Multi-Modal Biomarkers of Cerebral Edema in Low Resolution MRI

A central challenge of medical imaging studies is to extract quantitative biomarkers that characterize pathology or predict disease outcomes. In high-resolution, high-quality magnetic resonance images (MRI), state-of-the-art approaches have performed well. However, such methods may not translate to low resolution, lower quality images acquired on MRI scanners with lower magnetic field strength. Therefore, in low-resource settings where low field scanners are more common and there is a shortage of available radiologists to manually interpret MRI scans, it is essential to develop automated methods that can accommodate lower quality images and augment or replace manual interpretation. Motivated by a project in which a cohort of children with cerebral malaria were imaged using 0.35 Tesla MRI to evaluate the degree of diffuse brain swelling, we introduce a fully automated framework to translate radiological diagnostic criteria into image-based biomarkers. We integrate multi-atlas label fusion, which leverages high-resolution images from another sample as prior spatial information, with parametric Gaussian hidden Markov models based on image intensities, to create a robust method for determining ventricular cerebrospinal fluid volume. We further propose normalized image intensity and texture measurements to determine the loss of gray-to-white matter tissue differentiation and sulcal effacement. These integrated biomarkers are found to have excellent classification performance for determining severe cerebral edema due to cerebral malaria.

Diffuse brain swelling following falcine meningioma surgery

Initially described by Harvey Cushing at the beginning of the last century, meningioma is used for tumors that originate from meningothelial cells of the arachnoid, are usually well-circumscribed, slow growing and amenable to complete resection. The presence of peritumoral edema in meningiomas is known for a long time and has been studied regarding its etiology. The peritumoral edema can lead to technical difficulties during treatment as a limitation of the surgical field when the swelling is extensive. The present study describes a case of a patient who developed severe and persistent neurological impairment due to diffuse cerebral swelling after resection of parasagittal meningioma without complications perioperatively.

Epidemiology and pathophysiology of traumatic brain injury

Although medical management of traumatic brain injury (TBI) may have improved in developed countries, TBI is still a major cause of mortality and morbidity. The demographics are skewed towards the younger patient population, and affects males more than females, but in general follow a bimodal distribution with peaks affecting young adults and the elderly. As a result, the loss of functional years is devastating. Pathology due to brain trauma is a complex two-hit phenomenon, frequently divided into ‘primary’ and ‘secondary’ injury. Hypoxia, ischaemia, and inflammation all play a role, and the importance of each component varies between patients and in an individual patient over time. The initial injury may increase intracranial pressure and reduce cerebral perfusion due to the presence of mass lesions or diffuse brain swelling. Further secondary insults, such as hypotension, reduced cerebral perfusion pressure, hypoxia, or fever may exacerbate swelling and inflammation, and further compromise cerebral perfusion. Although there are currently no specific effective treatments for TBI, an improved understanding of the pathophysiology may eventually lead to treatments that will reduce mortality and improve long-term functional outcome.

Does “Second Impact Syndrome” Exist?

Second impact syndrome is a condition that is believed by some people to be a consequence of recurrent sports concussion. The only evidence to support its existence is anecdotal and, if it does exist, it is rare. The fear of this condition has driven the promulgation of concussion management guidelines and, more worryingly, the recent trend towards government regulation of the clinical management of concussion in the United States. Diffuse brain swelling following a single head injury, a well-recognized condition, is more common in children than in adults and usually has a poor outcome. It is posited that the so-called second impact syndrome simply represents diffuse brain swelling mistakenly attributed to repeated concussion.

Capillary Transit Time Heterogeneity and Flow-Metabolism Coupling after Traumatic Brain Injury

Most patients who die after traumatic brain injury (TBI) show evidence of ischemic brain damage. Nevertheless, it has proven difficult to demonstrate cerebral ischemia in TBI patients. After TBI, both global and localized changes in cerebral blood flow (CBF) are observed, depending on the extent of diffuse brain swelling and the size and location of contusions and hematoma. These changes vary considerably over time, with most TBI patients showing reduced CBF during the first 12hours after injury, then hyperperfusion, and in some patients vasospasms before CBF eventually normalizes. This apparent neurovascular uncoupling has been ascribed to mitochondrial dysfunction, hindered oxygen diffusion into tissue, or microthrombosis. Capillary compression by astrocytic endfeet swelling is observed in biopsies acquired from TBI patients. In animal models, elevated intracranial pressure compresses capillaries, causing redistribution of capillary flows into patterns argued to cause functional shunting of oxygenated blood through the capillary bed. We used a biophysical model of oxygen transport in tissue to examine how capillary flow disturbances may contribute to the profound changes in CBF after TBI. The analysis suggests that elevated capillary transit time heterogeneity can cause critical reductions in oxygen availability in the absence of ‘classic’ ischemia. We discuss diagnostic and therapeutic consequences of these predictions.

Central Nervous System Trauma

This chapter describes and illustrates the various pathological processes that result from head injury. Clinical, neuroradiological, and pathological data allow the separation of focal or diffuse damage. Focal lesions include scalp and skull lesions, contusions and lacerations of the brain, and intracranial hemorrhages. Diffuse lesions in traumatic brain injury include diffuse ischemia, diffuse traumatic axonal injury, and diffuse brain swelling. The consequences of penetrating injuries, blast injuries, and chronic traumatic encephalopathy resulting from repetitive head injury are also described. Separate sections are devoted to spinal cord injury and the consequences of brain injury in infants and children.

Role of barbiturate coma in the management of focally induced, severe cerebral edema in children

Barbiturates are widely used in the management of high intracranial pressure (ICP) caused by diffuse brain swelling. The cardiovascular, renal, and immunological side effects of these drugs limit them to last-line therapy. There are few published data regarding the role of barbiturates in focal brain lesions causing refractory elevated ICP and intraoperative brain swelling in the pediatric population. The authors here present 3 cases of nontraumatic, focally induced, refractory intracranial hypertension due to 2 tumors and 1 arteriovenous malformation, in which barbiturate therapy was used successfully to control elevated ICP. They focus on cardiovascular, renal, and immune function during the course of pentobarbital therapy. They also discuss the role of pentobarbital-induced hypothermia. From this short case series, they demonstrate that barbiturates in conjunction with standard medical therapy can be used to safely reduce postoperative refractory intracranial hypertension and intraoperative brain swelling in children with focal brain lesions.

Continuous ventricular cerebrospinal fluid drainage with intracranial pressure monitoring for management of posttraumatic diffuse brain swelling

BACKGROUND: Ventricular drainage has played an important role in the management of traumatic brain-injured patients. The aim of the present study was describe outcomes in a series of 57 patients with diffuse brain swelling underwent to intracranial pressure (ICP) monitoring. METHOD: Fifty-eight patients with diffuse posttraumatic brain swelling, were evaluated prospectively. The Glasgow Coma Scale (GCS) scores of patients varied from 4 to 12. Patients groups divided according to GCS and age. Patient neurological assessment was classified as favorable, unfavorable, and death. RESULTS: Mechanisms of injury were vehicle accidents in 72.4% and falls in 15.6%. 54% of patients had GCS scores between 6 and 8. There were no statistical differences, regarding outcome, between groups separated by age. In the adults group (n=47), 44.7% evolved favorably. CONCLUSION: Our results indicate a poor prognosis in patients with brain swelling. We believe that continuous ventricular CSF drainage with ICP monitoring is a simple method as an adjunct in the management of these patients.