Acute disseminated encephalomyelitis following HTLV-I associated myelopathy

Viral-induced neuroinflammation: Different mechanisms converging to similar exacerbated glial responses

There is increasing evidence that viral infections are the source/origin of various types of encephalitis, encephalomyelitis, and other neurological and cognitive disorders. While the involvement of certain viruses, such as the Nipah virus and measles virus, is known, the mechanisms of neural invasion and the factors that trigger intense immune reactions are not fully understood. Based on recent publications, this review discusses the role of the immune response, interactions between viruses and glial cells, and cytokine mediators in the development of inflammatory diseases in the central nervous system. It also highlights the significant gaps in knowledge regarding these mechanisms.

Human T-cell lymphotropic virus (HTLV)-associated encephalopathy: an under-recognised cause of acute encephalitis? Case series and literature review

Human T-cell lymphotropic virus (HTLV)-1-associated myelopathy (HAM) is well described. Clinical features are predominantly consistent with cord pathology, though imaging and autopsy studies also demonstrate brain inflammation. In general, this is subclinical; however, six cases have previously been reported of encephalopathy in HTLV-1-infected patients, without alternative identified aetiology. We describe three further cases of encephalitis in the UK HAM cohort (n = 142), whereas the annual incidence of acute encephalitis in the general population is 0.07-12.6 per 100,000. Clinical features included reduced consciousness, fever/hypothermia, headaches, seizures, and focal neurology. Investigation showed: raised CSF protein; pleocytosis; raised CSF:peripheral blood mononuclear cell HTLV-1 proviral load ratio; and MRI either normal or showing white matter changes in brain and cord. Four of the six previous case reports of encephalopathy in HTLV-infected patients also had HAM. Histopathology, reported in three, showed perivascular predominantly CD8+ lymphocytic infiltrates in the brain. One had cerebral demyelination, and all had cord demyelination. We have reviewed the existing six cases in the literature, together with our three new cases. In all seven with HAM, the spastic paraparesis deteriorated sub-acutely preceding encephalitis. Eight of the nine were female, and four of the seven treated with steroids improved. We propose that HTLV-associated encephalopathy may be part of the spectrum of HTLV-1-induced central nervous system disease.

Acuted disseminated encephalomyelitis

Acute disseminated encephalomyelitis (ADEM) is a disorder of the central nervous system (CNS) characterized by an acute event, typically with encephalopathy, in which diffuse CNS involvement occurs. It may follow an infectious event and occurs more commonly in young children. Pulse steroid treatment is frequently used to treat ADEM. Although ADEM is typically described as a benign condition, with children generally recovering motor function and resolution of lesions on magnetic resonance imaging (MRI), residual cognitive deficits may occur. This chapter aims to review the clinical features, typical presentation, differential diagnosis, treatment and prognosis of ADEM.

HTLV-1 and neurological conditions: when to suspect and when to order a diagnostic test for HTLV-1 infection?

HTLV-1 is a retrovirus associated with a myriad of clinical conditions, especially hematological and neurological ones. Regarding nervous system diseases, it is of utmost importance to select those cases in which HTLV-1 infection could really be associated. This is particularly true for patients from endemic areas and for HIV-infected patients and drug users, since that these groups are at a higher risk for HTLV infection. This caution in selecting neurological patients for HTLV diagnostic tests is justified by the fact that in some circumstances the seropositivity may merely represent an epiphenomenon. In this paper we enroll some neurological conditions that have been associated with HTLV-1/2 infection in the literature and discuss the real need for HTLV-1/2 diagnostic tests in each one. Because HIV/HTLV-co-infected patients seem to be at an increased risk for neurological diseases development, a special consideration about this matter is also made.

The HTLV-1 neurological complex

Human T-cell lymphotropic virus type 1 (HTLV-1) is a retrovirus that infects about 20 million people worldwide and causes immune-mediated diseases of the nervous system. The classic neurological presentation of HTLV-1 infection is a myelopathy called HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). However, HAM/TSP is not the only neurological outcome that can result from HTLV-1 infection. In this Personal View, we show that HTLV-1 has a broader neurological spectrum than the names HAM/TSP suggest and that people infected with this virus can present with various isolated or assorted syndromes.

Postinfectious encephalomyelitis

Postinfectious forms of encephalomyelitis, also termed acute disseminated encephalomyelitis (ADEM), form one of several categories of inflammatory demyelinating disorders of the central nervous system (CNS). Recent large, retrospective case series have refined our understanding of the clinical, laboratory, and neuroimaging characteristics of ADEM. The differences between childhood and adult ADEM, risks of development of multiple sclerosis, and the contributions of recent studies to refining the nosology of CNS demyelinating syndromes are discussed.

Pathological and virological assessment of acute HTLV-I-associated myelopathy complicated with encephalopathy and systemic inflammation

HTLV-I-associated myelopathy, also known as tropical spastic paraparesis (HAM/TSP), is a chronic inflammatory disease of the spinal cord. Acute cases are uncommon. We report the case of a 41-year-old woman with acute HAM/TSP complicated with encephalitis, an intense inflammatory reaction of the nervous system and lymphocytic infiltration of skeletal muscles, liver, salivary, adrenal and pituitary glands. The immunohistochemical studies of the lymphocytes surrounding blood vessels showed both B- and T-lymphocytes, in similar proportion, with both CD4- and CD8-positive cells. In addition, many perivascular and scattered macrophages were observed. Adult T-cell leukemia/lymphoma (ATL) was ruled out. The marrow aspirate was normal. Serial cerebrospinal fluid (CSF) analysis showed presence of HTLV-I antibodies, but without intrathecal synthesis of specific antibodies. Determination of HTLV-I viral loads demonstrated increased levels in the CSF relative to the peripheral blood and may be associated with widespread inflammation. The pathological and immunological findings may help understand the role of immune-reactive cells in the pathogenesis of HTLV-I-associated myelopathy.

Multiple sclerosis, acute disseminated encephalomyelitis, and related conditions

Multiple sclerosis (MS) and acute disseminated encephalomyelitis (ADEM) are conditions whose closely related pathology suggests shared pathophysiological elements, but whose clinical courses are usually, but not always quite dissimilar. The former is largely a disease of adulthood, the latter of childhood. Optic neuritis, demyelinative transverse myelitis, and Devic's syndrome are neurological syndromes that may occur as manifestations of either MS or ADEM. Patients with Miller-Fisher syndrome and encephalomyelradiculoneuropathy usually have features suggesting ADEM in combination with acute demyelinative polyneuropathy. These various conditions and other forms of ADEM share an indistinct border with encephalitides, granulomatous, and vasculitic conditions. MS, ADEM, and the pertinent syndromic subtypes, their differential diagnosis, treatment, and prognosis are considered in this review. Acute cerebellar ataxia is a syndrome that is likely to be pathophysiologically distinct from ADEM, although its occurrence as a postinfectious illness suggests a distant kinship. It is also reviewed.

Human T-cell lymphotropic virus-I in Latin America

HTLV-1 infection is endemic in several Latin American countries. HTLV-1-associated myelophathy/tropical spastic paraparesis (HAM/TSP) and adult T-cell leukemia lymphoma (ATLL) are emerging diseases in the region. Documented risk factors for acquiring the virus include breast-feeding, contaminated blood transfusion, and sexual intercourse, all of which are amenable to prevention efforts. Strongyloides stercoralis hyperinfection syndrome and therapeutic failure in apparently healthy patients with nondisseminated strongyloidiasis may be markers of HTLV-1 infection. HTLV-1 co-infection may adversely effect the clinical course of scabies and HIV disease. The new enzyme-linked immunosorbent assays (ELISA) are sensitive and specific, and Western blot technology is reliable for differentiating HTLV-1 from less common HTLV-2. HTLV-1 screening of blood donors and individuals with any disorder that suggests infection has become a necessity in Latin America to prevent the spread of this important emerging pathogen.

Acute disseminated encephalomyelitis (ADEM) or ADEM-like inflammatory changes in a heart-lung transplant recipient: a case report

Acute disseminated encephalomyelitis (ADEM) is a white matter inflammatory disease which usually follows a viral infection or pharmaceutical intervention. We describe a case of presumed ADEM in a heart/lung transplant patient, the etiology of which cannot be elucidated. The fascinating aspect is the mode of clinical presentation and the rapid resolution of radiologic abnormalities. Histologic examination of the brain is provided in an attempt to elucidate the radiographic abnormalities.