Dural Arteriovenous Fistulas: A Characteristic Pattern of Edema and Enhancement of the Medulla on MRI.

Medullary edema with enhancement is rarely reported at initial MR imaging in intracranial dural arteriovenous fistulas. We report a series of 5 patients with dural arteriovenous fistulas, all of whom demonstrated a characteristic pattern of central medullary edema and medullary enhancement at initial MR imaging. Cognard type V dural arteriovenous fistula, defined by drainage into the perimedullary veins and the veins surrounding the brain stem, is a rare yet well-described pathologic entity. Even more rarely reported, however, is its clinical presentation with predominantly bulbar symptoms and MR imaging findings of central medullary edema with enhancement. This constellation of findings frequently leads to a convoluted clinical picture, prompting work-up for alternative disease processes and delaying diagnosis. Because an expedited diagnosis is critical in preventing poor outcomes, it is paramount to make the referring physician and neuroradiologist more cognizant of this rare-yet-characteristic imaging manifestation of dural arteriovenous fistula.

The critical care research networks experience.

Neurocritical care is a subspecialty of critical care medicine, dedicated to the care and the advancement of care of critically ill patients with neurosurgical or neurological diseases. Neurocritical care patients are heterogeneous, in both their disease process and the therapies they receive, however, several studies demonstrate that care of these patients in dedicated NeuroIntensive Care Units (neuroICUs) by neurointensivists, who coordinate their care is associated with reduced mortality and resource utilization. NeuroICUs foster innovation, and yet despite all the recent advances, much research needs to be undertaken in neurocritical care to better understand the disease pathophysiology and to demonstrate improved outcome with the use of goal-directed therapy based on evolving techniques and therapies.

Hyperbaric oxygen for experimental intracerebral hemorrhage.

Acute brain edema formation contributes to brain injury after intracerebral hemorrhage (ICH). It has been reported that hyperbaric oxygen (HBO) is neuroprotective in cerebral ischemia, subarachnoid hemorrhage, and brain trauma. In this study, we investigated the effects of HBO on brain edema following ICH in rats. Male Sprague-Dawley rats received intracerebral infusion of autologous whole blood, thrombin, or ferrous iron. HBO (100% O2, 3.0 ATA for 1 h) was initiated 1 h after intracerebral injection. Control rats were exposed to air at room pressure. Brains were sampled at 24 or 72 h for water content, ion measurement, and Western blot analysis. We found that 1 session of HBO reduced perihematomal brain edema (p < 0.05) 24 h after ICH. HBO also reduced heat shock protein-32 (HSP-32) levels (p < 0.05) in ipsilateral basal ganglia 24h after ICH. However, HBO failed to attenuate thrombin-induced brain edema and exaggerated ferrous iron-induced brain edema (p < 0.05). Three sessions of HBO also failed to reduce brain edema 72h after ICH. In summary, HBO reduced early perihematomal brain edema and HSP-32 levels in brain. HBO-related brain protection does not occur through reduction in thrombin toxicity because HBO failed to attenuate thrombin-induced brain edema. Our results also indicate that HBO treatment after hematoma lysis for ICH may be harmful, since HBO amplifies iron-induced brain edema.

Hyperbaric oxygen preconditioning activates ribosomal protein S6 kinases and reduces brain swelling after intracerebral hemorrhage.

BACKGROUND: New protein synthesis is key to ischemic tolerance induced by preconditioning and ribosomal protein S6 kinases (p70 S6 K) are important enzymes in protein synthesis. Hyperbaric oxygen preconditioning (HBOP) reduces ischemic brain damage. This study investigated if HBOP can activate p70 S6 K and increase new protein synthesis and if HBOP induces brain tolerance against brain swelling after intracerebral hemorrhage (ICH). METHODS: There were two parts of the studies. 1) Rats received five consecutive sessions of HBOP. Twenty-four hours after HBOP, the rats had an ICH and were sacrificed one or three days later for brain edema measurement. 2) Rats received five sessions of HBOP or control pretreatment and were sacrificed for Western blot analysis and immunohistochemistry of activated p70 S6 K and heme oxygenase-1 (HO-1). FINDINGS: Five sessions of HBOP significantly reduced brain edema in the ipsilateral basal ganglia after ICH. Western blot analysis showed that HBOP activated p70 S6 K and increased HO-1 levels in the basal ganglia. Strong activated p70 S6 K immunoreactivity was also found in the basal ganglia. CONCLUSIONS: Our results suggest activation of p70 S6 K may have a role in heat shock protein synthesis after HBOP and may contribute to HBOP-induced brain protection.

Unsuspected swallowing of a partial denture.

We report a case of a swallowed partial denture in a 51-year-old man who presented with progressive dysphagia, odynophagia, and fevers. Imaging studies were initially interpreted as supraglottitis with laryngeal inflammation, which was confirmed by direct visualization with flexible endoscopy. Despite appropriate therapy, the patient's symptoms persisted and rigid laryngoscopy was performed, which revealed a partial denture in the hypopharynx and upper esophagus. The subtle imaging appearance of a swallowed denture is discussed.

Imaging-guided injection techniques with fluoroscopy and CT for spinal pain management.

Local spinal pain and radiculopathy are common conditions that debilitate millions of Americans annually. Most cases are successfully treated conservatively with rest or physical therapy. Chiropractic manipulation or, in some cases, surgery may also be performed. Percutaneous injection has been used for spinal pain management for many years, but many of these procedures have historically been performed without imaging guidance. Recently, however, newer minimally invasive, imaging-guided percutaneous techniques have been added to the list of available treatment options for spinal pain. Imaging-guided techniques with fluoroscopy or computed tomography increase the precision of these procedures and help confirm needle placement. Cervical, thoracic, lumbosacral, and sacroiliac pain can be evaluated and treated safely and effectively with injections of local anesthetics or long-acting steroids into facet joints, sacroiliac joints, selective nerve roots, spondylolytic areas, and the epidural space. Because imaging-guided techniques appear to provide better results and reduce complication rates, they are becoming more popular despite controversy regarding their effectiveness. Controversy will continue to surround these imaging-guided techniques until large, double-blinded studies become available. In the meantime, there is an increased demand for these procedures from referring physicians, and it is important to be able to safely perform them with a minimum of patient discomfort.

Low plasma thiamine levels in elder patients admitted through the emergency department.

OBJECTIVES: To determine the prevalence of thiamine deficiency in a high-risk group of elder emergency department (ED) patients who reside in nursing homes and need admission to the hospital, and to determine the effect of patients' diets on this prevalence. METHODS: This was an observational pilot study of 75 consecutive ED patients aged 65 years or older who lived in a nursing home and were admitted to the hospital. Plasma thiamine levels were measured by high-pressure liquid chromatography on serum samples collected within 24 hours of hospital admission. Nursing home records were reviewed to determine whether patients received nutritional supplementation or enteral tube feedings. RESULTS: Seventy patients participated and had a mean plasma thiamine level of 27.3 microg/dL (95% CI = 20.2 to 34.4). Fourteen percent (n = 10, 95% CI = 8% to 24%) were thiamine-deficient (<10 microg/dL). Patients not receiving dietary supplements or tube feedings (n = 26) had lower mean thiamine levels (20.3 microg/dL, 95% CI = 12.7 to 27.9) and were thiamine-deficient more often (27%) than patients receiving dietary support (n = 44, 31.5 microg/dL, 95% CI = 24.7 to 38.3, 7% thiamine-deficient). CONCLUSIONS: Elder nursing home patients seen in the ED and admitted to the hospital are frequently thiamine-deficient. Empiric thiamine supplementation is often used in the ED for other high-risk patients, such as alcoholic individuals, and may be appropriate for high-risk elder patients. Further research is needed to determine whether thiamine supplementation in these patients can improve their clinical outcomes.

Viral myocarditis presenting with seizure and electrocardiographic findings of acute myocardial infarction in a 14-month-old child.

Acute viral myocarditis is an uncommon but potentially fatal illness in children. Patients with myocarditis may present with nonspecific symptoms or atypical findings that make diagnosis in the emergency department difficult. We describe a previously healthy 14-month-old child with difficulty breathing and a tonic-clonic seizure who was subsequently found to have ECG changes and cardiac marker elevation consistent with acute myocardial infarction. The patient was immediately transferred from our community hospital ED to our tertiary care children's hospital. Shortly after admission, the patient developed intractable nonperfusing ventricular arrhythmias necessitating extracorporeal membrane oxygenation. Cardiac function did not recover, and the patient required heart transplantation before cessation of bypass. Serology and anatomic pathology confirmed coxsackievirus B myocarditis. This case illustrates (1) the nonspecific presentation of myocarditis as dyspnea and seizure, (2) the manner in which myocarditis can mimic myocardial infarction, and (3) the importance of early diagnosis in the ED and transfer to a tertiary care facility.

The persistent stapedial artery.

The persistent stapedial artery is a rare congenital vascular anomaly that may present as a pulsatile middle ear mass or that may appear as an incidental finding. Five cases of persistent stapedial artery are presented. The CT findings include the absence of the ipsilateral foramen spinosum and a soft-tissue prominence in the region of the tympanic segment of the facial nerve. Three cases were associated with an aberrant internal carotid artery. Imaging identification of this variant may obviate unnecessary surgery and may help in planning surgical or endovascular interventions.

Management of sickle cell pain crisis in the emergency department at teaching hospitals.

The purpose of this study is to determine the frequency and variety of strategies being used in the Emergency Department (ED) management of sickle cell pain crisis (SCPC). One thousand randomly selected academic emergency physicians received a multiple-choice survey; 549 (55%) completed the survey. Forty-five percent of respondents treat patients with SCPC every week or almost every shift. Twenty percent use protocols for management of SCPC. Respondents consider pain refractory to outpatient treatment if it is persistent after two (23%) or three (53%) doses of parenteral analgesic. Meperidine or morphine is the most common initial analgesic. In the routine management of uncomplicated SCPC, i.v. analgesics, i.v. hydration, oxygen therapy, and complete blood counts are often or always used by 67, 71, 66, and 82% of respondents, respectively. Some patterns in the diagnostic and therapeutic management of patients with SCPC in the ED are identified, but overall practice is highly variable. Some popular elements of care are divergent from those suggested by the scientific literature.

Lack of a neuroprotective effect from N-acetylcysteine after cardiac arrest and resuscitation in a canine model.

OBJECTIVE: Oxygen free radicals cause brain injury following resuscitation from cardiac arrest. In preclinical trials, some free radical scavenging drugs reduce oxidative neuronal damage after ischemia and reperfusion, but these drugs are generally not yet available for clinical testing or use. N-Acetylcysteine (NAC), a commonly used antidote in acetaminophen poisoning, is also a potent free radical scavenger that can ameliorate oxidative injury following ischemia and reperfusion in neuronal cell culture. We hypothesized that treatment with NAC would improve neurological outcome after cardiac arrest and resuscitation. METHODS: In 16 adult female beagles, 10 min of ventricular fibrillation was followed by 3 min of open-chest CPR, and defibrillation. Immediately following return of spontaneous circulation, animals randomly received either 150 mg/kg NAC (3% solution) (n = 8) or an equivalent volume of normal saline (n = 8). Twenty-three hours later, neurological deficit was scored (0 = normal, 100 = brain death). RESULTS: All animals were successfully resuscitated, and there were no apparent adverse effects to the administration of NAC in post resuscitative animals. There was, however, no significant difference in neurological deficit in the animals receiving NAC (40 +/- 12.9, mean +/- SD) compared to control animals (44 +/- 6.5, P = 0.73). CONCLUSION: No neuroprotective effect was found from the administration of NAC at currently used clinical dosages, to dogs subjected to 10 min of global cerebral ischemia from cardiac arrest and resuscitation.

Benign pneumoperitoneum associated with pneumomediastinum and pneumoretroperitoneum in ambulatory outpatients.

Perforation of a hollow viscus and other dangerous etiologies must always be considered in the evaluation of free peritoneal air. Pneumoperitoneum in the presence of pneumoretroperitoneum and pneumomediastinum, however, often results from air tracking from a pathologic source outside of the abdomen along the mesentery into the peritoneum. This syndrome is relatively benign, and should be considered when there are multiple sites of extraluminal air in order to minimize the risk of unnecessary exploratory laparotomy. Two cases of benign pneumoperitoneum associated with pneumomediastinum and pneumoretroperitoneum are presented.

Sarcomas of the head and neck.

Sarcomas are rare malignancies of mesenchymal origin. Computed tomographic and magnetic resonance imaging characteristics, as well as histologic findings and epidemiology, of sarcomas of the head and neck are reviewed. The sarcomas discussed include rhabdomyosarcoma, fibrosarcoma, osteosarcoma, chondrosarcoma, malignant fibrous histiocytoma, leiomyosarcoma, alveolar soft part sarcoma, Ewing's sarcoma, and synovial sarcoma. The imaging findings of these entities frequently are nonspecific. Imaging, particularly magnetic resonance imaging, has a major role in defining the extent of these tumors. This is important because complete surgical excision is the preferred method of treatment. Imaging also is useful in planning radiation therapy and determining prognosis.

Imaging of spinal intradural arachnoid cysts: MRI, myelography and CT.

Imaging studies in eight patients with surgically-confirmed spinal arachnoid cysts were analyzed retrospectively. All patients had preoperative MRI of the spine and seven preoperative myelography with postmyelographic CT. In all cases the correct diagnosis could be made preoperatively on the basis solely of MRI. The diagnosis could also be established from myelography and postmyelographic CT in six of the seven cases. In one case myelography and CT simply demonstrated an intradural extramedullary mass.

Absence of the supraclinoid internal carotid artery in association with intracranial aneurysms.

We report a case of absence of the supraclinoid segment of the left internal carotid artery associated with hypoplasia of the ipsilateral internal carotid artery and anterior communicating artery aneurysm formation. We discuss the embryology probably responsible for this anatomical variant and show the imaging findings.

Hypothermia from realistic fluid resuscitation in a model of hemorrhagic shock.

STUDY OBJECTIVE: To correlate changes in core body temperature with changes in mean arterial pressure (MAP) and cardiac output (CO) and with the administration of room-temperature intravenous fluids in a clinically relevant large-animal model of uncontrolled hemorrhage. METHODS: Ten swine were subjected to uncontrolled hemorrhage through a flow-monitored shunt placed between the femoral artery and the peritoneal cavity. Animals were randomly assigned to a treatment or a control group. The control group (n=5) received no intravenous fluids. The treatment group (n=5) received 80 mL/kg (3:1 crystalloid/blood loss) ambient-temperature lactated Ringer's solution over a 10-minute resuscitation phase initiated 10 minutes after injury. CO and core body temperature, measured with the use of a pulmonary artery catheter, and MAP were the primary outcomes. We analyzed differences between groups with the use of repeated-measures ANOVA. Change of temperature was analyzed against the change in CO, and against fluid infusion for each interval, by means of regression analysis. RESULTS: The unresuscitated control animals had no change in core temperature despite profound hemorrhagic shock and hypotension. The animals treated with fluids had a mean 2.6 degrees C decrease in core temperature during fluid resuscitation (95% confidence interval [CI], 1.8 to 3.5). A 1.5 degrees C decrease in core temperature (95% CI, .1 to 2.0) persisted at the end of 60 minutes (40 minutes after fluid resuscitation was discontinued). Core temperatures in control animals were 2.8 degrees C lower than those in treated animals after fluid resuscitation (95% CI, .8 to 4.8). Decreases in core temperature correlated with fluid infusion (beta=-35.2 mL/kg x degrees C, R2=.75) and increases in CO (beta=-1.46 L/min x degrees C, R2=.69). CONCLUSION: Ambient-temperature crystalloid resuscitation in a clinically relevant large-animal model of hemorrhagic shock causes small decreases in core body temperature. Resuscitation rather than shock is the main cause of decreased body temperature in this model.

Primary intraosseous hemangioma of the orbit: CT and MR appearance.

An 8-year-old girl had acute onset of blurred vision, proptosis, and lateral and vertical gaze palsies on the right. CT and MR examinations showed an expansile mass involving the greater wing of the right sphenoid bone. Pathologic analysis of the surgical specimen revealed a capillary hemangioma. The lesion was inhomogeneous but predominantly isointense with gray matter on T1-weighted images. On T2-weighted images the lesion was inhomogeneous with areas of both high and low signal intensity. The rim enhanced uniformly, and there was inhomogeneous enhancement of the bulk of the lesion.

MR of spinal meningeal melanocytoma.

We report an unusual case of meningeal melanocytoma, a rare pigmented lesion of the leptomeninges, that occurred within the leptomeninges of the thoracic spinal canal. The lesion showed increased signal intensity on T1-weighted MR images relative to gray matter, was isointense with gray matter on T2-weighted images, and enhanced mildly but homogeneously after administration of contrast material.

A new model of uncontrolled hemorrhage that allows correlation of blood pressure and hemorrhage.

OBJECTIVE: To compare hemodynamics, mortality rates, and bleeding rates at 3 severities of hemorrhage in a new model of uncontrolled intra-abdominal bleeding that uses an injury of varying severity and geometry unfavorable to thrombosis. METHODS: Ten swine were bled through a flow-monitored shunt placed between the femoral artery and the peritoneal cavity. The shunt was connected to catheters of varying diameters placed in the femoral artery to create 3 rates of hemorrhage. Blood flow through the shunt was measured with an in-line Doppler probe. Arterial pressures, cardiac output (CO), and ECGs were monitored. Survival and blood loss were calculated. RESULTS: The model successfully produced 3 hemorrhage severities. At all 3 rates of bleeding, blood flow was linearly related to mean arterial pressure, with R2 > 0.72. Bleeding was continuous in all groups. The mean numbers of minutes until death were 53, 45, and 25, respectively, at the increasing shock severities. Blood pressure (BP) and CO decreased continuously in all groups, but did so more rapidly with increasing severity of hemorrhage. CONCLUSIONS: In this model of uncontrolled hemorrhage, bleeding was continuous and linearly related to BP. The hemodynamic response to uncontrolled bleeding in this model differs markedly from those in previous wire aortotomy models where wound geometry is favorable to thrombosis. Hence, when injury geometry is favorable to thrombosis (as in aortotomy), thrombosis formation affects hemorrhage rates and hemodynamic responses.