Acquired immunodeficiency syndrome: correlation of radiologic and pathologic findings in the brain

CNS toxoplasmosis in an immunocompetent individual

Toxoplasmosis is a serious and life-threatening disease in humans with a high prevalence in immunocompromised persons. The disease has a wide spectrum, depending on the immune status of the person. A CNS manifestation of toxoplasmosis in an immunocompetent person is very rare and often undetected. Our case of CNS toxoplasmosis in an immunocompetent person emphasizes the radiological diagnosis, which was further confirmed by advanced microbiology technique.

HIV Associated Neurocognitive Disorders

Human immunodeficiency virus type 1 is associated with the development of neurocognitive disorders in many infected individuals, including a broad spectrum of motor impairments and cognitive deficits. Despite extensive research, the pathogenesis of HIV-associated neurocognitive disorders (HAND) is still not clear. This review provides a comprehensive view of HAND, including HIV neuroinvasion, HAND diagnosis and different level of disturbances, influence of highly-active antiretroviral therapy to HIV-associated dementia (HAD), possible pathogenesis of HAD, etc. Together, this review will give a thorough and clear understanding of HAND, especially HAD, which will be vital for future research, diagnosis and treatment.

Magnetic resonance spectroscopy findings of pyogenic, tuberculous, and Cryptococcus intracranial abscesses

Proton magnetic resonance spectroscopy (MRS) complements conventional methods used to differentiate intracranial cystic lesions. We report MRS findings of three cases that were diagnosed as pyogenic, tuberculous, and Cryptococcus abscesses before instituting any medical or surgical therapy. The pyogenic brain abscess had typical specific spectral findings (i.e., the demonstration of amino acids). Lactate and lipid peaks were visible in the tuberculous abscess. Cryptococcus neoformans can appear differently in different brain regions, which may lead to different spectral findings.

Neuroimaging of herpesvirus infections in children

Six members of the herpesvirus family cause well-described neurologic disease in children: herpes simplex virus-1 (HSV-1), herpes simplex virus-2 (HSV-2), varicella-zoster (VZV), Epstein-Barr (EBV), cytomegalovirus (CMV), and human herpes virus-6 (HHV-6). When herpesviruses infect the central nervous system (CNS), the clinical presentation is non-specific and often confounding. The clinical urgency is often underscored by progressive neurologic deficits, seizures, or even death, and prompt diagnosis and treatment rely heavily on neuroimaging. This review focuses on the spectrum of cerebral manifestations caused by these viruses, particularly on non-congenital presentations. Recent advances in our understanding of these viruses are discussed, including new polymerase chain reaction techniques that allow parallel detection, which has improved our recognition that the herpesviruses are neurotropic and involve the CNS more often than previously thought. Evolving knowledge has also better elucidated viral neuropathology, particularly the role of VZV vasculitis in the brain, HHV-6 in febrile seizures, and herpesvirus reactivation in immunosuppressed patients. The virology, clinical course, and CNS manifestations of each virus are reviewed, followed by descriptions of neuroimaging findings when these agents infect the brain. Characteristic but often subtle imaging findings are discussed, as well as technical pearls covering appropriate use of MRI and MRI adjuncts to help differentiate viral infection from mimics.

Neuroimaging of the child with developmental delay

Developmental delay (DD) affects approximately 1% to 3% of all children in the United States. This diagnosis significantly impedes quality of life and full participation in the life of the family, school, and community. In this setting, the clinician's ability to detect, diagnose, and possibly treat the cause for DD in a timely manner depends on a multimodality approach to neuroimaging and a robust understanding of the various imaging algorithms aimed at determining the etiology of disease, structural and/or anatomic defects, functional activity, metabolic profiles, and genetic characteristics. Taken separately and in combination, these features are effectively depicted and analyzed using an array of brain imaging modalities: ultrasound, computed tomography, nuclear medicine, magnetic resonance (MR) spectroscopy, and a growing mix of sophisticated MR imaging (MRI) techniques, including diffusion-weighted imaging, diffusion tensor imaging, perfusion MRI, and functional MRI. Thus, equipped with these advanced imaging capabilities, pediatric neurologists and neuroradiologists are now positioned to diagnose with greater accuracy and speed; this, in turn, results in more effective treatment plans and improved patient outcomes as measured by progress in reaching developmental milestones and in ameliorating secondary conditions such as seizures, poor motor control, incontinence, and impulsivity. The purpose of this article is to present the numerous causes of pediatric DD, describe their respective neuroimaging findings, discuss various neuroimaging approaches for elucidating etiology, and offer specific guidelines for optimizing imaging results in the setting of multimodality imaging capabilities.

MR and TL-210 spect imaging with pathologic correlation for the assessment of CNS lymphoma vs. toxoplasmosis in AIDS patients

PURPOSE

Analyze the value of TL-201 (Tl) brain single-photon emission computed tomography (SPECT), to differentiate CNS lymphoma from toxoplasmosis in AIDS patients.

MATERIAL AND METHODS

Twenty-four AIDS patients with MR enhancing lesion(s), underwent a brain Tl SPECT. Final diagnosis was established by pathology and clinical/MR follow-up.

RESULTS

Nine patients had CNS tumor, 9 toxoplasmosis and 6 other non-tumorous lesions. The sensitivity of T1 to diagnose CNS tumor was 77% and the specificity 93%. Two false negative studies correspond to tumors with significant necrosis.

CONCLUSIONS

T1 proved useful for differentiating brain neoplasm from toxoplasmosis. Tumors with significant necrosis, did not show the expected increase in T1 uptake. Determination of T1 uptake ratios help detect tumor with faint tracer uptake.

Antiretroviral therapy-induced psychosis: case report and brief review of the literature

OBJECTIVE

We present a case of psychosis in an individual with known HIV infection whose symptoms developed approximately 1 month following the commencement of combination antiretroviral therapy consisting of abacavir (ABC), nevirapine and combivir. She presented with severe persecutory delusions, accompanied by mutism, posturing and catatonia. Following cessation of therapy and the introduction of a low-dose antipsychotic, her mental state resolved to a stable premorbid level, and no further disturbances of behaviour were noted. Furthermore, when re-challenged with the above combination minus ABC, there were no further episodes of psychosis. It is proposed that the aetiology of the psychosis was related to her antiretroviral therapy.

METHODS

Cessation of antiretroviral medication and initiation of antipsychotic medication with appropriate monitoring and assessment.

RESULTS

Subjective and objective improvements in psychotic symptoms and presentation.

CONCLUSION

The current case suggests that sudden onset psychotic disturbances in HIV-infected individuals in the absence of other known organic or other causal factors could be related to treatment with antiretroviral therapy, and that cessation of this can markedly improve psychiatric morbidity. Furthermore, treatment with antipsychotic medication can lead to alleviation of psychotic symptoms and enable the re-introduction of antiretroviral medication.

Central nervous system: review of clinical use of contrast media

The clinical utility of intravenous contrast administration for magnetic resonance imaging in neoplastic disease of the brain, non-neoplastic disease of the brain, and in disease of the spine is reviewed. Magnetic resonance imaging (MRI) is the modality of choice for the evaluation of most suspected intracranial and spinal pathology. Contrast use substantially improves lesion detection and differential diagnosis. Applications are discussed in neoplastic disease, infection, vascular disorders, demyelinating disease, and trauma (specifically including in the spine disk herniation). Gadolinium chelates play as important a role in magnetic resonance imaging as do iodinated agents in computed tomography. Contrast administration facilitates time-efficient and cost-effective diagnosis.

Blood-brain barrier disruption in simian immunodeficiency virus encephalitis

Infected monocyte-derived macrophages (MDM) are thought by some investigators to play a central role in the neuropathogenesis of human immunodeficiency virus encephalitis (HIVE). It was recently proposed that these cells gain access to the central nervous system (CNS) through disruptions in blood-brain barrier (BBB) tight junctions, which occur in HIVE in association with accumulation of activated, HIV-1-infected, perivascular macrophages and serum protein extravasation (Am J Pathol 1999, 155: 1915-27). The present study tested this hypothesis in basal ganglia tissue from simian immunodeficiency virus (SIV)-infected macaques with encephalitis by examining vessels for immunohistochemical alterations in the tight junction-associated proteins, occludin and zonula occludens-1 (ZO-1). Compared to non-infected macaques and SIV-infected macaques without encephalitis, cerebral vessels from macaques with SIVE showed fragmentation and decreased immunoreactivity for both tight junction proteins. These alterations were associated with accumulation of perivascular macrophages and aberrant occludin and ZO-1 immunoreactivity within these cells. In addition, perivascular extravasation of fibrinogen, a plasma protein, and a change from a strong linear staining pattern to a more irregular pattern of glucose transporter isoform-1 (GLUT-1), a metabolic BBB marker, were observed in regions with vascular tight junction protein alterations. These findings demonstrate that tight junction disruption occurs in SIVE in association with perivascular macrophage accumulation. While it cannot be ascertained from these studies whether such changes precede macrophage infiltration, or are secondary to the chronic presence of macrophages around cerebral vessels, disruptions in BBB integrity could serve as portals for additional accumulation of perivascular macrophages in SIVE.

Blood-brain barrier tight junction disruption in human immunodeficiency virus-1 encephalitis

The blood-brain barrier (BBB) plays a critical role in regulating cell trafficking through the central nervous system (CNS) due to several unique anatomical features, including the presence of interendothelial tight junctions that form impermeable seals between the cells. Previous studies have demonstrated BBB perturbations during human immunodeficiency virus encephalitis (HIVE); however, the basis of these permeability changes and its relationship to infiltration of human immunodeficiency virus type 1 (HIV-1)-infected monocytes, a critical event in the pathogenesis of the disease, remains unclear. In this study, we examined CNS tissue from HIV-1-seronegative patients and HIV-1-infected patients, both with and without encephalitis, for alterations in BBB integrity via immunohistochemical analysis of the tight junction membrane proteins, occludin and zonula occludens-1 (ZO-1). Significant tight junction disruption (P < 0.001), as demonstrated by fragmentation or absence of immunoreactivity for occludin and ZO-1, was observed within vessels from subcortical white matter, basal ganglia, and, to a lesser extent, cortical gray matter in patients who died with HIVE. These alterations were also associated with accumulation of activated, HIV-1-infected brain macrophages, fibrinogen leakage, and marked astrocytosis. In contrast, no significant changes (P > 0.05) were observed in cerebellar tissue from patients with HIVE compared to HIV-seronegative patients or HIV-1-infected patients without encephalitis. Our findings demonstrate that tight junction disruption is a key feature of HIVE that occurs in regions of histopathological alterations in association with perivascular accumulation of activated HIV-1-infected macrophages, serum protein extravasation, and marked astrocytosis. We propose that disruption of this key BBB structure serves as the main route of HIV-1-infected monocyte entry into the CNS.

Diagnostic imaging in pediatric AIDS

The manifestations of acquired immune deficiency syndrome (AIDS) in children are mainly secondary to opportunistic infection, lymphoproliferative diseases, and AIDS-related neoplasms. This article reviews the pathologic findings of various disorders afflicting children with AIDS and emphasizes the imaging of these disorders. Although many of the radiologic findings are not specific for a particular infection or neoplasm, the differential diagnostic possibilities for an abnormality can be narrowed down significantly with proper clinical correlation and knowledge of the imaging findings and pathologies specific to children with AIDS.

A comparison of survival of patients treated for AIDS-related central nervous system lymphoma with and without tissue diagnosis

PURPOSE

This is a retrospective review of the treatment outcome of radiation therapy (RT) in acquired immune-deficiency syndrome (AIDS) patients with presumed primary central nervous system (CNS) non-Hodgkin's lymphoma (NHL), with and without tissue verification.

METHODS AND MATERIALS

Twenty-seven patients with AIDS-related CNS NHL were treated between 1986 and 1992. They were divided into two groups. Group 1 consisted of nine patients with a positive histology for NHL. They were treated with dexamethasone (DXM) and whole brain RT. Group 2 consisted of 18 patients who, because of unique circumstances, were treated without histologic confirmation of NHL. Rapid clinical and/or radiologic response to DXM and whole-brain RT was interpreted as NHL.

RESULTS

For group 1, the response rate was 87.5%, mean survival 6.1 months, and median survival 4.5 months. For group 2, the response rate was 72.2%, mean survival 5.2 months, and median survival 4.5 months. The overall response rate was 76.9%, mean survival 5.8 months, and median survival 4.5 months.

CONCLUSIONS

In instances where a tissue diagnosis cannot be established, a positive response to an empiric trial of DXM and RT to 20 Gy may constitute presumptive evidence of NHL.

Cytomegalovirus infection of the brain in AIDS: a clinicopathological study

Based on neuropathological findings, a retrospective case control study of 39 patients with acquired immune deficiency syndrome (AIDS) and confirmed cytomegalovirus (CMV) infection of the brain is presented. Since 1989, the incidence has increased progressively and, in 1994, CMV was the most frequent opportunistic central nervous system (CNS) infection. Of the patients with CMV infections of the brain 16 had one or more coexisting secondary opportunistic and/or tumorous lesions in the CNS. Cerebral involvement by CMV was more frequent in patients with multiple extracerebral organ infections, while 7 among the 39 reported cases showed isolated CMV infection of the brain. The evaluation of the clinical records of 21 patients revealed neuropsychiatric signs and symptoms in 10, while these were absent in 11. All of these patients revealed various types of cerebral lesions related to CMV infection: ventriculitis, focal lesions, and microglial nodule encephalitis. The extent and distribution of cerebral lesions showed no significant correlations with clinical, radiological, or laboratory findings. Further clinicopathological studies are warranted to recognize CMV infections of the CNS and to allow earlier and more efficient treatment of this rather frequent complication of AIDS.

Pediatric HIV infection: an imaging update

Infection with the human immunodeficiency virus (HIV) can produce a broad range of illness, including opportunistic infections, lymphoproliferative diseases, and benign and malignant neoplasms. Each conditions has its own spectrum of imaging findings. This paper will highlight those findings in children suffering from HIV infection/AIDS. We will stress the findings in the more frequently involved organ systems and those that are unique to children.

Mycotic encephalitis: predilection for grey matter

In mycotic infections of the brain three patterns of abnormality may be observed: meningitis, granuloma, and encephalitis. The first two, consisting of diffuse meningeal enhancement and mass lesion respectively, can easily be visualised by CT or MRI, but are nonspecific. The third pattern has been described histopathologically; as the clinical picture is nonspecific and the diagnosis is often unsuspected, especially in immunocompetent patients, acquaintance with the characteristic CT and MRI patterns of mycotic encephalitis may help in establishing the correct diagnosis, with important therapeutic consequences.

Blood-brain barrier abnormalities in the acquired immunodeficiency syndrome: immunohistochemical localization of serum proteins in postmortem brain

Abnormalities in the blood-brain barrier (BBB) may be important in mediating some of the tissue damage that accompanies human immunodeficiency virus (HIV) infection of the brain, as well as in facilitating viral entry into the central nervous system. Accordingly, immunohistochemical detection of fibrinogen (FIB) and immunoglobulin G (IgG) was used as a marker of vascular permeability in formalin-fixed, paraffin-embedded brains of patients with acquired immunodeficiency syndrome (AIDS) who had HIV encephalitis (HIVE) (n = 17) and those who did not have HIVE (n = 16); nonimmunosuppressed patients served as control subjects (n = 22). The sex ratios and postmortem intervals were similar in all groups (p > 0.05), but the age of the two AIDS groups were younger than the control group (43.2 and 40.9 versus 62.5 yr; p < 0.05). The two AIDS groups had higher immunostaining for FIB and IgG than the control group (p < 0.001 and p < 0.0001, respectively) but did not differ from one another. Furthermore, the two AIDS groups had a significantly higher incidence of combined extravasation of both FIB and IgG, whereas the control group had a significantly higher incidence of negative staining for both proteins (p < 0.002). More than 95% of the microglial nodules of HIV were negative for serum proteins; however, all focal lesions with tissue necrosis, including lymphoma, opportunistic infections, and HIV (rarely), contained extravasated serum proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebrospinal fluid (CSF) analyses in HIV-1 primary neurological disease

This paper will focus on CSF findings in HIV-1 Neurological Disease (ND). Why use CSF as exploration window of the HIV-CNS involvement? Traditionally, CSF analysis has been an effective diagnostic method as well as a means of monitoring treatment in several infectious and immune pathologies of the CNS. Consequently there is an abundance of mature background information [113, 145, 147] particularly in terms of detecting infectious agents, using IgG findings as immunological indexes, and utilizing CSF findings to map the evolution of ND. We will explore the papers that utilize CSF variables as dependent measures to explore the effects of HIV disease, particularly HIV ND, cited in Index Medicus and MEDLINE data base, and published in Spanish, Italian and English, between 1985 to 1991. We will restrict our review to those studies that exclude HIV cases with CNS opportunistic infections or neoplasms, and thus focus on what the CSF can tell us about the primary effects of HIV on the brain as defined above. The primary long-term goal is to find some elements of the CSF that would lead to an understanding of the etiopathogenesis of HIV ND. However, an almost equally important aim is to determine which CSF variables may be clinically predictive of HIV ND occurrence and progression. The latter variables can also be expected to provide the best measures of HIV ND treatment efficacy. This is particularly important since it is our contention that treatment of HIV ND will eventually be initiated and monitored on the basis of laboratory markers of HIV ND, most likely from the CSF. Finally, this summarized information would be useful in drafting a CSF profile in order to have a reference pattern for cases with complications. The data of this review will be broken down, when the information permits, according to clinical stage and presence or absence of clinical manifestations of ND.