Low levels of plasminogen in cerebrospinal fluid after intraventricular haemorrhage: a limiting factor for clot lysis?

Endoproteolysis of cellular prion protein by plasmin hinders propagation of prions

Many questions surround the underlying mechanism for the differential metabolic processing observed for the prion protein (PrP) in healthy and prion-infected mammals. Foremost, the physiological α-cleavage of PrP interrupts a region critical for both toxicity and conversion of cellular PrP (PrP ^C ) into its misfolded pathogenic isoform (PrP ^Sc ) by generating a glycosylphosphatidylinositol (GPI)-anchored C1 fragment. During prion diseases, alternative β-cleavage of PrP becomes prominent, producing a GPI-anchored C2 fragment with this particular region intact. It remains unexplored whether physical up-regulation of α-cleavage can inhibit disease progression. Furthermore, several pieces of evidence indicate that a disintegrin and metalloproteinase (ADAM) 10 and ADAM17 play a much smaller role in the α-cleavage of PrP ^C than originally believed, thus presenting the need to identify the primary protease(s) responsible. For this purpose, we characterized the ability of plasmin to perform PrP α-cleavage. Then, we conducted functional assays using protein misfolding cyclic amplification (PMCA) and prion-infected cell lines to clarify the role of plasmin-mediated α-cleavage during prion propagation. Here, we demonstrated an inhibitory role of plasmin for PrP ^Sc formation through PrP α-cleavage that increased C1 fragments resulting in reduced prion conversion compared with non-treated PMCA and cell cultures. The reduction of prion infectious titer in the bioassay of plasmin-treated PMCA material also supported the inhibitory role of plasmin on PrP ^Sc replication. Our results suggest that plasmin-mediated endoproteolytic cleavage of PrP may be an important event to prevent prion propagation.

Identifying the Specific Subtype of Intracerebral Hemorrhage that is Indicated for Minimally Invasive Craniopuncture

BACKGROUND

Surgeries for intracerebral hemorrhage (ICH) remain controversial. Our previous study found that postoperative cerebrospinal fluid (CSF) outflow was associated with high hematoma evacuation efficiency in ICH cases with intraventricular involvement (ICHV) treated with minimally invasive craniopuncture (MIC). This study was designed to identify factors that predict postoperative CSF outflow and the specific subtype of ICHV that may benefit from MIC.

METHODS

A total of 189 MIC needles applied to 125 ICHV patients were retrospectively analyzed. Univariate and multivariate analyses were used to identify independent predictive factors of postoperative CSF outflow.

RESULTS

A density of the whole hematoma of ≤ 59 HU [odds ratio (OR) = 8.572, 95% confidence interval (CI) 3.235-22.714, P < 0.001, standardization regression coefficients B' = 0.576] and a distance between the needle tip and the ventricular tear (tip-tear distance) of 21.79-34.15 mm (OR = 25.566, 95% CI 8.707-75.074, P < 0.001, B' = 0.883) were identified as independent predictive factors of postoperative CSF outflow. The density of the hematoma within 34.15 mm of the tear (clot 3.4) showed no statistical difference from that of the whole hematoma (P = 0.571). A density of clot 3.4 ≤ 60 HU was also a predictive factor of postoperative CSF outflow (area under curve: 0.771).

CONCLUSIONS

ICHV patients who meet the following conditions may benefit from MIC: (1) The MIC needle tip can be placed in the hematoma 21.79-34.15 mm from the ventricular tear; (2) the density of the whole hematoma is low (≤ 59 HU); and (3) the density of clot 3.4 is also low (≤ 60 HU). Future perspective studies should be conducted on this specific patient subtype.

uPA alleviates kaolin-induced hydrocephalus by promoting the release and activation of hepatocyte growth factor in rats

Urokinase-type plasminogen activator (uPA) was demonstrated to alleviate kaolin-induced communicating hydrocephalus via inhibiting subarachnoid space fibrosis, but the exact mechanism remains elusive. Thus, this study was designed to investigate if hepatocyte growth factor (HGF), which plays a vital role in uPA-triggered inhibiting of fibrosis in multiple systems, is involved in this process in hydrocephalus. There were 2 parts in this study. First, hydrocephalus was induced in rats by basal cistern injection of kaolin. Then rats were treated with saline or uPA and brain tissue and CSF were collected for Western blot and enzyme-linked immuno sorbent assay (ELISA) four days later. Second, kaolin-induced hydrocephalus rats were treated with saline, uPA, uPA + PHA665752 (antagonist of HGF) or PHA665752. Some animals received MRI four weeks later and brains were used for immunofluorescence. The others were euthanized four days later for ELISA. Both levels of total and activated HGF in the CSF was increased after uPA injections, but related mRNA expression of HGF showed no statistical significance when compared with the control group. Further, the effects of uPA that alleviating ventricular enlargement, subarachnoid fibrosis and reactive astrocytosis were partially reversed by PHA665752. Moreover, PHA665752 partially abolished uPA-induced reduction of transforming growth factor- β1(TGF- β1) level in CSF. Our data suggest that uPA effectively inhibited subarachnoid fibrosis and restricted the development of communicating hydrocephalus in rats in part by promoting HGF release and activation, which may further regulate the TGF-β1 expression in CSF.

Nonsurgical therapy for hydrocephalus: a comprehensive and critical review

Pharmacological interventions have been tested experimentally and clinically to prevent hydrocephalus and avoid the need for shunting beginning in the 1950s. Clinical trials of varied quality have not demonstrated lasting and convincing protective effects through manipulation of cerebrospinal fluid production, diuresis, blood clot fibrinolysis, or manipulation of fibrosis in the subarachnoid compartment, although there remains some promise in the latter areas. Acetazolamide bolus seems to be useful for predicting shunt response in adults with hydrocephalus. Neuroprotection in the situation of established hydrocephalus has been tested experimentally beginning more recently. Therapies designed to modify blood flow or pulsation, reduce inflammation, reduce oxidative damage, or protect neurons are so far of limited success; more experimental work is needed in these areas. As has been recommended for preclinical studies in stroke and brain trauma, stringent conditions should be met for preclinical studies in hydrocephalus.

Mechanisms of hydrocephalus after neonatal and adult intraventricular hemorrhage

Intraventricular hemorrhage (IVH) is a cause of significant morbidity and mortality and is an independent predictor of a worse outcome in intracerebral hemorrhage (ICH) and germinal matrix hemorrhage (GMH). IVH may result in both injuries to the brain as well as hydrocephalus. This paper reviews evidence on the mechanisms and potential treatments for IVH-induced hydrocephalus. One frequently cited theory to explain hydrocephalus after IVH involves obliteration of the arachnoid villi by microthrombi with subsequent inflammation and fibrosis causing CSF outflow obstruction. Although there is some evidence to support this theory, there may be other mechanisms involved, which contribute to the development of hydrocephalus. It is also unclear whether the causes of acute and chronic hydrocephalus after hemorrhage occur via different mechanisms; mechanical obstruction by blood in the former, and inflammation and fibrosis in the latter. Management of IVH and strategies for prevention of brain injury and hydrocephalus are areas requiring further study. A better understanding of the pathogenesis of hydrocephalus after IVH, may lead to improved strategies to prevent and treat post-hemorrhagic hydrocephalus.

Factors affecting clot lysis rates in patients with spontaneous intraventricular hemorrhage

BACKGROUND AND PURPOSE

In the treatment of severe intraventricular hemorrhage (IVH), thrombolytic use and clot size are known to influence clot lysis rates. We evaluated the effect of other variables on IVH clot lysis rates among patients treated with recombinant tissue-type plasminogen activator or placebo.

METHODS

One hundred patients with IVH and intracerebral hemorrhage volume <30 mL requiring emergency external ventricular drainage from 2 multicenter trials were treated with intraventricular administration of recombinant tissue-type plasminogen activator (n=78; 53 males, 25 females) or placebo (n=22; 7 males, 15 females). IVH volume was quantified daily by head CT. A segmented linear regression using an optimized spline knot for each patient was fit. Random effects linear regression was used to estimate the effect of prespecified patient characteristics on clot lysis rates over the first 6 days.

RESULTS

Stability IVH volumes were larger in males (N=60; 54 ± 5 mL) than females (N=40; 36 ± 5 mL; P=0.01). Intraventricular thrombolytic treatment was associated with an increase in clot lysis rate of 14.6% of stability IVH volume/day before the spline knot compared with the placebo group (P<0.001). After adjustment for thrombolytic, higher baseline serum plasminogen and lower baseline platelet count were independently associated with an increase in clot lysis of 1.28%/day per 10-g/dL increase (P<0.001) and 0.70% /day per 10×10(3)/uL decrease (P<0.001) before the knot, respectively.

CONCLUSIONS

Although thrombolysis remains the major determinant of IVH clot lysis rate, higher baseline serum plasminogen and lower platelet count also predict faster clot lysis. Further studies are needed to confirm whether plasminogen availability and thrombus structure impact IVH clot removal. Clinical Trial Registration- URL: http://clinicaltrials.gov. Unique identifier: NCT00650858.

Plasminogen stimulates propagation of protease-resistant prion protein in vitro

To clarify the role of plasminogen as a cofactor for prion propagation, we conducted functional assays using a cell-free prion protein (PrP) conversion assay termed protein misfolding cyclic amplification (PMCA) and prion-infected cell lines. Here, we report that plasminogen stimulates propagation of the protease-resistant scrapie PrP (PrP(Sc)). Compared to control PMCA conducted without plasminogen, addition of plasminogen in PMCA using wild-type brain material significantly increased PrP conversion, with an EC(50) = ∼56 nM. PrP conversion in PMCA was substantially less efficient with plasminogen-deficient brain material than with wild-type material. The activity stimulating PrP conversion was specific for plasminogen and conserved in its kringle domains. Such activity was abrogated by modification of plasminogen structure and interference of PrP-plasminogen interaction. Kinetic analysis of PrP(Sc) generation demonstrated that the presence of plasminogen in PMCA enhanced the PrP(Sc) production rate to ∼0.97 U/μl/h and reduced turnover time to ∼1 h compared to those (∼0.4 U/μl/h and ∼2.5 h) obtained without supplementation. Furthermore, as observed in PMCA, plasminogen and kringles promoted PrP(Sc) propagation in ScN2a and Elk 21(+) cells. Our results demonstrate that plasminogen functions in stimulating conversion processes and represents the first cellular protein cofactor that enhances the hypothetical mechanism of prion propagation.

Use of intrathecal urokinase in repeated shunt and external ventricular drain blockage from high CSF protein due to an optic pathway glioma

INTRODUCTION

High cerebrospinal fluid (CSF) protein is a recognised association of optic pathway gliomas. This can occlude ventriculoperitoneal (VP) shunt catheters or external ventricular drains (EVD).

CASE REPORT

We describe an 8-year-old boy with an optic pathway glioma, who had frequent episodes of a blocked VP shunt and EVD due to high CSF protein level. This responded favourably to repeated urokinase instillation into the catheter lumen. We present the course of treatment and the method of administration and review the literature behind thrombolytic therapy for occluded catheter devices.

CONCLUSION

Intrathecal urokinase was effective in unblocking the EVD and lysing the protein clots within the ventricle. We found no previously published cases of intrathecal urokinase for this problem. This novel intervention seemed promising as a safe and effective means of maintaining EVD patency in cases complicated by excessive protein loads in CSF and hydrocephalus.

Intracranial hemorrhage in the preterm infant: understanding it, preventing it

New discoveries in neonatal imaging, cerebral monitoring, and hemodynamics, and greater understanding of inflammatory and genetic mechanisms involved in intracranial hemorrhage (ICH) in the preterm infant are creating opportunities for innovative early detection and prevention approaches. This article covers the spectrum of ICH in the preterm infant, including germinal matrix intraventricular hemorrhage, its complications, and associated phenomena, such as the emerging role of cerebellar hemorrhage. The overall aim of this article is to review the current knowledge of the mechanisms, diagnosis, outcome, and management of preterm ICH; to revisit the origins from which they develop; and to discuss future expectations.

Intraventricular streptokinase after intraventricular hemorrhage in newborn infants

BACKGROUND

Hydrocephalus following intraventricular hemorrhage (IVH) is still one of the most serious complications of premature birth. Ventriculoperitoneal shunt surgery cannot be carried out early and permanent dependence on a shunt is associated with several serious complications. Streptokinase could be useful in the treatment of post-hemorrhagic hydrocephalus. This form of therapy is based on the hypothesis that multiple blood clots in the cerebrospinal fluid (CSF) are the initial cause of post-hemorrhagic ventricular dilatation and lysis of clots could reopen the pathways of circulation and re-absorption of CSF.

OBJECTIVES

To determine the effect of intraventricular streptokinase after intraventricular hemorrhage on the risk of permanent shunt dependence, neurodevelopmental disability or death in neonates at risk for, or actually developing post-hemorrhagic hydrocephalus (PHH).

SEARCH STRATEGY

Pediatric, Neurosurgical and General Medical Journals were handsearched from 1976 until October 2000, as well as the MEDLINE database (via PubMed) and the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library) up to April 2007. Personal contacts were used.

SELECTION CRITERIA

Randomized controlled trials and quasi-randomized controlled trials evaluating the use of injection of streptokinase into the CSF in infants having or at risk for post-hemorrhagic hydrocephalus.

DATA COLLECTION AND ANALYSIS

Details of patient selection, patient allocation and the interventions were extracted. The end-points examined were: ventriculoperitoneal shunt, death, meningitis, and secondary hemorrhage.

MAIN RESULTS

Two randomized trials evaluated intraventricular streptokinase in infants developing post-hemorrhagic ventricular dilatation were identified When intraventricular streptokinase was compared with conservative management of post-hemorrhagic ventricular dilatation, the numbers of deaths and babies with shunt dependence were similar in both groups. No information on the effect of intraventricular streptokinase on disability is available. There is cause for concern about meningitis and secondary intraventricular hemorrhage, but numbers are insufficient to quantify the risks.

AUTHORS' CONCLUSIONS

Intraventricular fibrinolytic therapy with streptokinase, given when post-hemorrhagic ventricular dilatation is established, cannot be recommended for neonates following IVH. A conservative approach with CSF drainage applied only to symptomatic raised intracranial pressure seems appropriate.

Intraventricular hemorrhage in the premature neonate

Intraventricular hemorrhage in the premature neonate has been and continues to be a cause of morbidity and mortality in NICUs around the globe. Much information is available concerning the etiology and preventative and treatment strategies to reduce the incidence of IVH in this patient population. As neonatal caregivers are struggling to care for and protect infants who are surviving despite extreme prematurity, this survival is complicated by the infant's cerebral vasculature, which is very susceptible to hemorrhage; by respiratory problems that require the use of lifesaving, but potentially harmful, ventilation interventions; and by the infant's compromised ability to self-regulate vascular responses to stress. The preventative treatments being explored and proposed may come with debilitating and potentially lethal sequelae. Research continues, however. New recommendations are being proffered, and perhaps, in the near future, the incidence of IVH and its associated morbidity and mortality will decline dramatically.

The pathogenesis of neonatal post-hemorrhagic hydrocephalus

Hydrocephalus after intraventricular hemorrhage (IVH) has emerged as a major complication of preterm birth and is especially problematic to treat. The hydrocephalus is usually ascribed to fibrosing arachnoiditis, meningeal fibrosis and subependymal gliosis, which impair flow and resorption of cerebrospinal fluid (CSF). Recent experimental studies have suggested that acute parenchymal compression and ischemic damage, and increased parenchymal and perivascular deposition of extracellular matrix proteins--probably due at least partly to upregulation of transforming growth factor-beta (TGF-beta)--are further important contributors to the development of the hydrocephalus. IVH is associated with damage to periventricular white matter and the damage is exacerbated by the development of hydrocephalus; combinations of pressure, distortion, ischaemia, inflammation, and free radical-mediated injury are probably responsible. The damage to white matter accounts for the high frequency of cerebral palsy in this group of infants. The identification of mechanisms and mediators of hydrocephalus and white matter damage is leading to the development of new treatments to prevent permanent hydrocephalus and its neurological complications, and to avoid shunt dependence.

Posthaemorrhagic ventricular dilatation: new mechanisms and new treatment

Post haemorrhagic ventricular dilatation is associated with a high rate of disability, multiple impairments and adverse effects of shunt surgery for hydrocephalus. Post haemorrhagic ventricular dilatation results initially from multiple small blood clots throughout the cerebrospinal fluid channels impeding circulation and re-absorption. Transforming growth factor beta is released into the cerebrospinal fluid and there is evidence that this cytokine stimulates the laying down of extracellular matrix proteins which produce permanent obstruction to the cerebrospinal fluid pathways. Prolonged raised pressure, pro-inflammatory cytokines and free radical damage from iron may contribute to periventricular white matter damage and subsequent disability. Interventions such as early lumbar punctures, diuretic drugs to reduce cerebrospinal fluid production and intraventricular fibrinolytic therapy have been tested and, not only fail to prevent shunt dependence, death or disability, but have significant adverse effects. Surgical interventions such as subcutaneous reservoir, external drain, choroid plexus coagulation and third ventriculostomy have not been subject to controlled trial. Ventriculoperitoneal shunt is not feasible in the early phase after intraventricular haemorrhage but, despite the problems with blockages and infections, remains the only option for infants with excessive head expansion over periods of weeks. We have piloted drainage, irrigation and fibrinolytic therapy as a way of removing blood early enough to stop the progressive deposition of matrix proteins, permanent hydrocephalus and shunt dependence.

Intraventricular streptokinase for the treatment of posthaemorrhagic hydrocephalus of preterm

Posthaemorrhagic hydrocephalus following intraventricular haemorrhage is still one of the most serious complications of premature birth. Small premature babies are not suitable for shunt surgery because of high cerebrospinal fluid protein and risk of obstruction. For this reason there is a great need for alternative approaches for treatment of posthaemorrhagic hydrocephalus. The objective of this study was to investigate if intraventricular streptokinase treatment reduces the need for ventriculoperitoneal shunt in posthaemorrhagic hydrocephalus. A case-control trial was carried out in 12 premature babies with posthaemorrhagic hydrocephalus. Six of them were treated with intraventricular streptokinase and 6 premature babies were in the control group. While 5 babies in the study group needed ventriculoperitoneal shunt, 3 of the control patients needed shunt surgery. There were no rebleeding, ventriculitis or meningitis in either groups. In conclusion on the basis of our results we do not recommend routine use of intraventricular streptokinase in posthaemorrhagic hydrocephalus.

Phase 1 trial of prevention of hydrocephalus after intraventricular hemorrhage in newborn infants by drainage, irrigation, and fibrinolytic therapy

OBJECTIVE

Treatment of posthemorrhagic ventricular dilation in premature infants is fraught with failures and complications. We have piloted a new treatment aimed at removing intraventricular blood and the cytokines associated with hydrocephalus.

METHODS

Twenty-four infants were enrolled with ventricular width enlarged to 4 mm over the 97th centile after a large intraventricular hemorrhage. Sixteen had parenchymal brain lesions before treatment. Median gestation was 28 weeks, and birth weight was 1150 g. At a median postnatal age of 17 days, 2 ventricular catheters (1 right frontal, 1 left occipital) were inserted with 13 infants also having a reservoir frontally. Tissue plasminogen activator 0.5 mg/kg was given intraventricularly 8 hours before the ventricles were irrigated with artificial cerebrospinal fluid at 20 mL/h for a median of 72 hours.

RESULTS

Seventeen of 23 survivors (74%) did not require a ventriculoperitoneal shunt. One infant (of 23 weeks' gestation) died. Two infants developed reservoir-associated infection, and 2 infants had a second intraventricular hemorrhage. Of the 19 survivors aged >12 months postterm, 8 were normal, 7 (37%) had single disability, and 4 (21%) had multiple disabilities.

CONCLUSIONS

Shunt surgery was reduced compared with historical controls with similar treatment criteria. Mortality and single and multiple disability rates all showed downward trends. Reducing pressure, free iron, and proinflammatory and profibrotic cytokines may reduce periventricular brain damage and permanent hydrocephalus. Additional advances will require a controlled trial and better knowledge of the mechanisms of hydrocephalus.

Posthemorrhagic ventricular dilation in the neonate: development and characterization of a rat model

Intraventricular hemorrhage is a common complication of prematurity. Posthemorrhagic ventricular dilation (PHVD) has a high rate of disability and no safe and effective treatment. Its pathogenesis is poorly understood, largely because of the lack of a satisfactory animal model. We have developed a model of neonatal PHVD in the rat. Seven-day-old (P7) Wistar rat pups were given 80-microl injections of citrated rat blood or artificial cerebrospinal fluid (CSF) into alternate lateral ventricles on P7 and P8. Intracranial pressure was monitored and increased briefly by over 8-fold. Some rats received further 10-microl intraventricular injections of India ink on P21. Animals were weighed daily and simple neurologic tests performed. On P21 (or P22 if India ink had been injected), the rats were perfusion-fixed and blocks processed for paraffin histology. Sixty-five percent of pups injected with blood and 50% injected with artificial CSF developed dilated lateral ventricles, with patchy loss of ependyma, marked astrocytic gliosis, and rarefaction of periventricular white matter. India ink injection revealed slow transit of CSF from the dilated lateral ventricles but eventual passage into the subarachnoid space. Pups that had received intraventricular injections but did not develop ventricular dilation nonetheless had lighter brains than littermate controls (p < 0.001). Body weights were not significantly different from controls. Hydrocephalic animals had reduced motor performance as assessed by a grip traction test (p = 0.0002). This model is well suited to studying the pathogenesis of PHVD.

Posthaemorrhagic ventricular dilatation

Posthaemorrhagic ventricular dilatation is the most serious direct complication of intraventricular haemorrhage after preterm birth. It results initially from multiple small blood clots throughout the cerebrospinal fluid channels impeding circulation and reabsorption. Management is difficult and new treatment approaches are needed.

Fibrinolytic therapy in intraventricular hemorrhage

OBJECTIVE

To review the literature concerning intraventricular administration of fibrinolytic agents to treat patients with intraventricular hemorrhage (IVH).

DATA SOURCES

An extensive literature search (MEDLINE, EMBASE, Conference Proceedings) was conducted to identify articles in English published between 1966 and May 2000 pertaining to the pathophysiology of IVH and its treatment by intraventricular administration of recombinant tissue plasminogen activator (alteplase) or urokinase (u-PA). The bibliographies of selected identified articles were also screened for publications not found in the computerized search.

STUDY SELECTION

All pertinent publications were reviewed and considered. Those describing the intraventricular administration of fibrinolytic agents to patients with IVH were included.

DATA SYNTHESIS

IVH has a poor prognosis, partly due to the mass effect of blood clots on the ventricular walls. The cerebrospinal fluid has a limited fibrinolytic system. Therefore, clots may remain in the ventricles for months after a hemorrhage. The management of IVH is primarily directed at controlling intracranial pressure through an external ventricular drain, but this catheter often becomes occluded by coagulated blood. To overcome this problem, and to dissolve the residual blood clot, investigators have administered alteplase or u-PA directly into the ventricles of patients with IVH. Complications of this therapy include infection and possible rebleeding. Clinical studies of fibrinolytic therapy for IVH have found a 30-35% reduction in mortality with treatment, but to date, have not clearly documented improved neurologic outcome of the survivors.

CONCLUSIONS

Fibrinolytic therapy with alteplase or u-PA may be life-saving in severe cases of IVH. Yet many technical issues remain to be resolved, such as the optimal dose, frequency, method, timing, and duration of administration of the agent. Additional randomized, double-blind, placebo-controlled studies need to be performed so that the true value of this therapy can be assessed.

Blood clot resolution in human cerebrospinal fluid: evidence of first-order kinetics

OBJECTIVE

To determine the kinetics of blood clot resolution in human cerebrospinal fluid.

METHODS

Computed tomographic scans of 17 adult patients with intraventricular hemorrhages were analyzed. Intraventricular clot volume was determined and analyzed over time to determine both a standardized percentage rate and an absolute rate of clot resolution. Results were analyzed by use of regression for cross sectional time-series data. To determine the kinetics of intraventricular clot resolution, the effect of the clot volume on the percentage rate of clot resolution, clot half-life, and absolute rate of clot resolution was analyzed. The potential effect of age, sex, type of hemorrhage, and treatment with external ventricular drainage on the percentage rate of clot resolution was assessed.

RESULTS

The percentage rate of clot resolution was 10.8% per day (95% confidence interval, 9.05-12.61 %), and it was independent of initial clot volume, age, sex, type of underlying hemorrhage, and use of external ventricular drainage. The absolute rate of clot resolution varied directly with the maximal clot volume (R2 = 0.88; P < 0.001). The percentage clot resolution data are consistent with events during the first 24 to 48 hours that antagonize clot resolution.

CONCLUSION

These findings demonstrate that intraventricular blood clot resolution in patients with intraventricular hemorrhage follows first-order kinetics. The thrombolytic enzyme system responsible for intraventricular clot resolution seems to be saturated at 24 to 48 hours after the initial hemorrhage.

Intraventricular haemorrhage and posthaemorrhagic hydrocephalus: pathogenesis, prevention and future interventions

Intraventricular haemorrhage (IVH) is still a major complication of preterm birth with serious disability resulting. The fragile blood vessels in the germinal matrix below the ventricular lining and the instability of blood flow to this highly vascular area are the main mechanisms behind IVH. There is good evidence that corticosteroid therapy before preterm delivery reduces mortality and IVH substantially with a trend towards a reduction in disability. There is good evidence that postnatal indomethacin reduces IVH but no evidence that mortality or disability is reduced. There is evidence that stabilizing cerebral blood flow with pancuronium in infants with respiratory distress reduces IVH in the minority of infants with marked fluctuations. There is limited evidence that postnatal vitamin E and ethamsylate reduce IVH but insufficient evidence of reduced mortality or disability. Hydrocephalus following IVH results initially from multiple small blood clots throughout the CSF channels impeding circulation and re-absorption. Transforming growth factor beta is released into the CSF and there is mounting evidence that this cytokine stimulates the laying down of extracellular matrix proteins such as laminin and fibronectin which produce permanent obstruction to the CSF pathways. Interventions such as early lumbar punctures, diuretic drugs to reduce CSF production and intraventricular fibrinolytic therapy have been tested and, not only fail to prevent shunt dependence, death or disability, but have significant adverse effects. Surgical interventions such as subcutaneous reservoir and external drain have not been subject to controlled trial. Ventriculoperitoneal shunt is not feasible in the early phase after IVH but, despite the problems with blockages and infections, remains the only option for infants with excessive head expansion over periods of weeks. New treatment approaches aimed at preventing hydrocephalus are needed.

Intraventricular streptokinase after intraventricular hemorrhage in newborn infants

BACKGROUND

Hydrocephalus following intraventricular hemorrhage (IVH) is still one of the most serious complications of premature birth. Ventriculoperitoneal shunt surgery cannot be carried out early and permanent dependence on a shunt is associated with several serious complications.

OBJECTIVES

To determine whether intraventricular streptokinase after intraventricular hemorrhage reduces the risk of permanent shunt dependence, neurodevelopmental disability or death in neonates at risk of, or actually developing, post-hemorrhagic hydrocephalus (PHH). This form of therapy is based on the hypothesis that multiple blood clots in the CSF are the initial cause of post-hemorrhagic ventricular dilatation and lysis of clots could reopen the pathways of circulation and re-absorption of CSF.

SEARCH STRATEGY

Pediatric, Neurosurgical and General Medical Journals were handsearched from 1976, as well as the Medline database. Personal contacts were used.

SELECTION CRITERIA

One randomised trial evaluated intraventricular streptokinase in infants developing post-hemorrhagic ventricular dilatation.

DATA COLLECTION AND ANALYSIS

Details of patient selection, patient allocation and the interventions were extracted. The end-points examined were: ventriculoperitoneal shunt, death, meningitis, and secondary hemorrhage.

MAIN RESULTS

When intraventricular streptokinse was compared with conservative management of post-hemorrhagic ventricular dilatation, the numbers of deaths and babies with shunt dependence were identical in both groups. No information on the effect of intraventricular streptokinase on disability is available. There is cause for concern about meningitis and secondary intraventricular hemorrhage but numbers are insufficient to quantify the risks.

REVIEWER'S CONCLUSIONS

Intraventricular fibrinolytic therapy with streptokinase, given when post-hemorrhagic ventricular dilatation is established, cannot be recommended for neonates following IVH. A conservative approach with CSF drainage applied only to symptomatic raised intracranial pressure seems appropriate.

Nonproteolytic neuroprotection by human recombinant tissue plasminogen activator

Human recombinant tissue plasminogen activator (tPA) may benefit ischemic stroke patients by dissolving clots. However, independent of thrombolysis, tPA may also have deleterious effects on neurons by promoting excitotoxicity. Zinc neurotoxicity has been shown to be an additional key mechanism in brain injuries. Hence, if tPA affects zinc neurotoxicity, this may provide additional insights into its effect on neuronal death. Independent of its proteolytic action, tPA markedly attenuated zinc-induced cell death in cortical culture, and, when injected into cerebrospinal fluid, also reduced kainate seizure-induced hippocampal neuronal death in adult rats.

Recombinant tissue plasminogen activator for the treatment of spontaneous adult intraventricular hemorrhage

BACKGROUND

Intraventricular hemorrhage (IVH) has a poor prognosis with mortality rates of between 80 and 100% when all four ventricles are involved. Fibrinolytic therapy has been reported to improve overall outcome.

METHODS

Patients with severe primary IVH were treated by direct intraventricular injection of recombinant tissue plasminogen activator (rt-PA) into the lateral ventricles, followed by cerebrospinal fluid (CSF) drainage if the intracranial pressure rose above 20 mm Hg.

RESULTS

Over a 15-month period from 1995 through 1996, 10 patients were treated, (4 male and 6 female, mean age 35 years; range, 21-55 years). The mean Glasgow Coma Scale score on admission was 6 (range, 4-8) and the mean Graeb score for severity of IVH on the first CT scan was 10 (range, 8-12). Angiography was negative in five cases but identified arteriovenous malformations in three, a post-traumatic pseudoaneurysm in one, and Moya-moya disease in one. The mean total dose requirement of rt-PA was 8.25 mg (range, 6-12 mg) with a significant reduction in the mean Graeb score after 7 days to 3.9 (range, 2-7, p<0.0001). Outcome at 3 months was death in one case (mortality 10%), severe disability in two (20%), moderate disability in three (30%), and good result in four (40%). Four patients (40%) required subsequent CSF shunting. No complications of rehemorrhage, infection, or catheter obstruction were encountered.

CONCLUSION

Intraventricular fibrinolysis with rt-PA seems to be safe and effective for the treatment of severe IVH.

Posthemorrhagic hydrocephalus and brain injury in the preterm infant: dilemmas in diagnosis and management

Advances in neonatal critical care have reduced the incidence of intraventricular hemorrhage (IVH) in the newborn. Paradoxically, however, the prevalence of the complications of IVH including posthemorrhagic hydrocephalus (PHHC) has increased. By virtue of its association with long-term neurodevelopmental disability, posthemorrhagic hydrocephalus is an ominous diagnosis in the premature infant. Animal models have demonstrated that ventricular distention may cause direct cerebral parenchymal injury. Evidence for secondary parenchymal injury in the premature infant with PHHC is by necessity indirect. The precise impact of secondary parenchymal injury on the overall neurological outcome of premature infants with PHHC remains unclear in large part because of the vulnerability of the immature brain to other forms of injury (e.g., periventricular leukomalacia) that may be difficult to distinguish from injury due to distention. Furthermore, parenchymal injury due to PVL may cause ventricular enlargement that does not benefit from CSF diversion. Because these primary and secondary mechanisms of injury may operate concurrently, the precise or dominant cause of ventricular enlargement is often difficult to establish with certainty in the neonatal period. These diagnostic dilemmas have in turn impeded the development and evaluation of therapies specifically aimed at reversing ventricular distention and preventing secondary parenchymal injury. This article focuses on the current dilemmas in diagnosis and management of this potentially reversible form of injury as well as on potential future strategies for its prevention.

Intraventricular urokinase for the treatment of posthemorrhagic hydrocephalus

This case series pilot study assessed the safety of intraventricular urokinase administration, alternating with cerebrospinal fluid (CSF) drainage. A secondary objective was to comment on whether this therapy achieves fibrinolysis, and whether this fibrinolysis is sufficient to prevent progression of hydrocephalus to requirement for ventriculoperitoneal shunt. Six preterm infants with progressive posthemorrhagic hydrocephalus requiring treatment with a ventricular drain received an infusion of intraventricular urokinase alternating with CSF drainage for 3 days. Of the 6 treated patients, the median gestation at birth was 26.5 weeks and the median age at treatment was 30 days. One patient had an elevation in CSF erythrocyte count most likely due to successful clot lysis. One patient had an elevated CSF leukocyte count consistent with transient meningeal irritation. No other side effects were noted. Fibrinolysis was achieved in the CSF, as documented by markedly elevated D-dimer levels. Clot size diminished ultrasonographically. However, all 6 patients eventually required a ventriculoperitoneal shunt. We conclude that intermittent infusion of intraventricular urokinase alternating with periods of CSF drainage is probably a safe way to achieve a fibrinolytic state. However, when administered at the relatively late point in the neonatal course when a ventricular drain is required, this fibrinolytic state is not sufficient to decrease the requirement for ventriculoperitoneal shunt.

Cerebrospinal fluid plasminogen activator inhibitor-1: a prognostic factor in posthaemorrhagic hydrocephalus

Intraventricular fibrinolytic enhancement with plasminogen activators is an experimental treatment for posthaemorrhagic hydrocephalus, but some infants do not respond. The objectives of this study were to investigate whether plasminogen activator inhibitor-1 is detectable in normal or posthaemorrhagic neonatal cerebrospinal fluid and whether higher neonatal cerebrospinal fluid concentrations of plasminogen activator inhibitor-1 are associated with failure of fibrinolytic therapy. Cerebrospinal fluid samples from 7 controls and 16 infants with posthaemorrhagic hydrocephalus (15 treated with exogenous fibrinolytic agents) were analysed for plasminogen activator inhibitor-1. Plasminogen activator inhibitor-1 was not detectable in any of the control samples but was detectable in all but one of the posthaemorrhagic samples, and at significantly higher levels in the treatment failures (median 94 ng ml(-1)) than in the treatment successes (median 25 ng ml(-1)). High levels of plasminogen activator inhibitor-1 in the cerebrospinal fluid are predictive of, and provide a plausible biological explanation for, failure of intraventricular fibrinolytic therapy.

Phase I study of intraventricular recombinant tissue plasminogen activator for treatment of posthaemorrhagic hydrocephalus

AIM

Phase I study to evaluate intraventricular fibrinolytic treatment with recombinant tissue plasminogen activator (tPA) as a method of clearing blood from the cerebrospinal fluid, and thus preventing permanent hydrocephalus.

METHODS

Twenty two preterm infants, aged 7 to 26 days, with progressive posthaemorrhagic ventricular dilatation (ventricular width > 4 mm over 97th centile) received one to five intraventricular bolus injections of 1.0 mg or 0.5 mg tPA at intervals of one to seven days.

RESULTS

The mean cerebrospinal fluid concentration of tPA 24 hours after 1 mg was 1860 micrograms/ml. The half life of tPA in cerebrospinal fluid was about 24 hours. Twenty one (95%) infants survived, 12 (55%) without shunt surgery. One infant had secondary intraventricular haemorrhage.

CONCLUSION

Intraventricular tPA resulted in survival without a shunt for most of the infants, but with some risk. Failure may have been due to plasminogen deficiency, an inhibitor, or late intervention.