospital (range one–27 operations) or two per surgeon (range one–21 operations). For 29% of patients, their bypass procedure was the only one recorded at their particular hospital during that year; for these institutions the mean annual caseload was 0.4 admissions per year. For 42% of patients, their particular surgeon performed no other bypass procedure during that year. Older patient age (p < 0.001) and African-American race (p = 0.005) were risk factors for adverse outcome. In a multivariate analysis in which adjustments were made for age, sex, race, diagnosis, admission type, geographic region, medical comorbidity, and year of surgery, high-volume hospitals less frequently had an adverse discharge disposition (odds ratio 0.54, p = 0.03).
Conclusions. Most EC—IC bypasses performed in the US during the last decade were performed for occlusive cerebrovascular disease. Community mortality rates for aneurysm treatment including bypass procedures currently exceed published values from specialized centers and, during the period under study, the mortality rates increased with time for all diagnostic subgroups. This technically demanding procedure has become a very low-volume operation at most US centers.
Reduced mortality rate in patients with severe traumatic brain injury treated with brain tissue oxygen monitoring
Authors: Stiefel Michael F. , Spiotta Alejandro , Gracias Vincent H. , Garuffe Alicia M. , Guillamondegui Oscar , Maloney-Wilensky Eileen , Bloom Stephanie , Grady M. Sean , LeRoux Peter D. 
Published: May 2009

Object. An intracranial pressure (ICP) monitor, from which cerebral perfusion pressure (CPP) is estimated, is recommended in the care of severe traumatic brain injury (TBI). Nevertheless, optimal ICP and CPP management may not always prevent cerebral ischemia, which adversely influences patient outcome. The authors therefore determined whether the addition of a brain tissue oxygen tension (PO2) monitor in the treatment of TBI was associated with an improved patient outcome.
Methods. Patients with severe TBI (Glasgow Coma Scale [GCS] score < 8) who had been admitted to a Level I trauma center were evaluated as part of a prospective observational database. Patients treated with ICP and brain tissue PO2 monitoring were compared with historical controls matched for age, pathological features, admission GCS score, and Injury Severity Score who had undergone ICP monitoring alone. Therapy in both patient groups was aimed at maintaining an ICP less than 20 mm Hg and a CPP greater than 60 mm Hg. Among patients whose brain tissue PO2 was monitored, oxygenation was maintained at levels greater than 25 mm Hg. Twenty-five patients with a mean age of 44 ± 14 years were treated using an ICP monitor alone. Twenty-eight patients with a mean age of 38 ± 18 years underwent brain tissue PO2-directed care. The mean daily ICP and CPP levels were similar in each group. The mortality rate in patients treated using conventional ICP and CPP management was 44%. Patients who also underwent brain tissue PO2 monitoring had a significantly reduced mortality rate of 25% (p < 0.05).
Conclusions. The use of both ICP and brain tissue PO2 monitors and therapy directed at brain tissue PO2 is associated with reduced patient death following severe TBI.
Surgical management of adrenocorticotropic hormone—secreting macroadenomas: outcome and challenges in patients with Cushing's disease or Nelson's syndrome
Authors: De Tommasi Claudio , Vance Mary Lee , Okonkwo David O. , Diallo Alfa , Laws Edward R. 
Published: May 2009

Object. Adrenocorticotropic hormone (ACTH)—secreting pituitary macroadenomas are an uncommon cause of Cushing's disease (CD) and, subsequently, Nelson's syndrome (NS). They have been associated with low postoperative remission rates. The outcome of modern surgical treatment is unclear and thus was assessed in a series of 43 patients, with the goal of improving therapeutic results in patients with ACTH-secreting macroadenomas.
Methods. Thirty-seven patients presented with CD and six with NS. They represented 15% of the patients surgically treated at the authors' institution for ACTH-secreting adenomas. The median patient age was 38 years (range 14–71 years), and the mean duration of follow up was 37 months (range 1–108 months).
Remission occurred in 25 (67.6%) of 37 patients with CD, whereas the disease persisted in 12 (32.4%) of 37 patients. After an initial remission, three (12%) of 25 patients demonstrated signs and symptoms indicative of disease recurrence. Among patients with NS, only one (16.6%) displayed remission. Invasion of the dura mater by tumor was histologically demonstrated in 10 patients with CD and in two patients with NS.
Conclusions. Comprehensive management of CD caused by ACTH-secreting macroadenomas through the appropriate use of combination therapy, including surgery, radiotherapy, radiosurgery, and adrenalectomy, can lead to outcomes similar to those for microadenomas. Disease recurrence and persistence rates are higher, often because of the invasiveness associated with macroadenomas. Remission of NS-associated macroadenomas is difficult to achieve. Strategies for the characterization and treatment of invasive macroadenomas are needed.