An atypical case of neurotoxoplasmosis in immunocompetent patient.

Toxoplasmosis is an infection caused by Toxoplasma gondii, an intracellular protozoan that is often associated with immunocompromised patients and is rare in immunocompetent. A 60-year-old man was admitted with a history of 2 days of headache and right-sided weakness. There was no history of fever, surgeries, or any other comorbid illness. Cerebrospinal fluid showed just mild pleocytosis with 15 cells/mm3, predominantly lymphomononuclear. MRI showed Peripheral enhancing lesion with central diffusion restriction and perivascular enhancing lesion with restricted diffusion with vasogenic edema and leptomeningeal enhancement in the white matter. Viral serologies, tumor markers, protein electrophoresis were normal. The patient was submitted to brain biopsy, revealing necrotic brain parenchyma with predominantly acute inflammation, with diffuse encephalitis pattern, and cysts with bradyzoites (cystozoites) of Toxoplasma gondii in the brain parenchyma. The central nervous system infection by Toxoplasma gondii can present as meningoencephalitis during primary infection in an immunocompetent, although it is rare. Central nervous system lymphoma is the main differential diagnosis of neurotoxoplasmosis by imaging, especially in our case.

Corticospinal tract involvement in spinocerebellar ataxia type 3: a diffusion tensor imaging study.

PURPOSE: The aim of this study was to evaluate the integrity of the corticospinal tracts (CST) in patients with SCA3 and age- and gender-matched healthy control subjects using diffusion tensor imaging (DTI). We also looked at the clinical correlates of such diffusivity abnormalities. METHODS: We assessed 2 cohorts from different Brazilian centers: cohort 1 (n = 29) scanned in a 1.5 T magnet and cohort 2 (n = 91) scanned in a 3.0 T magnet. We used Pearson's coefficients to assess the correlation of CST DTI parameters and ataxia severity (expressed by SARA scores). RESULTS: Two different results were obtained. Cohort 1 showed no significant between-group differences in DTI parameters. Cohort 2 showed significant between-group differences in the FA values in the bilateral precentral gyri (p < 0.001), bilateral superior corona radiata (p < 0.001), bilateral posterior limb of the internal capsule (p < 0.001), bilateral cerebral peduncle (p < 0.001), and bilateral basis pontis (p < 0.001). There was moderate correlation between CST diffusivity parameters and SARA scores in cohort 2 (Pearson correlation coefficient: 0.40-0.59). CONCLUSION: DTI particularly at 3 T is able to uncover and quantify CST damage in SCA3. Moreover, CST microstructural damage may contribute with ataxia severity in the disease.

Neuroimaging of Emergent and Reemergent Infections.

Infectious diseases emerge and reemerge over the years, and many of them can cause neurologic disease. Several factors contribute to the emergence and reemergence of these conditions, including human population growth, an increase in international travel, the geographic expansion of recognized pathogens to areas where they were previously nonendemic, and greater contact with wild animal reservoirs. The antivaccination social movement has played an important role in the reemergence of infectious diseases, especially some viral conditions. The authors review different viral (arboviruses such as dengue, chikungunya, and Zika virus; enterovirus 71; measles; and influenza), bacterial (syphilis, Lyme disease, and listeriosis), and parasitic (Chagas disease) diseases, focusing primarily on their neurologic complications. Although there are several additional infectious diseases with central nervous system manifestations that could be classified as emergent or reemergent, those listed here are the most relevant from an epidemiologic standpoint and are representative of important public health issues on all continents. The infections caused by these pathogens often show a variety of neuroimaging patterns that can be identified at CT and MRI, and radiology is central to the diagnosis and follow-up of such conditions. Given the increasing relevance of emerging and reemerging infections in clinical practice and public health scenarios, radiologists should be familiar with these infections. Online supplemental material is available for this article. ©RSNA, 2019.