Raj K. Narayan

Clinical Trials in Head Injury

Secondary brain damage, following severe head injury is considered to be a major cause for bad outcome. Impressive reductions of the extent of brain damage in experimental studies have raised high expectations for cerebral neuroprotective treatment, in the clinic. Therefore multiple compounds were and are being evaluated in trials. In this review we discuss the pathomechanisms of traumatic brain damage, based upon their clinical importance. The role of hypothermia, mannitol, barbiturates, steroids, free radical scavengers, arachidonic acid inhibitors, calcium channel blockers, N-methyl-D-aspartate (NMDA) antagonists, and potassium channel blockers, will be discussed. The importance of a uniform strategic approach for evaluation of potentially interesting new compounds in clinical trials, to ameliorate outcome in patients with severe head injury, is proposed. To achieve this goal, two nonprofit organizations were founded: the European Brain Injury Consortium (EBIC) and the American Brain Injury Consortium (ABIC). Their aim lies in conducting better clinical trials, which incorporate lessons learned from previous trials, such that the succession of negative, or incomplete studies, as performed in previous years, will cease.

Preliminary findings of the minimally-invasive surgery plus rtPA for intracerebral hemorrhage evacuation (MISTIE) clinical trial

INTRODUCTION Compared to ischemic stroke, intracerebral hemorrhage (ICH) is easily and rapidly identified, occurs in younger patients, and produces relatively small initial injury to cerebral tissues--all factors suggesting that interventional amelioration is possible. Investigations from the last decade established that extent of ICH-mediated brain injury relates directly to blood clot volume and duration of blood exposure to brain tissue. Using minimally-invasive surgery plus recombinant tissue plasminogen activator (rtPA), MISTIE investigators explored aggressive avenues to treat ICH. METHODS We investigated the difference between surgical intervention plus rtPA and standard medical management for ICH. Subjects in both groups were medically managed according to standard ICU protocols. Subjects randomized to surgery underwent stereotactic catheter placement and clot aspiration. Injections of rtPA were then given through hematoma catheter every 8 h, up to 9 doses, or until a clot-reduction endpoint. After each injection the system was flushed with sterile saline and closed for 60 min before opening to spontaneous drainage. RESULTS Average aspiration of clots for all patients randomized to surgery plus rtPA was 20% of mean initial clot size. After acute treatment phase (aspiration plus rtPA), clot was reduced an average of 46%. Recorded adverse events were within safety limits, including 30-day mortality, 8%; symptomatic re-bleeding, 8%; and bacterial ventriculitis, 0%. Patients randomized to medical management showed 4% clot resolution in a similar time window. Preliminary analysis indicates that clot resolution rates are greatly dependent on catheter placement. Location of ICH also affects efficacy of aggressive treatment of ICH. CONCLUSION There is tentative indication that minimally-invasive surgery plus rtPA shows greater clot resolution than traditional medical management.

Progression of Traumatic Intracerebral Hemorrhage: A Prospective Observational Study

ABSTRACT Preliminary evidence has shown that intracerebral hemorrhages, either spontaneous (sICH) or traumatic (tICH) often expand over time. An association between hemorrhage expansion and clinical outcomes has been described for sICH. The intent of this prospective, observational study was to characterize the temporal profile of hemorrhage progression, as measured by serial computed tomography (CT) scanning, with the aim of better understanding the natural course of hemorrhage progression in tICH. There was also a desire to document the baseline adverse event (AE) profile in this patient group. An important motive for performing this study was to set the stage for subsequent studies that will examine the role of a new systemic hemostatic agent in tICH. Subjects were enrolled if they had tICH lesions of at least 2 mL on a baseline CT scan obtained within 6 h of a head injury. CT scans were repeated at 24 and 72 h. Clinical outcomes and pre-defined AEs were documented. The data showed that 51% of the subjects demonstrated an increase in tICH volume, and that most of the increase occurred early. In addition, larger hematomas exhibited the greatest expansion. Thromboembolic complications were identified in 13% of subjects. This study demonstrates that tICH expansion between the baseline and 24-h CT scans occurred in approximately half of the subjects. The earlier after injury that the initial CT scan is obtained, the greater is the likelihood that the hematoma will expand on subsequent scans. The time frame during which hemorrhagic expansion occurs provides an opportunity for early intervention to limit a process with adverse prognostic implications.

Low-Dose Recombinant Tissue-Type Plasminogen Activator Enhances Clot Resolution in Brain Hemorrhage: The Intraventricular Hemorrhage Thrombolysis Trial

Background and Purpose— Patients with intracerebral hemorrhage and intraventricular hemorrhage have a reported mortality of 50% to 80%. We evaluated a clot lytic treatment strategy for these patients in terms of mortality, ventricular infection, and bleeding safety events, and for its effect on the rate of intraventricular clot lysis. Methods— Forty-eight patients were enrolled at 14 centers and randomized to treatment with 3 mg recombinant tissue-type plasminogen activator (rtPA) or placebo. Demographic characteristics, severity factors, safety outcomes (mortality, infection, bleeding), and clot resolution rates were compared in the 2 groups. Results— Severity factors, including admission Glasgow Coma Scale, intracerebral hemorrhage volume, intraventricular hemorrhage volume, and blood pressure were evenly distributed, as were adverse events, except for an increased frequency of respiratory system events in the placebo-treated group. Neither intracranial pressure nor cerebral perfusion pressure differed substantially between treatment groups on presentation, with external ventricular device closure, or during the active treatment phase. Frequency of death and ventriculitis was substantially lower than expected and bleeding events remained below the prespecified threshold for mortality (18% rtPA; 23% placebo), ventriculitis (8% rtPA; 9% placebo), symptomatic bleeding (23% rtPA; 5% placebo, which approached statistical significance; P=0.1). The median duration of dosing was 7.5 days for rtPA and 12 days for placebo. There was a significant beneficial effect of rtPA on rate of clot resolution. Conclusions— Low-dose rtPA for the treatment of intracerebral hemorrhage with intraventricular hemorrhage has an acceptable safety profile compared to placebo and historical controls. Data from a well-designed phase III clinical trial, such as CLEAR III, will be needed to fully evaluate this treatment. Clinical Trial Registration— Participant enrollment began before July 1, 2005.

Recombinant factor VIIA in traumatic intracerebral hemorrhage: results of a dose-escalation clinical trial.

OBJECTIVEIntracerebral hemorrhages, whether spontaneous or traumatic (tICH), often expand, and an association has been described between hemorrhage expansion and worse clinical outcomes. Recombinant factor VIIa (rFVIIa) is a hemostatic agent that has been shown to limit hemorrhage expansion and which, therefore, could potentially reduce morbidity and mortality in tICH. This first prospective, randomized, placebo-controlled, dose-escalation study evaluated the safety and preliminary effectiveness of rFVIIa to limit tICH progression. METHODSPatients were enrolled if they had tICH lesions of at least 2 ml on a baseline computed tomographic scan obtained within 6 hours of injury. rFVIIa or placebo was administered within 2.5 hours of the baseline computed tomographic scan but no later than 7 hours after injury. Computed tomographic scans were repeated at 24 and 72 hours. Five escalating dose tiers were evaluated (40, 80, 120, 160, and 200 μg/kg rFVIIa). Clinical evaluations and adverse events were recorded until Day 15. RESULTSNo significant differences were detected in mortality rate or number and type of adverse events among treatment groups. Asymptomatic deep vein thrombosis, detected on routinely performed ultrasound at Day 3, was observed more frequently in the combined rFVIIa treatment group (placebo, 3%; rFVIIa, 8%; not significant). A nonsignificant trend for rFVIIa dose-response to limit tICH volume increase was observed (placebo, 21.0 ml; rFVIIa, 10.1 ml). CONCLUSIONIn this first prospective study of rFVIIa in tICH, there appeared to be less hematoma progression in rFVIIa-treated patients (80–200 μg/kg) compared with that seen in placebo treated patients. The potential significance of this biological effect on clinical outcomes and the significance of the somewhat higher incidence of ultrasound-detected deep vein thromboses in the rFVIIa-treated group need to be examined in a larger prospective randomized clinical trial.

Nanotube electrodes and biosensors

This article reviews the state of the art in carbon nanotube electrode and biosensor research. Carbon nanotubes have unique mechanical, electrical, and geometrical properties that are ideal for developing different types of nanoscale electrodes and biosensors. Carbon nanotube synthesis and subsequent functionalization strategies to immobilize special biomolecules are discussed first. Then different types of carbon nanotube biosensors and electroanalytical methods are reviewed particularly considering their capabilities for low detection limits, point-of-care applications, and label-free use. Detection strategies for proteins and nucleic acids, as well as mammalian and bacterial cells are also outlined. We conclude with some speculations and predictions on future exciting and challenging directions for nanotube biosensor research and applications.

Prolonged Cyclooxygenase-2 Induction in Neurons and Glia Following Traumatic Brain Injury in the Rat

Cyclooxygenase-2 (COX2) is a primary inflammatory mediator that converts arachidonic acid into precursors of vasoactive prostaglandins, producing reactive oxygen species in the process. Under normal conditions COX2 is not detectable, except at low abundance in the brain. This study demonstrates a distinctive pattern of COX2 increases in the brain over time following traumatic brain injury (TBI). Quantitative lysate ribonuclease protection assays indicate acute and sustained increases in COX2 mRNA in two rat models of TBI. In the lateral fluid percussion model, COX2 mRNA is significantly elevated (>twofold, p < 0.05, Dunnett) at 1 day postinjury in the injured cortex and bilaterally in the hippocampus, compared to sham-injured controls. In the lateral cortical impact model (LCI), COX2 mRNA peaks around 6 h postinjury in the ipsilateral cerebral cortex (fivefold induction, p < 0.05, Dunnett) and in the ipsilateral and contralateral hippocampus (two- and six-fold induction, respectively, p < 0.05, Dunnett). Increases are sustained out to 3 days postinjury in the injured cortex in both models. Further analyses use the LCI model to evaluate COX2 induction. Immunoblot analyses confirm increased levels of COX2 protein in the cortex and hippocampus. Profound increases in COX2 protein are observed in the cortex at 1-3 days, that return to sham levels by 7 days postinjury (p < 0.05, Dunnett). The cellular pattern of COX2 induction following TBI has been characterized using immunohistochemistry. COX2-immunoreactivity (-ir) rises acutely (cell numbers and intensity) and remains elevated for several days following TBI. Increases in COX2-ir colocalize with neurons (MAP2-ir) and glia (GFAP-ir). Increases in COX2-ir are observed in cerebral cortex and hippocampus, ipsilateral and contralateral to injury as early as 2 h postinjury. Neurons in the ipsilateral parietal, perirhinal and piriform cortex become intensely COX2-ir from 2 h to at least 3 days postinjury. In agreement with the mRNA and immunoblot results, COX2-ir appears greatest in the contralateral hippocampus. Hippocampal COX2-ir progresses from the pyramidal cell layer of the CA1 and CA2 region at 2 h, to the CA3 pyramidal cells and dentate polymorphic and granule cell layers by 24 h postinjury. These increases are distinct from those observed following inflammatory challenge, and correspond to brain areas previously identified with the neurological and cognitive deficits associated with TBI. While COX2 induction following TBI may result in selective beneficial responses, chronic COX2 production may contribute to free radical mediated cellular damage, vascular dysfunction, and alterations in cellular metabolism. These may cause secondary injuries to the brain that promote neuropathology and worsen behavioral outcome.

Cyclooxygenase-2-specific Inhibitor Improves Functional Outcomes, Provides Neuroprotection, and Reduces Inflammation in a Rat Model of Traumatic Brain Injury

OBJECTIVE:Increases in brain cyclooxygenase-2 (COX2) are associated with the central inflammatory response and with delayed neuronal death, events that cause secondary insults after traumatic brain injury. A growing literature supports the benefit of COX2-specific inhibitors in treating brain injuries. METHODS:DFU [5,5-dimethyl-3(3-fluorophenyl)-4(4-methylsulfonyl)phenyl-2(5H)-furanone] is a third-generation, highly specific COX2 enzyme inhibitor. DFU treatments (1 or 10 mg/kg intraperitoneally, twice daily for 3 d) were initiated either before or after traumatic brain injury in a lateral cortical contusion rat model. RESULTS:DFU treatments initiated 10 minutes before injury or up to 6 hours after injury enhanced functional recovery at 3 days compared with vehicle-treated controls. Significant improvements in neurological reflexes and memory were observed. DFU initiated 10 minutes before injury improved histopathology and altered eicosanoid profiles in the brain. DFU 1 mg/kg reduced the rise in prostaglandin E2 in the brain at 24 hours after injury. DFU 10 mg/kg attenuated injury-induced COX2 immunoreactivity in the cortex (24 and 72 h) and hippocampus (6 and 72 h). This treatment also decreased the total number of activated caspase-3–immunoreactive cells in the injured cortex and hippocampus, significantly reducing the number of activated caspase-3–immunoreactive neurons at 72 hours after injury. DFU 1 mg/kg amplified potentially anti-inflammatory epoxyeicosatrienoic acid levels by more than fourfold in the injured brain. DFU 10 mg/kg protected the levels of 2-arachidonoyl glycerol, a neuroprotective endocannabinoid, in the injured brain. CONCLUSION:These improvements, particularly when treatment began up to 6 hours after injury, suggest exciting neuroprotective potential for COX2 inhibitors in the treatment of traumatic brain injury and support the consideration of Phase I/II clinical trials.

Traumatic brain injury.

Traumatic brain injury (TBI) is physical injury to brain tissue that temporarily or permanently impairs brain function. Diagnosis is suspected clinically and confirmed by imaging [primarily computed tomography (CT), although magnetic resonance imaging (MRI) can be helpful later when it is logistically possible to obtain]. Initial treatment consists of ensuring a reliable airway and maintenance of adequate ventilation and blood pressure. Surgery is often needed in more severe cases to remove intracranial hematomas, provide room for the brain to swell, or place monitors to track intracranial pressure (ICP) and brain oxygenation. In the first few days after the injury, significant efforts are made to maintain adequate brain perfusion and oxygenation, and prevent complications that can result from an altered sensorium. Various periods of rehabilitation are often needed. In the United States, as in much of the world, TBI is a common cause of death and disability. Causes include motor vehicle crashes and other transportation-related causes (eg, bicycle crashes, collisions with pedestrians), falls (especially in older adults and young children), assaults, and sports activities.

Dual-mode operation of flexible piezoelectric polymer diaphragm for intracranial pressure measurement

The dual-mode operation of a polyvinylidene fluoride trifluoroethylene (PVDF-TrFE) piezoelectric polymer diaphragm, in a capacitive or resonant mode, is reported as a flexible intracranial pressure (ICP) sensor. The pressure sensor using a capacitive mode exhibits a higher linearity and less power consumption than resonant mode operated pressure sensor. In contrast, the latter provides better sensitivity and easier adaption for wireless application. The metrological properties of the dual-mode ICP sensor being described are satisfactory in vitro. We propose that the piezoelectric polymer diaphragm has a promising future in intracranial pressure monitoring.