Edema Zone Research Articles

A photothrombotic model of small early ischemic infarcts in the rat brain with histologic and MRI correlation

Over the last two decades several studies have suggested the role of photothrombotic occlusion of cerebral microvessels using rose bengal, resulting in small strokes in rodents that resemble those in humans. This paper describes such a photothrombotic method of acute small stroke induction in rats with histopathologic and in vivo magnetic resonance imaging (MRI) observations from 3 to 6 h after irradiation, which is homologous to a human autopsy specimen. Utilizing 30 min of irradiation with minimal beam intensity (0.1 W/cm 2) cold white light in conjunction with 20 mg of intravenous (iv) rose bengal as a rapid infusion, small infarcts were induced photochemically in the frontal lobes of six rats. The infarcts showed a consistent pattern on histologic and in vivo MR sections when examined within 7 h or less of irradiation. Both MRI and histologic sections were comprised of (a) a superior zone of infarcted neurons, (b) a middle curvilinear transition zone of edema on MRI and histologically vacuolated neuropil, and (c) an inferior zone of normal neurons. Shorter duration water-sensitive (T2)- and postgadolinium longer duration (T1)-weighted signal decay images both showed a curvilinear hyperintense transition zone of edema. The mean infarct and transition zone areas measured from the histologic sections were comparable to those measured on the MRI. The infarct model described above allows in vivo observations using MRI with the potential for use in testing putative neuroprotective agents. As demonstrated by a comparison with the histologic features of such infarcts in surgical and autopsy brain specimens, the model is relevant to acute human ischemic infarcts.

Comparative Magnetic Resonance Image-Based Evaluation of Thalamotomy and Pallidotomy Lesion Volumes

Acute thalamotomy and pallidotomy lesion volumes based on magnetic resonance (MR) images were measured in 22 patients (11 thalamotomy and 11 pallidotomy patients). Thalamotomy inner lesion volumes (0.06 ± 0.04 ml; thermocoagulative zone) were smaller than pallidotomy inner lesion volumes (0.14 ± 0.08 ml) as determined using T₁-weighted 3D-MPRAGE (1.5-mm slice spacing). Similar results were found using T₁-weighted (6-mm slice spacing) image sets (0.09 ± 0.05 ml, thalamotomy; 0.13 ± 0.05 ml, pallidotomy). No differences were found when comparing thalamic or pallidal inner lesion volumes when the comparison was based on T₂ weighted images. Thalamotomy total lesion volumes (thermocoagulative and surrounding edematous zones) were less than pallidotomy total lesion volumes independent of the MR protocol. The difference in thalamotomy and pallidotomy lesion volumes is most likely based on the distance between each discrete lesion placed along the lesioning tracts. In 7 of 11 thalamotomies, this distance was 1 mm with the remaining having 2 mm between each discrete lesion. All pallidotomy discrete lesions were 2 mm apart. More overlap between discrete lesioning sites for thalamotomies is likely to produce reduced lesion volumes.

Quantification of functional retinal damage in branch retinal vein thromboses

Branch retinal vein occlusion (BRVO) induces variable functional deficits depending on the grade of vascular occlusion and its localisation. Theses deficiences are not easily defined by visual acuity measurements. However, microperimetry offers topical mapping of retinal function, allowing precise documentation of the intensity and dimension of retinal functional loss in BRVO. Retinal sensitivity was examined using a Rodenstock Scanning Laser Ophthalmoscope (SLO). A standardized grading system of stimuli ranging from 0 to 32 dB was used to document the retinal threshold in three different areas: regions presenting vascular occlusion, the collateral edematous zone and adjacent areas with intact perfusion. Absolute and relative scotomas as well as the fixation behavior were studied. Forty-two patients with isolated BRVO within the vascular arcades were examined with microperimetry and angiography. At initial presentation with BRVO the retinal sensitivity in the area of occlusion on average diminished to 4.1 dB. In the collateral edematous zone retinal threshold was reduced to 21.5 dB; area with intact perfusion demonstrated a threshold of 23.2 dB. Within the occluded area itself defects of significantly differing intensity were found which only partially correlated with the angiographic evidence. Intense scotomas (0 dB) were observed in 59% of the eyes examined: angiographically nonperfused areas or extended intraretinal hemorrhage were present. Relative scotomas (12.1 dB) were seen in 19.1% and minimal, non-significant defects (19.5 dB) were documented in 21.4% of the BRVO. The level of angiographically documented leakage did not correlate with the functional deficits present in these two groups. Measurements performed after 6-8 weeks revealed noticeable spontaneous recovery of retinal sensitivity, unless an additional progressive closure occurred. The average functional improvement in the area of leakage found after laser therapy was less than the results shown in spontaneous resolution of edema. BRVO may lead to significant reductions of central and paracentral retinal function. Angiographically observed leakage is not always directly correlated to the magnitude of retinal sensitivity loss. As spontenous remission is frequent in one group and intact retinal function can be shown in areas of angiographic leakage, therapeutic interventions, e.g., laser treatment, should be carefully considered. Scanning laser ophthalmoscopy provides additional information for precise evaluation and follow-up of the retinal damage in BRVO.

Brain parenchyma/pO2 catheter interface: a histopathological study in the rat.

Local cerebral oxygenation can be monitored continuously using an intraparenchymal Clark-type pO2 sensitive catheter. Measured values of brain tissue pO2 (PbrO2) not only depend on the clinically interesting balance between oxygen offer and demand, but also on catheter properties and characteristics of the probe tissue interface. Microdamage surrounding pO2-sensitive needles, inserted into various tissues, has been reported; we evaluated histologic changes at the probe tissue interface after insertion of pO2 probes, suitable for clinical use, in the rat brain. The effect of insertion of the probe itself (mechanical damage), the application of micropotential during the measurements, and the effect of time was evaluated using digital image analysis of H&E-stained histological slices. Surrounding the probe tract, a zone of edema with an average radius of 126.8 microm was seen; microhemorrhages with an average surface area of 56.2 x 10(3) microm2 were observed in nearly all cases. The area of edema and the presence of microhemorrhages were not influenced by performed measurements or by time. Intraventricular blood was observed in 10 of 19 rats studied. Measured low PbrO2 values were related to the presence of a microhemorrhage in either probe tract or ventricles. Tissue damage due to the measurements is negligible, and the amount of edema itself does not influence the accuracy or response time of the pO2 probe. Low PbrO2 readings, however, could be caused by local microhemorrhages, undetectable on CT or MRI.

Pallidotomy lesion locations: significance of microelectrode refinement.

To determine whether stereotactic pallidotomy requires refinement using microelectrode recording to ensure proper lesion placement. The experiment approach was based on retrospective comparisons of microelectrode-refined radiofrequency lesion locations with hypothetical unrefined lesion positions. Actual and hypothetical pallidotomy lesions were classified based on their lesion center (thermocoagulative zone) locations and their total lesion areas (surrounding edematous zone) relative to the pallidal target. Assessments were made using postoperative T2-weighted magnetic resonance axial images, which showed both the lesion and globus pallidus (GP). The magnitude of microelectrode refinement from an initial preoperative starting point determined by computed tomography was calculated using stereotactic coordinates and included corrections for the lesioning tract trajectory angle. In all 25 patients, the center of the actual pallidotomy lesion was within the GP. Without microelectrode refinement, 13 of 25 hypothetical lesion positions would have been localized such that the lesion center would not have remained in the GP. In eight cases, microelectrode refinement resulted in no significant change in lesion location, but in one case, microelectrode refinement resulted in lesion center placement away from the GP. Kinesthetically driven microelectrode refinement in pallidotomy lesioning seems to be required to ensure proper lesion location within the GP.

Local tumor progression in zone of peritumor vasogenic edema following boron neutron capture therapy for glioblastoma multiforme

Local tumor progression in zone of peritumor vasogenic edema following boron neutron capture therapy for glioblastoma multiforme

Damaging effects of anal stretching on the external anal sphincter.

This study was undertaken to investigate the effects of anal stretching on anal pressures and damage to the external anal sphincter. This study was performed on 37 guinea pigs. Animals were divided into three groups: control group, quick stretching group, and continuous overstretching group. Anal stretching was conducted by an 8-F Foley catheter balloon. It was found that if the muscle was stretched from 100 to 300 percent of its original length, anal resting pressure (ARP) kept relatively steady, but anal contracting pressure (ACP) gradually increased; from 300 to 370 percent, a sharp ARP increase was developed, but ACP gradually decreased to zero; beyond 370 percent, ARP remained unchanged (plateau phase). By histologic examination, it was revealed that when the muscle was stretched at the ARP plateau phase, an ischemic zone of necrosis and an edematous zone of necrosis could be clearly identified in the muscle. This study shows that length of the external anal sphincter definitively influences muscle strengths, and severe anal stretching will result in muscle damage. These results imply that the sphincteric muscle complex in high or intermediate anorectal anomalies may be injured during present conventional surgical approaches.

Animal experiment studies of laser effects on lymphatic vessels. A contribution to the discussion of laser surgery segmental resection of carcinomas

The potential effect of laser surgery on the process of lymphogenic metastases is subject to controversy. In this context it would be of interest to identify a morphological basis for an increased intraoperative entry of tumor cells into the lymphatic system during resection of advanced carcinomas in two or more pieces via laser surgery. The tissue effect of laser incisions (CO2 laser: 3030 W/cm2; Nd:YAG-laser: 3180 W/cm2) on the lymphatics of the buccal mucosa in 60 Wistar rats was studied by light microscopy, histochemistry, and lymphography during surgery and subsequent wound healing. These incisions were compared to conventional scalpel incisions. No lymphatic vessels were detected in the zone of carbonization, they were mostly dilated whereas in the zone of edema. In the zone of necrosis, the lymphatic were occluded by coagulation. The mid and long-term effect of the laser light on the regeneration of lymphatics was mainly correlated to wound healing which--when compared to conventional surgery--is delayed after laser surgery. Following scalpel incision, the first lymphatics enter the wound region after 4 days, a opposed to 10 days following laser surgery. Intact continuity of the lymphatic vasculature was detectable 15 days after scalpel incision and 42 days after laser incision. The regeneration of lymphatics was slightly more delayed after CO2 laser incision than after Nd:YAG laser incision. The results of this study do not indicate that the laser resection of carcinomas facilitates an intraoperative entry of tumor cells into the lymphatic vasculature. These experimental results verify clinical reports which do not observe an increased frequency of postoperative metastases after laser resection of carcinomas in two or more pieces.

Focal ischemia due to traumatic contusions documented by stable xenon-CT and ultrastructural studies.

A traumatic cerebral contusion causes a zone of perifocal neuronal necrosis, the cause of which is not known; the surgical management of these lesions remains controversial. To determine the pathophysiological mechanisms responsible for brain damage after contusions, the authors performed cerebral blood flow (CBF) mapping studies and related these to change in local cerebral blood volume (CBV) and ultrastructure. In 11 severely head injured patients with contusion, CBF and CBV were measured in pericontusional areas using stable xenon-computerized tomography (CT). These studies demonstrated a profound reduction in perilesional CBF (mean 17.5 +/- 4 ml/100 g/min), which was always accompanied by a zone of edema defined by CT density measurements. Mean CBV in these regions was 2.3 +/- 0.4 ml/100 g, a reduction to approximately one-half the value of 4.8 ml/100 g found in the nonedematous regions, and to approximately 35% of the value of 6.0 ml/100 g found in normal volunteers. Ultrastructural analysis of the pericontusional tissue, taken at surgery in four patients with high intracranial pressure showed glial swelling with narrowing of the microvascular lumina due to massive podocytic process swelling. Additionally, some suggestion of vascular occlusion due to erythrocyte and leukocyte stasis was seen. These data support the conclusion that microvascular compromise by compression and/or occlusion is a major event associated with profound perilesional hypoperfusion, which is a uniform finding within edematous pericontusional tissue.

Ultrastructure of Contusion Cataract

We investigated the histopathologic condition of four lenses with contusion rosette cataract by light and electron microscopy; periods between blunt trauma and cataract extraction varied from 4 months to 40 years. The initial morphologic changes appear to be the formation of intercellular vacuoles within the lens epithelium and the swelling of superficial cortical lens fibers. Signs of beginning fiber degeneration within the edematous zone include fragmentation of fiber cytoplasm into droplets and globules, formation of abnormal membrane arrangements, and enlargement of intercellular spaces. Late rosette opacities manifest as sharply demarcated layers of vacuolic degeneration in the deeper cortex. We suggest that in contusion cataract, a traumatically induced dysfunction of the lens epithelium leads to an edema of superficial cortical lens fibers that subsequently undergo degeneration and produce a localized and permanent lamellar zone of vacuolation. With time and with the formation of new clear lens cells, this layer becomes gradually compressed and displaced deeper into the cortex.

Expression of p53 and proliferating cell nuclear antigen in lichen sclerosus et atrophicus with different histological features.

In this study, immunohistochemistry was used to investigate p53 and proliferating cell nuclear antigen (PCNA) expression in 40 cases of lichen sclerosus et atrophicus (LSA). Nuclear immunoreactivity for both p53 and PCNA was found in the basal and parabasal keratinocytes in the majority (91%) of the lesions. Typically, there was a widely varying positivity for PCNA, suggesting a wide range of proliferative capacity in individual LSA lesions. Lesions with p53 positivity in 5% or more of the basal cells also presented a strong (> 14% of basal cells positive) PCNA positivity (p = 0.030) and exhibited a higher mitotic rate (p = 0.002), suggesting a causal relationship between enhanced p53 expression and elevated cell proliferation. Lesions with a low number of PCNA-positive cells (< 15% of basal and parabasal cells positive) exhibited a wider subepithelial edematous zone and a thinner epithelium than in the lesions with a higher number of PCNA-positive cells. The results show that later stages of LSA, typified by subepithelial edema and epithelial atrophy, are associated with decreased proliferative activity of the basal and parabasal cells.

MR appearance of skeletal neoplasms following cryotherapy.

Cryotherapy is an increasingly popular mode of therapy adjunctive to surgical curettage in the treatment of certain skeletal neoplasms, such as giant cell tumors or chondrosarcomas. The magnetic resonance (MR) findings following cryotherapy have not been previously reported. We reviewed the MR findings in seven patients with skeletal neoplasms following curettage and cryotherapy. In six cases we found a zone of varying thickness extending beyond the surgical margins, corresponding to an area of cryoinjury to medullary bone. This zone displayed low signal intensity on T1-weighted images and high signal intensity on T2-weighted images, consistent with the presence of marrow edema. This zone of edema almost certainly reflects underlying thermal osteonecrosis. This zone may vary in size and intensity over time as the area of cryoinjury evolves or resolves. MR is currently the imaging procedure of choice for follow-up of most musculoskeletal neoplasms. Knowledge of the MR findings following cryotherapy should help prevent confusion during the interpretation of follow-up MR examinations.

Histopathological Changes of the Cat Brain in Experimental Sparganosis

Histopathological changes of the brain were observed in 22 mongrel cats each of which was subjected to intracranial inoculation of 3 or 5 plerocercoids of Spirometra erinacei. The brains were examined at 2 weeks, 1, 3, and 6 months post-inoculation (PI). Grossly, the brain lesion consisted of a mass of worm capsule and/or hemorrhagic tract. Microscopically hypertrophied astrocytes, lymphocytes, plasma cells, RBCs, polymorphonuclear leukocytes, and hemosiderin laden macrophages were found around the worms or tracts in all groups. The number of reactive astrocytes increased mainly in the white matter. In the lesions 3 months PI, the sectioned worms were encircled with fibrous tissue along with numerous RBCs, inflammatory cells, and necrotic debris. Collagenous fibers were also demonstrated. Outside the inflammation, a wide edematous zone developed and numerous neuroglial fibers were also found. The location of the worms or the tracts was random in the brain lobes, but the worm seemed to migrate mainly along the white matter.

Angiomyofibroblastoma of the vulva. A benign neoplasm distinct from aggressive angiomyxoma.

Aggressive angiomyxoma of pelvic soft parts is a rare lesion with a high risk of recurrence. We report 10 cases of angiomyofibroblastoma, a hitherto uncharacterized benign tumor of the vulva histologically mimicking aggressive angiomyxoma. All patients had a vulval mass, often clinically diagnosed as a Bartholin's cyst. There was no recurrence after excision. The tumors were well circumscribed, measuring 0.5-12 cm in maximum dimension. They were characterized by alternating hypercellular and hypocellular edematous zones in which abundant blood vessels (predominantly of the capillary type) were irregularly distributed. Spindled, plump spindled, and oval stromal cells were aggregated around the blood vessels, sometimes forming solid compact foci, or were loosely dispersed in the hypocellular areas. Their nuclei were bland, but rare ones were enlarged and hyperchromatic in four cases. Some cells had abundant eosinophilic hyaline cytoplasm and eccentrically placed nuclei. Mitotic figures were absent or very sparse. Scattered throughout were thin, wavy strands or thick bundles of collagen. Mast cells were readily seen in eight cases. Immunohistochemically, the stromal cells were reactive for vimentin and desmin, but not cytokeratin, muscle-specific actin, alpha-smooth muscle actin, or S-100 protein. Ultrastructural studies showed well-developed rough endoplasmic reticulum, Golgi apparatus, abundant intermediate filaments, and pinocytotic vesicles in the stromal cells. Angiomyofibroblastoma can be distinguished from aggressive angiomyxoma by its circumscribed borders, much higher cellularity, more numerous blood vessels (which lack prominent hyalinization), frequent presence of plump stromal cells, minimal stromal mucin, and rarity of erythrocyte extravasation.

Prognostic significance of magnetic resonance imaging in the acute phase of cervical spine injury

Fifty-seven patients with acute cervical spine injuries and associated major neurological deficit were examined within 2 weeks of injury by magnetic resonance (MR) imaging. All patients had abnormal scans, indicating intramedullary lesions. This study was undertaken to determine if the early MR imaging pattern had a prognostic relationship to the eventual neurological outcome. Three different MR imaging patterns were observed in these patients: 21 patients had patterns characteristic of intramedullary hematoma (Group 1); 17 had intramedullary edema over more than one spinal segment, but no hemorrhage (Group 2); and 19 had restricted zones of intramedullary edema involving one spinal segment or less (Group 3). The neurological state was determined using standard motor index scores at admission and at follow-up examination. Characteristically, the patients in Group 1 had admission motor scores significantly lower than the other two groups. At follow-up examination, the median percent motor recovery was 9% for Group 1, 41% for Group 2, and 72% for Group 3. These studies suggest that the MR imaging pattern observed in the acutely injured human spinal cord has a prognostic significance in the final outcome of the motor system. It is only when an accurate prognosis can be given at the outset that useful treatment data might be collected for homogeneous injury groups, and accurately based long-term planning made for the best patient care.

Ultrasonic Features of the Osgood–Schlatter Lesion

Ultrasound was used to compare the knees of 10 boys and four girls with typical clinical Osgood-Schlatter lesions with 27 symptomless knees. The normal sonographic changes of the tibial tubercle with advancing age are described. In all children with Osgood-Schlatter lesions, the distal patellar tendon thickened and became more echogenic than normal tendons, and an anechoic zone of edema was seen anterior to the tibial tuberosity. Four knees disclosed a thin shell-like elevated fragment of the tibial tuberosity seen as an echogenic surface. In 12 knees, single or multiple fragments of the tibial tuberosity were easily shown. Ultrasound is proposed as a simple, fast, and reliable method for the diagnosis of the Osgood-Schlatter lesion.

Production of Corneal Lesions Using High-Intensity Focused Ultrasound

In order to study the potential use of ultrasound as a noninvasive system for altering corneal curvature, we used high-density focused ultrasound at a frequency of 4.8 MHz and 7.9 MHz to produce corneal lesions in the rabbit eye. Intensity and duration threshold exposure conditions were determined for the production of minimally visible lesions. Threshold lesions were initially apparent as discrete white opacities resulting from stromal edema and disruption. Light and scanning electron microscopy of higher-energy, suprathreshold lesions revealed more extensive disruption, including the formation of a superficial stromal depression and a larger zone of edema and disorganization surrounding each lesion. Posterior stromal lamellae, endothelium, and Descemet's membrane were intact. Healing and reepithelialization resulted in a smooth corneal surface with no residual opacification. Threshold determinations predict safe exposure levels to the cornea during insonification of other ocular structures. Selective heating of the peripheral cornea using focused ultrasound may be a useful technique for correcting astigmatism.

Changes in Brain Microvascular Architecture following Experimental Cold Injury

Sequential changes in the microvascular architecture of rat brains following local freezing injury were studied by scanning electron microscopy involving the cerebrovascular casting method. Repair of the microvascular architecture was initiated on day 3 after injury. Hematogenous cells and reactive astrocytes within the edematous zone participated in the regenerative process. The microvascular architecture was reconstructed from the edge of the lesion toward the brain surface. On the other hand, in small parts of the brain surface subjected to severe, focal freezing, the microvascular architecture was newly formed and resembled that of fetal and newborn rat cortices. Within 7 days after injury, the microvascular architecture was completely repaired.

Computed tomography of bowel infarction.

Bowel infarction is a potentially lethal disorder that is notoriously difficult to diagnose clinically and radiographically. Computed tomography is often used in the early radiographic evaluation of patients with severe abdominal pain of unknown etiology. This study defines the CT findings in patients with bowel infarction. The findings in 22 patients with mesenteric infarction were reviewed. Seven were due to mesenteric arterial occlusion, six due to mesenteric venous occlusion, and nine were nonocclusive. The CT abnormalities were diffuse or focal bowel wall thickening (19 patients), bowel dilatation without mural thickening (three patients), intramural low attenuation zones of edema (eight patients), intramural gas (11 patients), mesenteric gas (five patients), portal or mesenteric venous gas (one patient), mesenteric vascular occlusion (eight patients), and peritoneal gas or fluid (12 patients). The diagnosis of bowel infarction must be considered when performing CT in patients with abdominal pain of unknown etiology.

Detection of a permeability factor produced byHaemophilus pleuropneumoniae

Toxigenic profiles ofHaemophilus pleuropneumoniae were determined for isolates rom serotypes 1 and 5. None of the 18 strains investigated produced hemolytic or proteolytic activity. Intradermal injection of rabbits with culture supernatants induced an edematous zone (permeability factor, PF) for strains of either serotypes. The presence of this PF seemed to depend on the component freshness of the culture media, especially for isolates of serotype 5. PF activity appeared at two different time intervals: at 2–3 h of culture and at 12 h of culture. Isolates ofH. pleuropneumoniae from serotypes 1 and 5 can produce a PF that is not related to hemolytic no proteolytic activity.