The Promise of Molecular Imaging: Focus on Central Nervous System Infections.

Central nervous system (CNS) infections can lead to high mortality and severe morbidity. Diagnosis, monitoring, and assessing response to therapy of CNS infections is particularly challenging with traditional tools, such as microbiology, due to the dangers associated with invasive CNS procedures (ie, biopsy or surgical resection) to obtain tissues. Molecular imaging techniques like positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging have long been used to complement anatomic imaging such as computed tomography (CT) and magnetic resonance imaging (MRI), for in vivo evaluation of disease pathophysiology, progression, and treatment response. In this review, we detail the use of molecular imaging to delineate host-pathogen interactions, elucidate antimicrobial pharmacokinetics, and monitor treatment response. We also discuss the utility of pathogen-specific radiotracers to accurately diagnose CNS infections and strategies to develop radiotracers that would cross the blood-brain barrier.

Role of imaging in CNS infections.

Neuroinfections are seen in both adults and children. These can result in serious morbidity and if left untreated and/or associated with comorbidities can be life threatening. Cross-sectional imaging like computed tomography (CT) and magnetic resonance imaging (MRI) are advised by the clinicians for the diagnosing, confirmation of the diagnosis, assess any complications of the infection, and also for follow up. Though CT is the initial imaging investigation commonly asked by the clinician, due to its lesser soft tissue resolution, early brain changes may not be seen on CT. MRI has better soft tissue resolution with no ionizing radiation to the patient and helps in detecting the early signs of infection. Appropriate MRI, not only helps the radiologist to reduce the number of possibilities of the causative organism but also differentiates tumors from infection. However, CT is useful to assess the bony changes and also easily available and affordable cross-sectional imaging modality worldwide. The review summarizes the approach of the radiologist to central nervous system (CNS) infections and their typical imaging characteristic features.

[Neurological complications in haematopoietic stem cell transplant patients]. / Complicaciones neurológicas en pacientes sometidos a trasplante de progenitores hematopoyéticos.

INTRODUCTION: Neurological complications are some of the most important complications that can occur in a patient undergoing haematopoietic stem cell transplantation (HSCT), not only because of the high mortality rate, but also because of the sequelae that appear in survivors. The causes of such complications are manifold and very often coexist in the same patient: toxicity of the conditioning regimen, graft-versus-host disease and its treatment, infections and their treatment, platelets and coagulation disorders, liver failure or arterial hypertension with low platelet count. AIMS: The aim of the present study is to provide a clinical description and to describe the risk factors for complications involving the central nervous system that may occur during the course of HSCT, in order to assist in the early detection of these disorders that may have a negative influence on the morbidity and mortality of these patients. DEVELOPMENT: The following types of neurological complications are described: central nervous system infections, vascular complications, pharmacological toxicity, metabolic complications, immune-mediated disorders and post-HSCT carcinogenesis, and effects of graft-versus-host disease and thrombotic microangiopathy on the nervous system. CONCLUSIONS: The patient undergoing HSCT is at particular risk for the development of neurological complications. Early diagnosis and treatment are needed to try to reduce the high morbidity and mortality in these patients.

TITLE: Complicaciones neurológicas en pacientes sometidos a trasplante de progenitores hematopoyéticos.Introducción. Las complicaciones neurológicas son algunas de las más importantes que se pueden presentar en un paciente sometido a un trasplante de progenitores hematopoyéticos (TPH), no sólo porque conllevan una mortalidad elevada, sino también por las secuelas que aparecen en los supervivientes. Las causas de dichas complicaciones son múltiples y, muy frecuentemente, coexisten en el mismo paciente: toxicidad del régimen de acondicionamiento, enfermedad del injerto contra el hospedador y su tratamiento, infecciones y su tratamiento, plaquetopenia y trastornos de la coagulación, fallo hepático o hipertensión arterial con plaquetopenia. Objetivos. El objetivo del presente estudio es el de aportar una descripción clínica y de los factores de riesgo de las complicaciones sobre el sistema nervioso central que pueden presentarse en el curso de un TPH, para ayudar en la detección precoz de estos trastornos que pueden influir negativamente en la morbimortalidad de estos pacientes. Desarrollo. Se describen los siguientes tipos de complicaciones neurológicas: infecciones sobre el sistema nervioso central, complicaciones vasculares, toxicidad farmacológica, complicaciones metabólicas, trastornos inmunomediados y carcinogenia pos-TPH, y efectos de la enfermedad del injerto contra el hospedador y de la microangiopatía trombótica sobre el sistema nervioso. Conclusiones. El paciente sometido a TPH es de especial riesgo para el desarrollo de complicaciones neurológicas. Se precisan un diagnóstico y un tratamiento precoces para intentar disminuir la elevada morbimortalidad de estos pacientes.

Non-traumatic pediatric intracranial hypertension: key points for different etiologies, diagnosis, and treatment.

Intracranial hypertension can be an acute life-threatening event or slowly deteriorating condition, leading to a gradual loss of neurological function. The diagnosis should be taken in a timely fashioned process, which mandates expedite measures to save brain function and sometimes life. An optimal management strategy is selected according to the causative etiology with a core treatment paradigm that can be utilized in various etiologies. Distinct etiologies are intracranial bleeds caused by traumatic brain injury, spontaneous intracranial hemorrhage (e.g., neonatal intraventricular hemorrhage), or the rare pediatric hemorrhagic stroke. The other primary pediatric etiologies for elevated intracranial pressure are intracranial mass (e.g., brain tumor) and hydrocephalus related. Other unique etiologies in the pediatric population are related to congenital diseases, infectious diseases, metabolic or endocrine crisis, and idiopathic intracranial pressure. One of the main goals of treatment is to alleviate the growing pressure and prevent the secondary injury to brain parenchyma due to inadequate blood perfusion and eventually inadequate parenchymal oxygenation and metabolic state. Previous literature discussed essential characteristics of the treatment paradigm derived mainly from pediatric brain traumatic injuries' treatment methodology. Yet, many of these etiologies are not related to trauma; thus, the general treatment methodology must be tailored carefully for each patient. This review focuses on the different possible non-traumatic etiologies that can lead to intracranial hypertension with the relevant modification of each etiology's treatment paradigm based on the current literature.

Neuroradiology of infectious diseases.

PURPOSE OF REVIEW: Early diagnosis of central nervous system (CNS) infections is crucial given high morbidity and mortality. Neuroimaging in CNS infections is widely used to aid in the diagnosis, treatment and to assess the response to antibiotic and neurosurgical interventions. RECENT FINDINGS: The Infectious Diseases Society of America (IDSA) guidelines have clear recommendations for obtaining a computerized tomography of the head (CTH) prior to lumbar puncture (LP) in suspected meningitis. In the absence of indications for imaging or in aseptic meningitis, cranial imaging is of low utility. In contrast, cranial imaging is of utmost importance in the setting of encephalitis, bacterial meningitis, ventriculitis, bacterial brain abscess, subdural empyema, epidural abscess, neurobrucellosis, neurocysticercosis, and CNS tuberculosis that can aid clinicians with the differential diagnosis, source of infection (e.g., otitis, sinusitis), assessing complications of meningitis (e.g., hydrocephalus, venous sinus thrombosis, strokes), need for neurosurgical interventions and to monitor for the response of therapy. Novel imaging techniques such as fast imaging employing steady-state acquisition (FIESTA), susceptibility-weighted imaging (SWI), and chemical exchange saturation transfer (CEST) contrast are briefly discussed. SUMMARY: Though the radiological findings in CNS infections are vast, certain patterns along with clinical clues from history and examination often pave the way to early diagnosis. This review reiterates the importance of obtaining cranial imaging when necessary, and the various radiological presentations of commonly encountered CNS infections.

Neuroimaging of CNS infection in haematological malignancy: important signs and common diagnostic pitfalls.

Patients with haematological malignancy are at increased risk of developing central nervous system (CNS) infections, which are associated with significant morbidity and mortality. Neuroimaging plays a pivotal role in the diagnostic pathway of these patients; however, layers of complexity are added to image interpretation by the heterogeneity in imaging manifestations of haematological malignancies in the CNS, overlapping imaging features of CNS infection, treatment-related parenchymal changes and the presence of intracranial comorbidity. In this article, we review important intracranial findings of CNS infection cases accrued in 1,855 studies over more than a decade at a specialist tertiary centre. We offer schema to identify common and important neuroimaging features, discuss key differential diagnoses and frequent diagnostic pitfalls.

Cerebral protothecosis mimicking high-grade glioma.

Prototheca wickerhamii is a common, indolent alga that seldom causes central nervous system infections in humans. We report the first UK case of cerebral protothecosis in an immunocompetent 56-year-old woman who presented with a 5-month history of intermittent fatigue followed by a 2-week history of symptoms, including right arm and leg weakness, a loss of fine motor coordination, worsening gait, right facial tingling, diplopia and a metallic oral taste. MRI scans revealed a multifocal abnormality suggestive of high-grade glioma. Given the clinical presentation, absence of immunodeficiency and characteristic MRI features, a diagnosis of high-grade glioma was deemed most likely by the multidisciplinary team. Surgical biopsy provided material for histopathological and microbiological diagnosis. She underwent a 2-year course of antimicrobials with surveillance MRI scans. The patient made a good functional recovery but still retains mild neurological sequelae.

Neonatal Neuroimaging.

Significant advances in the field of neonatal imaging has resulted in the generation of large complex data sets of relevant information for routine daily clinical practice, and basic and translational research. The evaluation of this data is a complex task for the neonatal imager who must distinguish normal and incidental findings from clinically significant abnormalities which are often adjunctive data points applicable to clinical evaluation and treatment. This review provides an overview of the imaging manifestations of disease processes commonly encountered in the neonatal brain. Since MRI is currently the highest yield technique for the diagnosis and characterization of the normal and abnormal brain, it is therefore the focus of the majority of this review. When applicable, discussion of some of the pertinent known pathophysiology and neuropathological aspects of disease processes are reviewed.

Morphological characteristics of infected subdural hematoma: Comparison with images of chronic subdural hematoma.

OBJECTIVES: Infected subdural hematoma (ISH) is a rare type of subdural empyema, with fewer than 50 cases reported to date. Its radiological features have not been adequately described, making diagnosis challenging. At our institution, two adults presented with ISH, which exhibited a characteristic shape on preoperative imaging. PATIENTS AND METHODS: This study examined ISH cases and chronic subdural hematoma (CSH) cases that underwent surgery at the Ishikawa Prefectural Central Hospital between January 2016 and March 2018. To distinguish ISH from CSH, we focused on three specific radiological features: the biconvex shape of the hematoma, presence of a high-density region at the lower end of the hematoma on plain computed tomography (CT), and presence of a hyper-intense signal within the hematoma on diffusion weighted imaging (DWI). RESULTS: We analyzed 30 ISH (current and previously reported) and 102 CSH cases in our study. We found no statistically significant associations between the hematoma type (ISH or CSH) and the presence of a high-density region at the lower end of the hematoma on plain CT (p = 0.13) or the presence of hyperintensity in the hematoma on DWI (p = 1.00). Conversely, a statistically significant association was found between the hematoma type and the biconvex shape of the hematoma (p < 0.01). CONCLUSION: These results suggest that the shape of the hematoma on imaging provides valuable information that can be used to differentiate ISH from CSH and optimize therapeutic approaches.

Unusual cranial infection caused by Citrobacter Koseri.

A 60-year-old female had a frontal bone intraosseous meningioma resected 10 years previously. On follow up CT head, an enlarging intraosseous frontal bone lesion was noted. This was thought to be a recurrent frontal meningioma. Intraooperatively, she was found to have an abscess deep to the cranioplasty.

Comparison of medical and/or surgical management of 23 cats with intracranial empyema or abscessation.

OBJECTIVES: Feline intracranial abscessation or empyema is infrequently reported in the veterinary literature. To date, the largest study is based on a population of 19 cats with otogenic infection. The aim of this study was to review a larger population of cats with intracranial empyema from multiple aetiologies and document their signalment, imaging findings, treatment protocols (including medical and/or surgical management) and to compare outcomes. METHODS: Cases presenting to a single referral centre over a 10 year period with compatible history, neurological signs and imaging findings consistent with intracranial abscessation and empyema were reviewed retrospectively. RESULTS: Twenty-three cats met the inclusion criteria. Advanced imaging (CT and/or MRI) was performed in 22/23 cats; one case was diagnosed via ultrasound. Ten cases underwent medical and surgical management combined, 10 underwent solely medical management and three were euthanased at the time of diagnosis. Short-term outcome showed that 90% of surgically managed and 80% of medically managed cats were alive at 48 h post-diagnosis. Long-term survival showed that surgically managed cases and medically managed cases had a median survival time of 730 days (range 1-3802 days) and 183 days (range 1-1216 days), respectively. No statistical significance in short- or long-term survival ( P >0.05) was found between medically and surgically managed groups. CONCLUSIONS AND RELEVANCE: Feline intracranial abscessation and empyema are uncommon conditions that have historically been treated with combined surgical and medical management. This study documents that, in some cases, intracranial abscessation and empyema can also be successfully treated with medical management alone.

Central Nervous System Infections Complicating Immunosuppression and Transplantation.

PURPOSE OF REVIEW: This article reviews infections associated with cancer treatments and immunosuppressive/immunomodulatory therapies used in both neoplastic and non-neoplastic conditions, including hematopoietic cell transplantation and solid organ transplantation. It provides a clinical approach to the most commonly affected patient groups based on clinicoanatomic presentation and disease-specific risks resulting from immune deficits and drugs received. RECENT FINDINGS: The clinical presentations, associated neuroimaging findings, and CSF abnormalities of patients with central nervous system infections who are immunocompromised may differ from those of patients with central nervous system infections who are immunocompetent and may be confused with noninfectious processes. Triggering of brain autoimmunity with emergence of neurotropic antibodies has emerged as a recognized parainfectious complication. New unbiased metagenomic assays to identify obscure pathogens help clinicians navigate the increasing range of conditions affecting the growing population of patients with altered immunity. SUMMARY: Despite evidence-based prophylactic regimens and organism-specific antimicrobials, central nervous system infections continue to cause significant morbidity and mortality in an increasing range of patients who are immunocompromised by their conditions and therapies. Multiple new drugs put patients at risk for progressive multifocal leukoencephalopathy, which has numerous imaging and clinical manifestations; patients at risk include those with multiple sclerosis, for whom infection risk is becoming one of the most important factors in therapeutic decision making. Efficient, early diagnosis is essential to improve outcomes in these often-devastating diseases.

Diffusion-weighted MRI in paediatric neuroimaging.

Diffusion-weighted imaging (DWI) is a well-established technique in neuroimaging, but the diagnostic value of DWI outside the setting of acute infarct and abscess is sometimes under-recognised particularly in paediatric neuroimaging. DWI also plays an important role in the evaluation of intracranial infection, brain tumours, demyelinating diseases, and metabolic disorders. DWI can assist in the early detection and characterisation of intraocular and skull-base pathology. The cases presented in this article demonstrate the utility of DWI in paediatric neuroimaging. DWI can improve diagnostic sensitivity and in conjunction with other magnetic resonance imaging (MRI) sequences can aid in early diagnosis and management. Obtaining an early diagnosis may avoid potential complications and improve patient outcome.

Defining diagnostic approaches and outcomes in patients with inflammatory CSF: A retrospective cohort study.

OBJECTIVE: Define the etiologies, clinical features, time to diagnosis, and outcomes of patients that present with cerebral spinal fluid (CSF) pleocytosis. PATIENTS AND METHODS: This is retrospective cohort study of patients with CSF pleocytosis, defined as WBC count >5 cells/mm3 in the CSF, from July 2015 to June 2016 at a large tertiary care hospital. The proportion of patients within specific diagnostic categories were analyzed for differences in diagnostic testing and outcomes. RESULTS: 53% of patients had CSF pleocytosis due to an unknown etiology. The leading known cause of neuroinflammation was CNS infection (n = 43/244, 18%), followed by malignancy (n = 28/244, 11%). Mean time to diagnosis was 125 days in patients with autoimmune neuroinflammation and was 16 days in patients with an infection or malignancy. CSF parameters and peripheral white blood cell counts did not distinguish between categories of disease. The presence of CSF oligoclonal bands or a positive biopsy result most commonly supported a diagnosis of an autoimmune disease or malignancy, respectively. Neuroimaging changes were present in only 44% of infections but were found in 80-90% of other categories of neuroinflammation. Patients presenting with a severe neurologic deficit had 22.29 higher odds of a severe deficit at the last neurologic assessment, and mortality was highest (29%) in patients with malignancy-associated neuroinflammation. CONCLUSIONS: This study to defines general diagnostic categories of neuroinflammatory disease in patients and provides new insight on the value of specific diagnostic testing, time to diagnosis, and outcomes in these patient populations.

Management of spinal infection: a review of the literature.

Spinal infection (SI) is defined as an infectious disease affecting the vertebral body, the intervertebral disc, and/or adjacent paraspinal tissue and represents 2-7% of all musculoskeletal infections. There are numerous factors, which may facilitate the development of SI including not only advanced patient age and comorbidities but also spinal surgery. Due to the low specificity of signs, the delay in diagnosis of SI remains an important issue and poor outcome is frequently seen. Diagnosis should always be supported by clinical, laboratory, and imaging findings, magnetic resonance imaging (MRI) remaining the most reliable method. Management of SI depends on the location of the infection (i.e., intraspinal, intervertebral, paraspinal), on the disease progression, and of course on the patient's general condition, considering age and comorbidities. Conservative treatment mostly is reasonable in early stages with no or minor neurologic deficits and in case of severe comorbidities, which limit surgical options. Nevertheless, solely medical treatment often fails. Therefore, in case of doubt, surgical treatment should be considered. The final result in conservative as well as in surgical treatment always is bony fusion. Furthermore, both options require a concomitant antimicrobial therapy, initially applied intravenously and administered orally thereafter. The optimal duration of antibiotic therapy remains controversial, but should never undercut 6 weeks. Due to a heterogeneous and often comorbid patient population and the wide variety of treatment options, no generally applicable guidelines for SI exist and management remains a challenge. Thus, future prospective randomized trials are necessary to substantiate treatment strategies.

Infected multilocular hydrocephalus treated by rigid and flexible endoscopes with electromagnetic-guided neuronavigation: a case report.

BACKGROUND: Endoscopic surgery assisted by a navigation system has greatly aided treatment of infected multilocular hydrocephalus, especially in children. CASE REPORT: We describe a 2-year-old boy with multilocular hydrocephalus caused by repeated shunt infection, presenting with fever and vomiting. Magnetic resonance images (MRI) showed extraventricular cysts and severe ventricular deformity. There were three ventriculoperitoneal shunts and one residual ventricular catheter. With a flexible endoscope, we fenestrated the wall of extraventricular cysts and removed the residual catheter. We then used a rigid endoscope to fenestrate ventricular components. Both procedures were guided by electromagnetic (EM) navigation, and hydrocephalus was controlled with one ventricular catheter. CONCLUSION: We have successfully treated a case suffered from infected multilocular hydrocephalus in infants using rigid and flexible endoscopes combined with EM navigation.

[Central nervous system infection by Bartonella henselae associated with a choroid plexus papilloma]. / Infección por Bartonella henselae con compromiso de sistema nervioso central, asociado a un papiloma del plexo coroídeo.

Bartonella henselae infection is a prevalent illness in Chile. It presents generally as a cat scratch disease or as a prolonged fever syndrome. There are atypical manifestations, which include central nervous system, bone, cardiac and hepato-esplenic compromised. We present an adolescent case with a history of fever, vomiting and ataxia, whose diagnosis was a central nervous system infection by Bartonella henselae associated with a choroid plexus papilloma. This case corresponds to an unusual presentation, with a challenging diagnosis. It is controversial whether to treat this patient, which antimicrobial is the right choice and how long the treatment should be.

Infección por Bartonella henselae con compromiso de sistema nervioso central, asociado a un papiloma del plexo coroídeo / Central nervous system infection by Bartonella henselae associated with a choroid plexus papilloma

Resumen La infección por Bartonella henselae es una enfermedad prevalente en nuestro país. En general, se presenta como la enfermedad por arañazo de gato o un síndrome febril prolongado. Existen manifestaciones atípicas dentro de las cuales está el compromiso óseo, cardíaco, hepatoesplénico y del sistema nervioso central. Se presenta el caso de una adolescente con historia de vómitos, fiebre y ataxia, en que se diagnosticó una infección por Bartonella henselae con compromiso del sistema nervioso central, asociada a un papiloma del plexo coroídeo. Este caso corresponde a una presentación inusual, de difícil diagnóstico. Su tratamiento es motivo de controversia, tanto en si es necesario tratar, la elección del antimicrobiano, como su duración.

Bartonella henselae infection is a prevalent illness in Chile. It presents generally as a cat scratch disease or as a prolonged fever syndrome. There are atypical manifestations, which include central nervous system, bone, cardiac and hepato-esplenic compromised. We present an adolescent case with a history of fever, vomiting and ataxia, whose diagnosis was a central nervous system infection by Bartonella henselae associated with a choroid plexus papilloma. This case corresponds to an unusual presentation, with a challenging diagnosis. It is controversial whether to treat this patient, which antimicrobial is the right choice and how long the treatment should be.

Masa selar, no siempre un adenoma: presentación de 3 casos clínicos / A sellar mass, not always an adenoma: A report of 3 cases

El absceso hipofisario es un proceso infeccioso dentro de la silla turca, infrecuente, grave y de difícil diagnóstico debido a sintomatología variada e inespecífica. Presentamos 3 casos clínicos de abscesos hipofisarios, teniendo en común la presencia de lesiones preexistentes. Todos fueron intervenidos quirúrgicamente, 2 pacientes resultaron ser abscesos asépticos y en un paciente se aisló Aspergillus capsulatum. Presentaron buena evolución con el tratamiento médico pero con secuelas de hipopituitarismo. Es muy importante tener en cuenta el absceso hipofisario entre los diagnósticos diferenciales de las masas que se localicen en esa región debido a que el diagnóstico oportuno y el tratamiento correcto son relevantes para el pronóstico de estos pacientes.

Pituitary abscess is due to a severe and uncommon infection in the sella. It is difficult to diagnose due to varied and non-specific symptoms. A report is presented of 3 cases of pituitary abscess, which had the presence of pre-existing injuries in common. All were subjected to surgery, with aseptic abscesses found in 2 patients, and Aspergillus capsulatum was isolated in 1 patient. They showed good progress with medical treatment, but with sequelae of hypopituitarism. It is very important to consider the pituitary abscess in the differential diagnosis of the masses that are located in that region, as a timely diagnosis and proper treatment can be important for the prognosis of these patients.