From the archives of the AFIP: central nervous system infections associated with human immunodeficiency virus infection: radiologic-pathologic correlation

Atypical Demyelinating Disorders: MR Imaging Features, Atypical Triggers, and Etiopathogenesis

Atypical demyelinating lesions (ADLs) can be idiopathic, occurring as isolated and self-limited events, or can appear in different stages of relapsing demyelinating diseases. Not infrequently, ADLs occur in inflammatory syndromes associated with exogenous or endogenous toxic factors, metabolic imbalance, or infectious agents. It is important to recognize imaging patterns that indicate an inflammatory/demyelinating substrate in central nervous system lesions and to investigate potential triggers or complicating factors that might be associated. The prognostic and treatment strategies of ADLs are influenced by the underlying etiopathogenesis.

Novel and characteristic radiological features of neurosyphilis: a case series

BACKGROUND

Treponema pallidum can invade the central nervous system (CNS) early in its infection, causing neurosyphilis. Neurosyphilis typically presents with meningovasculitis in the acute or subacute phase, while tabes dorsalis and dementia paralytica are classical conditions in the later stages. However, syphilis is often misdiagnosed as other conditions such as tumors or autoimmune diseases including vasculitis and encephalitis, which is why the condition is known as "The Great Mimicker." The increasing incidence of syphilis in recent years emphasizes the importance of early diagnosis and treatment; however, its multiple clinical manifestations impose diagnostic challenges for clinicians because it resembles other diseases. In this case series, we present the impressive manifestations of neurosyphilis through three unique radiological presentations.

CASE PRESENTATION

Case 1 details optic nerve involvement in an HIV-positive male, where MRI and fundoscopic findings confirmed syphilitic optic neuritis. Case 2 describes a patient in her pregnancy initially suspected of acoustic neuroma on MRI, later diagnosed with syphilitic gumma affecting the inner ear canal. Case 3 is a young male with clinical features mimicking temporal arteritis, ultimately identified as skull osteomyelitis secondarily causing inflammation of the musculus temporalis and meningitis.

CONCLUSIONS

These cases underscore the necessity of considering syphilis in differential diagnoses, given the diversity of its clinical presentations. Radiology plays an important role in avoiding unnecessary interventions. The increasing prevalence of recurrent syphilis imposes diagnostic challenges, emphasizing the importance of the early diagnosis and treatment of neurosyphilis by clinicians.

Association between neuroimaging and clinical outcomes in individuals with central nervous system cryptococcosis

BACKGROUND

The radiological manifestations of central nervous system (CNS) cryptococcosis are diverse and often subtle. There is heterogeneity on how different neuroimaging patterns impact prognosis. This study aims to assess the association between the neuroimaging and clinical outcomes of CNS cryptococcosis.

METHODS

All patients with CNS cryptococcosis between July 2017 and April 2023 who underwent brain magnetic resonance imaging (MRI) were included. The primary outcome was mortality during hospitalisation. Secondary outcomes were readmission, ventricular shunting, duration of hospitalisation and time to the first negative cerebrospinal fluid culture. We compared the outcomes for each of the five main radiological findings on the brain MRI scan.

RESULTS

We included 46 proven CNS cryptococcosis cases. The two main comorbidity groups were HIV infection (20, 43%) and solid organ transplantation (10, 22%), respectively. Thirty-nine patients exhibited at least one radiological abnormality (85%), with the most common being meningeal enhancement (34, 74%). The mortality rates occurred at 11% (5/46) during hospitalisation. We found no significant disparities in mortality related to distinct radiological patterns. The presence of pseudocysts was significantly associated with the need for readmission (p = .027). The ventricular shunting was significantly associated with the presence of pseudocysts (p = .005) and hydrocephalus (p = .044).

CONCLUSION

In this study, there is no association between brain MRI findings and mortality. Larger studies are needed to evaluate this important issue.

FDG-PET in HIV-Positive Patient with Extranodal Diffuse Large B-Cell Lymphoma

Extranodal diffuse large B-cell lymphoma (DLBCL) is a heterogeneous disease process and an aggressive form of non-Hodgkin's lymphoma. We present a case of multiorgan involvement of DLBCL in a patient with documented risk factors, including [ 18 F] fluorodeoxyglucose positron emission tomography/magnetic resonance imaging findings highlighting striking perineural spread involving intracranial and extracranial segments of the bilateral trigeminal nerves.

Neuroimaging of the Most Common Meningitis and Encephalitis of Adults: A Narrative Review

Meningitis is the infection of the meninges, which are connective tissue membranes covering the brain, and it most commonly affects the leptomeninges. Clinically, meningitis may present with fever, neck stiffness, altered mental status, headache, vomiting, and neurological deficits. Encephalitis is an infection of the brain, which usually presents with fever, altered mental status, neurological deficits, and seizure. Meningitis and encephalitis are serious conditions which could also coexist, with high morbidity and mortality, thus requiring prompt diagnosis and treatment. Imaging plays an important role in the clinical management of these conditions, especially Magnetic Resonance Imaging. It is indicated to exclude mimics and evaluate the presence of complications. The aim of this review is to depict imaging findings of the most common meningitis and encephalitis.

Primary central nervous system lymphoma: Imaging features and differential diagnosis

Primary central nervous system lymphoma (PCNSL) represents 5% of malignant primary brain tumors. The clinical presentation typically includes focal neurological symptoms, increased intracranial pressure, seizures, and psychiatric symptoms. Although histological examination remains the gold standard for diagnostic confirmation, non-invasive imaging plays a crucial role for the diagnosis. In immunocompetent individuals, PCNSL usually appears as a single, well-defined, supratentorial lesion with a predilection for periventricular areas, iso- or hypointense on T1- and T2-weighted magnetic resonance imaging, with restricted diffusion, slightly increased perfusion, and homogenous gadolinium-enhancement. Differential diagnoses include high-grade glioma and pseudotumoral demyelinating disease. In immunocompromised patients, PCNSL may present as multiple lesions, with a higher likelihood of hemorrhage and necrosis and less restricted diffusion than immunocompetent individuals. Differential diagnoses include neurotoxoplasmosis, progressive multifocal leukoencephalopathy, and cerebral abscess. Atypical forms of lymphoma are characterized by extra-axial lymphoma, lymphomatosis cerebri, and intravascular lymphoma. Extra-axial lymphoma presents as single or multiple extra-axial dural lesions with diffuse leptomeningeal contrast-enhancement. Lymphomatosis cerebri appears as an infiltrative and symmetric lesion, primarily affecting deep white matter and basal ganglia, appearing hyperintense on T2-weighted imaging, without significant contrast-enhancement or perfusion changes. Intravascular lymphoma presents as multiple rounded or oval-shaped "infarct-like" lesions, located cortically or subcortically. This study aims to highlight the imaging characteristics of PCNSL, focusing on magnetic resonance imaging and its differential diagnosis.

The dark side of T2: central nervous system lesions with low signal intensity on T2-weighted imaging

The majority of central nervous system diseases show high signal intensity on T2-weighted magnetic resonance imaging. Diseases of the central nervous system with low signal intensity are less common, which makes it a finding that helps narrow the differential diagnosis. This was a retrospective analysis of brain and spine magnetic resonance imaging examinations in which that finding was helpful in the diagnostic investigation. We selected the cases of patients examined between 2015 and 2022. All diagnoses were confirmed on the basis of the clinical-radiological correlation or the histopathological findings. We obtained images of 14 patients with the following central nervous system diseases: arteriovenous malformation; cavernous malformation; metastasis from lymphoma; medulloblastoma; embryonal tumor; metastasis from melanoma; Rathke's cleft cyst; Erdheim-Chester disease; aspergillosis; paracoccidioidomycosis; tuberculosis; syphilis; immunoglobulin G4-related disease; and metastasis from a pulmonary neuroendocrine tumor. We described lesions of different etiologies in which the T2-weighted imaging profile helped narrow the differential diagnosis and facilitated the definitive diagnosis.

Neurological Complications Caused by Human Immunodeficiency Virus (HIV) and Associated Opportunistic Co-infections: A Review on their Diagnosis and Therapeutic Insights

Neurocognitive disorders associated with human immunodeficiency virus (HIV) infected individuals increase the risk of mortality and morbidity that remain a prevalent clinical complication even in the antiretroviral therapy era. It is estimated that a considerable number of people in the HIV community are developing neurological complications at their early stages of infection. The daily lives of people with chronic HIV infections are greatly affected by cognitive declines such as loss of attention, learning, and executive functions, and other adverse conditions like neuronal injury and dementia. It has been found that the entry of HIV into the brain and subsequently crossing the blood-brain barrier (BBB) causes brain cell damage, which is the prerequisite for the development of neurocognitive disorders. Besides the HIV replication in the central nervous system and the adverse effects of antiretroviral therapy on the BBB, a range of opportunistic infections, including viral, bacterial, and parasitic agents, augment the neurological complications in people living with HIV (PLHIV). Given the immuno-compromised state of PLHIV, these co-infections can present a wide range of clinical syndromes with atypical manifestations that pose challenges in diagnosis and clinical management, representing a substantial burden for the public health system. Therefore, the present review narrates the neurological complications triggered by HIV and their diagnosis and treatment options. Moreover, coinfections that are known to cause neurological disorders in HIV infected individuals are highlighted.

An HIV-positive woman with massive brain lesion due to toxoplasmosis: A case report

Key Clinical Message

Toxoplasmosis-related huge brain lesions may require decompressive craniectomy and lesion excision to avoid brain damage. In this situation, injectable cotrimoxazole is a better choice for treatment.

Abstract

Toxoplasma gondii is a worldly distributed obligate intracellular protozoa. Toxoplasmosis is a prevalent opportunistic infection in HIV-infected people, but it was rarely recorded prior to the identification of HIV infection. Here, we report a toxoplasmosis brain lesion in an Iranian HIV-positive patient. A 45-year-old woman with a complaint of malaise was referred to the Valiasr Hospital in Arak city. In her past clinical history, the patient had a history of anemia, deep vein thrombosis (DVT), and positive HIV. The patient was informed of the diagnosis of massive brain toxoplasmosis as a definite diagnosis. The patient was then taken to the operating room for a left decompressive craniectomy, during which the ensuing brain lesion was excised. After a few days, she was discharged from the hospital in good condition and without any complications.

Single thalamic localization of brain toxoplasmosis mimicking brain tumors: Radiological and clinical findings

Background:

Cerebral toxoplasmosis is a relatively rare disorder that usually affects immunocompromised patients. The most common scenario occurs among human immunodeficiency virus (HIV)-positive patients. In those patients, toxoplasmosis is the most frequent cause of expansive brain lesion and continues to cause elevated morbidity and mortality. In typical cases of toxoplasmosis, both computed tomography and magnetic resonance imaging reveal single/ multiple nodular or ring-enhancing lesions with surrounding edema. Nevertheless, cases of cerebral toxoplasmosis with atypical radiological features have been reported. Diagnosis can be obtained by finding organisms in the cerebrospinal fluid or in stereotactic biopsy samples of the brain lesion. If untreated, cerebral toxoplasmosis is uniformly fatal, so prompt diagnosis is mandatory. A prompt diagnosis is necessary, as untreated cerebral toxoplasmosis is uniformly fatal.

Case Description:

We discuss imaging and clinical findings of a patient – not aware of being HIV-positive – with a solitary atypical brain localization of toxoplasmosis mimicking a brain tumor.

Conclusion:

Although relatively uncommon, neurosurgeons should be aware of the potential occurrence of cerebral toxoplasmosis. High index of suspicion is needed for timely diagnosis and prompt initiation of therapy.

Imaging features of neurosyphilis

Syphilis is an infectious disease caused by the spirochete Treponema pallidum, subspecies pallidum. Although its incidence has declined after the widespread availability of penicillin, it has recently re-emerged, especially in men who have sex with men and in people living with human immunodeficiency virus (HIV). The neurological manifestations of syphilis, generally known as neurosyphilis, may appear at any time during the infection, including the initial years after the primary infection. Neurosyphilis can be asymptomatic, only with cerebrospinal fluid abnormalities, or symptomatic, characterized by several different clinical syndromes, such as meningitis, gumma, meningovascular, brain parenchyma involvement, meningomyelitis, tabes dorsalis, and peripheral nervous system involvement. However, these syndromes may simulate several other diseases, making the diagnosis often a challenge. In addition, syphilis can also be vertically transmitted from mother to child during pregnancy, leading to neurological manifestations. Neuroimaging is essential to demonstrate abnormal brain or spinal cord findings in patients with neurosyphilis, aiding in the diagnosis, treatment, and follow-up of these patients. This article aims to review the imaging features of neurosyphilis, including the early and late stages of the infection.

CD8 Encephalitis: A Diagnostic Dilemma

CD8+ encephalitis is a subacute encephalopathy associated with HIV infection. Pathophysiology is thought to be auto-reactive CD8+ cells attacking on HIV infected CD4+ cells and ‘viral escape’ phenomena (replication of CD8+ cells in CSF). We present a case of a 45-year-old man with well controlled HIV who developed CD8 encephalitis following Herpes simplex encephalitis. He had persistent encephalopathy for several weeks with status epilepticus and agitated delirium, and diagnosis remained elusive until a brain biopsy confirmed the diagnosis.

Are We Aware of the Neurological Manifestations of Cytomegalovirus Infection in Immunocompetent Individuals?

BACKGROUND

While cytomegalovirus (CMV) infection usually causes disease in immunosuppressed individuals, it mostly progresses as an asymptomatic infection in healthy adults. However, very rarely, immunocompetent individuals may also suffer from encephalitis and stroke.

METHODS

Nine patients who were admitted to the Neurology Clinic of Abant Izzet Baysal University Faculty of Medicine from 2016 to 2020 who had various neurological symptoms and were diagnosed with CMV infection were retrospectively analyzed. Symptoms, examination findings, laboratory results, radiologic imaging, and treatments were recorded and evaluated.

RESULTS

Although severe infections because of CMV generally occur in newborns and immunosuppressed adults, it is estimated that the disease is more common in immunocompetent adults than known. This may be associated with unrecognized risks, in part because of immune dysfunction or comorbidities such as renal failure or diabetes mellitus. Also, CMV replication in arterial endothelial cells can restrict blood flow, inducing an atherosclerotic environment and causing stroke. Diagnosis is based on clinical suspicion and serology. Ganciclovir is administered for treatment.

CONCLUSION

CMV infection should be considered in the differential diagnosis of patients presenting with neurological symptoms, even among immunocompetent individuals, because of the high possibility that patients can greatly benefit from antiviral treatment at the early stage.

Differentiating central nervous system infection from disease infiltration in hematological malignancy

Hematological malignancies place individuals at risk of CNS involvement from their hematological disease and opportunistic intracranial infection secondary to disease-/treatment-associated immunosuppression. Differentiating CNS infection from hematological disease infiltration in these patients is valuable but often challenging. We sought to determine if statistical models might aid discrimination between these processes. Neuroradiology, clinical and laboratory data for patients with hematological malignancy at our institution between 2007 and 2017 were retrieved. MRI were deep-phenotyped across anatomical distribution, presence of pathological enhancement, diffusion restriction and hemorrhage and statistically modelled with Bayesian-directed probability networks and multivariate logistic regression. 109 patients were studied. Irrespective of a diagnosis of CNS infection or hematological disease, the commonest anatomical distributions of abnormality were multifocal-parenchymal (34.9%), focal-parenchymal (29.4%) and leptomeningeal (11.9%). Pathological enhancement was the most frequently observed abnormality (46.8%), followed by hemorrhage (22.9%) and restricted diffusion (19.3%). Logistic regression could differentiate CNS infection from hematological disease infiltration with an AUC of 0.85 where, with OR > 1 favoring CNS infection and < 1 favoring CNS hematological disease, significantly predictive imaging features were hemorrhage (OR 24.61, p = 0.02), pathological enhancement (OR 0.17, p = 0.04) and an extra-axial location (OR 0.06, p = 0.05). In conclusion, CNS infection and hematological disease are heterogeneous entities with overlapping radiological appearances but a multivariate interaction of MR imaging features may assist in distinguishing them.

HIV-associated dementia presenting predominantly with clinical motor deficits: A case report

HIV-associated dementia is commonly seen in older individuals and presents as a subcortical dementia associated with concentration, attention, and memory impairments. Motor signs, such as difficulty with gait, and mood changes are less prominent findings but are considered during diagnosis. We present a case of HIV-associated dementia in a young 29-year-old man who presented with progressive lower extremity weakness and difficulty ambulating.

Magnetic Resonance Imaging in Otosyphilis: A Rare Manifestation of Neurosyphilis

We report magnetic resonance imaging (MRI) in a case with otosyphilis, which is a rare manifestation of neurosyphilis. A 50-year-old male presented with progressive hearing loss on the left side and recent-onset palsy of the left 7th and 12th cranial nerves. Computed tomography imaging showed destructive bone lesions involving the petrous temporal bone, middle ear, and mastoid region with a pathognomonic pattern of bone destruction depicted in the volume rendering technique images. MRI showed features of destructive bone lesions (gummatous lesion), meningoneuritis, and labyrinthitis. Pathological examination and treponemal antibody absorption test favored the diagnosis. Otosyphilis should be considered as a differential diagnosis in an adult patient with destructive lesions of the petrous temporal bone. To the best of our knowledge, MRI in otosyphilis has not been reported.

Hemorrhagic Lesions in the Central Nervous System: Toxoplasmosis in a Person Living With Human Immunodeficiency Virus Infection and Acquired Immunodeficiency Syndrome

Central nervous system (CNS) toxoplasmosis is one of the common causes of hemorrhagic brain lesions in people living with HIV and AIDS (PLWHA), resulting in high mortality and morbidity. It has a broad clinical and neuro-radiological spectrum, which may or may not be limited to typical findings of focal and subacute neurological deficits or ring-enhancing lesions in the basal ganglia. Here, we present a case of a patient who is a newly detected person living with HIV and AIDS with a low CD₄ cell count and classical imaging findings of central nervous system toxoplasmosis on his magnetic resonance imaging (MRI) of the brain. The incidence of opportunistic infections has been reduced after introducing highly active antiretroviral therapy (HAART); this case will be helpful to clinicians in identifying CNS toxoplasmosis as it has classical imaging findings on the MRI brain.

Preliminary comparative study of cortical thickness in HIV-infected patients with and without working memory deficit

Purpose

Changes in cerebral cortical regions occur in HIV-infected patients, even in those with mild neurocognitive disorders. Working memory / attention is one of the most affected cognitive domain in these patients, worsening their quality of life. Our objective was to assess whether cortical thickness differs between HIV-infected patients with and without working memory deficit.

Methods

Forty-one adult HIV-infected patients with and without working memory deficit were imaged on a 1.5 T scanner. Working memory deficit was classified by composite Z scores for performance on the Digits and Letter-Number Sequencing subtests of the Wechsler Adult Intelligence Scale (third edition; WAIS-III). Cortical thickness was determined using FreeSurfer software. Differences in mean cortical thickness between groups, corrected for multiple comparisons using Monte-Carlo simulation, were examined using the query design estimate contrast tool of the FreeSurfer software.

Results

Greater cortical thickness in left pars opercularis of the inferior frontal gyrus, and rostral and caudal portions of the left middle frontal gyrus (cluster 1; p = .004), and left superior frontal gyrus (cluster 2; p = .004) was observed in HIV-infected patients with working memory deficit compared with those without such deficit. Negative correlations were found between WAIS-III–based Z scores and cortical thickness in the two clusters (cluster 1: ρ = –0.59; cluster 2: ρ = –0.47).

Conclusion

HIV-infected patients with working memory deficit have regions of greater thickness in the left frontal cortices compared with those without such deficit, which may reflect increased synaptic contacts and/or an inflammatory response related to the damage caused by HIV infection.

Approach to Neurologic Complications in the Immunocompromised Patient

Neurologic complications are common in immunocompromised patients, including those with advanced human immunodeficiency virus, transplant recipients, and patients on immunomodulatory medications. In addition to the standard differential diagnosis, specific pathogens and other conditions unique to the immunocompromised state should be considered in the evaluation of neurologic complaints in this patient population. A thorough understanding of these considerations is critical to the inpatient neurologist in contemporary practice, as increasing numbers of patients are exposed to immunomodulatory therapies. In this review, we provide a chief complaint-based approach to the clinical presentations and diagnosis of both infectious and noninfectious complications particular to immunocompromised patients.

The neurological sequelae of pandemics and epidemics

Neurological manifestations in pandemics frequently cause short and long-term consequences which are frequently overlooked. Despite advances in the treatment of infectious diseases, nervous system involvement remains a challenge, with limited treatments often available. The under-recognition of neurological manifestations may lead to an increase in the burden of acute disease as well as secondary complications with long-term consequences. Nervous system infection or dysfunction during pandemics is common and its enduring consequences, especially among vulnerable populations, are frequently forgotten. An improved understanding the possible mechanisms of neurological damage during epidemics, and increased recognition of the possible manifestations is fundamental to bring insights when dealing with future outbreaks. To reverse this gap in knowledge, we reviewed all the pandemics, large and important epidemics of human history in which neurological manifestations are evident, and described the possible physiological processes that leads to the adverse sequelae caused or triggered by those pathogens.

Emerging role of white matter lesions in cerebrovascular disease

White matter lesions have been implicated in the setting of stroke, dementia, intracerebral haemorrhage, several other cerebrovascular conditions, migraine, various neuroimmunological diseases like multiple sclerosis, disorders of metabolism, mitochondrial diseases and others. While much is understood vis a vis neuroimmunological conditions, our knowledge of the pathophysiology of these lesions, and their role in, and implications to, management of cerebrovascular diseases or stroke, especially in the elderly, are limited. Several clinical assessment tools are available for delineating white matter lesions in clinical practice. However, their incorporation into clinical decision-making and specifically prognosis and management of patients is suboptimal for use in standards of care. This article sought to provide an overview of the current knowledge and recent advances on pathophysiology, as well as clinical and radiological assessment, of white matter lesions with a focus on its development, progression and clinical implications in cerebrovascular diseases. Key indications for clinical practice and recommendations on future areas of research are also discussed. Finally, a conceptual proposal on putative mechanisms underlying pathogenesis of white matter lesions in cerebrovascular disease has been presented. Understanding of pathophysiology of white matter lesions and how they mediate outcomes is important to develop therapeutic strategies.

Retrospective Hospital-based Study of Opportunistic Neuroinfections in HIV/AIDS

Background

Patients with retroviral disease are prone to opportunistic infections (OIs) of the central nervous system which cause significant mortality and morbidity. Cryptococcosis, tuberculosis, and toxoplasma are the most commonneuroinfections occurring at all stages of the disease.

Objective

This study was undertaken to evaluate the clinical pattern of OIs and in-hospital mortality in patients with acquired immunodeficiency syndrome (AIDS).

Materials and Methods

This retrospective analysis was conducted in a teaching hospital from 2001 to2014. Clinical data, laboratory investigations, and outcome of patients with meningoencephalitis were obtainedfrom case records.

Results

The total number of patients with human immunodeficiency virus (HIV) and AIDS with neurological manifestations was 277, among whom 167 (60.3%) had meningoencephalitis. There were 131 malesand 36 femaleswith a male-to-female ratio of 3.63:1andage ranging from 16 to 67 years (39.25 ± 8.85 years). Clinical presentation was acute in 58%, subacute in 32%, and chronic in 10%. Symptoms includedheadache (85.8%), fever (65.7%), altered sensorium (37.1%), and seizures (25.1%). Cryptococcal meningitis was the most commoninfection (67) followed by tuberculosis (32), mixed meningitis (24), and toxoplasmosis (10), and 16 patients had progressive multifocal leucoencephalopathy. Pathogenic organism could not be identified in 18 patients. Fifteen patients died during hospital admission. Mortality was the highest in mixed meningitis (16.7%) followed by cryptococcal meningitis (10.4%). Opportunistic neuroinfection occurred as AIDS-defining illness in 59.3%. Prior use of highly active anti-retroviral therapy did not affect the outcome.

Conclusion

Opportunistic neuroinfections are the most commonneurological manifestation in patients with AIDS, with cryptococcal meningitis being the most commonopportunistic neuroinfection occurring as AIDS-defining illness in one-third of the patients with neuro-AIDS.

MRI imaging features of HIV-related central nervous system diseases: diagnosis by pattern recognition in daily practice

With the advent of antiretroviral therapy (ART), the prognosis of people infected with human immunodeficiency virus (HIV) has improved, and the frequency of HIV-related central nervous system (CNS) diseases has decreased. Nevertheless, mortality from HIV-related CNS diseases, including those associated with ART (e.g., immune reconstitution inflammatory syndrome) remains significant. Magnetic resonance imaging (MRI) can improve the outlook for people with HIV through early diagnosis and prompt treatment. For example, HIV encephalopathy shows a diffuse bilateral pattern, whereas progressive multifocal leukoencephalopathy, HIV-related primary CNS lymphoma, and CNS toxoplasmosis show focal patterns on MRI. Among the other diseases caused by opportunistic infections, CNS cryptococcosis and CNS tuberculosis have extremely poor prognoses unless diagnosed early. Immune reconstitution inflammatory syndrome shows distinct MRI findings from the offending opportunistic infections. Although distinguishing between HIV-related CNS diseases based on imaging alone is difficult, in this review, we discuss how pattern recognition approaches can contribute to their early differentiation.

Central nervous system Cryptococcoma mimicking demyelinating disease: a case report

Background

Cerebral cryptococcomas is a rare form of central nervous system cryptococcosis. Most previous cases were mistaken for neoplasm before surgery. We present a case of cerebral cryptococcomas whose radiological profiles resembled demyelinating disease, especially tumefactive demyelinating lesion.

Case presentation

A 40-year-old male was admitted for 1-week-long unconsciousness. Brain MRI revealed a rim-enhanced mass within the corpus callosum body. Central nervous system demyelinating disease was suspected. Empirical corticosteroid treatment led to some improvement, but his condition deteriorated 2 months later. Brain MRI revealed punctate new foci. Cryptococcus neoformans was detected in cerebrospinal fluid. Cryptococcus antigen test was positive in his current and previous cerebrospinal fluid samples. The patient died despite standard antifungal treatment.

Conclusion

Diagnosis of cerebral cryptococcomas is challenging. It may mimic demyelinating diseases.

Bilateral lesions of the basal ganglia and thalami (central grey matter)-pictorial review

The basal ganglia and thalami are paired deep grey matter structures with extensive metabolic activity that renders them susceptible to injury by various diseases. Most pathological processes lead to bilateral lesions, which may be symmetric or asymmetric, frequently showing characteristic patterns on imaging studies. In this comprehensive pictorial review, the most common and/or typical genetic, acquired metabolic/toxic, infectious, inflammatory, vascular and neoplastic pathologies affecting the central grey matter are subdivided according to the preferential location of the lesions: in the basal ganglia, in the thalami or both. The characteristic imaging findings are described with emphasis on the differential diagnosis and clinical context.

Central nervous system and spinal cord tuberculosis: Revisiting an important disease

Tuberculosis is a worldwide pandemic. Estimated that about 25% humans are colonized by Mycobacterium tuberculosis and about 1% are believed to develop the infection in the central nervous system (CNS-TB). Given the importance of this disease and its high levels of morbidity and mortality, it is imperative that every radiologist must be reminded of the most common findings of CNS-TB as there are several related differential diagnoses for this disease. The most common form CNS-TB is tuberculous meningitis (TBM), characterized mostly by basal meningitis, but infarction, hydrocephalus and tuberculomas could be present. Intracerebral tuberculosis is characterized by tuberculomas that can have different imaging features according to their stage. Vascular and spinal complications of tuberculosis are also reported. This review compiles the classic and unusual findings regarding CNS-TB together with new diagnostic scores in which neuroimaging have an important role.

[Toxic changes of the central nervous system]

CLINICAL ISSUES

Various toxic agents can cause changes to the white matter of the brain leading to leukoencephalopathies. These changes often lead to signal alterations of the white matter with or without a diffusion restriction signal. White matter lesions can be reversible or irreversible. There are many differential diagnoses of toxic leukoencephalopathies.

PRACTICAL RECOMMENDATIONS

For the radiologist it is necessary to be familiar with the causes, the clinical and the imaging presentation of toxic leukoencephalopathies because early treatment often leads to improved prognosis.

Human immunodeficiency virus-related cerebral white matter disease in children

The human immunodeficiency virus (HIV) epidemic seems largely controlled by anti-retroviral treatment with resultant large numbers of children growing up with the disease on long-term treatment, placing them at higher risk to develop HIV-related brain injury, ongoing cognitive impairment and treatment-related neurological complications. Cerebral white matter involvement is a common radiologic finding in HIV infection and the causes of this have overlapping appearances, ranging from diffuse widespread involvement to focal lesions. The varied pathophysiology is broadly grouped into primary effects of HIV, opportunistic infection, vascular disease and neoplasms. White matter changes in children can be different from those in adults. This review provides guidance to radiologists with the diagnostic dilemma of nonspecific cerebral white matter lesions in children with HIV. The authors discuss common causes of HIV-related cerebral white matter disease as well as the role of neuroimaging in the management of these children.

Progressive multifocal leukoencephalopathy: a challenging diagnosis established at autopsy

Progressive multifocal leukoencephalopathy (PML) is a feared entity that occurs most frequently in conditions of extreme immunodeficiency. The diagnosis is often made long after the onset of symptoms due to the physicians’ unfamiliarity, and the unavailability of diagnostic tests in some medical centers. Although the incidence of PML is decreasing among HIV patients with the advent of highly active antiretroviral therapy (HAART), in Brazil this entity is the fourth highest neurological complication among these patients. The authors present the case of a middle-aged man who tested positive for HIV concomitantly with the presentation of hyposensitivity in the face and the right side of the body, accompanied by mild weakness in the left upper limb. The clinical features worsened rapidly within a couple of weeks. The diagnostic work-up pointed to the working diagnosis of PML after brain magnetic resonance imaging; however, the detection of the John Cunningham virus (JCV) in the cerebral spinal fluid was negative. HAART was started but the patient died after 7 weeks of hospitalization. The autopsy revealed extensive multifocal patchy areas of demyelination in the white matter where the microscopy depicted demyelination, oligodendrocytes alterations, bizarre atypical astrocytes, and perivascular lymphocytic infiltration. The immunohistochemistry was positive for anti-SV40, and the polymerase chain reaction of the brain paraffin-embedded tissue was positive for JCV. The authors highlight the challenges for diagnosing PML, as well as the devastating outcome of PML among HIV patients.

CMV Encephalitis/Radiculitis: The Difficulty in Diagnosing in an Intubated Patient

Cytomegalovirus (CMV) can cause severe disease including colitis, pneumonitis, and less commonly encephalitis, in profoundly immunocompromised individuals. CNS imaging findings are nonspecific and diagnosis is made by identifying CMV in cerebral spinal fluid through PCR testing or cell culture. Early initiation of antiviral therapy is key with an overall poor outcome. Here we present a patient with newly diagnosed AIDS and pneumocystis jiroveci pneumonia who was febrile and remained encephalopathic for the first 6 weeks of his admission despite treatment and extensive work up for encephalopathy. Ultimately, he was diagnosed with CMV encephalitis and radiculitis and failed to improve significantly. This case is important because of multiple points (1) the uncommon presentation of CMV encephalitis/radiculitis occurring over 1 month into a hospitalization; (2) in the era of highly active antiretroviral therapy (HAART) severe complications of AIDS are rarely seen by newer generations of physicians and are not typically thought of; (3) the difficulties in evaluating altered mental status and weakness in an intubated patient receiving sedation. In immunosuppressed patients on mechanical ventilation, early evaluation with LP should be considered when altered mental status and fever of unclear etiology are present.

Changes in resting-state functional brain activity are associated with waning cognitive functions in HIV-infected children

Delayed brain development in perinatally HIV-infected children may affect the functional brain activity and subsequently cognitive function. The current study evaluated the functional brain activity in HIV-infected children by quantifying the amplitude of low frequency fluctuations (ALFF) and functional connectivity (FC). Additionally, correlation of ALFF and FC with cognitive measures was performed. Twenty-six HIV-infected children and 20 control children underwent neuropsychological (NP) assessment and resting-state functional magnetic resonance imaging (rs-fMRI). ALFF and FC maps were generated and group differences were analyzed using two-sample t-test. Furthermore, ALFF and FC showing significant group differences were correlated with NP scores using Pearson's correlation. Significantly lower ALFF in the left middle temporal gyrus, precentral and post central gyrus was observed in HIV-infected children compared to controls. FC was significantly reduced in the right inferior parietal, vermis, middle temporal and left postcentral regions, and significantly increased in the right precuneus, superior parietal and left middle frontal regions in HIV-infected children as compared to control. HIV-infected children showed significantly lower NP scores in various domains including closure, exclusion, memory, verbal meaning, quantity and hidden figure than controls. These waning cognitive functions were significantly associated with changes in ALFF and FC in HIV-infected children. The findings suggest that abnormal ALFF and FC may responsible for cognitive deficits in HIV-infected children. ALFF and FC in association with cognitive evaluation may provide a clinical biomarker to evaluate functional brain activity and to plan neurocognitive intervention in HIV-infected children undergoing standard treatment.

Toxoplasmosis in an Immunocompetent Patient

Toxoplasmosis is an obligate intracellular, food borne parasite disease with variable clinical presentation. Although the neurological presentation of toxoplasmosis in immunocompetent patients is uncommon, broad differential diagnosis should be kept in consideration when attending to similar patients. Twenty years old man with no known co-morbid conditions presented with fever and unilateral limb weakness for three weeks. It increased gradually, associated with altered level of consciousness for the last five days, diagnosed as acute toxoplasmosis. MRI Brain showed multiple ring enhancing lesions in frontal, parietal and temporal lobes. Serology for toxoplasmosis denoted raised IgM levels 36IU/mL (cut off value > 18IU/mL). This case report describes the clinical presentation and management of neurological toxoplasmosis in immunocompetent patient. Early diagnosis and prompt management can resolve the symptoms at an earlier stage.

Posttubercular syringomyelia in HIV-infected patients: A report of 10 cases and literature review

OBJECTIVES

To describe the clinical presentation, spinal magnetic resonance imaging (MRI) findings and outcome of HIV-infected patients with tuberculosis (TB)-associated syringomyelia and to compare these findings between all HIV-infected and -uninfected cases published in the literature.

METHODS

A retrospective observational study conducted over a 12.5-year period at a public-sector referral hospital in South Africa. HIV-infected adults with neurological TB in whom MRI confirmed a syrinx were included. We searched PubMed to identify all published syringomyelia cases.

RESULTS

Ten patients were enrolled. Syringomyelia complicated neurological TB within four years of initial diagnosis in all patients (median: 21 months, range: 0-39) after initial diagnosis. Six patients were treated conservatively (TB treatment = 5, no treatment = 1); four improved, but only one was ambulant during follow-up. Four patients underwent syringoperitoneal shunting; three improved and one died three months later. Our literature review identified 50 additional cases (HIV-infected = 2, HIV-uninfected = 9, HIV status not documented = 39 [presumed HIV-uninfected]). Clinical and imaging findings and outcomes were similar between HIV-infected and -uninfected cases, except for time of presentation following neurological TB diagnosis, which was delayed (>4 years) in 46% of HIV-uninfected cases, compared to 8% of HIV-infected cases. Conclusions Syringomyelia is a disabling complication of neurological TB that usually presents early after neurological TB diagnosis in HIV coinfected patients.

Diffusion Kurtosis Imaging Shows Similar Cerebral Axonal Damage in Patients with HIV Infection and Multiple Sclerosis

BACKGROUND AND PURPOSE

In this pilot study, we sought to investigate the pathological changes in the white matter (WM) of medically complex, combination antiretroviral therapy (cART)-treated patients with human immunodeficiency virus (HIV), comparing them to patients with long-standing, secondary progressive multiple sclerosis (SPMS).

METHODS

Using diffusion kurtosis imaging (DKI)-derived WM tract integrity (WMTI) metrics, 15 HIV and 15 age- and sex-matched SPMS patients with similar disease duration underwent magnetic resonance imaging analysis. Maps of WMTI metrics were created. Tract-based spatial statistics analysis of the whole brain and regions of interest analysis of the corpus callosum (CC) and the anterior thalamic radiations (ATRs) were performed and the derived WMTI metrics were compared between the groups of patients.

RESULTS

Axonal water fraction, an index of chronic axonal loss, showed similarities between HIV and the chronic MS patients in all regions; in contrast, tortuosity, a measure more sensitive to myelin loss, was regionally variable. In addition, in HIV patients, WMTI metrics of the CC and left ATR were associated with cognitive test scores, suggesting clinical relevance for these measures of WM damage.

CONCLUSIONS

We conclude that DKI-derived WMTI metrics may be a valuable tool in assessing the WM changes of medically complex HIV-infected individuals. While not powered to examine potential etiologies of WM changes in this pilot sample, regional variations in WMTI metrics were seen. When contrasted with changes consequent to chronic MS of similar duration, HIV and its comorbidities appear to result in similar degrees of axonal damage, but regionally variable amounts of myelin loss and extraxonal abnormality.

Advances in serological, imaging techniques and molecular diagnosis of Toxoplasma gondii infection

BACKGROUND

Toxoplasmosis is worldwide distributed zoonotic infection disease with medical importance in immunocompromised patients, pregnant women and congenitally infected newborns. Having basic information on the traditional and new developed methods is essential for general physicians and infectious disease specialists for choosing a suitable diagnostic approach for rapid and accurate diagnosis of the disease and, consequently, timely and effective treatment.

METHODS

We conducted English literature searches in PubMed from 1989 to 2016 using relevant keywords and summarized the recent advances in diagnosis of toxoplasmosis.

RESULTS

Enzyme-linked immunosorbent assay (ELISA) was most used method in past century. Recently advanced ELISA-based methods including chemiluminescence assays (CLIA), enzyme-linked fluorescence assay (ELFA), immunochromatographic test (ICT), serum IgG avidity test and immunosorbent agglutination assays (ISAGA) have shown high sensitivity and specificity. Recent studies using recombinant or chimeric antigens and multiepitope peptides method demonstrated very promising results to development of new strategies capable of discriminating recently acquired infections from chronic infection. Real-time PCR and loop-mediated isothermal amplification (LAMP) are two recently developed PCR-based methods with high sensitivity and specificity and could be useful to early diagnosis of infection. Computed tomography, magnetic resonance imaging, nuclear imaging and ultrasonography could be useful, although their results might be not specific alone.

CONCLUSION

This review provides a summary of recent developed methods and also attempts to improve their sensitivity for diagnosis of toxoplasmosis. Serology, molecular and imaging technologies each has their own advantages and limitations which can certainly achieve definitive diagnosis of toxoplasmosis by combining these diagnostic techniques.

Longitudinally Extensive Transverse Myelitis Due to Toxoplasma: An Autopsy Study

Toxoplasma is an obligate intracellular parasite that remains asymptomatic in humans but, at times, can cause devastating disease. Here, we describe an autopsy study of a young immunocompetent gentleman with no comorbidities whose presentation was acute transverse myelitis. Magnetic resonance imaging spine showed longitudinally extensive spinal cord lesion (LESCL) that mimicked neuromyelitis optica with normal brain imaging at presentation. Investigations showed albuminocytological dissociation which prompted a course of parenteral steroid. However, the lesion relentlessly progressed to involve the brain stem and cerebrum leading to toxoplasmic encephalitis that terminated fatally. This report highlights that toxoplasma can present as LESCL and needs to be considered in the differential diagnosis of atypical myelitis.

Imaging studies of the HIV-infected brain

Human immunodeficiency virus (HIV) enters the brain early after infecting humans and may remain in the central nervous system despite successful antiretroviral treatment. Many neuroimaging techniques were used to study HIV+ patients with or without opportunistic infections. These techniques assessed abnormalities in brain structures (using computed tomography, structural magnetic resonance imaging (MRI), diffusion MRI) and function (using functional MRI at rest or during a task, and perfusion MRI with or without a contrast agent). In addition, single-photon emission computed tomography with various tracers (e.g., thallium-201, Tc99-HMPAO) and positron emission tomography with various agents (e.g., [18F]-dexoyglucose, [11C]-PiB, and [11C]-TSPO tracers), were applied to study opportunistic infections or HIV-associated neurocognitive disorders. Neuroimaging provides diagnoses and biomarkers to quantitate the severity of brain injury or to monitor treatment effects, and may yield insights into the pathophysiology of HIV infection. As the majority of antiretroviral-stable HIV+ patients are living longer, age-related comorbid disorders (e.g., additional neuroinflammation, cerebrovascular disorders, or other dementias) will need to be considered. Other highly prevalent conditions, such as substance use disorders, psychiatric illnesses, and the long-term effects of combined antiretroviral therapy, all may lead to additional brain injury. Neuroimaging studies could provide knowledge regarding how these comorbid conditions impact the HIV-infected brain. Lastly, specific molecular imaging agents may be needed to assess the central nervous system viral reservoir.

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.

Primary central nervous system lymphoma presenting as multiple space-occupying lesions in advanced human immunodeficiency virus infection

A 31-year-old man presented with seizures and cerebellar symptoms on a background of weight loss and lethargy. He was found to be infected with human immunodeficiency virus (HIV) and following radiological imaging, was commenced on treatment for presumed cerebral toxoplasmosis. Due to a lack of response, both clinically and on interval imaging, a positron-emission tomography-computed tomography and brain biopsy were undertaken, which demonstrated high-grade primary central nervous system lymphoma (PCNSL). Awareness amongst both clinicians and radiologists of the multifarious patterns of intra-cranial involvement in patients with HIV is, therefore, of utmost importance, as the treatment and prognosis of these entities are entirely different.

Computerised tomography findings in HIV-associated cryptococcal meningoencephalitis at a tertiary hospital in Pretoria

Objective

Computerised tomography (CT) scans of 30 patients, admitted with HIV-associated cryptococcal meningoencephalitis (CM), were retrospectively reviewed and the different neuroradiological findings categorised. In addition to the characterisation of the cohort, we looked at whether positive CT scans can indicate negative outcomes when compared with normal imaging.

Methods

We identified all patients admitted with CM to Kalafong Hospital in Pretoria, South Africa, over a 2-year period and selected those who underwent brain CT. Abnormal findings were divided into cryptococcal-related lesions and other pathological findings. Clinical data, as well as laboratory data and information about the outcomes were collected.

Results

Thirty-nine (44.8%) out of 87 patients had a CT done during the hospital admission, of which 30 were reviewed and independently reported by the authors. The majority of CT scans were non-contrasted (n = 21). Four patients (13.3%) had normal imaging. Amongst the 26 patients with abnormal CTs, we found 16 brain scans (53.3%) with changes most likely attributed to CM. Dilated Virchow–Robin (VR) spaces, found on eight scans (26.7%), were the most common CT finding related to neurocryptococcosis. Global cerebral atrophy, present in 17 patients (56.7%), was the prevailing generalised abnormality. The mortality of all patients who underwent imaging was similar (33.3%) to the mortality in the total cohort of patients with cryptococcal meningitis (31%). In the group with cryptococcal-related changes on imaging, the mortality was higher (53.3%) than in both groups and a subgroup of five patients with hydrocephalus showed 100% mortality.

Conclusion

Computerised tomography brain imaging was performed in 44.8% of all patients admitted with CM into our hospital. More than half of the images showed cryptococcal-related pathological findings, of which dilated VR spaces were the most common. Only 13.3% of scans were normal. Mortality was higher in the patients with cryptococcal-related pathology (53.3% vs. 31%), with hydrocephalus being associated with a 100% mortality. No scan in our cohort showed any pathology requiring neurosurgical intervention or contraindicating the procedure of a lumbar puncture.

Magnetic resonance imaging findings in central nervous system cryptococcosis: comparison between immunocompetent and immunocompromised patients

Objective

To assess the magnetic resonance imaging (MRI) patterns associated with central nervous system infection with Cryptococcus sp. in relation to patient immune status.

Materials and Methods

This was a retrospective study of MRI data for 19 patients with neurocryptococcosis who underwent the examination between January 2000 and March 2014. The MRI characteristics examined included lesion topography, aspects of diffusion, T1-weighted images, T2-weighted images, and contrast enhancement patterns.

Results

In all cases, cryptococcal infection was confirmed by cerebrospinal fluid analysis. Of the 19 patients, 10 were immunocompromised and 9 were immunocompetent. Abnormal imaging patterns occurred alone or in conjunction with other manifestations. The imaging patterns found in immunocompromised patients included the following: leptomeningeal enhancement, in 6; pachymeningeal enhancement, in 3 (due to intracranial hypotension in 2); perivascular space involvement, in 4; granulomas, in 2; hydrocephalus, in 2; miliary nodules, in 1; and plexitis, in 1. In immunocompetent patients, the following imaging patterns were observed: leptomeningeal enhancement, in 5; perivascular space involvement, in 3; granulomas, in 3; cryptococcoma, in 1; ventriculitis, in 1; and hydrocephalus, in 1. In 2 immunocompetent patients, diffusion-weighted imaging showed diffusion restriction in cerebral cryptococcal granuloma.

Conclusion

In both groups, the most common imaging finding was leptomeningeal enhancement, followed by dilatation of perivascular spaces with the presence of mucoid material. Rare presentations, such as miliary nodules, plexitis, ventriculitis, and pachymeningeal enhancement, were also observed. None of the imaging patterns common to immunocompetent and immunocompromised patients differed significantly in frequency between them.

White Matter Diseases with Radiologic-Pathologic Correlation

White matter diseases include a wide spectrum of disorders that have in common impairment of normal myelination, either by secondary destruction of previously myelinated structures (demyelinating processes) or by primary abnormalities of myelin formation (dysmyelinating processes). The pathogenesis of many white matter diseases remains poorly understood. Demyelinating disorders are the object of this review and will be further divided into autoimmune, infectious, vascular, and toxic-metabolic processes. Autoimmune processes include multiple sclerosis and related diseases: tumefactive demyelinating lesions, Balo concentric sclerosis, Marburg and Schilder variants, neuromyelitis optica (Devic disease), acute disseminated encephalomyelitis, and acute hemorrhagic leukoencephalopathy (Hurst disease). Infectious processes include Lyme disease (neuroborreliosis), progressive multifocal leukoencephalopathy, and human immunodeficiency virus (HIV) encephalopathy. Vascular processes include different types of small-vessel disease: arteriolosclerosis, cerebral amyloid angiopathy, cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), primary angiitis of the central nervous system, Susac syndrome, and neurolupus. Toxic-metabolic processes include osmotic myelinolysis, methotrexate leukoencephalopathy, and posterior reversible encephalopathy syndrome. The imaging spectrum can vary widely from small multifocal white matter lesions to confluent or extensive white matter involvement. Understanding the pathologic substrate is fundamental for understanding the radiologic manifestations, and a systematic approach to the radiologic findings, in correlation with clinical and laboratory data, is crucial for narrowing the differential diagnosis. (©)RSNA, 2016.

Infectious and inflammatory diseases of the central nervous system-the spectrum of imaging findings and differential diagnosis

The infectious and inflammatory diseases of the central nervous system (CNS) including the brain and spine can present with a wide spectrum of clinical symptoms, locations, and appearance. The purpose of this exhibit is to review the different patterns of their presentations, to illustrate their imaging characteristics and techniques, and to discuss their clinical features and pathology so that the correct diagnosis can be made and prompt intervention can be initiated on a timely fashion.