bluuebunny/crossref_metadata_2025_split huggingface dataset:
Validation of the optic nerve sheath response to changing cerebrospinal fluid pressure: ultrasound findings during intrathecal infusion tests
Authors: Hansen Hans-Christian , Helmke Knut 
Published: June 2009

✓ Raised intracranial pressure leads to increased pressure around the optic nerve (ON), which underlies the formation of papilledema and the enlargement of the dural optic nerve sheath (ONS). In clinical practice, the presence of widened ONSs is demonstrable on neuroimaging, but their relationship to cerebrospinal fluid (CSF) pressure remains unknown. The authors investigated the ONS response to pressure during CSF absorption studies in 12 patients undergoing neurological testing. The ONS diameter was evaluated by serial B-mode ultrasound scans of the anterior ON near its entry into the globe.
All patients tested showed ONS diameter changes that exhibited covariance with the alteration of lumbar CSF pressure and were completely reversible during the infusion tests. The maximum difference in ONS diameter between baseline and peak pressure conditions was 1.8 mm on average (range 0.7–3.1 mm), corresponding to an average ONS diameter variation of 45% (range 15–89%). Regression analysis yielded a linear covariance between ONS diameter and CSF pressure with different slopes across subjects (0.019–0.071 mm/mm Hg, mean r = 0.78). However, this linear relationship was only present within a CSF pressure interval. This interval differed between patients: ONS dilation commenced at pressure thresholds between 15 mm Hg and 30 mm Hg and in some patients saturation of the response (constant ONS diameter) occurred between 30 mm Hg and 40 mm Hg. With a single exception, definitely enlarged ONS diameters (> 5 mm) were present when CSF pressure exceeded levels of 30 mm Hg. Retrospectively, discrimination between normal and elevated outflow resistance was possible on the basis of the ONS response to intrathecal infusion alone.
It is concluded that the human ONS has sufficient elasticity to allow a detectable dilation in response to intracranial hypertension. Because of a variable pressure—diameter relationship, the subarachnoid pressure cannot be predicted exactly by single scans. Therefore, the clinical relevance of this method relies on the demonstration of pathologically enlarged sheaths or ongoing enlargement on serial ultrasonography studies.
Cerebrospinal fluid interleukin-1 receptor antagonist and tumor necrosis factor—α following subarachnoid hemorrhage
Authors: Mathiesen Tiit , Edner Göran , Ulfarsson Elfar , Andersson Birger 
Published: June 2009

✓ Subarachnoid hemorrhage (SAH) causes an inflammatory reaction and may lead to ischemic brain damage. Experimental ischemia has been shown to be connected with the alarm-reaction cytokines interleukin-1 receptor antagonist (IL-1Ra) and tumor necrosis factor—α (TNFα). Increased levels of these cytokines, however, have not been detected thus far in patients following an SAH event.For this reason daily cerebrospinal fluid (CSF) samples were collected from 22 consecutively enrolled patients with SAH and from 10 non-SAH patients (controls). The CSF samples were studied using immunoassays for IL-1Ra and TNFα to investigate whether an SAH caused increased cytokine levels.The mean IL-1Ra levels were significantly higher in patients with SAH who were in poor clinical condition on admission than in those who were in good condition (318 pg/ml vs. 82 pg/ml, p < 0.02). The IL-1Ra levels increased during delayed ischemic episodes and after surgery in patients who were in poor clinical condition. Significant increases in IL-1Ra and TNFα were detected during Days 4 through 10 in patients suffering from SAH who eventually had a poor outcome (p < 0.05). Patients with good outcomes and control patients had low levels of these cytokines.The levels of IL-1Ra increased after surgery in patients with Hunt and Hess Grades III through V, but not in those with Grade I or II. This finding indicates that patients in poor clinical condition have a labile biochemical state in the brain that is reflected in increased cytokine levels following the surgical trauma.Both IL-1Ra and TNFα are known to induce fever, malaise, leukocytosis, and nitric oxide synthesis and to mediate ischemic and traumatic brain injuries. The present study shows that levels of these cytokines increase after SAH occurs and that high cytokine levels correlate with brain damage. It is therefore likely that fever, leukocytosis, and nitric oxide synthesis are also mediated by IL-1 in patients suffering from SAH and it is probable that the inflammatory mediators contribute to brain damage.
Microcirculation after cerebral venous occlusions as assessed by laser Doppler scanning
Authors: Nakase Hiroyuki , Kempski Oliver S. , Heimann Axel , Takeshima Toshikazu , Tintera Jaroslav 
Published: June 2009

✓ Research on cerebral venous circulation disturbances (CVCDs) has been limited partly by the paucity of animal models that produce consistent venous infarction. Occlusion of two adjacent cortical veins in rats by means of a photochemical thrombotic technique provides a minimally invasive, clinically relevant, and reproducible model suited to study the pathophysiology of CVCDs. In this study, the effects of venous occlusion on regional cortical blood flow and the brain damage that ensues were evaluated.
Cortical vein occlusion was induced by photoactivation of rose bengal via 100-µm fiberoptic illumination. The cerebral venous flow pattern was examined using fluorescence angiography until 90 minutes after venous occlusion, and regional cerebral blood flow (rCBF) was determined at 48 locations by using laser Doppler scanning. Histological damage was assessed 48 hours after vein occlusion. Occlusion of two cortical veins (Group T; seven animals) was compared with single-vein occlusion and its ensuing brain damage (Group S; five animals) and with sham-operated control (five animals). An rCBF reduction occurred 30 minutes after occlusion in Group T and was more extensive than the decrease in Group S after 60 minutes. Observation frequency histograms based on local CBF data obtained in Group T demonstrated that local CBF at some sites decreased to a level below the ischemic threshold within 90 minutes. Six of the seven rats in Group T had a growing venous thrombus with extravasation of fluorescein. The resulting infarction was significantly larger in Group T (9.8 ± 4.5% of the hemispheric area) than in Group S (only 3 ± 1.5% of the hemispheric area).
In conclusion, microcirculation perturbations occur early after venous occlusion and result in the formation of a venous thrombus accompanied by local ischemia and severe venous infarction. The extent of vein occlusion determines the resulting brain damage. Based on the results of this study, the authors conclude that CVCDs may be attenuated by prevention of venous thrombus progression together with the use of protective measures against the consequences of ischemia.
The transcallosal—transforaminal approach to the third ventricle with regard to the venous variations in this region
Authors: Türe Uğur , Yaşargil M. Gazi , Al-Mefty Ossama 
Published: June 2009

✓ Surgical approaches to lesions located in the anterior and middle portions of the third ventricle are challenging, even for experienced neurosurgeons. Various exposures involving the foramen of Monro, the choroidal fissure, the fornices, and the lamina terminalis have been advocated in numerous publications. The authors conducted a microsurgical anatomical study in 20 cadaveric brain specimens (40 hemispheres) to identify an exposure of the third ventricle that would avoid compromising vital structures.
An investigation of the variations in the subependymal veins of the lateral ventricle in the region of the foramen of Monro was performed, as these structures are intimately associated with the surgical exposure of the third ventricle. In 16 (80%) of the brain specimens studied, 19 (47.5%) of the hemispheres displayed a posterior location of the anterior septal vein—internal cerebral vein (ASV—ICV) junction, 3 to 13 mm (average 6 mm) beyond the foramen of Monro within the velum interpositum, not adjacent to the posterior margin of the foramen of Monro (the classic description). Based on this finding, the authors advocate opening the choroidal fissure as far as the ASV—ICV junction to enlarge the foramen of Monro posteriorly. This technique achieves adequate access to the anterior and middle portions of the third ventricle without causing injury to vital neural or vascular structures.
The high incidence of posteriorly located ASV—ICV junctions is a significant factor influencing the successful course of surgery. Precise planning of the surgical approach is possible, because the location of the junction is revealed on preoperative neuroradiological studies, in particular on magnetic resonance venography. It can therefore be determined in advance which foramen of Monro qualifies for posterior enlargement to gain the widest possible access to the third ventricle. This technique was applied in three patients with a third ventricular tumor, and knowledge of the venous variations in this region was an important resource in guiding the operative exposure.
Noninvasive optical imaging of the subarachnoid space and cerebrospinal fluid pathways based on near-infrared fluorescence
Authors: Sakatani Kaoru , Kashiwasake-Jibu Masaki , Taka Yoshinori , Wang Shijie , Zuo Huancong , Yamamoto Katsuyuki , Shimizu Koichi 
Published: June 2009

✓ The authors have developed a noninvasive optical method to image the subarachnoid space and cerebrospinal fluid pathways in vivo based on the near-infrared fluorescence of indocyanine green (ICG).The ICG was bound to purified lipoproteins (ICG—lipoprotein) and injected into the subarachnoid space of neonatal and adult rats. The ICG fluorescence was detected by a cooled charge-coupled device camera. After injection of ICG—lipoprotein into the cerebral subarachnoid space of the neonatal rat, ICG fluorescence was clearly detected at the injection site through the skull and skin. The ICG fluorescence was observed in the cerebellum and the lumbar spinal cord 1 and 8 hours postinjection, respectively. After injection of ICG—lipoprotein into the lumbar spinal subarachnoid space of an adult rat, ICG fluorescence was observed from the injection site to the thoracic levels along the spinal subarachnoid space. In addition, with the rat's head tilted downward, ICG fluorescence had extended to the cerebral subarachnoid space by 1 hour postinjection. The ICG fluorescence imaging of the cerebral subarachnoid space demonstrated an increase in fluorescence intensity around the lambdoid suture and the forebrain. On dissection of the rat brain the former location was identified as the supracerebellar cistern and the latter as the olfactory cistern.The results of this study are the first to demonstrate that an optical technique is applicable to imaging of the subarachnoid space and cerebrospinal fluid pathways in vivo. In addition, ICG—lipoprotein provides a sensitive optical tracer for imaging extravascular biological structures. Finally, ICG fluorescence imaging does not require an intricate imaging system because ICG is localized near the surface of the body.
Temporary occlusion of the middle cerebral artery in intracranial aneurysm surgery: time limitation and advantage of brain protection
Authors: Lavine Sean D. , Masri Lena S. , Levy Michael L. , Giannotta Steven L. 
Published: June 2009

✓ The risk of focal infarction secondary to the induced reversible arrest of local arterial flow during microsurgical dissection of middle cerebral artery (MCA) aneurysms was evaluated further to define the optimal approach to temporary arterial occlusion. To compare the effectiveness of potential brain-protection anesthetics, a group of patients treated with the intravenous agents propofol, etomidate, and pentobarbital, administered individually or in combination, was compared to a group treated with the inhalational agent isoflurane.
Forty-nine consecutive MCA aneurysm surgeries involving the temporary clipping of the parent vessel were retrospectively reviewed. Thirty-eight patients received intravenous brain-protection (IVBP) anesthesia. Groups of patients with and without infarctions, and receiving and not receiving IVBP anesthesia, were compared based on the duration and nature of temporary arterial occlusion. Postoperative radiographic evidence of new infarction was used as the threshold for failure of occlusion tolerance. The overall infarction rate was 22.4% (11 of 49 patients), including 15.8% (six of 38 patients) in the IVBP group versus 45.5% (five of 11 patients) in the group that did not receive brain protection (NBP). In the NBP group, the mean duration of temporary occlusion was 3.9 ± 2.2 minutes for patients without infarction versus 12.2 ± 4.3 minutes for patients with focal infarction (p < 0.01). In contrast, the mean duration was 13.6 ± 10.6 minutes for patients without infarction and 18.5 ± 9.9 minutes for patients with infarction in the IVBP group. All patients (four of four) in the NBP group who underwent occlusion lasting 10 minutes or longer suffered an infarction versus five of 23 patients in the IVBP group (p < 0.0001). Patients with multiple aneurysms were found to be at increased risk of developing focal infarction, whereas those treated with intermittent temporary clip application were at decreased risk.
It is concluded that patients in whom focal iatrogenic ischemia is induced during MCA aneurysm clip ligation have a significant advantage compared with those receiving isoflurane when they are given pentobarbital as the primary neuroprotective agent or when they receive propofol or etomidate titrated to achieve electroencephalographic burst suppression, particularly if more than 10 minutes of occlusion time is required. It is also concluded that 10 minutes is a general guideline for safe, temporary occlusion of the MCA. The use of intermittent temporary arterial occlusion and its use in patients with multiple aneurysms need further evaluation before specific recommendations can be made.
Incidence of cerebral vasospasm after endovascular treatment of acutely ruptured aneurysms: report on 69 cases
Authors: Murayama Yuichi , Malisch Tim , Guglielmi Guido , Mawad Michel E. , Viñuela Fernando , Duckwiler Gary R. , Gobin Y. Pierre , Klucznick Richard P. , Martin Neil A. , Frazee John 
Published: June 2009

✓ Cerebral vasospasm is the most common cause of morbidity and mortality in patients admitted to the hospital after suffering aneurysmal subarachnoid hemorrhage (SAH). The early surgical removal of subarachnoid clots and irrigation of the basal cisterns have been reported to reduce the incidence of vasospasm. In contrast to surgery, the endovascular treatment of aneurysms does not allow removal of subarachnoid clots. In this study the authors measured the incidence of symptomatic vasospasm after early endovascular treatment of acutely ruptured aneurysms with Guglielmi detachable coils (GDCs).
Sixty-nine patients classified as Hunt and Hess Grades I to III underwent occlusion of intracranial aneurysms via GDCs within 72 hours of rupture. The amount of blood on the initial computerized tomography (CT) scan was classified by means of Fisher's scale. Symptomatic vasospasm was defined as the onset of neurological deterioration verified with angiographic or transcranial Doppler studies. Hypertensive, hypervolemic, hemodilution therapy, with or without intracranial angioplasty, was used to treat vasospasm after GDC placement.
Symptomatic vasospasm occurred in 16 (23%) of 69 patients. The clinical grade at admission and the amount of blood on the initial CT were both associated with the incidence of subsequent vasospasm. At 6-month clinical follow-up examination, 12 of these 16 patients experienced a good recovery, two were moderately disabled, and two patients had died of vasospasm.
In conclusion, the 23% incidence of symptomatic vasospasm in this series compares favorably with that found in conventional surgical series of patients with acute aneurysmal SAH. These results indicate that endovascular therapy does not have an unfavorable impact on cerebral vasospasm.
Cervical cord neurapraxia: classification, pathomechanics, morbidity, and management guidelines
Authors: Torg Joseph S. , Corcoran Thomas A. , Thibault Lawrence E. , Pavlov Helene , Sennett Brian J. , Naranja R. John , Priano Steven 
Published: June 2009

✓ One hundred ten cases of the transient neurological phenomenon, cervical cord neurapraxia (CCN), are presented. The authors established a classification system for CCN, developed a new computerized measurement technique for magnetic resonance (MR) imaging, investigated the relationship of the cervical cord to the canal, and analyzed clinical, x-ray, and MR data. One hundred nine males and one female were included in the study; the average age of the participants was 21 years (range 13–33 years). All episodes occurred during sports participation; 87% occurred while the patient was playing football. Follow-up review lasting an average of 3.3 years was available for 105 patients (95%).Narrowing of the sagittal diameter of the cervical canal in the adult spine was confirmed to be a causative factor. Cervical cord neurapraxia was not associated with permanent neurological injury and no permanent morbidity occurred in patients who returned to contact activities. Of the patients returning to contact activities, 35 (56%) experienced a recurrent episode. The risk of recurrence was increased with smaller spinal canal/vertebral body ratio (p < 0.05), smaller disc-level canal diameter (p < 0.05), and less space available for the cord (p < 0.05). There was no correlation between either the classification of the CCN episode or the disease noted on MR imaging and x-ray films and the risk of recurrence.The authors conclude that: 1) CCN is a transient neurological phenomenon and individuals with uncomplicated CCN may be permitted to return to their previous activity without an increased risk of permanent neurological injury; 2) congenital or degenerative narrowing of the sagittal diameter of the cervical canal is a causative factor; 3) the overall recurrence rate after return to play is 56%; and 4) the risk of recurrence is strongly and inversely correlated with sagittal canal diameter and it is useful in the prediction of future episodes of CCN (p < 0.001). These data will enable the physician to counsel individuals regarding a predicted risk of recurrence based on canal measurements.
Pre- and postischemic effects of the NMDA receptor antagonist dizocilpine maleate (MK-801) on collateral cerebral blood flow
Authors: Robertson Scott C. , Wetjen Nicholas M. , Beer Bradley J. , Loftus Christopher M. 
Published: June 2009

✓ The authors studied the effects of pre- and postischemic administration of dizocilpine maleate (MK-801) on collateral and regional cerebral blood flow (CBF). The ischemic penumbra appears to benefit most from the neuroprotective effects of MK-801. The precise mechanism by which MK-801 provides this neuroprotection remains controversial. Alterations in CBF have been demonstrated with MK-801 administration, but whether the response is an increase or decrease in flow has remained unclear.
A left-sided craniectomy was performed in 20 dogs. A branch of the middle cerebral artery (MCA) was cannulated and collateral blood supply—dependent tissue (CDT) was identified using the “shadow flow” technique. Regional CBF was measured using radiolabeled microspheres. Six dogs received MK-801 (1 mg/kg administered intravenously) before they underwent MCA branch occlusion; the remaining 14 dogs received MK-801 after they underwent MCA occlusion. Cerebral blood flow and vascular pressures were measured 30 and 60 minutes after MK-801 administration. In animals that received MK-801 before MCA occlusion, CBF did not change significantly from baseline values before or after occlusion. In contrast, in animals that received MK-801 after MCA occlusion, CBF was significantly reduced in all regions of the brain, including the CDT. Collateral blood supply—dependent tissue showed a 51.7% reduction in flow, whereas normal CBF was reduced by 29.7%. The MK-801 induced cerebral vasoconstriction in both groups. The neuroprotective effects of MK-801 do not appear to be caused by the augmentation of collateral or global cerebral circulation and, in fact, may block the glutamate-mediated vasodilation that occurs during ischemia.
Liquid Crystal Emulsions as the Basis of Biological Sensors for the Optical Detection of Bacteria and Viruses
Authors: Sivakumar Sri , Wark Kim L. , Gupta Jugal K. , Abbott Nicholas L. , Caruso Frank 
Published: June 2009

AbstractA versatile sensing method based on monodisperse liquid crystal (LC) emulsion droplets detects and distinguishes between different types of bacteria (Gram +ve and −ve) and viruses (enveloped and non‐enveloped). LCs of 4‐cyano‐4'‐pentylbiphenyl transition from a bipolar to radial configuration when in contact with Gram −ve bacteria (E. coli) and lipid‐enveloped viruses (A/NWS/Tokyo/67). This transition is consistent with the transfer of lipid from the organisms to the interfaces of the micrometer‐sized LC droplets. In contrast, a transition to the radial configuration is not observed in the presence of Gram +ve bacteria (Bacillus subtilis and Micrococcus luteus) and non‐enveloped viruses (M13 helper phage). The LC droplets can detect small numbers of E. coli bacteria (1–5) and low concentrations (104 pfu mL−1) of A/NWS/Tokyo/67 virus. Monodisperse LC emulsions incubated with phosholipid liposomes (similar to the E. coli cell wall lipid) reveal that the orientational change is triggered at an area per lipid molecule of ∼46 Å2 on an LC droplet (∼1.6 × 108 lipid molecules per droplet). This approach represents a novel means to sense and differentiate between types of bacteria and viruses based on their cell‐wall/envelope structure, paving the way for the development of a new class of LC microdroplet‐based biological sensors.
Mechanisms of particle dispersion in a turbulent, square duct flow
Authors: Fairweather Michael , Yao Jun 
Published: June 2009

AbstractParticle dispersion in a square duct flow is studied using large eddy simulation combined with Lagrangian particle tracking under conditions of one‐way coupling. The flow has a bulk Re = 250 k, with six particle sizes ranging from 5 to 1000 μm. Results obtained for the fluid phase show good agreement with experimental data. For particles, predictions demonstrate that secondary flows within the duct dominate small particle dispersion and result in a uniform distribution, whereas gravity promotes the deposition of large particles on the duct floor. For the largest particles, the secondary flows contribute to particle concentration in corners on the duct floor, with these particles also clustering in low‐velocity regions close to the floor. A detailed analysis of the influence of the flow on particle distribution is provided through consideration of the particle dispersion function, with the mechanisms of particle dispersion elucidated using a dynamical analysis. © 2009 American Institute of Chemical Engineers AIChE J, 2009