Viral Meningitis and Encephalitis.

PURPOSE OF REVIEW: This article discusses meningitis and encephalitis infections caused by viruses, excluding herpes family and human immunodeficiency virus (HIV). RECENT FINDINGS: The viral infections of the nervous system detailed in this article have no specific treatment other than supportive care. However, many of the viruses discussed are highly preventable by vaccination, proper skin protection against transmitting vectors, and postexposure prophylaxis. SUMMARY: While meningitis and encephalitis caused by viruses may have some clinical overlap, the management and outcomes can be highly disparate, making distinction between the two imperative. Furthermore, despite their relative rarity in terms of clinical disease, many of the viral infections discussed herein are highly preventable. Given the morbidity and mortality attached to such infections, provider and patient education are the best approach available to prevent these potentially devastating illnesses.

HIV and spinal cord disease.

The epidemiology of spinal cord disease in human immunodeficiency virus (HIV) infection is largely unknown due to a paucity of data since combination antiretroviral therapy (cART). HIV mediates spinal cord injury indirectly, by immune modulation, degeneration, or associated infections and neoplasms. The pathologies vary and range from cytotoxic necrosis to demyelination and vasculitis. Control of HIV determines the differential for all neurologic presentations in infected individuals. Primary HIV-associated acute transverse myelitis, an acute inflammatory condition with pathologic similarities to HIV encephalitis, arises in early infection and at seroconversion. In contrast, HIV vacuolar myelopathy and opportunistic infections predominate in uncontrolled disease. There is systemic immune dysregulation as early as primary infection due to initial depletion of gut-associated lymphoid tissue CD4 cells and allowance of microbial translocation across the gut that never fully recovers throughout the course of HIV infection, regardless of how well controlled. The subsequent proinflammatory state may contribute to spinal cord diseases observed even after cART initiation. This chapter will highlight an array of spinal cord pathologies classified by stage of HIV infection and immune status.

Infections of the Nervous System.

Microorganisms can affect the entire neuraxis, producing a variety of neurologic complications that frequently entail prolonged hospitalizations and complicated treatment regimens. The spread of pathogens to new regions and the reemergence of opportunistic organisms in immunocompromised patients pose increasing challenges to health care professionals. Because rapid diagnosis and treatment may prevent long-term neurologic sequelae, providers should approach these diseases with a structured, neuroanatomic framework, incorporating a thorough history, examination, laboratory analysis, and neuroimaging in their clinical reasoning and decision-making.

Intravenous Thrombolysis for Stroke and Presumed Stroke in Human Immunodeficiency Virus-Infected Adults: A Retrospective, Multicenter US Study.

BACKGROUND AND PURPOSE: Human immunodeficiency virus (HIV) infection has been shown to increase both ischemic and hemorrhagic stroke risks, but there are limited data on the safety and outcomes of intravenous thrombolysis with tPA (tissue-type plasminogen activator) for acute ischemic stroke in HIV-infected patients. METHODS: A retrospective chart review of intravenous tPA-treated HIV patients who presented with acute stroke symptoms was performed in 7 large inner-city US academic centers (various search years between 2000 and 2017). We collected data on HIV, National Institutes of Health Stroke Scale score, ischemic stroke risk factors, opportunistic infections, intravenous drug abuse, neuroimaging findings, and modified Rankin Scale score at last follow-up. RESULTS: We identified 33 HIV-infected patients treated with intravenous tPA (mean age, 51 years; 24 men), 10 of whom were stroke mimics. Sixteen of 33 (48%) patients had an HIV viral load less than the limit of detection while 10 of 33 (30%) had a CD4 count <200/mm3. The median National Institutes of Health Stroke Scale score at presentation was 9, and mean time from symptom onset to tPA was 144 minutes (median, 159). The median modified Rankin Scale score for the 33-patient cohort was 1 and for the 23-patient actual stroke cohort was 2, measured at a median of 90 days poststroke symptom onset. Two patients had nonfatal hemorrhagic transformation (6%; 95% confidence interval, 1%-20%), both in the actual stroke group. Two patients had varicella zoster virus vasculitis of the central nervous system, 1 had meningovascular syphilis, and 7 other patients were actively using intravenous drugs (3 cocaine, 1 heroin, and 3 unspecified), none of whom had hemorrhagic transformation. CONCLUSIONS: Most HIV-infected patients treated with intravenous tPA for presumed and actual acute ischemic stroke had no complications, and we observed no fatalities. Stroke mimics were common, and thrombolysis seems safe in this group. We found no data to suggest an increased risk of intravenous tPA-related complications because of concomitant opportunistic infections or intravenous drug abuse.

Clinical pathologic case report: A 70-year-old man with inflammatory cerebral amyloid angiopathy causing headache, cognitive impairment, and aphasia.

A 70-year-old man presented with two months of worsening cognitive impairment, hallucinations, and difficulty speaking, with superimposed headaches. Cerebrospinal fluid analysis was notable for lymphocytic pleocytosis and elevated protein. Imaging studies revealed multiple acute and subacute infarcts with cortical microhemorrhages. The patient underwent a stereotactic brain biopsy. In this article, we discuss the patient's differential diagnosis, pathologic findings, ultimate diagnosis, and clinical outcome.

Infectious Meningitis and Encephalitis.

The clinician who is evaluating a patient with a suspected central nervous system infection often faces a large differential diagnosis. There are several signs, symptoms, geographical clues, and diagnostic testing, such as cerebrospinal fluid abnormalities and magnetic resonance imaging abnormalities, which can be helpful in identifying the etiological agent. By taking a systematic approach, one can often identify life-threatening, common, and/or treatable etiologies. Here the authors describe some of the pearls and pitfalls in diagnosing and treating acute infectious meningitis and encephalitis.

Myeloradiculopathy associated with chikungunya virus infection.

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that is endemic to parts of Africa, South and Southeast Asia, and more recently the Caribbean. Patients typically present with fever, rash, and arthralgias, though neurologic symptoms, primarily encephalitis, have been described. We report the case of a 47-year-old woman who was clinically diagnosed with CHIKV while traveling in the Dominican Republic and presented 10 days later with left lower extremity weakness, a corresponding enhancing thoracic spinal cord lesion, and positive CHIKV serologies. She initially responded to corticosteroids, followed by relapsing symptoms and gradual clinical improvement. The time lapse between acute CHIKV infection and the onset of myelopathic sequelae suggests an immune-mediated phenomenon rather than direct activity of the virus itself. Chikungunya virus should be considered in the differential diagnosis of myelopathy in endemic areas. The progression of symptoms despite corticosteroid administration suggests more aggressive immunomodulatory therapies may be warranted at disease onset.

Emerging Cases of Powassan Virus Encephalitis in New England: Clinical Presentation, Imaging, and Review of the Literature.

BACKGROUND: Powassan virus (POWV) is a rarely diagnosed cause of encephalitis in the United States. In the Northeast, it is transmitted by Ixodes scapularis, the same vector that transmits Lyme disease. The prevalence of POWV among animal hosts and vectors has been increasing. We present 8 cases of POWV encephalitis from Massachusetts and New Hampshire in 2013-2015. METHODS: We abstracted clinical and epidemiological information for patients with POWV encephalitis diagnosed at 2 hospitals in Massachusetts from 2013 to 2015. We compared their brain imaging with those in published findings from Powassan and other viral encephalitides. RESULTS: The patients ranged in age from 21 to 82 years, were, for the most part, previously healthy, and presented with syndromes of fever, headache, and altered consciousness. Infections occurred from May to September and were often associated with known tick exposures. In all patients, cerebrospinal fluid analyses showed pleocytosis with elevated protein. In 7 of 8 patients, brain magnetic resonance imaging demonstrated deep foci of increased T2/fluid-attenuation inversion recovery signal intensity. CONCLUSIONS: We describe 8 cases of POWV encephalitis in Massachusetts and New Hampshire in 2013-2015. Prior to this, there had been only 2 cases of POWV encephalitis identified in Massachusetts. These cases may represent emergence of this virus in a region where its vector, I. scapularis, is known to be prevalent or may represent the emerging diagnosis of an underappreciated pathogen. We recommend testing for POWV in patients who present with encephalitis in the spring to fall in New England.

Stroke in HIV-infected African Americans: a retrospective cohort study.

The risk of having a first stroke is nearly twice as high among African Americans compared to Caucasians. HIV/AIDS is an independent risk factor for stroke. Our study aimed to report the risk factors and short-term clinical outcomes of African Americans with HIV infection and new-onset stroke admitted at the Johns Hopkins Hospitals (2000-2012). Multivariate linear regression was used to examine the association between potential predictors and odds of an unfavorable outcome, defined as a higher modified Rankin Scale (mRS) score on hospital discharge. African Americans comprised 105/125 (84%) of HIV-infected new-onset stroke inpatients (median age 50 years; 69% men; median CD4 140/mL; ischemic 77%; 39% taking highly active antiretroviral therapy). Vascular risk factors were common: hypertension (67%), cigarette smoking (66%), dyslipidemia (42%), hepatitis C (48%), intravenous drug abuse (32%), and prior myocardial infarction (29%). Prior aspirin and statin use were uncommon (18%, 9%). Unfavorable outcome (mRS score 4-6, n = 22 of 90 available records) was noted in 24% of patients, including seven in-hospital deaths. On multivariate analyses, higher CD4 count on hospital admission was associated with a lower mRS (-0.2 mRS points per 1 unit increase in CD4, 95% CI (-0.3, 0), p = 0.03). Intracerebral hemorrhage was also associated with a lower mRS (1.0 points lower, 95% CI (0.2, 1.8) compared to ischemic stroke, p = 0.01) after adjustment for other potential predictors. This underscores the importance of HIV infection on functional stroke outcomes beyond its recognized influence on stroke risk.

HIV-associated Neurocognitive Disorders and Antiretroviral Therapy: Current Concepts and Controversies.

Antiretroviral drugs may help prevent neurological decline in individuals with HIV infection by suppressing viral replication and associated chronic immune activation in the central nervous system. However, HIV control in the brain may come at the price of drug-induced neurotoxicity. Herein, we review recent advances in the balance between adequate viral suppression in the nervous system and adverse effects of the medications used in HIV treatment.

Neurosyphilis Update: Atypical is the New Typical.

Syphilis has reemerged as an important cause of neurological disease, affecting any part of the neuraxis at any stage of infection. What was once a dwindling diagnosis is now redoubling, particularly in the HIV-positive and in men who have sex with men populations. In the era of antibiotics and HIV coinfection, neurosyphilis presentations are protean, making diagnosis notoriously challenging. Advanced disease may be irreversible, and so early detection and treatment are ideal. Herein, we review recent advances in understanding neurosyphilis.

Imaging in Neurologic Infections II: Fungal and Viral Diseases.

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

Myelopathy associated with microorganisms.

PURPOSE OF REVIEW: This article reviews the common infectious etiologies of spinal cord dysfunction that span the globe epidemiologically and vary pathophysiologically. RECENT FINDINGS: Many microorganisms have the ability to directly or indirectly result in spinal cord dysfunction. These agents may have the ability to infect the spinal cord itself, but frequently cause indirect damage by parainfectious or postinfectious immune-mediated destruction or external compression of the spinal cord. SUMMARY: Infectious myelopathies can pose diagnostic difficulty but are potentially reversible causes of spinal cord dysfunction. The often complex relationship among the infectious agent, the immune system, and the neuraxis can create a difficult management conundrum whereby immune modulation may be the preferred approach.

Utility of measuring (1,3)-ß-d-glucan in cerebrospinal fluid for diagnosis of fungal central nervous system infection.

(1-3)-ß-d-Glucan (BDG) from cerebrospinal fluid (CSF) is a promising marker for diagnostic and prognostic aid of central nervous system (CNS) fungal infection, but its relationship to serum values has not been studied. Herein, we detected BDG from CSF at levels 2-fold lower than those in serum in patients without evidence of fungal disease but 25-fold higher than those in in serum in noncryptococcal CNS fungal infections. CSF BDG may be a useful biomarker in the evaluation of fungal CNS disease.

Neurologic complications in infective endocarditis: identification, management, and impact on cardiac surgery.

Neurologic complications of infective endocarditis (IE) are common and frequently life threatening. Neurologic events are not always obvious. The prediction and management of neurologic complications of IE are not easily approached algorithmically, and the impact they have on timing and ability to surgically repair or replace the affected valve often requires a painstaking evaluation and joint effort across multiple medical disciplines in order to achieve the best possible outcome. Although specific recommendations are always tailored to the individual patient, there are some guiding principles that can be used to help direct the decision-making process. Herein, we review the pathophysiology, epidemiology, manifestations, and diagnosis of neurological complications of IE and further consider the impact they have on clinical decision making.