Bryan Pukenas

Brain hypoxia is associated with short-term outcome after severe traumatic brain injury independently of intracranial hypertension and low cerebral perfusion pressure.

BACKGROUND Brain hypoxia (BH) can aggravate outcome after severe traumatic brain injury (TBI). Whether BH or reduced brain oxygen (Pbto2) is an independent outcome predictor or a marker of disease severity is not fully elucidated. OBJECTIVE To analyze the relationship between Pbto2, intracranial pressure (ICP), and cerebral perfusion pressure (CPP) and to examine whether BH correlates with worse outcome independently of ICP and CPP. METHODS We studied 103 patients monitored with ICP and Pbto2 for > 24 hours. Durations of BH (Pbto2 < 15 mm Hg), ICP > 20 mm Hg, and CPP < 60 mm Hg were calculated with linear interpolation, and their associations with outcome within 30 days were analyzed. RESULTS Duration of BH was longer in patients with unfavorable (Glasgow Outcome Scale score, 1-3) than in those with favorable (Glasgow Outcome Scale, 4-5) outcome (8.3 ± 15.9 vs 1.7 ± 3.7 hours; P < .01). In patients with intracranial hypertension, those with BH had fewer favorable outcomes (46%) than those without (81%; P < .01); similarly, patients with low CPP and BH were less likely to have favorable outcome than those with low CPP but normal Pbto2 (39% vs 83%; P < .01). After ICP, CPP, age, Glasgow Coma Scale score, Marshall computed tomography grade, and Acute Physiology and Chronic Health Evaluation II score were controlled for, BH was independently associated with poor prognosis (adjusted odds ratio for favorable outcome, 0.89 per hour of BH; 95% confidence interval, 0.79-0.99; P = .04). CONCLUSION Brain hypoxia is associated with poor short-term outcome after severe traumatic brain injury independently of elevated ICP, low CPP, and injury severity. Pbto2 may be an important therapeutic target after severe traumatic brain injury. ABBREVIATIONS AOR: adjusted odds ratio APACHE II: Acute Physiology and Chronic Health Evaluation II CI: confidence interval CPP: cerebral perfusion pressure GCS: Glasgow Coma Scale ICP: intracranial pressure IQR: interquartile range MAP: mean arterial pressure TBI: traumatic brain injury

Sports-Related Concussion Testing

Due to the recent focus on concussion in sports, a number of tests have been developed to diagnose and manage concussion. While each test measures different brain functions, no single test has been shown to quickly and reliably assess concussion in all cases. In addition, most of the current concussion tests have not been validated by scientific investigation. This review identifies the pros and cons of the most commonly used noninvasive tests for concussion in order to provide a more complete picture of the resources that are available for concussion testing. The potential utility of research tools such as the head impact telemetry system, advanced magnetic resonance imaging protocols, and biomarkers are discussed in the context of the currently employed tools.

Heterogeneous practice patterns regarding antiplatelet medications for neuroendovascular stenting in the USA: a multicenter survey

Background Adequate dual antiplatelet (AP) therapy is imperative when performing neurovascular stenting procedures. Currently, no consensus for the ideal AP regimen exists. Thus the present study aimed to gain a better understanding of real world practice AP patterns by surveying neurointerventional surgeons. Methods Survey links were emailed to 296 neurointerventional surgeons practicing in the USA, asking 51 questions including demographics, stent specific use, AP pre and post-medication, types of APs, point of care (POC) assessment, complications, and outcomes. Data were collected and analyzed using Research Electronic Data Capture (REDCap). Results 74 participants responded; 56.8% were from academic centers. Participants treated an average of 5.5 aneurysms per month. They placed an average of 1.6 intracranial stents and 1.4 cervical stents per month. Mean number of pipeline embolization devices (PEDs) placed per year was 15.2. Heterogeneity existed regarding AP regimens; the most frequent included acetylsalicylic acid (ASA) 325 mg+Plavix 75 mg daily (for 7 days prior) and ASA 325 mg+Plavix 75 mg daily (for 5 days prior) for routine placement of intracranial and cervical stents, respectively. For emergency placement, ASA 325 mg+Plavix 600 mg (at time of surgery) was the most frequently used. 46.8% routinely used POC testing, most frequently VerifyNow (Accumetrics, San Diego, California, USA); the most common threshold determining a non-responder was <30% inhibition. 85.7% used POC for PED placement. Management changes based on POC testing were diverse. Conclusions The results highlight the heterogeneity of current practices regarding AP medication regimens during neurovascular stenting. Given its importance, evidence based protocols are imperative. Minimal literature exists focusing on neurovasculature, and therefore understanding current practice patterns represents a first step toward generating these protocols.

Mechanical embolectomy for ischemic stroke in a pediatric ventricular assist device patient

The reported incidence of cerebral embolic or hemorrhagic complications related to mechanical circulatory support in children is high, even while subjects are managed with aggressive antithrombotic therapy. The safety and utility of endovascular treatment for stroke in the pediatric VAD population has not been established in the published literature. We describe a nine‐yr‐old patient on BiVAD support who experienced threatened AIS on two separate occasions. He was treated successfully via mechanical embolectomy on both occasions and survived to transplantation with minimal neurologic deficits.

Widespread gene transfer in the central nervous system of cynomolgus macaques following delivery of AAV9 into the cisterna magna

Adeno-associated virus serotype 9 (AAV9) vectors have recently been shown to transduce cells throughout the central nervous system of nonhuman primates when injected into the cerebrospinal fluid (CSF), a finding which could lead to a minimally invasive approach to treat genetic and acquired diseases affecting the entire CNS. We characterized the transduction efficiency of two routes of vector administration into the CSF of cynomolgus macaques—lumbar puncture, which is typically used in clinical practice, and suboccipital puncture, which is more commonly used in veterinary medicine. We found that delivery of vector into the cisterna magna via suboccipital puncture is up to 100-fold more efficient for achieving gene transfer to the brain. In addition, we evaluated the inflammatory response to AAV9-mediated GFP expression in the nonhuman primate CNS. We found that while CSF lymphocyte counts increased following gene transfer, there were no clinical or histological signs of immune toxicity. Together these data indicate that delivery of AAV9 into the cisterna magna is an effective method for achieving gene transfer in the CNS, and suggest that adapting this uncommon injection method for human trials could vastly increase the efficiency of gene delivery.

Intracranial vertebrobasilar artery dissection associated with postpartum angiopathy.

Background. Cervicocephalic arterial dissection (CCAD) is rare in the postpartum period. To our knowledge this is the first reported case of postpartum angiopathy (PPA) presenting with ischemic stroke due to intracranial arterial dissection. Case. A 41-year-old woman presented with blurred vision, headache, and generalized seizures 5 days after delivering twins. She was treated with magnesium for eclampsia. MRI identified multiple posterior circulation infarcts. Angiography identified a complex dissection extending from both intradural vertebral arteries, through the basilar artery, and into both posterior cerebral arteries. Multiple segments of arterial dilatation and narrowing consistent with PPA were present. Xenon enhanced CT (Xe-CT) showed reduced regional cerebral blood flow that is improved with elevation in blood pressure. Conclusion. Intracranial vertebrobasilar dissection causing stroke is a rare complication of pregnancy. Eclampsia and PPA may play a role in its pathogenesis. Blood pressure management may be tailored using quantitative blood flow studies, such as Xe-CT.

Contrast-enhanced magnetic resonance angiography.

Magnetic resonance (MR) angiography is a powerful tool for the evaluation of cervical and intracranial vasculature. Both noncontrast and contrast-enhanced MR angiography can provide exquisite vascular contrast and detail without the use of ionizing radiation. More advanced techniques such as time-resolved MR angiography and parallel imaging provide dynamic information in rapid fashion. This article describes the basic principles and techniques of MR angiography image acquisition.

Combined use of Solitaire FR and Penumbra devices for endovascular treatment of cerebral venous sinus thrombosis in a child

A pre-teenager with newly diagnosed ulcerative colitis presented to an emergency department with acute headache, altered mental status and bilateral lower extremity weakness. Head CT demonstrated acute thrombus in the vein of Galen and straight sinus, and the patient was started on a heparin infusion. The patient clinically deteriorated and became unresponsive. In view of the rapid deterioration despite anticoagulation therapy, the patient was taken for endovascular treatment. A novel endovascular approach was performed with combined use of Solitaire FR and Penumbra devices to enhance access to the straight sinus and to limit intraprocedural blood loss. The post-treatment head CT demonstrated a decrease in hyperattenuation within the vein of Galen and straight sinus. The neurologic status improved within 24 h. The patient was discharged home with a normal neurologic examination.

The accuracy of mobile teleradiology in the evaluation of chest X-rays:

We assessed the diagnostic accuracy of digital photographs of plain film chest X-rays (CXRs) obtained using a mobile phone. The study was a randomized, non-inferiority trial, in which physical plain film CXRs viewed on a light box were compared with digital photographs of plain film CXRs. CXRs were selected from a database of radiology studies to show common pathologies found in Botswana associated with pneumonia, lung carcinoma, tuberculosis, pneumothorax and interstitial disease, as well as normal findings. The pre-selected diagnoses were subsequently verified by a second radiologist. Seven radiologists were randomized to review 75 plain film CXRs on light boxes before viewing 75 digital photographs, or vice versa. Their responses were considered correct if they matched the pre-defined diagnosis. For both modalities, the correct diagnosis was provided in 79% of cases; for plain film CXRs, the correct diagnosis was provided in 82% of cases and for digital photographs the correct diagnosis was provided in 76% of cases. The difference in diagnostic accuracy was −5.7% (95% CI: −10.8% to −0.5%), which confirmed non-inferiority (P < 0.001) for the primary outcome of diagnostic accuracy. A subgroup analysis demonstrated non-inferiority for lung carcinoma and pneumonia images, although non-inferiority was not achieved for pneumothorax, tuberculosis, interstitial disease or normal images. The study demonstrates that digital photographs of CXRs obtained via a mobile phone equipped with a digital camera are non-inferior to plain film CXRs.

Normal Brain Anatomy on Magnetic Resonance Imaging

Over the past few decades, spinal magnetic resonance imaging (MR imaging) has largely replaced computed tomography (CT) and CT myelography in the assessment of intraspinal pathology at institutions where MR imaging is available. Given its high contrast resolution, MR imaging allows the differentiation of the several adjacent structures comprising the spine. This article illustrates normal spinal anatomy as defined by MR imaging, describes commonly used spinal MR imaging protocols, and discusses associated common artifacts.