Watershed Zone Research Articles

Reversibility of White Matter Hyperintensity by Revascularization Surgery in Moyamoya Disease

White matter lesions (WMLs) indicate progressive cerebral small vessel disease and are frequently observed in aging people and stroke patients. The purpose of this study was to evaluate WMLs and the influence of revascularization surgery for WMLs in patients with moyamoya disease. A total of 42 hemispheres in 21 patients with moyamoya disease were included in this analysis. WMLs were detected on fluid-attenuated inversion recovery (FLAIR) imaging in 24 hemispheres. The distribution pattern of WMLs was categorized. WMLs were measured by manually creating a region of interest, and the total WML volume in the hemisphere was estimated and compared with the control group. Clinical features of patients with WMLs and postoperative changes were analyzed. The total WML volume in moyamoya disease was significantly higher than that of controls (P = .014). WMLs were observed in the internal watershed zone, especially in the watershed zone between the anterior cerebral artery and the middle cerebral artery. Patients with WMLs had significantly higher magnetic resonance angiography scores compared with controls (P = .015). A given patient's total WML volume per hemisphere was significantly decreased after surgery (P = .001). WMLs on FLAIR imaging increase in patients with moyamoya disease and are reversible by revascularization surgery. Improvement of cerebral blood flow is partly related to the decrease in WMLs. The present results provide insight into the potential role of revascularization surgery.

Intracranial bleeding from collaterals following carotid artery occlusion

A 53-year-old right-handed woman developed left pulsatile tinnitus. One year later she presented with a severe occipital headache with neck stiffness while defecating. On admission to hospital she was normotensive...

Lenticulostriate arterial distribution pathology may underlie pediatric anoxic brain injury in drowning.

Drowning is a leading cause of neurological morbidity and mortality in young children. Anoxic brain injury (ABI) can result from nonfatal drowning and typically entails substantial neurological impairment. The neuropathology of drowning-induced pediatric ABI is not well established. Specifically, quantitative characterization of the spatial extent and tissue distribution of anoxic damage in pediatric nonfatal drowning has not previously been reported but could clarify the underlying pathophysiological processes and inform clinical management. To this end, we used voxel-based morphometric (VBM) analyses to quantify the extent and spatial distribution of consistent, between-subject alterations in gray and white matter volume. Whole-brain, high-resolution T1-weighted MRI datasets were acquired in 11 children with chronic ABI and 11 age- and gender-matched neurotypical controls (4–12 years). Group-wise VBM analyses demonstrated predominantly central subcortical pathology in the ABI group in both gray matter (bilateral basal ganglia nuclei) and white matter (bilateral external and posterior internal capsules) (P < 0.001); minimal damage was found outside of these deep subcortical regions. These highly spatially convergent gray and white matter findings reflect the vascular distribution of perforating lenticulostriate arteries, an end-arterial watershed zone, and suggest that vascular distribution may be a more important determinant of tissue loss than oxygen metabolic rate in pediatric ABI. Further, these results inform future directions for diagnostic and therapeutic modalities.

Analysis of Fundus Photography and Fluorescein Angiography in Nonarteritic Anterior Ischemic Optic Neuropathy and Optic Neuritis.

PurposeWe evaluated fundus and fluorescein angiography (FAG) findings and characteristics that can help distinguish nonarteritic anterior ischemic optic neuropathy (NAION) from optic neuritis (ON).MethodsTwenty-three NAION patients and 17 ON with disc swelling patients were enrolled in this study. We performed fundus photography and FAG. The disc-swelling pattern, hyperemia grade, presence of splinter hemorrhages, cotton-wool spots, artery/vein ratio and degree of focal telangiectasia were investigated. The FAG findings for each patient were compared with respect to the following features: the pattern of disc leakage in the early phase, arteriovenous (artery/vein) transit time (second), and the presence and pattern of the filling delay.ResultsCotton-wool spots, focal telangiectasia, and venous congestion were more common in the affected eyes of NAION patients. Upon FAG, 76.5% of the patients in the ON group exhibited normal choroidal circulation. However, 56.5% of patients in the NAION group demonstrated abnormal filling defects, such as peripapillary, generalized, or watershed zone filling delays.ConclusionsFundus findings, including cotton-wool spots, focal telangiectasia, and venous congestion in the affected eye, may be clues that can be used to diagnose NAION. In addition, choroidal insufficiencies on FAG could be also helpful in differentiating NAION from ON.

Bilateral retinal pigment epithelial rips in hypertensive choroidopathy

Severe systemic hypertension can cause significant damage to the eye. Although hypertensive retinopathy is a well-known complication, hypertensive optic neuropathy and hypertensive choroidopathy are much less common. The aim of this article is to report an unusual case of hypertensive choroidopathy with bullous exudative retinal detachments in both eyes. The retinal detachments spontaneously resolved after blood pressure was controlled. However, multiple large retinal pigment epithelial (RPE) rips were found in both eyes. These RPE rips may be related to severe choroidal ischemia, and their locations may be compatible with the watershed zones of the choroidal perfusions.

Topographical relationship between the choroidal watershed zone and submacular idiopathic choroidal neovascularisation

AimsTo investigate the relationship between idiopathic choroidal neovascularisation (CNV) and choroidal watershed zones (CWZs) using indocyanine green angiography (ICGA).DesignMulticentre, retrospective, interventional case series.MethodsThe medical records and ICGA findings of 44...

Characteristic neuroradiologic features in hemorrhagic shock and encephalopathy syndrome.

Hemorrhagic shock and encephalopathy syndrome is a devastating disease, but the pathogenesis remains unclear. The aim of this study was to examine the usefulness of neuroimaging in establishing a diagnosis and elucidating the pathogenesis. We analyzed the neuroradiologic features of 22 patients who fulfilled the Levin criteria. All patients underwent brain computed tomography (CT), and 14 patients underwent brain magnetic resonance imaging (MRI) including diffusion-weighted imaging in 10 patients. Initial CT showed normal findings in 14 of 18 (78%) patients, but subsequently hypodensities appeared in bilateral watershed zones and progressed to whole brain edema. MRI revealed cytotoxic edema, showing hyperintensities in bilateral watershed zones on diffusion-weighted imaging with a low apparent diffusion coefficient. Serial neuroimaging showed characteristic features of a widespread brain ischemic event mainly in watershed zones in hemorrhagic shock and encephalopathy syndrome.

The collateral circulation in pediatric moyamoya disease.

The descriptions of collateral circulation in moyamoya have so far been a mixture of topography-based and vessels' source-based analyses. We aimed to investigate the anatomy and systematize the vascular anastomotic networks in pediatric moyamoya disease. From a series of 25 consecutive complete angiographic studies of newly diagnosed children with moyamoya, 14 children had moyamoya disease and 11 were diagnosed with moyamoya syndrome, i.e., moyamoya angiopathy with some additional concomitant systemic disease. We retrospectively analyzed the arterial branches supplying the moyamoya anastomotic networks, their origin, course, location, and connections with the recipient vessels. We describe four types of anastomotic networks in children with moyamoya disease, two superficial-meningeal and two deep-parenchymal. As superficial-meningeal, we defined the leptomeningeal and the durocortical networks. Apart from the previously described leptomeningeal network observed in the convexial watershed zones, we report on the basal temporo-orbitofrontal leptomeningeal network. The second superficial-meningeal network is the durocortical network, which can be basal or calvarian in location. We define as deep-parenchymal networks the nonpreviously described subependymal network and the inner striatal and inner thalamic networks. The subependymal network is fed by the intraventricular branches of the choroidal system and diencephalic perforators, which at the level of the periventricular subependymal zone, anastomose with medullary-cortical arteries as well as with striatal arteries. The inner striatal and thalamic networks are constituted by intrastriatal connections among striatal arteries and intrathalamic connections among thalamic arteries when the disease compromises the origin of one or more sources of their supply. The previously inexplicitly described "moyamoya abnormal network" in pediatric moyamoya disease can be described as a composition of four anastomotic networks with distinct angioarchitecture. A better understanding of the collateralization in moyamoya may help in defining a new staging system of the disease with clinical relevance.

Effect of Lower Extremity Fasciotomy Length on Intracompartmental Pressure in an Animal Model of Compartment Syndrome

Background: There has been an increase in minimally invasive surgery for chronic exertional compartment syndrome (CECS), despite the potential for incomplete compartment release and iatrogenic injuries. To our knowledge, no study has examined the effect of the length of fascial release on compartment pressures. Purpose/Hypothesis: The purpose was to explain the high failure rate seen in fascial release for CECS by evaluating the effect of fasciotomy length on intracompartmental pressures. We hypothesized that complete fascial release would need to be performed to return pressures to baseline levels. Study Design: Controlled laboratory study. Methods: Five male swine (10 lower extremities) were anesthetized. A slit catheter, connected to a pressure monitor, was inserted into the anterior compartment and a solution containing 5% swine albumin was injected into the compartment until the compartment pressure was >25 mm Hg for 10 minutes. Pressures were measured at rest, after the injection, and after each 10% incremental fasciotomy release. Results: The mean resting intracompartmental pressure was 3.2 mm Hg (range, 0-6 mm Hg), which increased after the injection to a mean of 37 mm Hg (range, 26-67 mm Hg). After complete fasciotomy, the mean pressure was 1.1 mm Hg (range, 0-4 mm Hg). There was a strong negative correlation (r = −0.693) between fasciotomy length and intracompartmental pressure. In 90% of the specimens, the pressures were <15 mm Hg after 80% fascial release, and after 90% release, all pressures were ≤8 mm Hg. Conclusion: This study demonstrates a strong correlation between fasciotomy length and a reduction in intracompartmental pressures in a swine model. Our study suggests that 90% fascial release may represent a possible watershed zone, returning the intracompartmental pressure to a value at or near baseline values. Clinical Relevance: The results suggest that even in cases with near complete fascial release, intracompartmental pressures may decrease enough to provide symptomatic relief and avoid possible iatrogenic injuries associated with percutaneous release. It is unknown whether the swine model may adequately translate to the clinical setting; thus, recommendations should be taken with caution, and future studies should be performed to examine the correlation in a human model.

Patterns of Cerebral Ischemia in Children With Moyamoya

BackgroundMoyamoya disease is characterized by progressive cerebrovascular stenosis with recurrent cerebral ischemic events. Transient ischemic attacks are often associated with hyperventilation in children with moyamoya, suggesting hypoperfusion rather than thrombotic vaso-occlusion as a prominent mechanism. The patterns of ischemia and severity of steno-occlusive disease in such children may elucidate these mechanisms. MethodsChildren, 1 month to 18 years, with moyamoya, observed over 11 years were analyzed. A study neuroradiologist reviewed all presurgical neuroimaging. Ischemic injury was categorized into cortical, subcortical, and watershed infarction. Angiographic findings were staged using a standardized method. ResultsTwenty children, 15 girls, median age 6.4 years, were included. All children had magnetic resonance imaging and angiography, and in 16, conventional angiography was available. All 40 hemispheres, in 20 children, were evaluated. The initial clinical presentation included neurological deficits in 17, recurrent transient ischemic attacks in 7, headache in 8, seizures in 8, and alteration in consciousness in 4 children. Infarcts were bilateral in 13 (65%) children (ischemia alone in 14, ischemic stroke with hemorrhagic transformation in two, and primary hemorrhage in two). Infarcts were cortical and/or subcortical in 13 (65%), both deep and cortical watershed in 11 (55%), and cortical watershed alone in 5 (25%) children. The predominant vascular territory involved was the middle cerebral artery. The internal carotid arterial system was involved in all, with stage IV being the most frequent angiographic stage. ConclusionsIschemic injury in deep watershed zones is common in childhood moyamoya and may reflect non–vaso-occlusive ischemic mechanisms. Location and severity of vascular involvement may correlate with various patterns of ischemic infarction in moyamoya disease and requires further study.

Periconal arterial anastomotic circle and posterior lumbosacral watershed zone of the spinal cord

BackgroundThe existence of spinal cord watershed territories was suggested in the 1950s. Segmental infarcts within the junctional territories of adjacent radiculomedullary contributors and isolated spinal gray matter ischemia constitute two...

The Clinical Spectrum of Microcystic Macular Edema

Microcystic macular edema (MME), originally described in British literature as microcystic macular oedema (MMO), defines microcysts in the inner nuclear layer (INL) of the retina. Microcystic macular edema was described in multiple sclerosis (MS), but can be found in numerous disorders. The presence of MME has important prognostic and therapeutic implications; however, the differential diagnosis is unknown. This study aimed to describe the clinical spectrum of MME. A single-center, retrospective cohort study. A bootstrap analysis was performed to reduce the 5865 patients (22,376 scans), who had undergone OCT imaging between January 2010 and February 2013, to a representative dataset. The presence of MME was rated by independent observers. The dataset consisted of 1368 patients (mean age 62, range, 4-101 years), 2589 eyes and 6449 scans. Microcystic macular edema was present in 133/1303 (10%) of patients and 0/65 (0%) of healthy controls. The interrater agreement for detecting MME was substantial (kappa 0.6) and could be further improved after refining the criteria (kappa 0.8). The clinical spectrum included age-related macular degeneration, epiretinal membranes, postoperative lesions, diabetic retinopathy, vascular occlusion, MS (with/without optic neuritis), optic neuropathy, central serous chorioretinopathy, medication, and miscellaneous causes. The longitudinal pattern of MME was transient (84%) or static. Microcystic macular edema could be associated with an increase or decrease in INL thickness and was predominantly located nasally (48%) and/or temporally (50%). This study substantially widened the clinical spectrum of MME. Diagnostic criteria were refined and validated. The associated phenotype may imply Müller cell dysfunction within the watershed zone. The longitudinal data and evidence from previous studies suggest follow-up of these patients and their visual function.

Relationship among Water-Shed Zone, Nocturnal Dip and Visual Field Progression in Open Angle Glaucoma

Purpose: To investigate the influence of water-shed zone (WSZ) and nocturnal dip (ND) on the progression of the glaucomatous visual field (V/F) defects in open-angle glaucoma (OAG) patients when the intraocular pressure (IOP) was maintained under the target pressure. Methods: We performed fluorescence angiography (FAG), 24-hour ambulatory blood pressure monitoring (24-hr ABPM), and V/F tests. We examined the relationships among WSZ in early-FAG, ND over 10% (dip), and the progression of the glaucomatous V/F defects using chi-square, Fisher’s exact, and multivariate logistic regression tests. A p-value < 0.05 was considered statistically significant. Results: When considering the correlation between WSZ and dip, statistical significance was found in OAG (p = 0.024, odds ratio (OR) = 3.308) and normal tension glaucoma (NTG) (p = 0.029, OR = 4.364) patients. In patients with dip, glaucomatous V/F defects significantly progressed (OAG: p = 0.003, OR = 5.938, NTG: p = 0.005, OR = 13.929). In patients with WSZ, the glaucomatous V/F defects progressed in all groups (OAG: p = 0.002, OR = 5.156, NTG: p = 0.024, OR = 4.750, primary open angle glaucoma (POAG): p = 0.021, OR = 8.750). In the patients with WSZ involving optic nerve head, the glaucomatous V/F defects had progressed in OAG (p = 0.004, OR = 5.958) and NTG (p = 0.009, OR = 8.333) groups. Based on binary logistic regression analysis, dip (p = 0.010, OR = 6.227) significantly affected V/F progression only in OAG patients. Conclusions: In the OAG and NTG groups, ND over 10% influenced the progression of the glaucomatous V/F defects. The patients with WSZ tended to have ND over 10% in OAG and NTG groups and glaucomatous V/F defects progressed in all patients. Therefore, performing early FAG and 24-hr ambulatory blood pressure monitoring may be helpful for glaucoma patients with progressing glaucomatous V/F defects even when the IOP was maintained under the target pressure. J Korean Ophthalmol Soc 2014;55(7):1030-1038

Cerebral perfusion changes in patients with carotid artery stenosis after surgical revascularization

Assessment of cerebral perfusion and collateral circulation in patients with carotid stenosis might have prognostic value for effective blood flow restoration after carotid revascularization. To evaluate the changes of cerebral perfusion we studied 41 patients with moderate and severe carotid stenosis before and after surgical or endovascular treatment. Perfusion CT at the level of basal ganglia was performed in 17 patients with moderate (50–69%) and 24 patients with severe (70–99%) carotid stenosis for 3 times: before intervention (transluminal angioplasty with stenting or carotid endarterectomy), 3 to 7 days and 1 to 3 months after treatment. Additionally, single CT perfusion study was done in 39 patients without carotid stenosis (control group). We found that surgical recanalization of internal carotid artery may aid restoring cerebral blood flow characteristics in the MCA area to the levels similar to those in control group (namely, decrease of MTT and CBV and increase of CBF). However, in anterior and posterior watershed zones, which are known to be the most vulnerable by chronic hypoperfusion, blood flow normalization was seen only in patients with complete circle of Willis and with moderate carotid stenosis.Thus, prognostic factors for inadequate blood flow restoration in patients with carotid artery stenosis after revascularization include severe stenosis (>70%) and incomplete circle of Willis.

Predominant Hypertensive Brainstem Encephalopathy with Supratentorial Involvement: Case Report and Literature Review

Hypertensive encephalopathy is an acute disorder characterized by severe hypertension, headache, vomiting, altered mental status, visual changes, and seizures. Syndromes of hypertensive encephalopathy are usually reversible if quickly diagnosed and treated. The most common finding of hypertensive encephalopathy is bilateral edema in the supratentorial white matter, especially in the parieto-occipital area. However, atypical feature of hypertensive encephalopathy involving the frontal lobes, brainstem, cerebellum, cortical watershed zones, and basal ganglia has been sporadically reported. Brainstem and/or cerebellar lesions may be presented as the only abnormalities in unusual cases (1). Here we report three cases of hypertensive encephalopathy involving brainstem showing characteristic alternating linear bright and low signals in the pons on T2-weighted magnetic resonance imaging (MRI), although many brainstem lesions showed no peripheral sparing compared to those of osmotic demyelination (2). This retrospective study has been approved by our Institutional Review Board. The requirement for obtaining informed consent from patients was waived.

The Artery of von Haller

Although recognized since the 18th century, radiculomedullary arteries (RMAs) originating from upper thoracic intersegmental arteries are generally considered to be inconstant branches of little clinical importance. Yet, such vessels are commonly observed during spinal angiography. To evaluate the angiographic prevalence of upper thoracic RMAs, in particular, branches supplying the anterior spinal artery (ASA). Fifty spinal angiograms were reviewed. Anterior and posterior RMAs originating in the upper thoracic region (T3 to T7) were recorded. The level of origin of the artery of Adamkiewicz (T8 to L3) was also noted. Forty-three patients (86%) had at least 1 ASA contributor between T3 and T7. Of the other 7 patients, 4 had one at an immediately adjacent level (T2 or T8). The most frequent origin of upper thoracic anterior RMAs was left T5 (n = 10). Only left T9 (n = 12) and left T8 (n = 11) were more common. When combining the left and right sides, an ASA contributor was more frequent at T5 (n = 16) than at any other level (n = 15 for T9, n = 14 for T8). The sum of ASA contributors at T4 and T5 (n = 27) represented 54% of all upper thoracic anterior RMAs, and 23% of all anterior RMAs between T3 and L3. A significant upper thoracic anterior RMA distinct from the artery of Adamkiewicz appears to be a constant anatomic feature, which undermines the classic concept of an arterial watershed zone in the thoracic region. We propose to name this artery after Albrecht von Haller, who documented its existence in 1754.

Postoperative Increase in Cerebral White Matter Fractional Anisotropy on Diffusion Tensor Magnetic Resonance Imaging Is Associated With Cognitive Improvement After Uncomplicated Carotid Endarterectomy

Carotid endarterectomy (CEA) might improve cognitive function. Fractional anisotropy (FA) values in the cerebral white matter derived from diffusion tensor magnetic resonance imaging (DTI) correlate with cognitive function in patients with various central nervous system diseases. To use tract-based spatial statistics to determine whether postoperative changes of FA values in the cerebral white matter derived from DTI are associated with cognitive improvement after uncomplicated CEA. In 80 patients undergoing CEA for ipsilateral internal carotid artery stenosis (≥70%), FA values in the cerebral white matter were derived from DTI before and 1 month after surgery and were analyzed by using tract-based spatial statistics. Neuropsychological testing, consisting of the Wechsler Adult Intelligence Scale Revised, the Wechsler Memory Scale and the Rey-Osterreith Complex Figure test, was also performed preoperatively and after the first postoperative month. Based on the neuropsychological assessments, 11 (14%) patients were defined as having postoperatively improved cognition. The difference between the 2 mean FA values (postoperative values minus preoperative values) in the cerebral hemisphere ipsilateral to surgery was significantly associated with postoperative cognitive improvement (95% confidence intervals, 2.632-9.877; P = .008). White matter FA values in patients with postoperative cognitive improvement were significantly increased after surgery in the whole ipsilateral cerebral hemisphere, in the contralateral anterior cerebral artery territory, and in the watershed zone between the contralateral anterior and middle cerebral arteries. Postoperative increase in cerebral white matter FA on DTI is associated with cognitive improvement after uncomplicated CEA.

Predicting climate-induced changes in groundwater resources on the basis of hydrogeological model research: Case study of the Carpathian flysch belt

The level of water in aquifers depends mostly on precipitation. However, recent research has shown that greater annual rainfall values do not necessarily trigger off an automatic increase in groundwater recharge. The lowering of the water table may result not only from lower precipitation, but also from intensification in evaporation and a decreased natural infiltration capacity of drieddown soil. Also extreme rainfall conditions (such as torrential rain and storms) that occur in mountainous regions may, owing to a rise in surface runoff and decreased infiltration, lead to a lower groundwater recharge. Studies seem to indicate that in the upper drainage basin of the river Muszynka (southern Poland) a ten year period of precipitation equal to 62% of the long-term average is likely to cause the groundwater levels (present in the Palaeogene flysch formations) to drop by two metres in river valleys and 40 metres in watershed zones and central parts of slopes. This will result in a reduction of groundwater resources related to aquifer compressibility makes up only 3.4x10 -5 % of the annual underground runoff; therefore, it is not necessary to include it in the overall water balance.

Localized Reticular Pseudodrusen and Their Topographic Relation to Choroidal Watershed Zones and Changes in Choroidal Volumes

We identified a topographic relation of localized reticular pseudodrusen (RPD) to choroidal watershed zones (CWZ) and to changes in choroidal volumes (CV). We included 30 eyes of 30 patients with RPD in an area <10 mm(2) and no other retinal alteration (76.7 ± 6.9 years). Patients underwent spectral-domain optical coherence tomography (SD-OCT), enhanced depth imaging (EDI) OCT, fluorescein video-angiography (vFA), indocyanine green video-angiography (vICG), and confocal scanning laser ophthalmoscopy (cSLO). vICG was evaluated for the presence, localization, and configuration of CWZ. Retinal areas affected by RPD were measured, and their localization was determined in relation to CWZ. CV was measured using a choroidal thickness map of the posterior pole and the Early Treatment of Diabetic Retinoscopy Study (ETDRS) grid. In all study eyes, RPD could be demonstrated clearly in SD-OCT, EDI-OCT, FA, ICG, and cSLO. CWZ were identified in 25 eyes (83.3%). The area affected by RPD was 7.45 ± 2.25 mm(2). RPD area was located fully or partly within the CWZ in 22 eyes (88.0%). Mean CV in the full ETDRS grid area was reduced significantly (4.49 ± 1.44 mm(3)). Foveal CV and CV in the grid sector affected mostly by RPD were significantly diminished to 0.14 ± 0.05 mm(3) and 0.85 ± 0.38 mm(3), respectively. The site of localized RPD seems to be related to presence and site of CWZ, suggesting that choroidal hypoxia may have a role in RPD pathogenesis. Reduced CV in eyes with localized RPD could be demonstrated and may be cause or consequence of RPD development.

Isolated Bilateral Middle Cerebellar Peduncle Infarcts

Our objective is to report an interesting case of a patient with known severe vertebrobasilar disease who presented with isolated bilateral middle cerebellar peduncle (MCP) infarction. Isolated infarction of the MCP is uncommon, occurring in roughly 0.12% of acute strokes. Isolated bilateral MCP infarction is extremely rare and has been described in only a few cases in the literature. The MCP is a watershed zone between the anterior inferior cerebellar artery and the superior cerebellar artery and its occurrence suggests hypoperfusion.