Case 3 -

Neurobrucellosis Benjamin M. Greenberg The Johns Hopkins University School of Medicine Baltimore, MD

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Clinical Summary A 65-year-old Iranian immigrant man living in the United States was in his usual state of good health until a return visit to Iran 15 months prior to his diagnosis. In Iran, he developed right upper quadrant pain accompanied by a fever. An abdominal ultrasound examination revealed gallstones, and a cholecystectomy was performed. His postoperative course was uncomplicated, but 2 months later he developed right flank pain and bilateral knee pain. He then developed bitemporal headaches without constitutional symptoms, followed by otalgia and subtotal hearing loss on the right. Within weeks, there was progression and extension of hearing loss to the left. His symptoms persisted despite antibiotic treatment for presumed ear infection. He developed horizontal diplopia along with anorexia, nausea, and vomiting in association with his headaches. Evaluation of a cerebrospinal fluid sample was ''normal,'' although no results were available for review. The patient experienced a gradual, slowly progressive neurocognitive decline characterized by mild confusion, dysarthria, low mood, anhedonia, insomnia, and sexual dysfunction. By the time he returned to the United States 9 months after his initial presentation, the patient had suffered a 13.6-kg weight loss and had persistent gastrointestinal and neurologic signs. An audiogram confirmed bilateral sensorineural hearing loss. There were mild cognitive impairments in verbal fluency, sequencing, and copying of written figures. Other neurologic functions were normal. A magnetic resonance image of the brain revealed diffuse, bilateral white matter T2 hyperintensities without parenchymal enhancement. Cerebrospinal fluid studies revealed a mild pleocytosis (white blood cells, 13/mm3, predominantly mononuclear cells) with normal protein (35 mg/dL) and glucose (54 mg/dL) concentrations. There were 2 oligoclonal bands, and the immunoglobulin (Ig) G index was 0.7 (normal range, up to 0.9). Serologic studies for human immunodeficiency virus, syphilis, neuroborreliosis, Ehrlichiosis, and Whipple disease's PCR were negative, as were routine blood and cerebrospinal fluid cultures. Serologic studies for known autoimmune and rheumatologic disorders were negative. Serologic studies for hepatitis C, A, and B surface antigens were negative, but there was evidence of anti-hepatitis B surface antibodies. Because of the magnetic resonance image evidence of a diffuse and symmetric white matter involvement, including prominent involvement of the subcortical u-fibers, and lack of enhancement, a panel of studies directed at late-onset leukodystrophies was obtained, again without diagnostic benefit. Despite clinical improvement in cognitive deficits with antidepressant treatment, the magnitude of white matter lesions led to a decision to obtain a brain biopsy. Perioperative magnetic resonance images revealed an evolving, leptomeningeal enhancing lesion in the left Sylvian fissure. Following pathologic interpretation of the biopsy, neurobrucellosis entered the differential diagnosis, and the patient was found to have mildly elevated (1:64) cerebrospinal fluid titers of IgG antibodies directed against B abortus, with negative serum titers. The patient's postoperative course was uneventful until 4 weeks after the biopsy, when he presented to the emergency room with headaches, confusion, and urinary incontinence. A head computed tomography scan revealed a 2.0-cm abscess in the region of the previous biopsy. A right frontal craniotomy and abscess drainage was performed, and B melitensis was cultured from the abscess contents. The patient significantly improved after 2 months of intravenous antibiotics (gentamicin and ceftriaxone) and 4 months of oral antibiotics (rifampin and doxycycline). However, 6 months after the brain biopsy, the patient presented to the hospital with fever, back pain, and rapidly progressive paraplegia over 1-2 days. He had myelitis with a central cord distribution that extended through the thoracic cord. While initially he was thought to have primary Brucella myelitis, she ultimately had a relapsing remitting course of inflammatory myelitis that was thought to be post-infectious. It was treated with immunosuppression with some success. Case 3 - Slide 1 Click to view with ImageScope Click to view with a Web-Based Viewer Case 3 - Figure 1 Right frontal cortex and white matter biopsy reveal meningoencephalitis characterized by a lymphocytic infiltrate in the leptomeninges and surrounding cortical vessels (H&E). Case 3 - Figure 2 Right frontal cortex and white matter biopsy reveal meningoencephalitis characterized by a lymphocytic infiltrate in the leptomeninges and surrounding cortical vessels (H&E). Case 3 - Figure 3 Inflammatory cells were especially abundant in the white matter around vessels and infiltrating through the parenchyma (H&E). Case 3 - Figure 4 Inflammatory cells were especially abundant in the white matter around vessels and infiltrating through the parenchyma (H&E). Case 3 - Figure 5 Marked reactive astrogliosis is demonstrated throughout the cortex and white matter (H&E). Case 3 - Figure 6 Marked reactive astrogliosis is demonstrated throughout the cortex and white matter (H&E). Case 3 - Figure 7 Immunostaining of major histocompatibility complex class II antigens (human leukocyte antigen DR marker) demonstrates the marked activation of microglia. Case 3 - Figure 8 Immunophenotyping of the T cell infiltrates in the white matter and cortex revealed that the majority of the CD4 and CD8 T cells were CD81 lymphocytes. Case 3 - Figure 9 No significant myelin destruction was shown in Luxol fast blue stains. Diagnosis: Neurobrucellosis Description: Examination of the biopsy specimen of the right frontal cortex and white matter revealed meningoencephalitis. A lymphocytic infiltrate was present in the leptomeninges and surrounding cortical vessels (Figures 1, 2). Inflammatory cells were especially abundant in the white matter around vessels and infiltrating through the parenchyma (Figures 3, 4). No evidence of vasculitis or granulomatous inflammation was detected. Methenamine silver, periodic acid-Schiff, Brown and Hopps, and tissue Gram stains failed to reveal any microorganisms. No toxoplasma, papovavirus, adenovirus, or herpes virus antigens were detected immunohistochemically. Marked reactive astrogliosis was seen throughout the cortex and white matter (Figures 5, 6). Macrophage markers such as Ham 56 highlighted numerous microglia, but macrophages were rare and predominantly located in perivascular spaces. Marked activation of microglia was demonstrated by immunostaining of major histocompatibility complex class II antigens (human leukocyte antigen DR marker) (Figure 7). Band T-cell immunostains (CD20 and CD3) revealed the inflammatory infiltrate to be predominantly T cells, with only scattered B cells in the leptomeninges and perivascular spaces. CD4 and CD8 immunophenotyping of the T cell infiltrates in the white matter and cortex revealed that the majority of the T cells were CD81 lymphocytes (Figure 8). Luxol fast blue stains showed no significant myelin destruction (Figure 9). Microscopic examination of material resected from the abscess revealed necrotic tissue with acute and chronic inflammation and numerous macrophages. Although special stains were used, no microorganisms were identified in the abscess material. Discussion: Brucellosis is a major zoonosis infamous for its protean clinical manifestations [1, 4]. Brucella melitensis remains an important human pathogen in endemic regions, most notably the Mediterranean basin, Arabian Peninsula, and Indian subcontinent. Brucellae are facultative intracellular, nonmotile, gram-negative coccobacilli that are capable of replication within mononuclear phagocytes. Most commonly, ingestion of infectious products is followed by hematogenous dissemination, residence in the reticuloendothelial system, and subsequent involvement of any organ system. Accordingly, the most common symptoms are nonspecific (fever, malaise, anorexia, and headaches), gastrointestinal (abdominal pain, nausea, vomiting, and diarrhea), and hematologic (anemia, leukopenia, thrombocytopenia, and clotting disorders). Pathologic changes are most often identified in the reticuloendothelial system. Involvement of the central nervous system is seen in 4% to 13% of patients with brucellosis [2, 3, 5]. Meningitis, meningoencephalitis, polyradiculoneuritis, and cranial nerve palsies are the most frequent features of neurobrucellosis. Involvement of the white matter is rare in neurobrucellosis. In 2 earlier reports, discrete white matter lesions were initially confused with multiple sclerosis [6, 7]. One research group hypothesized that the infection resulted in a demyelinating process.7 However, the white matter involvement in our case was more diffuse and symmetric than that in these earlier cases, and demyelination was not an important histopathologic feature. Instead, we found a florid reactive astrogliosis and marked activation of microglia in association with an extensive infiltration by cytotoxic T lymphocytes. Cytotoxic T lymphocytes play a key role in the immune response to Brucella in murine models and in humans [8, 9]. Although generally beneficial, excessive or autoimmune cytotoxic T cell responses have also been documented in a wide range of central nervous system diseases [10]. The abundance of immune cells and the paucity of organisms in this case suggest that the clinical deficits and magnetic resonance image abnormalities associated with neurobrucellosis may be mediated at least in part by immunopathogenic mechanisms associated with direct T-cell-mediated cytotoxic injury of the white matter and cerebral cortex with concomitant microglial activation. Our inability to detect organisms directly in the infected tissue is not unusual. Gram stains of tissues are generally negative in cases of brucellosis, and cultures are positive in less than 25% of cases. Currently, identification of antibodies against Brucella in the serum or cerebrospinal fluid is the most sensitive and specific way to detect the presence of the organism. Enzyme-linked immunosorbent assays are considered superior to agglutination assays, particularly for the detection of chronic disease or neurobrucellosis.5 In the present case, cerebrospinal fluid titers of antibodies directed against B. abortus (the organism most commonly screened for in a search for antibodies directed against Brucella) were positive despite the absence of such antibodies in serum. This case of meningoencephalitis in a 65-year-old Iranian man was caused by B. melitensis infection and was complicated by the formation of a brain abscess and the development of acute myelitis. Although neurobrucellosis is extremely rare in the United States, it should be considered in the differential diagnosis for patients suffering from chronic neurologic diseases, particularly patients with an appropriate travel history. The present case highlights the chronic, slowly progressive nature of the disease in some patients, the possibility of predominantly white matter involvement in the central nervous system, and the absence of specific systemic symptoms, signs, or laboratory findings in some cases. In addition, the prominence of CD81 T cells suggests that direct cytotoxic damage could mediate some of the observed white matter changes in cases of chronic disease. Treatment of Brucella infections relies on a prolonged course of combination doxycycline and rifampin. Selected references: Corbel MJ. Brucellosis: an overview. Emerging Infect Dis. 1997;3:213-221. Kochar DK, Agarwal N, Jain N, Sharma BV, Rastogi A, Meena CB. Clinical profile of neurobrucellosis-a report on 12 cases from Bikaner (north-west India). J Assoc Physicians India. 2000;48:376-380. Pascual J, Combarros O, Polo JM, Berciano J. Localized CNS brucellosis: report of 7 cases. Acta Neurol Scand. 1988;78:282-289. Boschiroli ML, Foulongne V, O'Callaghan D. Brucellosis: a worldwide zoonosis. Curr Opin Microbiol. 2001;4:58-64. Lulu AR, Araj GF, Khateeb MI, Mustafa MY, Yusuf AR, Fenech FF. Human brucellosis in Kuwait: a prospective study of 400 cases. Q J Med. 1988;66(249):39-54. Bussone G, La Mantia L, Grazzi L, Lamperti E, Salmaggi A, Strada L. Neurobrucellosis mimicking multiple sclerosis: a case report. Eur Neurol. 1989;29: 238-240. Krystkowiak P, Vermersch P, Beaucaire G, Petit H. Regressive leukoencephalopathy in chronic brucellosis. Rev Neurol. 1997;153:781-784. Oliveira SC, Splitter GA. CD81 type 1 CD44hi CD45 RBlo T lymphocytes control intracellular Brucella abortus infection as demonstrated in major histocompatibility complex class I- and class II-deficient mice. Eur J Immunol. 1995;25:2551-2557. Moreno-Lafont MC, Lopez-Santiago R, Zumaran-Cuellar E, et al. Antigenspecific activation and proliferation of CD41 and CD81 T lymphocytes from brucellosis patients. Trans R Soc Trop Med Hyg. 2002;96:340-347. Neumann H, Medana IM, Bauer J, Lassmann H. Cytotoxic T lymphocytes in autoimmune and degenerative CNS diseases. Trends Neurosci. 2002;25:313-319. Seidel G, Pardo C., Newman-Toker D, Olivi A, Eberhart C. Neurobrucellosis Presenting as Leukoencephalopathy: The Role of Cytotoxic T Lymphocytes. Arch Pathol Lab Med. 2003; 127:374-377