Krishna Amuluru

Emerging Markers of Early Brain Injury and Delayed Cerebral Ischemia in Aneurysmal Subarachnoid Hemorrhage

BACKGROUNDnDelayed cerebral ischemia after aneurysmal subarachnoid hemorrhage is characterized by a highly complex pathophysiology and results in neurologic deterioration after the inciting bleed. Despite its significant consequences, prompt diagnosis can be elusive and treatment is often administered too late. Early brain injury, which occurs within the first 72 hours after ictus, may be an important factor for delayed cerebral ischemia and poor overall outcome. Here, we explore the purported clinical and pathologic manifestations of early brain injury to identify biomarkers that could have prognostic value.nnnMETHODSnWe review the literature and discuss potential emerging markers of delayed cerebral ischemia in the context of early brain injury.nnnRESULTSnThe following clinical features and biomarkers were examined: global cerebral edema, ictal loss of consciousness, ultra early angiographic vasospasm, continuous electroencephalogram monitoring, systemic inflammatory response syndrome, cellular mediators of the inflammatory response, and hematologic derangements.nnnCONCLUSIONSnSome of these markers possess independent value for determining the risk of complications after aneurysmal subarachnoid hemorrhage. However, their use is limited because of a variety of factors, but they do provide an avenue of further study to aid in diagnosis and management.

Low Glasgow Coma Score in Traumatic Intracranial Hemorrhage Predicts Development of Cerebral Vasospasm

BACKGROUNDnThe exact mechanism, incidence, and risk factors for cerebral vasospasm after traumatic intracranial hemorrhage (ICH) continue to be poorly characterized. The incidence of post-traumatic vasospasm (PTV) varies depending on the detection modality.nnnOBJECTIVEnWe aimed to shed light on the predictors, associations, and true incidence of cerebral vasospasm after traumatic ICH using digital subtraction angiography (DSA) as the gold standard.nnnMETHODSnWe examined a prospectively maintained database of traumatic brain injury (TBI) patients to identify patients with ICH secondary to TBI enrolled between 2002 and 2015 at our trauma center. Patients with TBI-associated ICH and evidence of elevated velocities on transcranial Doppler and computed tomography angiograms, confirmed with DSA were included. The diagnostic cerebral angiograms were evaluated by 2 blinded neurointerventionalists for cerebral vasospasm. Statistical analyses were conducted to determine predictors of PTV.nnnRESULTSnTwenty patients with ICH secondary to TBI and evidence of vasospasm underwent DSAs. Seven patients (7/20; 35%) with traumatic ICH developed cerebral vasospasm and of those, 1 developed delayed cerebral ischemia (1/7; 14%). Of these 7 patients, 6 presented with subarachnoid hemorrhage (6/7; 85%). Vasospasm was substantially more common in patients with a Glasgow Coma Scale <9 (Pxa0= 0.017) than in all other groups.nnnCONCLUSIONSnPTV as demonstrated by DCA may be more common than previously reported. Patients who exhibit PTV were more likely to have a Glasgow Coma Scale <9. This subgroup of patients may benefit from more systematic screening for the development of PTV, and earlier monitoring for signs of delayed cerebral ischemia.

Endovascular Retrieval of Migrated Coil within the Distal Middle Cerebral Artery Using Stentriever Device

BACKGROUNDnDisplacement of endovascular coils during endovascular embolization of an intracranial aneurysm is a potentially life-threatening complication. Several methods for coil retrieval have been described, including the use of microsnares and microforceps retrieval devices. With the recent surge of stentriever implementation in the treatment of ischemic stroke, some operators are now using such devices in the retrieval of migrated coils. Wexa0present a case of a balloon-assisted coil embolization of a communicating segment internal carotid artery aneurysm, complicated by coil migration far distally into the middle cerebral artery, which was retrieved successfully with a stentriever. To the best of our knowledge, this is the furthest migration of a coil to be successfully retrieved with a stentriever. We review conservative and invasive management of displaced coils and the technical advantages of stentrievers over retrieval devices.nnnMETHODSnThe patients medical records were retrospectively reviewed, including clinical and radiographic information. This study received institutional review board approval.nnnRESULTSnThe patient was treated with balloon-assisted coil embolization of the internal carotid artery aneurysm. The migrated coil was retrieved successfully using a novel application of a stentriever.nnnCONCLUSIONSnIn certain situations, a stentriever does not mandate complete ensnaring of the target to be retrieved and thus need not always be deployed distal to a migrated coil mass to be successful. Due to the mechanical advantage of strut-engagement, stentrievers can afford to be positioned in relatively suboptimal positions, and this is especially useful in cases involving tortuous and small distal vessels (<2 mm diameter).

Mechanical Thrombectomy of Acute Middle Cerebral Artery Occlusion Using Trans-Anterior Communicating Artery Approach

BACKGROUNDnA cross-circulation technique involves gaining access to a cerebral vessel through a patent anterior or posterior communicating artery. This technique may be used in patients with emergent large-vessel occlusions and an unfavorable direct route to the occlusion. While few previous reports have demonstrated a successful cross-circulation technique for treatment of emergent large-vessel occlusions, we present the first 2 cases of transanterior communicating artery stent retriever thrombectomy.nnnCASE DESCRIPTIONnCase #1: A 64-year-old female presented with acute right middle cerebral artery (MCA) occlusion. She demonstrated a triple-tandem brachiocephalic-internal carotid artery-middle cerebral artery occlusion, thus precluding direct access to the right MCA. Successful stent retriever mechanical thrombectomy was performed across the anterior communicating artery, using a left internal carotid artery approach. Case #2: A 70-year old female presented with acute occlusion of the left MCA and tandem occlusion of the cervical left internal carotid artery. Multiple attempts to catheterize the left common carotid artery were unsuccessful. She underwent successful stent retriever mechanical thrombectomy across a patent anterior communicating artery, using a right internal carotid artery approach.nnnCONCLUSIONSnTimely recanalization of an occluded artery plays a critical role in the prognosis of patients with acute ischemic stroke. Successful stent retriever mechanical thrombectomy of an occluded MCA is possible using a transanterior communicating artery approach in patients without a direct access route to the occluded intracranial vessel. We review the pathophysiology of tandem lesions, access routes to intracranial occlusions, and the literature on cross-circulation techniques to treat emergent large-vessel occlusions.

Rescue Therapy for Procedural Complications Associated With Deployment of Flow-Diverting Devices in Cerebral Aneurysms

Flow diverting devices (FDDs) have revolutionized the treatment of morphologically complex intracranial aneurysms such as wide-necked, giant, or fusiform aneurysms. Although FDDs are extremely effective, they carry a small yet significant risk of intraprocedural complications. As the implementation of these devices increases, the ability to predict and rapidly treat complications, especially those that are iatrogenic or intraprocedural in nature, is becoming increasingly more necessary.Our objective in this paper is to provide a descriptive summary of the various types of intraprocedural complications that may occur during FDDs deployment and how they may best be treated. A systematic and qualitative review of the literature was conducted using electronic databases MEDLINE and Google Scholar. Searches consisted of Boolean operators AND and OR for the following terms in different combinations: aneurysm, endovascular, flow diverter, intracranial, and pipeline.A total of 94 papers were included in our analysis; approximately 87 of these papers dealt with periprocedural endovascular (mainly related to FDDs) complications and their treatment; 7 studies concerned background material. The main categories of periprocedural complications encountered during deployment of FDDs are failure of occlusion, parent vessel injury and/or rupture, spontaneous intraparenchymal hemorrhage, migration or malposition of the FDDs, thromboembolic or ischemic events, and side branch occlusionPeriprocedural complications occur mainly due to thromboembolic events or mechanical issues related to device deployment and placement. With increasing use and expanding versatility of FDDs, the understanding of these complications is vital in order to effectively manage such situations in a timely manner.

Radiation Physics: Stereotactic Radiosurgery for Arteriovenous Malformations

Recent advances in stereotactic radiosurgery have allowed new treatment strategies for cerebral arteriovenous malformations that are not amenable to surgical resection because of the morbidity related to their deep or critical brain locations. Stereotactic radiosurgery is advantageous due to its noninvasive nature and the minimal risk of acute complications. The primary disadvantage of radiosurgery is that cure is not immediate and a latent period exists during which the risk of hemorrhage remains. Rates of successful obliteration and complications are primarily dependent on the location and volume of the lesion treated and radiation dose. Complications of stereotactic radiosurgery include hemorrhage during the latent period, radiation necrosis, and treatment failure. The avoidance and management of stereotactic radiosurgery complications require an in-depth knowledge of the underlying radiation physics, the indications for treatment, and the predictors for both success and failure.

Novel minimally invasive multi-modality monitoring modalities in neurocritical care

Elevated intracranial pressure (ICP) following brain injury contributes to poor outcomes for patients, primarily by reducing the caliber of cerebral vasculature, and thereby reducing cerebral blood flow. Careful monitoring of ICP is critical in these patients in order to determine prognosis, implement treatment when ICP becomes elevated, and to judge responsiveness to treatment. Currently, the gold standard for monitoring is invasive pressure transducers, usually an intraventricular monitor, which presents significant risk of infection and hemorrhage. These risks made discovering non-invasive methods for monitoring ICP and cerebral perfusion a priority for researchers. Herein we sought to review recent publications on novel minimally invasive multi-modality monitoring techniques that provide surrogate data on ICP, cerebral oxygenation, metabolism and blood flow. While limitations in various forms preclude them from supplanting the use of invasive monitors, these modalities represent useful screening tools within our armamentarium that may be invaluable when the risks of invasive monitoring outweigh the associated benefits.

Novel management strategies for medically-refractory vasospasm following aneurysmal subarachnoid hemorrhage

Delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (SAH) is an important cause of further morbidity and mortality after an already devastating condition. Though traditionally attributed to vasospasm of large capacitance arteries and the resulting down-stream disruption of cerebral blood flow, the pathogenesis of DCI has proven to be more complex with early brain injury, blood-brain barrier disruption, microthrombosis, cortical spreading depolarizations, and the failure of cerebral autoregulation as newly elucidated factors. Vasospasm is a known consequence of SAH. The standard of care includes close monitoring for neurological deterioration, most often with serial clinical examinations, transcranial Doppler ultrasonography, and vascular imaging (crucial for early detection of DCI and allows for prompt intervention). Nimodipine continues to remain an important pharmacological strategy to improve functional outcomes in patients with SAH at risk for developing vasospasm. The paradigm for first line therapy in patients with vasospasm of induced hypertension, hypervolemia, and hemodilution has recently been challenged. Current American Heart Association guidelines recommend targeting euvolemia and judicious use of the pharmacologically induced hypertension component. Symptomatic vasospasm patients who do not improve with this first line therapy require rescue intervention with mechanical or chemical angioplasty and optimization of cardiac output and hemoglobin levels. This can be escalated in a step-wise fashion to include adjunct treatments such as intrathecal administration of vasodilators and sympatholytic or thrombolytic therapies. This review provides a general overview of the treatment modalities for DCI with a focus on novel management strategies that show promising results for treating vasospasm to prevent DCI.

Isolated intraventricular hemorrhage secondary to dural arteriovenous fistula

Isolated intraventricular hemorrhage due to dural arteriovenous fistula (dAVF) is extremely rare and has been reported only a few times in the literature. The pathophysiological cause of isolated intraventricular hemorrhage in these cases was hypothetically attributed to retrograde venous flow into subependymal vessels, although none of these cases demonstrated radiographic evidence of such reflux. We present the first case of a dAVF with radiographic evidence of severe cortical venous reflux into the subependymal venous network causing isolated intraventricular hemorrhage, thus lending proof for the underlying pathophysiology. Furthermore, ours is the first case of dAVF with isolated intraventricular hemorrhage that was successfully treated using multimodality transvenous and transarterial embolization techniques. In cases of high-grade dAVF, multimodality treatment may offer the greatest chance for success, and should be strongly considered for management.

Endovascular intervention of acute ischemic stroke due to occlusion of fetal posterior cerebral artery

A fetal posterior cerebral artery (FPCA) is an anatomic variant in which the posterior cerebral artery is an embryological derivative of the internal carotid artery. Although most cases of ischemic strokes in patients with FPCAs involve embolic infarcts, emergent large vessel occlusion of a FPCA is extremely rare. We present two cases of successful endovascular intervention for emergent occlusion of a FPCA, one of which is only the second reported case of a mechanical thrombectomy of a FPCA. We review the embryology of FPCA, the controversy regarding its association with cerebral infarcts, and various approaches used in the treatment of such occlusive lesions.