Cerebral toxoplasmosis complicating the acquired immune deficiency syndrome: clinical and neuropathological findings in 27 patients

Calcified cerebral toxoplasmosis associated with recurrent perilesional edema causing neurological manifestations in an HIV-infected individual: case report with a decade-long follow-up

Four cases of people living with HIV/AIDS (PLWHA) with calcified cerebral toxoplasmosis associated with perilesional edema causing a single episode of neurological manifestations have recently been reported. Here, we describe the first detailed description of perilesional edema associated with calcified cerebral toxoplasmosis causing three episodes of neurological manifestations in a PLWHA, including seizures in two of them. These recurrences occurred over approximately a decade. Throughout this period, the patient showed immunological and virological control of the HIV infection, while using antiretroviral therapy regularly. This case broadens the spectrum of an emerging presentation of calcified cerebral toxoplasmosis, mimicking a well-described finding of neurocysticercosis in immunocompetent hosts.

Presynaptic Hemiparkinsonism Following Cerebral Toxoplasmosis: Case Report and Literature Review

Background

Cerebral toxoplasmosis (CTx) is a central nervous system opportunistic infection with variable neurological manifestations. Although tropism of Toxoplasma gondii for the basal ganglia is well known, movement disorders (MDs) represent only a small percentage of CTx-related neurological complications. CTx-associated MDs are usually hyperkinetic, whereas parkinsonism associated with evidence of presynaptic dopaminergic deficit has never been described.

Case

We report a human immunodeficiency virus-positive patient who developed a complex MD featuring unilateral tremor combined with parkinsonism and dystonia following an acute episode of disseminated CTx. Her dopamine transporter scan (DaTscan) documented contralateral presynaptic dopaminergic deficit. Levodopa initiation improved both tremor and parkinsonism after ineffective trials of several other medications over the years.

Literature Review

A total of 64 patients presenting with CTx-related MDs have been described. The most common MD was chorea (44%), followed by ataxia (20%), parkinsonism (16%), tremor (14%), dystonia (14%), myoclonus (3%), and akathisia (2%). DaTscan was performed only in 1 case, of Holmes tremor, that demonstrated reduced presynaptic dopaminergic uptake. Positive response to dopaminergic treatment was reported in 3 cases of Holmes tremor and 2 cases of parkinsonism.

Conclusions

Presynaptic dopaminergic deficit may occur in CTx-related tremor combined with parkinsonism. Its identification should prompt initiation of levodopa, thus avoiding unnecessary trials of other drugs.

Novel Nanotechnology-Based Approaches for Targeting HIV Reservoirs

Highly active anti-retroviral therapy (HAART) is prescribed for HIV infection and, to a certain extent, limits the infection’s spread. However, it cannot completely eradicate the latent virus in remote and cellular reservoir areas, and due to the complex nature of the infection, the total eradication of HIV is difficult to achieve. Furthermore, monotherapy and multiple therapies are not of much help. Hence, there is a dire need for novel drug delivery strategies that may improve efficacy, decrease side effects, reduce dosing frequency, and improve patient adherence to therapy. Such a novel strategy could help to target the reservoir sites and eradicate HIV from different biological sanctuaries. In the current review, we have described HIV pathogenesis, the mechanism of HIV replication, and different biological reservoir sites to better understand the underlying mechanisms of HIV spread. Further, the review deliberates on the challenges faced by the current conventional drug delivery systems and introduces some novel drug delivery strategies that have been explored to overcome conventional drug delivery limitations. In addition, the review also summarizes several nanotechnology-based approaches that are being explored to resolve the challenges of HIV treatment by the virtue of delivering a variety of anti-HIV agents, either as combination therapies or by actively targeting HIV reservoir sites.

Misdiagnosis of HIV With Toxoplasmosis Encephalopathy With Progressive Memory Loss as the Initial Symptom: A Case Report

Toxoplasmosis encephalopathy (TE) is a kind of encephalopathy parasitic disease caused by Toxoplasma gondii. It is the most common opportunistic for central system infection in patients with acquired immunodeficiency syndrome (AIDS) or human immunodeficiency virus. Without early diagnosis and proper treatment, this opportunistic infection can be life-threatening. The common clinical manifestations of the disease include altered mental state, epilepsy, cranial nerve damage, paresthesia, cerebellar signs, meningitis, motor disorders, and neuropsychiatry. The most common presentation in about 75% of cases is a subacute episode of focal neurological abnormalities such as hemiplegia, personality changes, or aphasia. Imaging needs to be differentiated from multiple sclerosis, lymphoma, and metastases. We report a case of acquired immune deficiency syndrome complicated with toxoplasma encephalopathy with rapid progressive memory loss as the initial symptom and misdiagnosed as multiple sclerosis. Through the comprehensive analysis of the clinical symptoms and imaging examination of this disease, we hope to enhance the confidence of clinicians in the diagnosis of this disease.

Epidemiology, Pathophysiology, Diagnosis, and Management of Cerebral Toxoplasmosis

Toxoplasma gondii is known to infect a considerable number of mammalian and avian species and a substantial proportion of the world's human population. The parasite has an impressive ability to disseminate within the host's body and employs various tactics to overcome the highly regulatory blood-brain barrier and reside in the brain. In healthy individuals, T. gondii infection is largely tolerated without any obvious ill effects. However, primary infection in immunosuppressed patients can result in acute cerebral or systemic disease, and reactivation of latent tissue cysts can lead to a deadly outcome. It is imperative that treatment of life-threatening toxoplasmic encephalitis is timely and effective. Several therapeutic and prophylactic regimens have been used in clinical practice. Current approaches can control infection caused by the invasive and highly proliferative tachyzoites but cannot eliminate the dormant tissue cysts. Adverse events and other limitations are associated with the standard pyrimethamine-based therapy, and effective vaccines are unavailable. In this review, the epidemiology, economic impact, pathophysiology, diagnosis, and management of cerebral toxoplasmosis are discussed, and critical areas for future research are highlighted.

Hemichorea-Hemiballismus as a Presentation of Cerebritis from Intracranial Toxoplasmosis and Tuberculosis

Background

There is limited literature documenting hemichorea-hemiballism (HCHB) resulting from co-infection of toxoplasmosis and tuberculosis (TB) in acquired immunodeficiency syndrome (AIDS). Toxoplasmic abscess is the most common cause while TB is a rare etiology.

Case Description

We describe a 24-year-old male with AIDS-related HCHB as the presentation of cerebritis on the right subthalamic nucleus and cerebral peduncle from intracranial toxoplasma and TB co-infection. Antimicrobials and symptomatic therapy were given. Marked improvement was seen on follow-up.

Discussion

HCHB may be the initial presentation of intracranial involvement of this co-infection in the setting of AIDS and is potentially reversible with timely management.

Highlights

Hemichorea-hemiballismus (HCHB) may be an initial presentation of intracranial involvement of concomitant toxoplasmosis and tuberculosis causing focal cerebritis in the contralateral subthalamic nucleus and cerebral peduncle, particularly in the setting of human immunodeficiency virus infection.Acquired immunodeficiency syndrome-related HCHB is potentially reversible with timely diagnosis and treatment.

Toxoplasmosis of the central nervous system: Manifestations vary with immune responses

Toxoplasmosis is an opportunistic infection caused by Toxoplasma gondii (TG), which affects one third of the global human population and commonly involves the central nervous system (CNS)/brain despite the so-called CNS immune privilege. Symptomatic clinical disease of TG infection is much more commonly associated with immunodeficiency; clinicopathological manifestations of CNS toxoplasmosis are linked to individual immune responses including the CNS infiltration of T-cells that are thought to prevent the disease. In patients with autoimmune diseases, immune status is complicated mainly byimmunosuppressant and/or immunomodulatory treatment but typically accompanied by infiltration of T-cells that supposedly fight against toxoplasmosis. In this article, we review characteristics of CNS toxoplasmosis comparatively in immunocompromised patients, immunocompetent patients, and patients with coexisting autoimmune diseases, as well as CNS immune responses to toxoplasmosis with a representative case to demonstrate brain lesions at different stages. In addition to general understanding of CNS toxoplasmosis, our review reveals that clinical manifestations of CNS toxoplasmosis are commonly nonspecific, and incidental pathological findings of TG infection are relatively common in immunocompetent patients and patients with autoimmune diseases (compared to immunocompromised patients); CNS immune responses such as T-cell infiltrates vary in acute and chronic lesions of brain toxoplasmosis.

Imaging in Differentiating Cerebral Toxoplasmosis and Primary CNS Lymphoma With Special Focus on FDG PET/CT

OBJECTIVE. The purpose of this article is to present a brief review of literature evaluating different imaging modalities with special focus on ¹⁸F-FDG PET/CT in differentiating cerebral toxoplasmosis and primary CNS lymphoma. CONCLUSION. Differentiating cerebral toxoplasmosis and primary CNS lymphoma is crucial in the care of patients with HIV infection. Delayed diagnosis can lead to considerable morbidity and mortality. The reference standard for diagnosis is biopsy and histopathologic examination. Biopsy has disadvantages due to its invasive nature and associated complications. Noninvasive imaging can be an alternative to biopsy for differentiation of toxoplasmosis and primary CNS lymphoma. Despite advances in MRI techniques, prophylaxis of opportunistic infection, and treatment of HIV infection, clinical situations continue to arise in which the diagnosis is not clear. In these instances, molecular imaging can be helpful.

Influence of the Host and Parasite Strain on the Immune Response During Toxoplasma Infection

Toxoplasma gondii is an exceptionally successful parasite that infects a very broad host range, including humans, across the globe. The outcome of infection differs remarkably between hosts, ranging from acute death to sterile infection. These differential disease patterns are strongly influenced by both host- and parasite-specific genetic factors. In this review, we discuss how the clinical outcome of toxoplasmosis varies between hosts and the role of different immune genes and parasite virulence factors, with a special emphasis on Toxoplasma-induced ileitis and encephalitis.

Treatment of Secondary Chorea: A Review of the Current Literature

Background

Chorea consists of involuntary movements affecting the limbs, trunk, neck or face, that can move from one body part to another. Chorea is conceptualized as being "primary" when it is attributed to Huntington's disease (HD) or other genetic etiologies, or "secondary" when it is related to infectious, pharmacologic, metabolic, autoimmune disorders, or paraneoplastic syndromes. The mainstay of the secondary chorea management is treating the underlying causative disorder; here we review the literature regarding secondary chorea. We also discuss the management of several non-HD genetic diseases in which chorea can be a feature, where metabolic targets may be amenable to intervention and chorea reduction.

Methods

A PubMed literature search was performed for articles relating to chorea and its medical and surgical management. We reviewed the articles and cross-references of pertinent articles to assess the current clinical practice, expert opinion, and evidence-based medicine to synthesize recommendations for the management of secondary chorea.

Results

There are very few double-blind randomized controlled trials assessing chorea treatments regardless of etiology. Most recommendations are based on small open-label studies, case reports, and expert opinion.

Discussion

Treatment of secondary chorea is currently based on expert opinion, clinical experience, and small case studies, with limited evidence-based medical data. When chorea is secondary to an underlying infection, medication, metabolic abnormality, autoimmune process, or paraneoplastic illness, the movements typically resolve following treatment of the underlying disease. Tardive dyskinesia is most rigorously studied secondary chorea with the best evidence-based medicine treatment guidelines recommending the use of pre-synaptic dopamine-depleting agents. Even though there is an insufficient pool of EBM, small clinical trials, case reports, and expert opinion are valuable for guiding treatment and improving the quality of life for patients with chorea.

Highlights

There is a dearth of well-controlled studies regarding the treatment of chorea. Expert opinion and clinical experiences are fundamental in guiding chorea management and determining successful treatment. In general, secondary chorea improves with treating the underlying medical abnormality; treatments include antibiotics, antivirals, immunosuppression, dopamine depleting agents, chelation, and supportive care.

Efficacy and safety of trimethoprim-sulfamethoxazole in HIV-infected patients with cerebral toxoplasmosis in Brazil: a single-arm open-label clinical trial

Cerebral toxoplasmosis continues to cause high morbidity and mortality in developing countries. The association of sulfadiazine and pyrimethamine is considered the standard therapy; however, it has potential disadvantages. This single-arm open-label clinical trial was carried out in a tertiary hospital in São Paulo, Brazil. We included patients of at least 18 years of age, whose HIV infection was confirmed, and clinical and brain computed tomography (CT) findings were compatible with cerebral toxoplasmosis upon admission. Patients received trimethoprim (TMP) 10 mg/kg/day sulfamethoxazole (SMX) 50 mg/kg/day, in two divided doses. Brain CT was performed at study entry and after two weeks. The endpoints of the study were: (i) the proportion of patients with clinical and radiological response after two weeks of TMP-SMX and (ii) the proportion of patients who discontinued TMP-SMX due to adverse events. Forty-six patients were included (23 males, median age 35 years). The main clinical manifestations were headache, hemiparesis and altered mental status. The proportion of patients who obtained clinical and radiological response after two weeks of anti-toxoplasma treatment was 85% (n = 39). Overall, TMP-SMX was safe, with only 2 (4%) discontinuations due to adverse events. In this study, TMP-SMX was effective and safe in the treatment of HIV-related cerebral toxoplasmosis.

HIV-Related Cerebral Toxoplasmosis Revisited: Current Concepts and Controversies of an Old Disease

Cerebral toxoplasmosis is the most common cause of expansive brain lesions in people living with HIV/AIDS (PLWHA) and continues to cause high morbidity and mortality. The most frequent characteristics are focal subacute neurological deficits and ring-enhancing brain lesions in the basal ganglia, but the spectrum of clinical and neuroradiological manifestations is broad. Early initiation of antitoxoplasma therapy is an important feature of the diagnostic approach of expansive brain lesions in PLWHA. Pyrimethamine-based regimens and trimethoprim-sulfamethoxazole (TMP-SMX) seem to present similar efficacy, but TMP-SMX shows potential practical advantages. The immune reconstitution inflammatory syndrome is uncommon in cerebral toxoplasmosis, and we now have more effective, safe, and friendly combined antiretroviral therapy (cART) options. As a consequence of these 2 variables, the initiation of cART can be performed within 2 weeks after initiation of antitoxoplasma therapy. Herein, we will review historical and current concepts of epidemiology, diagnosis, and treatment of HIV-related cerebral toxoplasmosis.

Imaging features of neurotoxoplasmosis: A multiparametric approach, with emphasis on susceptibility-weighted imaging

Background

Neurotoxoplasmosis is a common opportunistic infection in HIV/AIDS patients. Imaging identification of neurotoxoplasmosis assists in timely treatment.

Purpose

To delineate the frequency of imaging abnormalities in patients with neurotoxoplasmosis on different MR sequences with a particular focus on SWI, and NCCT.

Material and methods

The PACS database was retroactively searched over a 5-year period for patients with neurotoxoplasmosis who underwent MRI with SWI. Included patients had imaging features of neurotoxoplasmosis based on consensus review by two neuroradiologists, a clinical diagnosis of neurotoxoplasmosis at the time of MRI, and diagnostic confirmation based on positive serum or CSF serology or histopathology; 15 patients were included. The number of abnormal foci with restricted diffusion, increased FLAIR signal, intrinsic T1 hyperintensity, abnormal enhancement (CE-T1WI), and intrinsic hyperdensity on CT were recorded.

Results

Intralesional susceptibility signal (ISS) foci on SWI were observed in 93.3% of patients with neurotoxoplasmosis (mean size 5.2 ± 3.8 mm). The average number of ISS foci was 3.9 per patient; 3/15 (20.0%) had a single ISS. Amongst other MR sequences, hyperintense FLAIR foci were the most common abnormalities observed (12.4 lesions/patient), followed by enhancing foci (8.2 lesions/patient), foci of restricted diffusion (7.1 lesions/patient), and intrinsic T1 hyperintense foci (3.4 lesions/patient). Abnormalities were least frequently observed on NCCT: abnormalities were identified in 5/15 (33.3%) patients, at a rate of 0.4 lesions/patient.

Conclusion

ISS foci are present in the vast majority of neurotoxoplasmosis patients, likely representing hemorrhage. The incidence and frequency of other abnormal foci are highest on FLAIR, and lowest on NCCT.

Neurological Presentations of AIDS-when to Test for HIV

Nine of 122 patients dead from AIDS in central London presented with neurological disease, confirmed pathologically in seven. Seven had no other major systemic manifestations. AIDS needs to be considered in the differential diagnosis of meningitis, dementia, diffuse and focal encephalopathies, brainstem syndromes, myelopathy, visual failure and peripheral nerve syndromes. As AIDS becomes more widespread there will be an increasing need for diagnostic HIV testing in many neurological syndromes.

AIDS: Neurological Opportunist Infections in Central London

Twenty six (41%) of 64 central London cases of AIDS with nervous system involvement during the course of the illness had neurological opportunist infection. Cytomegalovirus and Toxoplasma gondii were the commonest agents in 22 cases with central nervous system (CNS) infection. Eight cases had herpes zoster radiculopathy. Other infections included those caused by Cryptococcus neoformans, Mycobacterium tuberculosis and papova JC virus. Prognosis was generally poor, irrespective of whether the opportunist infection was treatable.

Central nervous system infection with Toxoplasma gondii

Central nervous system infection by Toxoplasma gondii, or Toxoplasma encephalitis, is the most common cause of brain mass lesions in human immunodeficiency virus (HIV)-infected patients. It usually presents as one or more brain abscesses, but it can also cause a diffuse encephalitis or ventriculitis. Individuals who are Toxoplasma immunoglobulin G-seropositive, who have peripheral blood CD4+ T-cell concentrations below 200/μL, are not on antiretroviral therapy, and are not taking trimethoprim-sulfamethoxazole to prevent Pneumocystis pneumonia, are at particular risk for Toxoplasma encephalitis. Neuroimaging typically shows round, isodense or hyperdense lesions in the hemispheric gray-white junction, deep white matter, or basal ganglia that enhance with contrast in a ring, nodular, or homogeneous pattern. In appropriate patients, response to an empiric treatment trial can establish the diagnosis. Immune reconstitution inflammatory syndrome is uncommon in HIV-infected patients treated for Toxoplasma encephalitis and combination antiretroviral therapy is an integral part of toxoplasmosis treatment.

Toxoplasmic Encephalitis in Patient with Acquired Immunodeficiency Syndrome

Toxoplasmic encephalitis (TE) is an opportunistic infection found in immunocompromised patients and TE related cerebral mass lesion is often reported in acquired immunodeficiency acquired immunodeficiency syndrome (AIDS) patients. However, incidence of TE related AIDS in Korea is still rare and is unfamiliar to neurosurgeons. Differential diagnosis is needed to rule out other brain lesions. A 39-year-old man visited the emergency room with rapid progressive left hemiparesis. Magnetic resonance imaging showed a ring-enhanced mass lesion in his right frontal lobe. Human immunodeficiency virus and Toxoplasma gondii immunoglobulin G were tested positive by a serologic test. We report here a rare case of patient with TE related AIDS.

Spinal cord toxoplasmosis in human immunodeficiency virus infection/acquired immunodeficiency syndrome

Neurological complications in patients with human immunodeficiency virus infection/acquired immunodeficiency syndrome (HIV/AIDS) are still common, even in the era of highly active antiretroviral therapy. Opportunistic infections, immune reconstitution, the virus itself, antiretroviral drugs and neurocognitive disorders have to be considered when establishing the differential diagnosis. Toxoplasmic encephalitis remains the major cause of space-occupying lesions in the brain of patients with HIV/AIDS; however, spinal cord involvement has been reported infrequently. Here, we review spinal cord toxoplasmosis in HIV infection and illustrate the condition with a recent case from our hospital. We suggest that most patients with HIV/AIDS and myelitis with enhanced spine lesions, multiple brain lesions and positive serology for Toxoplasma gondii should receive immediate empirical treatment for toxoplasmosis, and a biopsy should be performed in those cases without clinical improvement or with deterioration.

Linfoma del sistema nervoso centrale in corso di AIDS

Il linfoma primitivo cerebrale (LPC) è la più comune delle neoplasie opportunistiche del SNC in pazienti AIDS, seguito dal linfoma di Kaposi e dai gliomi, e spesso rappresenta la patologia rivelatrice della condizione di immunodeficienza acquisita.

L'incidenza dei LPC è in costante aumento nelle ultime due decadi. Attualmente rappresentano il 6,6–15,4% di tutti i tumori cerebrali primitivi contro il 3,3% registrato prima del 1978. Nei pazienti AIDS, ha una frequenza compresa fra il 3% ed il 10%. Si tratta, peraltro, di una patologia ancora relativamente rara costituendo solo lo 0,7–0,9% di tutti i linfomi.

I LPC si localizzano in prevalenza in regione sopratentoriale (90%) specialmente nella sostanza grigia periventricolare e nella sostanza bianca; la localizzazione in fossa cranica posteriore è stimata intorno al 10%. Nel LPC l'interessamento leptomeningeo non è comune riscontrandosi in circa il 12% dei casi; più raro il coinvolgimento durale, rarissimo (circa 1%) il coinvolgimento del midollo spinale. Viceversa il linfoma secondario tende ad invadere la dura madre e le leptomeningi.

Il LPC in corso di AIDS si manifesta in forma multifocale fra il 50 ed il 75%.

Dal 1991 è stata documentata una quasi costante associazione del virus di Ebstein-Barr (EBV) con il LPC il che ha indotto a considerare la possibilità di usare l'EBV come un marker diagnostico di tale patologia.

La costante presenza del EBV nel LPC in immunodepressi è in contrasto con quanto visto negli immunocompetenti ove l'associazione è modesta.

Ad una valutazione macroscopica il LPC si manifesta come massa nodulare con consistenza molto variabile da friabile a solida e superficie granulare. La lesione è frequentemente circondata da edema, comunemente diffonde alla leptomeninge e alle regioni subpiali. È multifocale nel 11–50% dei pazienti immunocompetenti e nel 41–81% dei pazienti AIDS nei quali peraltro l'incidenza di multifocalità può raggiungere il 100%.

All'analisi istologica il LPC mostra strati uniformi di cellule neoplastiche, strettamente stipate; il processo di infiltrazione si diffonde ben oltre i margini macroscopici della lesione. Necrosi ed emorragie sono molto più frequenti nei pazienti immunocompromessi.

Neuroradiologicamente le lesioni risultano tipicamente iperdense alla TC e questo aspetto è attribuito ad un alto rapporto nucleo-citoplasma ed ad un elevata cellularità fittamente stipata. Dopo mdc praticamente tutti i LPC mostrano impregnazione la cui intensità è peraltro variabile e talora così debole e indefinita da non essere apprezzata se non utilizzando appropriate finestre.

In RM nelle immagini T1 la lesione è tipicamente da ipo- ad isointensa relativamente alla sostanza grigia e produce un effetto massa modesto rispetto alle sue dimensioni.

Nei primi riferimenti della letteratura tali lesioni erano descritte quasi uniformemente iperintense in T2. Più recentemente, e probabilmente in rapporto ad un affinamento del software che ha consentito una maggiore evidenza di fini dettagli, le lesioni si documentano prevalentemente iso-ipointense alla sostanza grigia in T2, aspetto che, come alla TC, riflette l'alto rapporto nucleo- citoplasma e l'elevata cellularità fittamente stipata.

Nella popolazione non AIDS il LPC mostra quasi costantemente alla RM un impregnazione dopo mdc che risulta omogeneo nei 2/3 dei casi.

Nella popolazione AIDS il LPC mostra impregnazione nel 100% dei casi che risulta disomogeneo nel 54% dei casi, con un pattern anulare nel 46% ed uno irregolare nell '8%.

Uno degli aspetti caratteristici del LPC è la tendenza a diffondere lungo l'ependima, le meningi o entrambe. Questa dtffusione è documentata in percentuali variabili che raggiungono il 75% e si attestano al 28% per la contiguità con la superficie ependimale e 1′8% per la contiguità con la meninge.

T1-Hypersignal Foci in Cerebral Toxoplasmosis after Stem Cell Transplantation

We present here the unique image of toxoplasma encephalitis in a transplant recipient, characterized by the finding of T1-hypersignal foci. It is emphasized that cerebral toxoplasmosis after stem cell transplantation may show a high signal on T1-weighted images even without any hemorrhagic or calcified lesions.

Cerebral toxoplasmosis in patients with acquired immune deficiency syndrome in the neurological emergency department of a tertiary hospital

INTRODUCTION

Cerebral toxoplasmosis is the most common cause of space occupying brain lesion in patients with HIV/AIDS in Brazil. In the post-HAART era, it is responsible for high rates of morbidity and mortality worldwide.

MATERIALS AND METHODS

This study consists of a case series of 56 patients diagnosed with cerebral toxoplasmosis whose clinical features, brain imaging and cerebrospinal fluid aspects were analyzed.

RESULTS

Cerebral toxoplasmosis led to the diagnosis of infection by the human immunodeficiency virus (HIV) in 27 (48.2%) of the patients, while 29 (51.2%) others already knew to be HIV seropositive. However, at the time of diagnosis of cerebral toxoplasmosis, only 9 (16.6%) reported being under antiretroviral therapy and 5 (8.9%) were receiving primary prophylaxis for toxoplasmosis. Headache, strength deficit and fever were the most frequent signs and symptoms throughout the study. Fifty-three patients showed changes consistent with toxoplasmosis in CT or MRI. Thirty-four (60.7%) CSF samples were positive in the indirect haemagglutination test and for the reaction of Toxoplasma gondii IgG ELISA, while 31 (55.4%) were positive in the direct haemagglutination test. Fifty (89.3%) patients underwent first-line treatment for toxoplasmosis.

CONCLUSION

Cerebral toxoplasmosis is still a very relevant neurological disease in individuals with AIDS admitted to neurology emergency departments. Early diagnosis and initiation of empiric treatment and antiretroviral therapy are important for good prognosis.

A systematic review and meta-analysis of the relative efficacy and safety of treatment regimens for HIV-associated cerebral toxoplasmosis: is trimethoprim-sulfamethoxazole a real option?

OBJECTIVES

The objective of this study was to perform a systematic review and meta-analysis of the literature to evaluate the efficacy and safety of therapies for cerebral toxoplasmosis in HIV-infected adults. The pyrimethamine plus sulfadiazine (P-S) combination is considered the mainstay therapy for cerebral toxoplasmosis and pyrimethamine plus clindamycin (P-C) is the most common alternative treatment. Although trimethoprim-sulfamethoxazole (TMP-SMX) has potential advantages, its use is infrequent.

METHODS

We searched PubMed and four other databases to identify randomized controlled trials (RCTs) and cohort studies. Two independent reviewers searched the databases, identified studies and extracted data. Risk ratios (RRs) were pooled across studies using random-effects models.

RESULTS

Nine studies were included (five RCTs, three retrospective cohort studies and one prospective cohort study). In comparison to P-S, treatment with P-C or TMP-SMX was associated with similar rates of partial or complete clinical response [P-C: RR 0.87; 95% confidence interval (CI) 0.70-1.08; TMP-SMX: RR 0.97; 95% CI 0.78-1.21], radiological response (P-C: RR 0.92; 95% CI 0.82-1.03), skin rash (P-C: RR 0.81; 95% CI 0.56-1.17; TMP-SMX: RR 0.17; 95% CI 0.02-1.29), gastrointestinal impairment (P-C: RR 5.16; 95% CI 0.66-40.11), and drug discontinuation because of adverse events (P-C: RR 0.32; 95% CI 0.07-1.47). Liver impairment was more frequent with P-S than P-C (P-C vs. P-S: RR 0.48; 95% CI 0.24-0.97).

CONCLUSIONS

The current evidence fails to identify a superior regimen in terms of relative efficacy or safety for the treatment of HIV-associated cerebral toxoplasmosis. Use of TMP-SMX as preferred treatment may be consistent with the available evidence and other real-world considerations. Larger comparative studies are needed.

Toxoplasma gondii

Toxoplasma gondii is an obligate intracellular parasite that is a worldwide cause of infections in virtually all mammalian species, including humans. Although toxoplasmosis is extremely common in humans, most cases are subclinical and are revealed only by the presence of antibodies to this parasite. Prior to the use of immunosuppresive therapy and the recognition of the acquired immune deficiency syndrome (AIDS), the most devastating consequence of toxoplasmosis was seen in children of women who acquired acute toxoplasmosis in their first trimester of pregnancy.

In the past two decades, this pathogen has become increasingly recognized in immunocompromised patients as a common cause of encephalitis. The tragedy of toxoplasmosis is that it is a preventable disease. French investigators, have clearly defined the risk and range of severity of congenital toxoplasmosis, the value of systemic screening and patient education, and the value of treatment of the mother during pregnancy to prevent transmission to the fetus. Prevention of a large portion of cerebral toxoplasmosis cases in immunocompromised patients might be possible if congenital toxoplasmosis was better controlled in the United States. The first step in controlling toxoplasmosis in the United States is a better appreciation of this infection.

Imaging of the brain in patients with human immunodeficiency virus infection

Neurologic disease in acquired immunodeficiency syndrome (AIDS) patients is related either to opportunistic pathogens or to direct central nervous system (CNS) invasion by the human immunodeficiency virus. Despite the increasing availability of antiretroviral therapy, opportunistic infections continue to afflict patients in the developing world and in other populations with limited access to appropriate treatment. Classic CNS infections in the setting of AIDS include toxoplasmosis, cryptococcosis, progressive multifocal leukoencephalopathy, and cytomegalovirus encephalitis. Additionally, AIDS patients are far more susceptible to acquiring CNS tuberculosis and neurosyphilis, both of which exhibit altered disease characteristics in the setting of immunosuppression. Neuroimaging is a crucial component of the diagnostic work-up of these conditions, and findings include, but are not limited to, intracranial mass lesions, white matter disease, meningoencephalitis, vascular complications, and hydrocephalus. Though various disease processes can produce imaging findings that overlap with one another, certain characteristic patterns may suggest a particular pathogen, and advanced imaging techniques and laboratory tests allow for definitive diagnosis. Knowledge of the imaging patterns seen in the setting of AIDS-related CNS disease is vital to the neuroradiologist, whose interpretation may guide decisions related to treatment and further work-up.

Magnetic resonance features of pyogenic brain abscesses and differential diagnosis using morphological and functional imaging studies: a pictorial essay

The aim of this paper is to illustrate the potential of magnetic resonance imaging (MRI) in diagnosis, differential diagnosis, treatment planning and evaluation of therapy effectiveness of pyogenic brain abscesses, through the use of morphological (or conventional) and functional (or advanced) sequences. Conventional MRI study is useful for the identification of lesions, to determine the location and morphology and allows a correct hypothesis of nature in the most typical cases. However, the differential diagnosis from other brain lesions, such as non-pyogenic abscesses or necrotic tumors (high-grade gliomas and metastases) is often only possible through the use of functional sequences, as the measurement of diffusion with apparent diffusion coefficient (DWI-ADC), proton magnetic resonance spectroscopy ((1)H-MRS) and perfusion weighted imaging (PWI), which complement the morphological sequences and provide essential information on structural, metabolic and hemodynamic characteristics allowing greater neuroradiological confidence. Modern diagnostic MRI of pyogenic brain abscesses cannot be separated from knowledge, integration and proper use of the morphological and functional sequences.

Neuropathological correlate of the "concentric target sign" in MRI of HIV-associated cerebral toxoplasmosis

Cerebral toxoplasmosis is a frequent cause of focal brain lesions in the setting of immunodeficiency states, particularly acquired immune deficiency syndrome (AIDS), and magnetic resonance imaging (MRI) is an important diagnostic modality to differentiate toxoplasmosis from tuberculoma, and primary central nervous system lymphoma with diverse therapeutic implications. Several imaging patterns have been described in cerebral toxoplasmosis. The "concentric target sign" is a recently described MRI sign on T2-weighted imaging of cerebral toxoplasmosis that has concentric alternating zones of hypo- and hyperintensities. It is believed to be more specific than the well-known "eccentric target sign" in the diagnosis of cerebral toxoplasmosis and hence more useful in differentiation from other focal brain lesions in the context of AIDS. The concentric target sign, seen in deep parenchymal lesions, is distinct from the surface-based cortical "eccentric" target sign. The histopathological correlate of the latter has been recently described, but that of the concentric target sign is not known. In this study we describe the neuropathological correlate of this concentric target sign from the postmortem of a 40-year-old man with AIDS-associated cerebral toxoplasmosis. The concentric alternating zones of hypo/hyper/iso/intensities corresponded to zones of hemorrhage/fibrin-rich necrosis with edema/coagulative compact necrosis/inflammation with foamy histiocytes admixed with hemorrhage forming the outermost zone, respectively. The exclusive specificity of this sign in cerebral toxoplasmosis remains to be further elucidated.

Usefulness of stereotactic biopsy and neuroimaging in management of HIV-1 Clade C associated focal brain lesions with special focus on cerebral toxoplasmosis

BACKGROUND

Focal brain lesions (FBL) in HIV/AIDS frequently pose a diagnostic dilemma as the etiology varies from infective (tuberculoma, toxoplasmosis and tuberculous abscesses) to neoplastic lesions like lymphoma. For determining etiology, advanced neuroimaging techniques, serological and molecular biological tests have been evolved with varying sensitivities/specificities. Stereotactic biopsy (STB) of the lesions is reserved for lesions unresponsive to appropriate therapy.

OBJECTIVE AND METHODS

In this study, the diagnostic yield of neuroimaging [cranial CT (n=25), MRI (n=24), and Th201/99Tc SPECT scan (n=18)] is compared with histopathological diagnosis obtained by STB (n=21) or autopsy (n=4) in 25 HIV-1 subtype C seropositive individuals with FBL identified by neuroimaging with special reference to cerebral toxoplasmosis in an eighteen month study period (2006-2007).

RESULTS AND CONCLUSION

Cerebral toxoplasmosis was the most frequent cause of FBL (21/25, 84%), followed by one case each of tuberculoma, progressive multifocal leukoencephalopathy (PML), primary central nervous system lymphoma (PCNSL) and measles inclusion body encephalitis (MIBE), the last two diagnosed at autopsy. Of the 21 cases of cerebral toxoplasmosis, definitive diagnosis with histopathological confirmation was available in 14/21 (66.6%), with indirect evidence suggesting probable toxoplasmosis in seven, all of whom responded to antitoxoplasma therapy. CT and MRI had comparable specificities (75%), while MRI had marginally higher sensitivity (85% versus 80.9%) in detecting multiple lesions. The positive predictive value of both CT and MRI was identical (94.4%), suggesting that CT maybe a cost effective screening tool in resource restricted settings, for evaluating FBL. Sensitivity of 99Tc SPECT scan for diagnosing inflammatory lesions was 75% but failed to differentiate PCNSL from toxoplasmosis. This study is the first of its kind from India analyzing FBL with specific focus on cerebral toxoplasmosis in the setting of HIV-1 subtype C.

Detection of toxoplasmosis in patients with end-stage renal disease by enzyme-linked immunosorbent assay and polymerase chain reaction methods

Toxoplasmosis caused by Toxoplasma gondii is an opportunistic infection. In healthy individuals, the infection is largely asymptomatic, but in immunocompromised people the parasite can become widely disseminated, causing severe toxoplasmosis. In patients undergoing haemodialysis, the phagocytic process shows a highly significant impairment. Therefore, this study aimed to investigate toxoplasmosis in patients with end-stage renal disease (ESRD) undergoing haemodialysis in Ahvaz hospitals, southwest of Iran. A total of 280 patients and 100 healthy subjects participated in this study. The presence of serum IgM and IgG antibodies against T. gondii was detected by ELISA and the presence of Toxoplasma parasites in whole blood was evaluated by GRA6 PCR. Anti-T. gondii IgG antibodies were detected in 82 (29.3 %) haemodialysis patients and 26 (26 %) controls. In addition, anti-T. gondii IgM antibodies were detected in 7.9 % of patients and in 4 % of controls. For both the antibodies, the differences were statistically significant (P < 0.05). PCR was performed with DNA extracted from blood samples of all patients and controls. PCR gave positive results with four of the 280 blood samples from patients but none for the control blood samples. The results revealed a high percentage of positivity for Toxoplasma antibodies in patients with ESRD undergoing haemodialysis and also confirmed the parasite in whole blood, indicating disseminated infection in these patients. Patients undergoing dialysis have a higher rate of active infection with Toxoplasma likely due to reactivation of a chronic infection. Thus, parasitological examinations of ESRD patients should be periodically carried out for monitoring and evaluating the possible dissemination of toxoplasmosis during haemodialysis.

Cerebral toxoplasmosis: unusual MRI findings

BACKGROUND

Single cerebral toxoplasmic lesions are rarely explored.

METHODS

Through magnetic resonance imaging, 10 lesions were analyzed regarding location, signal intensity, contrast enhancement, eccentric target, and meningeal uptake.

RESULTS

Five lesions were corticosubcortical and in the deep three (60%) had infratentorial locations. Iso- or hypointense signal predominated in T1 sequence, but in T2, there was variability. Perilesional edema and ring contrast enhancement occurred in 100% of lesions, but eccentric targets and meningeal uptake were less frequent.

CONCLUSION

Even in the presence of single lesions, iso- or hypointense signal in T1, perilesional edema, and ring enhancement are suggestive of cerebral toxoplasmosis.

Hemichorea-hemiballismus as an initial manifestation in a Moroccan patient with acquired immunodeficiency syndrome and toxoplasma infection: a case report and review of the literature

Neurologic signs and symptoms may represent the initial presentation of AIDS in 10-30% of patients. Movement disorders may be the result of direct central nervous system infection by human immunodeficiency virus (HIV) or the result of opportunistic infections. We report the case of a 59 years old woman who had hemichorea-hemiballismus subsequently found to be secondary to a cerebral toxoplasmosis infection revealing HIV infection. Movement disorders, headache and nausea were resolved after two weeks of antitoxoplasmic treatment. Brain MRI control showed a marked resolution of cerebral lesion. Occurrence of hemichorea-ballismus in patient without familial history of movement disorders suggests a diagnosis of AIDS and in particular the diagnosis of secondary cerebral toxoplasmosis. Early recognition is important since it is a treatable entity.

Seroprevalence of Toxoplasma gondii IgG antibody in HIV-infected patients at the Lagos University Teaching Hospital

BACKGROUND

Toxoplasmosis is caused by infection with a ubiquitous intracellular protozoan parasite, Toxoplasma gondii. With the advent of the HIV pandemic in Nigeria, toxoplasmic encephalitis has become one of the more frequent opportunistic infections and the most commonly implicated cause of focal brain lesions complicating the course of AIDS.

OBJECTIVES

This study was conducted to compare the pattern of seroprevalence of T. gondii (Toxo-IgG) antibodies among HIV-infected persons presenting with neurological complications and those without.

MATERIALS AND METHODS

Plasma specimens collected from 380 subjects were tested for Toxo- IgG antibodies by enzyme immunoassay technique and CD4 estimation by flow cytometry. Close-ended questionnaires were applied to all respondents to collect relevant data, with ethical approval from the hospital ethical committee. Plasma was obtained from two study groups comprising 300 HIV-positive respondents without neurological presentations, and 80 HIV-positive respondents with neurological complications.

RESULTS

Seroprevalence of Toxo-IgG antibodies was 58% in the HIV-positive study group without neurological complications (of these, 79.2% were males and 38.5% were females) and 40% in the study group with neurological complications (46.2% of these were males and 28.6% were females). The overall seroprevalence of Toxo-IgG antibodies among the HIV-positive respondents (with and without neurological complications) was 54.2% (206 of 380). Seroprevalence of Toxo-IgG antibodies was lowest among the educated subjects (19% of the respondents with tertiary education) and among females in both study groups. A higher proportion of the subjects with neurological complications had CD4 cell count <100 cells/μL compared with respondents without neurological defects (39% vs 22.7%; P = 0.000), but the seroprevalence of Toxo-IgG antibodies was higher in subjects without neurological complications (45% vs 31.3%; P = 0.000).

CONCLUSION

Toxoplasmosis, though an important opportunistic infection in our environment, may not account for the majority of neurological complications observed in patients with HIV infection in our center.

Differential diagnosis for bilateral abnormalities of the basal ganglia and thalamus

The basal ganglia and thalamus are paired deep gray matter structures that may be involved by a wide variety of disease entities. The basal ganglia are highly metabolically active and are symmetrically affected in toxic poisoning, metabolic abnormalities, and neurodegeneration with brain iron accumulation. Both the basal ganglia and thalamus may be affected by other systemic or metabolic disease, degenerative disease, and vascular conditions. Focal flavivirus infections, toxoplasmosis, and primary central nervous system lymphoma may also involve both deep gray matter structures. The thalamus is more typically affected alone by focal conditions than by systemic disease. Radiologists may detect bilateral abnormalities of the basal ganglia and thalamus in different acute and chronic clinical situations, and although magnetic resonance (MR) imaging is the modality of choice for evaluation, the correct diagnosis can be made only by taking all relevant clinical and laboratory information into account. The neuroimaging diagnosis is influenced not only by detection of specific MR imaging features such as restricted diffusion and the presence of hemorrhage, but also by detection of abnormalities involving other parts of the brain, especially the cerebral cortex, brainstem, and white matter. Judicious use of confirmatory neuroimaging investigations, especially diffusion-weighted imaging, MR angiography, MR venography, and MR spectroscopy during the same examination, may help improve characterization of these abnormalities and help narrow the differential diagnosis.

Central nervous system infection

This article outlines a practical imaging approach to CNS infection and reviews 5 basic imaging patterns commonly seen: (1) extra-axial lesion, (2) ring-enhancing lesion, (3) temporal lobe lesion, (4) basal ganglia lesion, and (5) white matter abnormality. Opportunistic infections in the setting of HIV are also discussed within the context of these 5 basic imaging patterns. Characteristic imaging features in conjunction with clinical history are also highlighted in order to narrow the differential diagnosis or suggest a specific diagnosis in some cases.

Hyperkinetic movement disorders associated with HIV and other viral infections

Viral infections of the central nervous system often result in a spectrum of movement disorders, ranging from slowness and rigidity to hyperkinetic movements such as chorea, ballism, dystonia, and myoclonus. The basal ganglia are especially susceptible to some viruses, because of their intrinsic neurotropism, a predilection of opportunistic infections for the deep gray matter of the brain, and possibly the mounting of an autoimmune response against basal ganglia antigens. Viral encephalitides reviewed here include those caused by the human immunodeficiency virus, influenza A virus, the Flavivirus family (such as West Nile virus, Japanese encephalitis virus), and herpes simplex. Hyperkinetic movement disorders associated with prion diseases will also be discussed. The clinical features, etiology, pathogenesis, diagnosis, and treatment of the underlying infections and ensuing movement disorders will be reviewed.

Eccentric target sign in cerebral toxoplasmosis: neuropathological correlate to the imaging feature

Cerebral toxoplasmosis remains one of the most common focal brain lesions in patients with acquired immune deficiency syndrome (AIDS). Diagnosis is a challenge because on cranial imaging it closely mimics central nervous system lymphoma, primary and metastatic central nervous system (CNS) tumors, or other intracranial infections like tuberculoma or abscesses. A magnetic resonance imaging (MRI) feature on postcontrast T1-weighted sequences considered pathognomonic of toxoplasmosis is the "eccentric target sign." The pathological correlate of this imaging sign has been speculative. Herein we correlate the underlying histopathology to the MR feature of eccentric target sign in a patient with autopsy-proven HIV/AIDS-related cerebral toxoplasmosis. The central enhancing core of the target seen on MRI was produced by a leash of inflamed vessels extending down the length of the sulcus that was surrounded by concentric zones of necrosis and a wall composed of histiocytes and proliferating blood vessels, with impaired permeability producing the peripheral enhancing rim.

Autophagy in immunity against Toxoplasma gondii

A decisive outcome during host-pathogen interaction is governed by whether pathogen-containing vacuoles fuse with lysosomes. Fusion with lysosomes typically kills microbes. Toxoplasma gondii represents a classical example of an intracellular pathogen that survives within host cells by preventing the endosomal-lysosomal compartments from fusing with the vacuoles that contain the pathogen. Thus, T. gondii provides an excellent model to determine if the immune system can target a pathogen for lysosomal degradation. CD40, a major regulator of cell-mediated immunity, activates macrophages to kill T. gondii through a process that requires recruitment of autophagosomes around the parasitophorous vacuole, leading to lysosomal degradation of the parasite. These studies demonstrate that cell-mediated immunity can activate autophagy to kill a pathogen. CD40-induced autophagy likely contributes to resistance against T. gondii, particularly in neural tissues, the main sites affected by this pathogen.

Frequent hemorrhagic lesions in cerebral toxoplasmosis in AIDS patients

Cerebral toxoplasmosis is a frequent complication in immunosuppressed patients such as AIDS (acquired immunodeficiency syndrome). Frequently, lesions are located deep in the brain which are inaccessible for biopsy making rapid diagnosis dependent on accurate interpretation of neuroimaging findings. The commonest cranial CT findings reported in toxoplasmosis are ring enhancing hypodense lesions in basal ganglia or cortical gray matter. Hemorrhage has only rarely been described and is usually seen following antitoxoplasma treatment. We reviewed the records of 11 AIDS patients with cerebral toxoplasmosis and found multiple hemorrhagic cerebral, cerebellar, or brain stem lesions in 7 of 11 patients. Six patients had hemorrhage at the time of initial clinical presentation and one developed hemorrhage following 2 weeks of antitoxoplasma treatment. We conclude that hemorrhagic lesions are frequently found on cranial MRI scans in cerebral toxoplasmosis. AIDS patients presenting with hemorrhagic cerebral lesions should be considered for a trial of presumptive antitoxoplasma treatment.

CD40 and the immune response to parasitic infections

The interaction between CD40 and CD154 regulates many aspects of cellular and humoral immunity. The CD40-CD154 pathway is important for resistance against a variety of parasites. Studies done with these pathogens have provided important insight into the various mechanisms by which this pathway enhances host protection, mechanisms by which pathogens subvert CD40 signaling, conditions in which the CD40-CD154 pathway promotes disease and on modulation of this pathway for immunotherapy.

Toxoplasma gondii cyclophilin 18-mediated production of nitric oxide induces Bradyzoite conversion in a CCR5-dependent manner

Toxoplasma gondii modulates pro- and anti-inflammatory responses to regulate parasite multiplication and host survival. Pressure from the immune response causes the conversion of tachyzoites into slowly dividing bradyzoites. The regulatory mechanisms involved in this switch are poorly understood. The aim of this study was to investigate the immunomodulatory role of T. gondii cyclophilin 18 (TgCyp18) in macrophages and the consequences of the cellular responses on the conversion machinery. Recombinant TgCyp18 induced the production of nitric oxide (NO), interleukin-12 (IL-12), and tumor necrosis factor alpha through its binding with cysteine-cysteine chemokine receptor 5 (CCR5) and the production of gamma interferon and IL-6 in a CCR5-independent manner. Interestingly, the treatment of macrophages with TgCyp18 resulted in the inhibition of parasite growth and an enhancement of the conversion into bradyzoites via NO in a CCR5-dependent manner. In conclusion, T. gondii possesses sophisticated mechanisms to manipulate host cell responses in a TgCyp18-mediated process.