Effect of age on cerebral venous circulation disturbances in the rat

Clinical Aspects of Cerebral Venous Thrombosis: Experiences in Two Institutions

Objective

Cerebral venous thrombosis (CVT) is a rare condition for which few clinical reviews have been conducted in Korea. Our aim was to investigate, risk factors, clinical presentations/courses, and outcomes of 22 patients treated for CVT at two centers.

Materials and Methods

A retrospective analysis was conducted, selecting 22 patients diagnosed with and treated for CVT at two patient care centers over a 10-year period (January 1, 2004 to August 31, 2015). Patient data, pathogenetic concerns (laboratory findings), risk factors, locations, symptoms, treatments, and clinical outcomes were reviewed.

Results

Mean patient age at diagnosis was 54.41 ± 16.19. Patients most often presented with headache (40%), followed by seizure (27%) and altered mental status (18%). Focal motor deficits (5%), visual symptoms (5%), and dysarthria (5%) were less common. Important predisposing factors in CVT included prothrombotic conditions (35%), infections (14%), hyperthyroidism (18%), trauma (14%), and malignancy (4%). By location, 9 patients (40%) experienced thrombosis of superior sagittal sinus predominantly, with involvement of transverse sinus in 20 (90%), sigmoid sinus in 12 (40%), and the deep venous system in 5 (23%). Treatment generally consisted of anticoagulants (63%) or antiplatelet (23%) drugs, but surgical decompression was considered if warranted (14%). Medical therapy in CVT yields good functional outcomes.

Conclusion

Mean age of patients with CVT in our study exceeded that reported in Europe or in America and had difference in risk factors. Functional outcomes are good with use of antithrombotic medication, whether or not hemorrhagic infarction is evident.

Frontotemporal epi- and subdural approach to a cavernous sinus tumor for sphenobasal vein preservation--technical case report

In cavernous sinus (CS) surgery, venous complication may occur in some types of venous drainage. The sphenobasal vein (SBV) drains from the superficial middle cerebral vein (SMCV) to the pterygoid venous plexus at the temporal skull base. A frontotemporal epi- and interdural approach (Dolenc approach), which is one of the CS approaches, may damage the SBV's route. We report a case of intracavernous trigeminal schwannoma that contained the SBV and discuss our modified surgical procedure that combined epi- and subdural approaches to preserve the SBV. A 64-year-old man complained of right progressive oculomotor palsy and was referred to our hospital for surgery. MR images revealed a hemorrhagic tumor in the right CS. Three-dimensional venography revealed that the SMCV drained into the pterygoid venous plexus via the SBV. After identifying the first branch of the trigeminal nerve epidurally, we incised the dura linearly along the sylvian fissure and entered the subdural space to visualize the SBV. The incision was continued to the meningeal dura of the lateral wall of the CS along the superior margin of the first branch of the trigeminal nerve, and the Parkinson's triangle was opened from the subdural side. The tumor was grossly totally removed, and the SBV was preserved. In conclusion, a frontotemporal epi- and subdural approach to the intracavernous trigeminal schwannoma can effectively preserve the SBV.

Various patterns of the middle cerebral vein and preservation of venous drainage during the anterior transpetrosal approach

OBJECTIVE

The drainage of the superficial middle cerebral vein (SMCV) has previously been classified into 4 subtypes. Extradural procedures and dural incisions during the anterior transpetrosal approach (ATPA) may interrupt the route of drainage from the SMCV. In this study, the authors examined the relationship between anatomical variations in the SMCV and the corresponding surgical modifications to the ATPA that are necessary for venous preservation.

METHODS

This study included 48 patients treated via the ATPA in whom the SMCV was examined using 3D CT venography. The drainage patterns of the SMCV were classified into 3 types: cavernous or absent (Type 1), sphenobasal (Type 2), and sphenopetrosal (Type 3). Type 2 was subdivided into medial (Type 2a) and lateral (Type 2b), and Type 3 was subdivided into vein (Type 3a), vein and sinus (Type 3b), and sinus (Type 3c). The authors performed 3 ATPA modifications to preserve the SMCV: epidural anterior petrosectomy with subdural visualization of the sphenobasal vein (SBV), modification of the dural incision, and subdural anterior petrosectomy. Standard ATPA can be performed with Type 1, Type 2a, and Type 3a drainage. With Type 2b drainage, an epidural anterior petrosectomy with subdural SBV visualization is appropriate. The dural incision should be modified in Type 3b. With Type 3c, a subdural anterior petrosectomy is required.

RESULTS

The frequency of each type was 68.7% (33/48) in Type 1, 8.3% (4/48) in Type 2a, 4.2% (2/48) in Type 2b, 14.6% (7/48) in Type 3a, 2.1% (1/48) in Type 3b, and 2.1% (1/48) in Type 3c. No venous complications were found.

CONCLUSIONS

The authors propose an SMCV modified classification based on ATPA modifications required for venous preservation.

Venous system in acute brain injury: Mechanisms of pathophysiological change and function

Cerebral vascular injury is a major component of acute brain injury. Currently, neuroprotective strategies primarily focus on the recanalization of cerebral arteries and capillaries, and the protection of insulted neurons. Hitherto, the role of vein drainage in the pathophysiology of acute brain injury has been overlooked, due to an under appreciation of the magnitude of the impact of veins in circulation. In this review, we summarize the changes in the vein morphology and functions that are known, or likely to occur related to acute brain injury, and aim to advance the therapeutic management of acute brain injury by shifting the focus from reperfusion to another term: recirculation. Recent progress in the neurobiological understanding of the vascular neural network has demonstrated that cerebral venous systems are able to respond to acute brain injury by regulating the blood flow disharmony following brain edema, blood brain barrier disruption, ischemia, and hemorrhage. With the evidence presented in this review, future clinical management of acutely brain injured patients will expand to include the recirculation concept, establishing a harmony between arterial and venous systems, in addition to the established recanalization and reperfusion strategies.

Intracranial nonjugular venous pathways: a possible compensatory drainage mechanism

BACKGROUND AND PURPOSE

The IJVs are considered to be the main pathway draining the intracranial venous system. There is increasing evidence for the existence of alternative venous pathways. Studies using extracranial sonography techniques have demonstrated a nonjugular venous system. In the current study, we used MR images to investigate the NJV drainage system and its components (vertebral plexus, pterygopalatine plexus). The exact visualization and measurement of the intracranial NJVs could be of diagnostic importance and may have clinical importance.

MATERIALS AND METHODS

A total of 64 participants with no history of neurologic disease were included in the study. All participants underwent scanning with a 2D time-of-flight, multisection sequence in the supine position. Image processing software was developed to identify and quantify the size of the IJVs and NJVs in the plane of the internal JF. For evaluation of software accuracy, all images were reviewed by a neuroradiologist experienced in neurovascular imaging preprocessing and postprocessing.

RESULTS

The CSA of the NJVs correlated inversely with the CSA of the IJVs (r(2) = 0.25; P < .0001). An inverse correlation was also significant when comparing IJV with NJV components (vertebral plexus: r(2) = 0.19; P = .0004; pterygopalatine plexus: r(2) = 0.11; P = .0069). Furthermore, only NJV cumulative CSA correlated inversely with participant age (r(2) = 0.2; P = .0002).

CONCLUSIONS

Our study indicates that the NJVs might serve as a compensatory drainage mechanism in the intracranial compartment. This mechanism appears less significant as the age of the patient progresses.

Cilostazol minimizes venous ischemic injury in diabetic and normal rats

We evaluated the effects of cilostazol on venous infarction produced by a photothrombotic two-vein occlusion (2VO) model in diabetic and control rats. The cerebral blood flow (CBF) between the occluded veins was measured by laser Doppler flowmetry for 4 hours after 2VO. Infarct size and immunohistochemistry were evaluated 24, 48, 96, and 168 hours after 2VO. Cilostazol was administered 1 hour after 2VO, and thereafter at a continuous oral dose of 60 mg/kg per day. Cilostazol reduced the infarct size, and the number of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL)-positive apoptotic and B-cell lymphoma 2-associated X protein (Bax)-positive cells, and improved the CBF in control rats. In diabetic rats, cilostazol reduced the infarct size, and the number of TUNEL-positive apoptotic and Bax-positive cells, 96 and 168 hours after 2VO, but did not improve the CBF 4 hours after 2VO. Cilostazol increased the number of B-cell lymphoma 2 (Bcl-2)-positive cells in both strains 48, 96, and 168 hours after 2VO, but did not improve vessel wall thickness or collagen deposits. Cilostazol appeared to limit venous infarcts by improving the penumbral CBF in nondiabetic rats, and inhibited pro-apoptotic changes through Bcl-2 overexpression, without improving the CBF in diabetic rats.

Incidence of venous infarction after sacrificing middle-third superior sagittal sinus cortical bridging veins in a pediatric population

OBJECT

The interhemispheric transcallosal approach offers an excellent surgical corridor for the treatment of deep-seated midline lesions. The approach typically requires the sacrifice of one or more middle-third superior sagittal sinus (SSS) cortical bridging veins, which introduces the risk of venous infarction and associated neurological injury. The authors studied the incidence of venous infarcts following this operative approach in a pediatric population.

METHODS

The authors performed a retrospective review of surgical cases involving pediatric patients treated at the Children's Hospital Los Angeles between 1990 and 2007, in which an interhemispheric transcallosal operative procedure was performed and one or more middle-third SSS cortical bridging veins were occluded. Postoperative MR imaging studies done 1-3 days following the procedure were analyzed and compared with preoperative studies.

RESULTS

Sixty-three patients met the inclusion criteria. No patient developed MR imaging evidence of venous infarction.

CONCLUSIONS

The occlusion of one or more middle-third SSS cortical bridging veins related to the interhemispheric transcallosal approach resulted in no incidence of cerebral venous infarction in this pediatric population.

Aging effects on cerebral blood and cerebrospinal fluid flows

Phase-contrast magnetic resonance imaging (PC-MRI) is a noninvasive reliable technique, which enables quantification of cerebrospinal fluid (CSF) and total cerebral blood flows (tCBF). Although it is used to study hydrodynamic cerebral disorders in the elderly group (hydrocephalus), there is no published evaluation of aging effects on both tCBF and CSF flows, and on their mechanical coupling. Nineteen young (mean age 27+/-4 years) and 12 elderly (71+/-9 years) healthy volunteers underwent cerebral MRI using 1.5 T scanner. Phase-contrast magnetic resonance imaging pulse sequence was performed at the aqueductal and cervical levels. Cerebrospinal fluid and blood flow curves were then calculated over the cardiac cycle, to extract the characteristic parameters: mean and peak flows, their latencies, and stroke volumes for CSF (cervical and aqueductal) and vascular flows. Total cerebral blood flow was (P<0.01) decreased significantly in the elderly group when compared with the young subjects with a linear correlation with age observed only in the elderly group (R(2)=0.7; P=0.05). Arteriovenous delay was preserved with aging. The CSF stroke volumes were significantly reduced in the elderly, at both aqueductal (P<0.01) and cervical (P<0.05) levels, whereas aqueduct/cervical proportion (P=0.9) was preserved. This is the first work to study aging effects on both CSF and vascular cerebral flows. Data showed (1) tCBF decrease, (2) proportional aqueductal and cervical CSF pulsations reduction as a result of arterial loss of pulsatility, and (3) preserved intracerebral compliance with aging. These results should be used as reference values, to help understand the pathophysiology of degenerative dementia and cerebral hydrodynamic disorders as hydrocephalus.

Sequential and spatial profiles of apoptosis in ischemic penumbra after two-vein occlusion in rats

Object

The two-vein occlusion model is known to be useful for ischemic penumbra studies in vivo. It was applied here to examine sequential changes in the expression of Bax and Bcl-2 proteins and in apoptotic cells to assess the relationship between penumbra and apoptosis.

Methods

Two cortical veins were occluded photochemically by using rose bengal dye in 27 Wistar rats. The animals were killed with perfusion fixation at the following intervals: 4, 12, 24, 48, 96, and 168 hours after vein occlusion (four at each interval; three additional rats were sham-treated). Immunohistochemical analysis for the Bcl-2 family of proteins was performed along with the terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick-end labeling (TUNEL) assay to examine the relationship to single-cell death.

Cells positive for antiapoptotic proteins began to appear in the TUNEL assay for animals killed 24 hours after vein occlusion, with a peak at 48 hours. These cells were localized in the core of infarction. Immunohistochemical staining for Bax protein showed an increased presence around ischemic lesions at 4 hours after vein occlusion, and the amounts continued to rise until 24 hours, when the localization was diffuse around the core of infarction. Negative findings on immunohistochemical studies for Bcl-2 protein were seen at the early phase after two-vein occlusion.

Conclusions

After vein occlusion, apoptosis appeared sequentially and widely in cortical lesions considered to be the penumbra. Therefore, control of apoptosis would be expected to offer a therapeutic window for treatment of venous infarction.

Adult neurogenesis and the ischemic forebrain

The recent identification of endogenous neural stem cells and persistent neuronal production in the adult brain suggests a previously unrecognized capacity for self-repair after brain injury. Neurogenesis not only continues in discrete regions of the adult mammalian brain, but new evidence also suggests that neural progenitors form new neurons that integrate into existing circuitry after certain forms of brain injury in the adult. Experimental stroke in adult rodents and primates increases neurogenesis in the persistent forebrain subventricular and hippocampal dentate gyrus germinative zones. Of greater relevance for regenerative potential, ischemic insults stimulate endogenous neural progenitors to migrate to areas of damage and form neurons in otherwise dormant forebrain regions, such as the neostriatum and hippocampal pyramidal cell layer, of the mature brain. This review summarizes the current understanding of adult neurogenesis and its regulation in vivo, and describes evidence for stroke-induced neurogenesis and neuronal replacement in the adult. Current strategies used to modify endogenous neurogenesis after ischemic brain injury also will be discussed, as well as future research directions with potential for achieving regeneration after stroke and other brain insults.

Cerebral Vein and Dural Sinus Thrombosis in Elderly Patients

Backgound and Purpose— The clinical features and prognosis of cerebral vein and dural sinus thrombosis (CVT) in elderly patients have not been previously described.

Methods— In a multicenter prospective observational study, we compared clinical and imaging features, risk factors, and outcome of adult patients aged <65 (young and middle-aged patients) and ≥65 years (elderly patients).

Results— A total of 624 adult patients with CVT were registered and followed-up for a median of 16 months. Fifty-one (8.2%) were aged ≥65 years. Presentation as an isolated intracranial hypertension syndrome was less frequent in elderly patients (4/51 versus 139/573, P =0.008), whereas depressed consciousness (17 versus 97, P =0.005), and mental status changes (22 versus 115, P =0.001) were more frequent in the elderly. The prognosis of elderly patients was considerably worse than that of younger patients, as only 49% of elderly patients made a complete recovery (versus 82% in younger patients), whereas 27% died and 22% were dependent at the end of follow-up (versus 7 and 2% respectively in younger patients). Carcinoma (5 cases) was more frequent as a risk factor for CVT in elderly patients ( P =0.017). During follow-up, elderly patients were more likely to experience thrombotic events (HR=4.8, 95% CI=1.9 to 11.9) and were less likely to experience severe headaches (HR=0.2, 95% CI=0.02, 0.97).

Conclusions— Elderly patients with CVT have a distinctive clinical presentation: isolated intracranial hypertension is uncommon, whereas mental status and alertness disturbances are common. The prognosis of CVT is worse in elderly patients.

Physiology of cerebral venous blood flow: from experimental data in animals to normal function in humans

In contrast to the cerebroarterial system, the cerebrovenous system is not well examined and only partly understood. The cerebrovenous system represents a complex three-dimensional structure that is often asymmetric and considerably represent more variable pattern than the arterial anatomy. Particular emphasis is devoted to the venous return to extracranial drainage routes. As the state-of-the-art-imaging methods are playing a greater role in visualizing the intracranial venous system at present, its clinically pertinent anatomy and physiology has gain increasing interest, even so only few data are available. For this reason, experimental research on specific biophysical (fluid dynamic, rheologic factors) and hemodynamic (venous pressure, cerebral venous blood flow) parameters of the cerebral venous system is more on the focus; especially as these parameters are different to the cerebral arterial system. Particular emphasis is devoted to the venous return to extracranial drainage routes. From the present point of view, it seems that the cerebrovenous system may be one of the most important factors that guarantee normal brain function. In the light of this increasing interest in the cerebral venous system, the authors have summarized the current knowledge of the physiology of the cerebrovenous system and discuss it is in the light of its clinical relevance.

Cerebral blood flow at one year after controlled cortical impact in rats: assessment by magnetic resonance imaging

Progressive tissue loss and delayed cognitive deficits are seen in rats during the initial year after experimental traumatic brain injury (TBI). As much as 10% of parenchymal volume is lost even in the contralateral hemisphere by 1 year after controlled cortical impact (CCI) in rats. Progressive declines in cerebral blood flow (CBF) are also associated with advanced age and neurodegenerative diseases. Surprisingly, the long-term effects of TBI on CBF remain undefined. CBF was quantified by continuous arterial spin-labeled magnetic resonance imaging (MRI) and measurements of spin-lattice relaxation time in a slice through the plane of injury at 1 year after experimental TBI produced by CCI (n = 4) or sham surgery (n = 4) in rats. CBF was quantified in six regions of interest (ROIs) that were anatomically identified on the control images in each hemisphere and included a medial cortical segment (contusion-enriched, beneath the impact site, on the ipsilateral side) cortex, hippocampus, thalamus, amygdala/pyriform cortex, and hemisphere. At 1 year after injury, CBF was dramatically (96%) reduced in structures within the large cystic lesion that was seen in three of four rats and variably included cortex and hippocampus. Overall, there was an 80% reduction in CBF in the ipsilateral medial cortical segment comparing CCI and sham groups. Similarly, 52% and 67% reductions were seen in CBF in the cortical and hippocampal ROIs ipsilateral to impact (CCI vs. sham), respectively. These are regions both with marked CBF disturbances early after injury and that ultimately suffer considerable tissue loss over the 1-year interval. However, at 1 year after CCI, CBF was not different from sham in other ROIs, including ipsilateral thalamus, or either contralateral hippocampus or hemisphere. We conclude that, at 1 year after CCI, CBF is reduced in anatomic structures at or near the impact site, including injured cortex and hippocampus, and this translates into a reduction in hemispheric CBF. However, despite both significant occult tissue loss ipsilateral and contralateral to the injury and delayed cognitive deficits, widespread reductions in CBF are not observed. This suggests the possibility of remodeling or repackaging of the brain that preserves CBF outside of the cystic lesion.