Neuroimaging of infections

Pediatric intracranial empyema complicating otogenic and sinogenic infection

OBJECTIVE

To describe and compare clinical and microbiological features, surgical and medical management, and outcomes of children with otogenic and sinogenic intracranial empyema (IE) in an institution with an established multidisciplinary protocol. To use the study findings to inform and update the institutional algorithm.

METHODS

Retrospective analysis was carried out on the electronic healthcare records of all children with oto-sinogenic IE admitted in a 5-year period.

RESULTS

A total of 76 patients were identified and treated according to an institutional protocol. Two distinct groups were identified: intracranial empyema related to otogenic infection (OI-IE, n = 36) or sinogenic infection (SI-IE, n = 40). SI-IE was seen in older children and had a significantly higher morbidity. Sub-dural IE was seen in a minority (n = 16) and only in SI-IE and required urgent collaborative ENT-neurosurgery. Extra-dural IE occurred more frequently and was seen in both SI-IE and OI-IE. No death and overall low morbidity were observed. Particularities found in SI-IE and OI-IE groups (as thrombosis, microbiology, antibiotic treatment, duration and outcome) permitted the delineation of these groups in our updated algorithm.

CONCLUSION

The presence of a collaborative multidisciplinary protocol permits the step-wise co-ordination of care for these complex patients in our institution. All patients received prompt imaging, urgent surgical intervention, and antibiotic treatment. Microbiological identification was possible for each patient and antibiotic rationalization was permitted through use of Polymerase chain reaction (PCR) testing in cases of sterile cultures. Of note, intracranial empyema related to sinogenic infection is shown to have significantly more severe clinical presentation, a higher morbidity, and a longer duration of antibiotic therapy than that related to otogenic infection. Study findings allowed for the update and clarification of the institutional protocol, which now clearly demarcates the clinical presentation, biological evidence, radiology, surgical and medical treatments in children with oto-sinogenic IE.

Utilising biosensor-based approaches for identifying neurotropic viruses

Neurotropic viruses, with their ability to invade the central nervous system, present a significant public health challenge, causing a spectrum of neurological diseases. Clinical manifestations of neurotropic viral infections vary widely, from mild to life-threatening conditions, such as HSV-induced encephalitis or poliovirus-induced poliomyelitis. Traditional diagnostic methods, including polymerase chain reaction, serological assays, and imaging techniques, though valuable, have limitations. To address these challenges, biosensor-based methods have emerged as a promising approach. These methods offer advantages such as rapid results, high sensitivity, specificity, and potential for point-of-care applications. By targeting specific biomarkers or genetic material, biosensors utilise technologies like surface plasmon resonance and microarrays, providing a direct and efficient means of diagnosing neurotropic infections. This review explores the evolving landscape of biosensor-based methods, highlighting their potential to enhance the diagnostic toolkit for neurotropic viruses.

Diagnostic clues in a stem cell transplant patient manifested with chronic central nervous system GVHD and IRIS

Transplant physicians should be aware of the immune deviation-related clinical conditions as allogeneic hematopoietic stem cell transplantation is widely used for the treatment of patients with malignant and non-malignant disorders. Neurological manifestations and graft-versus-host disease (GVHD) may commonly develop in transplant recipients. However, overlapping clinical immunological conditions may lead to diagnostic challenges. Herein, we discussed the differential diagnosis of a patient with immune reconstitution inflammatory syndrome (IRIS) developing on the basis of chronic GVHD.

Brain MRI findings in severe COVID-19 patients: a meta-analysis

Introduction

Neurocognitive symptoms and dysfunction of various severities have become increasingly recognized as potential consequences of SARS-CoV-2 infection. Although there are numerous observational and subjective survey-reporting studies of neurological symptoms, by contrast, those studies describing imaging abnormalities are fewer in number.

Methods

This study conducted a metanalysis of 32 studies to determine the incidence of the common neurological abnormalities using magnetic resonance imaging (MRI) in patients with COVID-19.

Results

We also present the common clinical findings associated with MRI abnormalities. We report the incidence of any MRI abnormality to be 55% in COVID-19 patients with perfusion abnormalities (53%) and SWI abnormalities (44%) being the most commonly reported injuries. Cognitive impairment, ICU admission and/or mechanical ventilation status, older age, and hospitalization or longer length of hospital stay were the most common clinical findings associated with brain injury in COVID-19 patients.

Discussion

Overall, the presentation of brain injury in this study was diverse with no substantial pattern of injury emerging, yet most injuries appear to be of vascular origin. Moreover, analysis of the association between MRI abnormalities and clinical findings suggests that there are likely many mechanisms, both direct and indirect, by which brain injury occurs in COVID-19 patients.

Utility of Gadolinium-Based Contrast in Initial Evaluation of Seizures in Children Presenting Emergently

BACKGROUND AND PURPOSE

The frequency and utility of gadolinium in evaluation of acute pediatric seizure presentation is not well known. The purpose of this study was to assess the utility of gadolinium-based contrast agents in MR imaging performed for the evaluation of acute pediatric seizure presentation.

MATERIALS AND METHODS

We identified consecutive pediatric patients with new-onset seizures from October 1, 2016, to September 30, 2021, who presented to the emergency department and/or were admitted to the inpatient unit and had an MR imaging of the brain for the evaluation of seizures. The clinical and imaging data were recorded, including the patient's age and sex, the use of IV gadolinium, and the underlying cause of epilepsy when available.

RESULTS

A total of 1884 patients were identified for inclusion. Five hundred twenty-four (28%) patients had potential epileptogenic findings on brain MR imaging, while 1153 (61%) patients had studies with normal findings and 207 (11%) patients had nonspecific signal changes. Epileptogenic findings were subclassified as the following: neurodevelopmental lesions, 142 (27%); intracranial hemorrhage (traumatic or germinal matrix), 89 (17%); ischemic/hypoxic, 62 (12%); hippocampal sclerosis, 44 (8%); neoplastic, 38 (7%); immune/infectious, 20 (4%); phakomatoses, 19 (4%); vascular anomalies, 17 (3%); metabolic, 3 (<1%); and other, 90 (17%). Eight hundred seventy-four (46%) patients received IV gadolinium. Of those, only 48 (5%) cases were retrospectively deemed to have necessitated the use of IV gadolinium: Fifteen of 48 (31%) cases were subclassified as immune/infectious, while 33 (69%) were neoplastic. Of the 1010 patients with an initial noncontrast study, 15 (1.5%) required repeat MR imaging with IV contrast to further evaluate the findings.

CONCLUSIONS

Gadolinium contrast is of limited additive benefit in the imaging of patients with an acute onset of pediatric seizures in most instances.

Pott's Puffy Tumor in Pediatric Patients: Case Series and Literature Review

BACKGROUND

Pott's puffy tumor (PPT) is a rare complication of frontal sinusitis. Although it may occur at any age, the incidence is higher during adolescence.

METHODS

We report a series of 10 pediatric patients (9-17 years of age) who presented with PPT in 2 tertiary care pediatric hospitals in central Israel between January 2018 and August 2022 and review the published literature on pediatric PPT.

RESULTS

The most common clinical presentations included headache (10 cases), frontal swelling (6 cases) and fever (5 cases). Symptom duration before admission was between 1 and 28 days (median 10 days). The diagnosis of PPT was made by imaging studies at a median of 1 day after admission. All 10 patients underwent computed tomography studies, and 6 patients also underwent magnetic resonance imaging. The overall rate of intracranial complications was 70%. All 10 children were treated with systemic antibiotics and surgical interventions. Streptococcus constellatus group was the most common causal bacteria. All 10 patients recovered uneventfully.

CONCLUSIONS

Our findings show that a high index of suspicion for PPT should be applied to adolescents presenting with prolonged headache and frontal swelling. Contrast-enhanced computed tomography is an appropriate first tool for the evaluation; however, an magnetic resonance imaging should be performed to determine the necessity of intracranial interventional treatments if there is any suspicion of intracranial involvement. Complete recovery can be expected with appropriate antibiotic treatment and surgical intervention in most of the cases.

A 42-Year-Old Man with a Seizure

A 42-Year-Old Man with a SeizureA 42-year-old man with acute myeloid leukemia presented for evaluation after an episode of convulsions. Six weeks before this event, he had a cough productive of yellow sputum. Two weeks later, he started having a headache and fevers. How do you approach the evaluation, and what is the diagnosis?

Magnetic Resonance Imaging in Neurocritically Ill Patients: Who Fails and How?

OBJECTIVES

Performing magnetic resonance imaging (MRI) in neurocritically ill patients is challenging because it often requires sedation and withholding care in the neurological intensive care unit. This study investigated the incidence of and reasons for failed or complicated MRI (MRI-FC) in such patients.

METHODS

A consecutive series of 218 neurocritically ill patients who underwent brain MRI were retrospectively evaluated. Failed or complicated MRI included failure to obtain all ordered sequences, unscheduled sedative administration, decrease in oxygen saturation to less than 90%, hypotension (≥40-mm Hg decrease and/or use of inotropic agents), and cardiac or respiratory arrest.

RESULTS

Failed or complicated MRI occurred in 66 patients (30.3%) and included failure to obtain MRI sequences (n = 13), unscheduled use of sedatives (n = 62), oxygen desaturation (n = 9), and hypotension (n = 6). Cardiac or respiratory arrest did not occur. Use of sedative agents while in intensive care (P < 0.01), high Acute Physiology and Chronic Health Evaluation II score (P = 0.031), and low Glasgow Coma Scale score on admission (P = 0.047) were associated with MRI-FC. Scan times were longer (P = 0.004) and Glasgow Coma Scale (P < 0.001) and Richmond Agitation Sedation Scale (P = 0.003) scores were lower (P = 0.004) after imaging in patients with MRI-FC. Previous use of sedative agents was independently associated with MRI-FC (adjusted odds ratio = 3.57, 95% confidence interval = 1.78 to 7.24, P < 0.001).

CONCLUSIONS

Failed or complicated MRI was common and was associated with the use of sedative agents, severity of illness, and lower level of consciousness. Studies to ensure effective and safe performance of MRI in neurocritically ill patients are needed.

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.

Butterfly lesion on MRI: Cryptococcus meningoencephalitis with unusual imaging in a patient with AIDS

In immunocompromised patients, including patients with AIDS, with neurologic complaints, we propose including Cryptococcus meningoencephalitis in the differential diagnoses when the butterfly pattern is encountered on MRI.

New-onset seizures in adults: Low diagnostic yield of gadolinium contrast in initial brain MRI evaluation

BACKGROUND AND PURPOSE

The diagnostic utility of contrast MR-imaging in adult new-onset seizures without clinically suspected neoplasia or infection is not well defined in the literature. Imaging guidelines consider both contrast and noncontrast MR-imaging examinations appropriate in this clinical scenario. The purpose of this study was to evaluate the utility of contrast MR-sequences in evaluation of seizure in patients without suspicion for neoplasia or infection.

METHODS

Imaging and clinical data were reviewed for 103 consecutive patients admitted for phase-1 seizure monitoring with the following criteria: (1) MRI-brain performed with/without intravenous contrast; (2) no clinical suspicion for central nervous system (CNS) infection; and (3) no history of CNS neoplasia, or suspected metastatic disease. Readers designated cases as lesional or nonlesional. Lesional cases were further categorized as either visualized on noncontrast sequences only, contrast sequences only, or both.

RESULTS

29/103 (28%) patients had epileptogenic lesions, 74/103 (72%) were nonlesional studies. 29/29 (100%) lesional abnormalities were detected on noncontrast sequences (sensitivity 100% [95 confidence interval (CI): 88-100], specificity 100% [95 CI: 95-100]). 23/29 (79.3%) lesional cases were visualized on both noncontrast and postcontrast sequences. 6/29 (20.7%) were visualized only on noncontrast sequences. No lesional cases were detected exclusively on postcontrast MR sequences. With an observed nonlesional extraneous contrast MR-imaging rate of 72%, estimated excess cost of contrast MR-imaging per 1000 patients using Medicare data was $103,680 USD.

CONCLUSIONS

Contrast MR-imaging has limited diagnostic utility in initial screening of adult new-onset seizure patients without clinically suspected neoplasia or infection. More judicious use of contrast MR-imaging in this patient population may reduce unnecessary exposure to gadolinium and lower associated healthcare costs.

Sarcoidosis: Pitfalls and Challenging Mimickers

Sarcoidosis, a systemic granulomatous disease of unknown etiology, may mimic other conditions at presentation often resulting in delayed diagnosis. These conditions include infections, neoplasms, autoimmune, cardiovascular, and drug-induced diseases. This review highlights the most common sarcoidosis mimics that often lead to pitfalls in diagnosis and delay in appropriate treatment. Prior to invasive testing and initiating immunosuppressants (commonly corticosteroids), it is important to exclude sarcoid mimickers.

Brain MRI findings in relation to clinical characteristics and outcome of tuberculous meningitis

Neuroradiological abnormalities in tuberculous meningitis (TBM) are common, but the exact relationship with clinical and inflammatory markers has not been well established. We performed magnetic resonance imaging (MRI) at baseline and after two months treatment to characterise neuroradiological patterns in a prospective cohort of adult TBM patients in Indonesia. We included 48 TBM patients (median age 30, 52% female, 8% HIV-infected), most of whom had grade II (90%), bacteriologically confirmed (71%) disease, without antituberculotic resistance. Most patients had more than one brain lesion (83%); baseline MRIs showed meningeal enhancement (89%), tuberculomas (77%), brain infarction (60%) and hydrocephalus (56%). We also performed an exploratory analysis associating MRI findings to clinical parameters, response to treatment, paradoxical reactions and survival. The presence of multiple brain lesion was associated with a lower Glasgow Coma Scale and more pronounced motor, lung, and CSF abnormalities (p-value <0.05). After two months, 33/37 patients (89%) showed worsening of MRI findings, mostly consisting of new or enlarged tuberculomas. Baseline and follow-up MRI findings and paradoxical responses showed no association with six-month mortality. Severe TBM is characterized by extensive MRI abnormalities at baseline, and frequent radiological worsening during treatment.

Haemorrhagic encephalitis in the garb of scrub typhus

A 19-year-old girl presented with fever, headache, vomiting and drowsiness. She had grade 1 papilloedema and neck rigidity but no focal deficits or seizures. Cerebrospinal fluid analysis revealed lymphocytic pleocytosis, slightly elevated protein and normal glucose. MRI of the brain showed a hyperintense lesion in left ganglio-capsular region on the fluid attenuation inversion recovery sequence with perilesional oedema and mild midline shift. Haemorrhage was seen in the region on susceptibility weighted imaging . The patient was thoroughly investigated for known causes of meningoencephalitis, but the diagnosis of scrub typhus was delayed till the 10th day of illness. She was treated with doxycycline for 2 weeks and had marked improvement, both clinically and radiologically. Literature review has revealed that although meningoencephalitis in scrub typhus is not uncommon, such atypical lesions on brain MRI are a rarity. Serial imaging was performed to document the disease progression and resolution on treatment.

Encephalitic syndrome and anosmia in COVID-19: Do these clinical presentations really reflect SARS-CoV-2 neurotropism? A theory based on the review of 25 COVID-19 cases

Since the discovery of coronavirus disease 2019 (COVID‐19), a disease caused by the new coronavirus severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), the pathology showed different faces. There is an increasing number of cases described as (meningo)encephalitis although evidence often lacks. Anosmia, another atypical form of COVID‐19, has been considered as testimony of the potential of neuroinvasiveness of SARS‐CoV‐2, though this hypothesis remains highly speculative. We did a review of the cases reported as brain injury caused by SARS‐CoV‐2. Over 98 papers found, 21 were analyzed. Only four publications provided evidence of the presence of SARS‐CoV‐2 within the central nervous system (CNS). When facing acute neurological abnormalities during an infectious episode it is often difficult to disentangle neurological symptoms induced by the brain infection and those due to the impact of host immune response on the CNS. Cytokines release can disturb neural cells functioning and can have in the most severe cases vascular and cytotoxic effects. An inappropriate immune response can lead to the production of auto‐antibodies directed toward CNS components. In the case of proven SARS‐CoV‐2 brain invasion, the main hypothesis found in the literature focus on a neural pathway, especially the direct route via the nasal cavity, although the virus is likely to reach the CNS using other routes. Our ability to come up with hypotheses about the mechanisms by which the virus might interact with the CNS may help to keep in mind that all neurological symptoms observed during COVID‐19 do not always rely on CNS viral invasion.

Review of 25 COVID‐19 cases with neurological symptoms.

Evidence of the SARS‐CoV‐2 presence in the brain is often lacking.

Brain magnetic resonance imagery is the most accurate exam to explore brain damages.

SARS‐CoV‐2 can cause anosmia and neurological symptoms without invading the brain.

The routes used by SARS‐CoV‐2 to invade the brain may lead to different symptoms.

Post-Traumatic Meningitis Is a Diagnostic Challenging Time: A Systematic Review Focusing on Clinical and Pathological Features

Post-traumatic meningitis is a dreadful condition that presents additional challenges, in terms of both diagnosis and management, when compared with community-acquired cases. Post-traumatic meningitis refers to a meningeal infection causally related to a cranio-cerebral trauma, regardless of temporal proximity. The PICO (participants, intervention, control, and outcomes) question was as follows: "Is there an association between traumatic brain injury and post-traumatic meningitis?" The present systematic review was carried out according to the Preferred Reporting Items for Systematic Review (PRISMA) standards. Studies examining post-traumatic meningitis, paying particular attention to victims of traumatic brain injury, were included. Post-traumatic meningitis represents a high mortality disease. Diagnosis may be difficult both because clinical signs are nonspecific and blurred and because of the lack of pathognomonic laboratory markers. Moreover, these markers increase with a rather long latency, thus not allowing a prompt diagnosis, which could improve patients' outcome. Among all the detectable clinical signs, the appearance of cranial cerebrospinal fluid (CSF) leakage (manifesting as rhinorrhea or otorrhea) should always arouse suspicion of meningitis. On one hand, microbiological exams on cerebrospinal fluid (CSF), which represent the gold standard for the diagnosis, require days to get reliable results. On the other hand, radiological exams, especially CT of the brain, could represent an alternative for early diagnosis. An update on these issues is certainly of interest to focus on possible predictors of survival and useful tools for prompt diagnosis.

Acute diffuse edematous-hemorrhagic Epstein-Barr virus meningoencephalitis: A case report

INTRODUCTION

In this study, we presented a rare case of Epstein-Barr virus (EBV) meningoencephalitis presented with meningoencephalitis-like symptoms and diffuse edematous hemorrhage.

PATIENT CONCERNS

A 77-year-old male patient was admitted to our hospital with fever, headache, confusion, and unconsciousness for 7 days. Physical examination revealed unconsciousness and stiffness of the neck.

DIAGNOSIS

The final diagnosis was EBV meningoencephalitis.

INTERVENTIONS

Ganciclovir (two times 350 mg/day, 21 days), methylprednisolone sodium succinate (120 mg, 5 days), and IV immunoglobulins (IV Ig) (0.4 g/kg, 5 days) were given to this patient.

OUTCOMES

But the patient's clinical symptoms did not improve, and he was still in a coma. His family refused to be further diagnosed and discharged. After discharge for 2 months, the patient was in a coma. Four months later, the patient died of complications of pulmonary infection.

CONCLUSION

The patient is an adult, and imaging was dominated by intracranial diffuse microhemorrhage and edema, which was different from the typical imaging characteristics of EBV encephalitis as previously reported. This specific imaging change may provide new clinical value for the diagnosis of EBV encephalitis.

Holohemispheric Invasive Aspergillus Granulomatous Cerebritis of the Brain

BACKGROUND

Invasive aspergillosis of the central nervous system, a saprophytic infection with a unique vascular tropism, carries the burden of increased morbidity and mortality. Early clinical and imaging findings can masquerade as an innocuous condition before a secondary inexorable progression. We highlight the clinical and imaging phenotype of a patient with fatal invasive granulomatous aspergillosis.

CASE DESCRIPTION

A 39-year-old man presented with progressive weakness of the left upper and lower limb for 4 months. Imaging demonstrated right holohemispheric extensive, numerous, confluent, ill-defined, T2 hypointense foci with moderate perilesional edema. Numerous foci of microhemorrhages with cortical asymmetric mineralization were seen. Post-contrast heterogeneous, variegate, punctiform enhancement of the lesions was observed extending to the ventricular margins. Volume loss of the left cerebral peduncle and ipsilateral long white matter descending tracts was noted. Histopathologic examination of a stereotactic biopsy specimen from the frontal region lesion showed dense inflammatory infiltrate with granulomas, a few in a perivascular distribution and branching septate hyphae resembling Aspergillus. The patient was initiated on antifungal therapy and in the following week, he had progressive drowsiness. The patient succumbed the next day.

CONCLUSIONS

Diffuse holohemispheric, progressive presentation of a granulomatous form of invasive aspergillosis is a rare entity. The miliary pattern of heterogenous enhancement, holohemispheric conglomerate T2 hypointensities, interspersed hemorrhage, juxtacortical punctate T2 hyperintense foci, low perfusion, and the relative absence of diffusion abnormality are distinctive features. Early diagnosis of this atypical imaging phenotype of Aspergillus infection and appropriate treatment is critical for better prognosis.

Combination of Dexmedetomidine and Ketamine for Magnetic Resonance Imaging Sedation

Objectives: The use of dexmedetomidine and ketamine (DEX-KET) combination for magnetic resonance imaging (MRI) sedation has not been evaluated. We investigated the efficacy and safety of DEX-KET for sedation of patients undergoing MRI of the brain. Methods: This quasi-experimental study was conducted to compare the DEX-KET combination and midazolam for MRI sedation. We included 72 patients undergoing brain MRI following bolus injection of midazolam or DEX-KET. In August 1, 2016 a new MRI sedation protocol was implemented. After protocol implementation, bolus doses of DEX-KET were administered (DEX-KET group). Thirty-six patients from the MIDA group and 36 patients from the DEX-KET group underwent MRI sequences and were compared regarding the MRI scan time and sedation-related complications (desaturation, hypotension, cardiorespiratory arrest, and aspiration pneumonia). Results: All MRI sequences were completed for 30 patients (83.3%) from the MIDA group and for 33 patients (91.7%) from the DEX-KET group (P = 0.476). The median MRI scan time was 100.0 min (interquartile range, 87.0-111.5 min) in the MIDA group and 53.5 min (interquartile range, 45.0-60.5 min) in the DEX-KET group (P < 0.001). Complications occurred in 24 (66.7%) and 8 (22.2%) patients of the MIDA and DEX-KET group, respectively (P < 0.001). Conclusions: The efficacy of DEX-KET sedation was comparable to that of midazolam for MRI examination. DEX-KET was related to shorter scan time and lower occurrence of complications compared to midazolam.

Diffusion-weighted magnetic resonance imaging may be useful in differentiating fungal abscess from malignant intracranial lesion: Case report

Background

Diffusion-weighted magnetic resonance has a well-defined role in differentiating between important intracranial lesions. Sometimes, the surgeon is faced with a dilemma of how to diagnose an infectious versus malignant lesion.

Case Description

A 28-year-old male presented to the neurosurgery clinic with complaints of headache and left-sided weakness for 2 weeks. Neurological examination was intact. Magnetic resonance imaging (MRI) scan showed a large infiltrating heterogeneous mass involving the right parietal lobe. On further reviewing, there was homogenous diffusion restriction in the center of lesion. In addition, its aggressive behavior confirmed it to be a fungal abscess.

Conclusions

Correctly identifying an infectious versus tumor etiology is important. Research has been carried out to employ diffusion-weighted imaging (DWI) in differentiating the variable radiological findings. The role of DWI in diagnosing bacterial abscess is more commonly seen in comparison to fungal abscess. DWI has a high diagnostic potential, but more works need to be done.

Ramsay Hunt syndrome with pontine lesion: A case report

RATIONALE

The coexistence of Ramsay Hunt syndrome (RHS) and varicella-zoster virus (VZV) encephalitis is rare. A patient who developed RHS after being infected with VZV, along with a pontine lesion, is reported in the present study.

PATIENT CONCERNS

A 41-year-old male patient presented with his mouth askew for 7 days, and dizziness, accompanied by hearing loss for 3 days.

DIAGNOSES

The patient was initially diagnosed with RHS. Brainstem encephalitis was confirmed by lumbar puncture and cerebrospinal fluid. Brain magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) revealed how VZV entered the intracranial space along the vestibulocochlear nerve and facial nerve in the acute period.

INTERVENTIONS

Intravenous acyclovir, IV, immunoglobulins (IVIg) and methylprednisolone were administered.

OUTCOMES

The herpes was cleared up and left facial nerve palsy was improved, but hearing loss in the left ear did not improve.

LESSONS

An MRI was necessary for some VZV infections limited to the cranial nerve, although there was no evidence of brain stem injury. DWI provided evidence, showing how VZV entered the brain in the early stage. This allowed the doctor to judge the necessity of a lumbar puncture.

A Tangible Educative 3D Printed Atlas of the Rat Brain

In biology and neuroscience courses, brain anatomy is usually explained using Magnetic Resonance (MR) images or histological sections of different orientations. These can show the most important macroscopic areas in an animals’ brain. However, this method is neither dynamic nor intuitive. In this work, an anatomical 3D printed rat brain with educative purposes is presented. Hand manipulation of the structure, facilitated by the scale up of its dimensions, and the ability to dismantle the “brain” into some of its constituent parts, facilitates the understanding of the 3D organization of the nervous system. This is an alternative method for teaching students in general and biologists in particular the rat brain anatomy. The 3D printed rat brain has been developed with eight parts, which correspond to the most important divisions of the brain. Each part has been fitted with interconnections, facilitating assembling and disassembling as required. These solid parts were smoothed out, modified and manufactured through 3D printing techniques with poly(lactic acid) (PLA). This work presents a methodology that could be expanded to almost any field of clinical and pre-clinical research, and moreover it avoids the need for dissecting animals to teach brain anatomy.

Neuroimaging in Central Nervous System Infections

Radiologic imaging is often employed to supplement clinical evaluation in cases of suspected central nervous system (CNS) infection. While computed tomography (CT) is superior for evaluating osseous integrity, demineralization, and erosive changes and may be more readily available at many institutions, magnetic resonance imaging (MRI) has significantly greater sensitivity for evaluating the cerebral parenchyma, cord, and marrow for early changes that have not yet reached the threshold for CT detection. For these reasons, MRI is generally superior to CT for characterizing bacterial, viral, fungal, and parasitic infections of the CNS. The typical imaging features of common and uncommon CNS infectious processes are reviewed.

A Case of Streptococcus anginosus Brain Abscess Caused by Contiguous Spread from Sinusitis in an Immunocompetent Patient

Brain abscesses are infections of the brain parenchyma that can arise from either contiguous spread from local infection or by hematogenous spread from a distant site. Streptococcus anginosus of the Streptococcus anginosus group (SAG) is a commensal microbe of the mucosae of the oral cavity, gastrointestinal tract, and urogenital tract. We present a case of mono-microbial brain abscess caused by contiguous spread from relatively asymptomatic sinusitis that initially presented as a subdural hemorrhage on computed tomography.

A 70-year-old male presented, obtunded, with a Glasgow Coma Score of eight. The patient seized on arrival. A computed tomography scan was read as a subdural hemorrhage, and magnetic resonance imaging showed a heterogeneous area at the anterior tip of the left frontal lobe interpreted as a frontoparietal abscess, along with pansinusitis. Craniotomy revealed a loculated abscess. Culture grew only Streptococcus anginosus. The patient did well postoperatively, was extubated by day five with rapidly improving neurological function, and was discharged to inpatient rehab by hospital-day eight for the continuation of intravenous antibiotics.

This case represents a frontal lobe abscess caused by the contiguous spread of Streptococcus anginosus from a frontal sinus infection. This is a relatively rare presentation of SAG infection in an immunocompetent patient. The case outlines the importance of imaging modality choice in the various stages of brain abscess formation, and the necessity of maintaining an index of suspicion for brain abscess in patients with few traditional risk factors and little to no history on presentation.

Qualitative and Quantitative Comparison of Contrast-Enhanced Fluid-Attenuated Inversion Recovery, Magnetization Transfer Spin Echo, and Fat-Saturation T1-Weighted Sequences in Infectious Meningitis

Objective

To compare the contrast-enhanced fluid-attenuated inversion recovery (CE-FLAIR), the CE T1-weighted (CE-T1W) sequence with fat suppression (FS) and magnetization transfer (MT) for early detection and characterization of infectious meningitis.

Materials and Methods

Fifty patients and 10 control subjects were evaluated with the CE-FLAIR and the CE-T1W sequences with FS and MT. Qualitative assessment was done by two observers for presence and grading of abnormal leptomeningeal enhancement. Quantitative assessment included computation of net meningeal enhancement, using single pixel signal intensity software. A newly devised FLAIR based scoring system, based on certain imaging features including ventricular dilatation, ependymal enhancement, infarcts and subdural effusions was used to indicate the etiology. Data were analysed using the Student's t test, Cohen's Kappa coefficient, Pearson's correlation coefficient, the intraclass correlation coefficient, one way analysis of variance, and Fisher's exact test with Bonferroni correction as the post hoc test.

Results

The CE-FLAIR sequence demonstrated a better sensitivity (100%), diagnostic accuracy (95%), and a stronger correlation with the cerebrospinal fluid, total leukocyte count (r = 0.75), protein (r = 0.77), adenosine deaminase (r = 0.81) and blood glucose (r = -0.6) values compared to the CE-T1W sequences. Qualitative grades and quantitative meningeal enhancement on the CE-FLAIR sequence were also significantly greater than those on the other sequences. The FLAIR based scoring system yielded a diagnostic accuracy of 91.6% and a sensitivity of 96%. A strong inverse Pearson's correlation (r = -0.95) was found between the assigned score and patient's Glasgow Coma Scale at the time of admission.

Conclusion

The CE-FLAIR sequence is better suited for evaluating infectious meningitis and could be included as a part of the routine MR imaging protocol.

Brain-Eating Amoebae: Predilection Sites in the Brain and Disease Outcome

Acanthamoeba spp. and Balamuthia mandrillaris are causative agents of granulomatous amoebic encephalitis (GAE), while Naegleria fowleri causes primary amoebic meningoencephalitis (PAM). PAM is an acute infection that lasts a few days, while GAE is a chronic to subacute infection that can last up to several months. Here, we present a literature review of 86 case reports from 1968 to 2016, in order to explore the affinity of these amoebae for particular sites of the brain, diagnostic modalities, treatment options, and disease outcomes in a comparative manner.

Aspergillus niger infection in an immunosuppressed patient confined solely to the brain

A 68-year-old woman with a background of hypertension, stroke and rheumatoid arthritis presented to her local hospital after a 4-week history of gradual deterioration and increasing confusion with new onset right-sided weakness. Her initial CT scan revealed a rim enhancing mass lesion with surrounding oedema in the left parietal lobe for which she underwent CT stealth-guided biopsy. Microbiology culture of the 2 biopsy samples yielded Aspergillus niger and she was started on the antifungal agent voriconazole. MRI 2 weeks after the procedure also demonstrated radiological findings consistent with intracranial aspergillosis. She later developed leucopenia with neutrophils of 1.5×10⁹/L and her methotrexate and voriconazole were stopped. Voriconazole was changed to oral posaconazole. She did not undergo surgical resection and has continued to improve clinically on posaconazole, with recovery in her white cell count.

Proton NMR metabolic profiling of CSF reveals distinct differentiation of meningitis from negative controls

BACKGROUND

Cerebrospinal fluid (CSF) is an essential bio-fluid of the central nervous system (CNS), playing a vital role in the protection of CNS and performing neuronal function regulation. The chemical composition of CSF varies during onset of meningitis, neurodegenerative disorders (positive controls) and in traumatic cases (negative controls).

METHODS

The study design was broadly categorized into meningitis cases, negative controls and positive controls. Further differentiation among the three groups was carried out using Principal Component Analysis (PCA) followed by supervised Partial Least Square Discriminant Analysis (PLS-DA).

RESULTS

The statistical analysis of meningitis vs. negative controls using PLS-DA model resulted in R² of 0.97 and Q² of 0.85. There was elevation in the levels of ketone bodies, total free amino acids, glutamine, creatine, citrate and choline containing compounds (choline and GPC) in meningitis cases. Similarly, meningitis vs. positive controls resulted in R² of 0.80 and Q² of 0.60 and showed elevation in the levels of total free amino acids, glutamine, creatine/creatinine and citrate in the meningitis group. Four cases of HIV were identified by PLS-DA model as well as by clinical investigations.

CONCLUSION

On the basis of metabolic profile it was found that negative control CSF samples are more appropriate for differentiation of meningitis than positive control CSF samples.

Imaging spectrum of central nervous system complications of hematopoietic stem cell and solid organ transplantation

Neurologic complications are common after hematopoietic stem cell transplantation (HSCT) and solid organ transplantation (SOT) and affect 30-60% of transplant recipients. The aim of this article is to provide a practical imaging approach based on the timeline and etiology of CNS abnormalities, and neurologic complications related to transplantation of specific organs. The lesions will be classified based upon the interval from HSCT procedure: pre-engraftment period <30 days, early post-engraftment period 30-100 days, late post-engraftment period >100 days, and the interval from SOT procedure: postoperative phase 1-4 weeks, early posttransplant syndromes 1-6 months, late posttransplant syndromes >6 months. Further differentiation will be based on etiology: infections, drug toxicity, metabolic derangements, cerebrovascular complications, and posttransplantation malignancies. In addition, differentiation will be based on complications specific to the type of transplantation: allogeneic and autologous hematopoietic stem cells (HSC), heart, lung, kidney, pancreas, and liver. Thus, in this article we emphasize the strategic role of neuroradiology in the diagnosis and response to treatment by utilizing a methodical approach in the work up of patients with neurologic complications after transplantation.

Cerebral Vasculitis in a Case of Meningitis

Cerebral vasculitis is a serious complication of meningitis with Streptococcus pneumoniae. We report a 5 yr old girl who was admitted in May 2015 at Fortis Hospital, Kolkata, India and was diagnosed to have pneumococcal meningitis with vasculitis on DWMRI within a week of onset of fever. She was given high dose of methyl-prednisolone simultaneously with antibiotics and successfully treated without any neuro-sequelae. Although vasculitis has been documented to develop as sequelae to bacterial meningitis usually in the second week, our patient had an early presentation. Treatment with high dose steroid along with antibiotics resulted in dramatic improvement with no neurodeficit. DW-MRI is an important investigation to pick up early, evidence of vasculitis in a patient with meningitis who is showing neurological deteriorations despite improvement in blood parameters.

Bifrontal brain abscesses secondary to orbital cellulitis and sinusitis extension

Background

Intracranial abscesses are rare and life-threatening conditions that typically originate from direct extension from nearby structures, hematogenous dissemination or following penetrating cerebral trauma or neurosurgery.

Findings

A 36-year-old male presented to our emergency department with complaints of left eye swelling, headache and drowsiness. On physical exam, the patient was febrile and his left upper eyelid was markedly swollen with fluctuance and drainage. Maxillofacial computed tomography was obtained to evaluate for orbital pathology but revealed bifrontal brain abscesses.

Conclusions

Brain abscesses should be considered in the differential diagnosis for patients who present with the classic triad of headache, fever and neurological deficit.

Arterial Spin-labeling in Central Nervous System Infection

Purpose:

To investigate the characteristics of arterial spin-labeling magnetic resonance imaging (ASL-MRI) in central nervous system (CNS) infection.

Methods:

Thirty-two patients with CNS infections underwent a pulsed ASL-MRI. The findings on ASL-MRI were retrospectively assessed for the pathogens as well as each of the following four pathology classified based on conventional MRI findings: non-purulent parenchymal involvement, meningeal involvement, abscess formation, and ventricular involvement.

Results:

Among the 17 patients with non-purulent parenchymal involvement, ASL-MRI revealed high perfusion in 8 patients (47%) and low perfusion 1 patient (6%). Especially, four of five patients (80%) with definite or suspected herpes simplex virus (HSV) infection showed high perfusion on ASL-MRI. Seventeen of 22 patients (77%) with meningeal involvement showed high perfusion along the cerebral sulci irrespective of the pathogens. Meanwhile, 4 of 16 lesions (25%) with abscess formation showed low perfusion and one of six patients (17%) with ventricular involvement had high perfusion.

Conclusions:

The characteristics of ASL-MRI in CNS infections were clearly delineated. ASL-MRI could be helpful for monitoring the brain function in CNS infections noninvasively.

CCR5 limits cortical viral loads during West Nile virus infection of the central nervous system

Background

Cell-mediated immunity is critical for clearance of central nervous system (CNS) infection with the encephalitic flavivirus, West Nile virus (WNV). Prior studies from our laboratory have shown that WNV-infected neurons express chemoattractants that mediate recruitment of antiviral leukocytes into the CNS. Although the chemokine receptor, CCR5, has been shown to play an important role in CNS host defense during WNV infection, regional effects of its activity within the infected brain have not been defined.

Methods

We used CCR5-deficient mice and an established murine model of WNV encephalitis to determine whether CCR5 activity impacts on WNV levels within the CNS in a region-specific fashion. Statistical comparisons between groups were made with one- or two-way analysis of variance; Bonferroni’s post hoc test was subsequently used to compare individual means. Survival was analyzed by the log-rank test. Analyses were conducted using Prism software (GraphPad Prism). All data were expressed as means ± SEM. Differences were considered significant if P ≤ 0.05.

Results

As previously shown, lack of CCR5 activity led to increased symptomatic disease and mortality in mice after subcutaneous infection with WNV. Evaluation of viral burden in the footpad, draining lymph nodes, spleen, olfactory bulb, and cerebellum derived from WNV-infected wild-type, and CCR5^−/− mice showed no differences between the genotypes. In contrast, WNV-infected, CCR5^−/− mice exhibited significantly increased viral burden in cortical tissues, including the hippocampus, at day 8 post-infection. CNS regional studies of chemokine expression via luminex analysis revealed significantly increased expression of CCR5 ligands, CCL4 and CCL5, within the cortices of WNV-infected, CCR5^−/− mice compared with those of similarly infected WT animals. Cortical elevations in viral loads and CCR5 ligands in WNV-infected, CCR5^−/− mice, however, were associated with decreased numbers of infiltrating mononuclear cells and increased permeability of the blood-brain barrier.

Conclusions

These data indicate that regional differences in chemokine expression occur in response to WNV infection of the CNS, and that cortical neurons require CCR5 activity to limit viral burden in this brain region.

Miliary pattern of brain metastases - a case report of a hyperacute onset in a patient with malignant melanoma documented by magnetic resonance imaging

Background

Miliary brain metastases are a rare condition but associated with an exceedingly poor prognosis. We present the case of a patient suffering from malignant melanoma with an acute progressively worsening of neurological symptoms up to the loss of consciousness. The magnetic resonance imaging (MRI) demonstrated a new onset of disseminated, miliary spread of central nervous system metastases from a malignant melanoma within 4 days.

Case presentation

We report on a 57-year-old woman suffering from metastatic malignant melanoma positive for BRAF-V600E mutation who developed an acute onset of neurological symptoms. The patient received vemurafenib and dacarbacin as chemotherapeutic regime for treatment of malignant melanoma. After admission to our hospital due to progressive disturbance of memory and speech difficulty a magnetic resonance tomography (MRI) was performed. This showed no evidence of cerebral tumour manifestation. The symptoms progressed until a loss of consciousness occurred on day five after admission and the patient was admitted to our intensive care unit for orotracheal intubation. No evidence for infectious, metabolic or autoimmune cerebral disorders was found. Due to the inexplicable acute worsening of the neurological symptoms a second MRI was performed on day five. This revealed a new onset of innumerable contrast-enhancing miliary lesions, especially in the grey matter which was proven as metastases from malignant melanoma on histopathology.

Conclusion

This case describes an unique hyperacute onset of tumour progression correlating with an acute deterioration of neurological symptoms in a patient suffering from miliary brain metastasis from BRAF positive malignant melanoma.

Radiogenomics and imaging phenotypes in glioblastoma: novel observations and correlation with molecular characteristics

Radiogenomics is a provocative new area of research based on decades of previous work examining the association between radiological and histological features. Many generalized associations have been established linking anatomical imaging traits with underlying histopathology, including associations between contrast-enhancing tumor and vascular and tumor cell proliferation, hypointensity on pre-contrast T1-weighted images and necrotic tissue, and associations between hyperintensity on T2-weighted images and edema or nonenhancing tumor. Additionally, tumor location, tumor size, composition, and descriptive features tend to show significant associations with molecular and genomic factors, likely related to the cell of origin and growth characteristics. Additionally, physiologic MRI techniques also show interesting correlations with underlying histology and genomic programs, including associations with gene expression signatures and histological subtypes. Future studies extending beyond simple radiology-histology associations are warranted in order to establish radiogenomic analyses as tools for prospectively identifying patient subtypes that may benefit from specific therapies.

Virus and Immune-Mediated Encephalitides: Epidemiology, Diagnosis, Treatment, and Prevention

Virus encephalitis remains a major cause of acute neurological dysfunction and permanent disability among children worldwide. Although some disorders, such as measles encephalomyelitis, subacute sclerosing panencephalitis, and varicella-zoster virus-associated neurological conditions, have largely disappeared in resource-rich regions because of widespread immunization programs, other disorders, such as herpes simplex virus encephalitis, West Nile virus-associated neuroinvasive disease, and nonpolio enterovirus-induced disorders of the nervous system, cannot be prevented. Moreover, emerging viral disorders pose new, potential threats to the child's nervous system. This review summarizes current information regarding the epidemiology of virus encephalitis, the diagnostic methods available to detect central nervous system infection and identify viral pathogens, and the available treatments. The review also describes immune-mediated disorders, including acute disseminated encephalomyelitis and N-methyl-D-aspartate receptor antibody encephalitis, conditions that mimic virus encephalitis and account for a substantial proportion of childhood encephalitis.

Histoplasmosis with Deep CNS Involvement: Case Presentation with Discussion and Literature Review

Central nervous system (CNS) histoplasmosis is rare and difficult to diagnose because it is often overlooked or mistaken for other pathologies due to its nonspecific symptoms. A 32-year-old Hispanic man with advanced acquired immunodeficiency virus presented with altered mental status and reported confusion for the past 3 months. He had a Glasgow Coma Scale of 12, repetitive nonfluent speech, and a disconjugate gaze with a right gaze preference. Lung computed tomography (CT) findings indicated a pulmonary histoplasmosis infection. Magnetic resonance imaging of the brain revealed a ring-enhancing lesion in the left caudate nucleus. A CT-guided left retroperitoneal node biopsy was performed and indicated a benign inflammatory process with organisms compatible with fungal yeast. Treatment with amphotericin B followed by itraconazole was initiated in spite of negative cerebrospinal fluid (CSF) cultures and proved effective in mitigating associated CNS lesions and resolving neurologic deficits. The patient was discharged 3 weeks later in stable condition. Six weeks later, his left basal ganglia mass decreased. Early recognition of symptoms and proper steps is key in improving outcomes of CNS histoplasmosis. Aggressive medical management is possible in the treatment of intracranial deep mass lesions, and disseminated histoplasmosis with CNS involvement can be appropriately diagnosed and treated, despite negative CSF and serology studies.

Successful treatment of toxoplasmic encephalitis diagnosed early by polymerase chain reaction after allogeneic hematopoietic stem cell transplantation: two case reports and review of the literature

Toxoplasmic encephalitis represents a rare, but often fatal infection after allogeneic hematopoietic stem cell transplantation. Polymerase chain reaction (PCR)-based preemptive therapy is considered promising for this disease, but is not routinely applied, especially in low seroprevalence countries including Japan. We encountered 2 cases of toxoplasmic encephalitis after transplantation that were successfully treated. The diagnosis of toxoplasmic encephalitis in these cases was confirmed by PCR testing when neurological symptoms were observed. Both patients received pyrimethamine and sulfadiazine treatments within 2 weeks of the development of neurological symptoms, and remained free of recurrence for 32 and 12 months. These results emphasized the importance of the PCR test and immediate treatment after diagnosis for the management of toxoplasmic encephalitis.

Imaging in Neurologic Infections II: Fungal and Viral Diseases

Infections of the nervous system have a significant impact on global mortality and morbidity. These infections are medical emergencies that are frequently diagnostically challenging. Incorporation of neuroimaging can be essential for early diagnosis and initiation of proper treatment. In this second part of this two-part review, we focus on diagnostic imaging features of selected fungal and viral nervous system infections.

Advances in magnetic resonance imaging of the skull base

Introduction Over the past 20 years, magnetic resonance imaging (MRI) has advanced due to new techniques involving increased magnetic field strength and developments in coils and pulse sequences. These advances allow increased opportunity to delineate the complex skull base anatomy and may guide the diagnosis and treatment of the myriad of pathologies that can affect the skull base. Objectives The objective of this article is to provide a brief background of the development of MRI and illustrate advances in skull base imaging, including techniques that allow improved conspicuity, characterization, and correlative physiologic assessment of skull base pathologies. Data Synthesis Specific radiographic illustrations of increased skull base conspicuity including the lower cranial nerves, vessels, foramina, cerebrospinal fluid (CSF) leaks, and effacement of endolymph are provided. In addition, MRIs demonstrating characterization of skull base lesions, such as recurrent cholesteatoma versus granulation tissue or abscess versus tumor, are also provided as well as correlative clinical findings in CSF flow studies in a patient pre- and post-suboccipital decompression for a Chiari I malformation. Conclusions This article illustrates MRI radiographic advances over the past 20 years, which have improved clinicians' ability to diagnose, define, and hopefully improve the treatment and outcomes of patients with underlying skull base pathologies.

Presumptive Subdural Empyema in a Dog

A 13 mo old mixed-breed dog was referred for acute lateralized forebrain signs. MRI of the brain demonstrated abnormalities consistent with severe meningitis and subdural empyema secondary to a retrobulbar abscess. The dog’s clinical signs improved with antibiotic therapy, and repeat imaging showed resolution of subdural fluid accumulation presumed to be empyema with mild residual meningeal enhancement. Subdural empyema is an infrequent cause of encephalopathy in small animals and usually develops through direct extension of a pericranial infection. This report presents a case of presumptive subdural empyema in a dog that was successfully treated without surgical intervention. MRI is the preferred imaging modality for diagnosis of subdural empyema, and the characteristic imaging features are described.