Granulomatous amebic encephalitis due to Balamuthia mandrillaris (Leptomyxiidae): report of four cases from Mexico.

In this report, we describe four cases of granulomatous amebic encephalitis caused by Balamuthia (Leptomyxid ameba) in four previously healthy Mexican patients. All four cases were characterized by focal neurologic signs, increased intracranial pressure, and cerebral hyperdense lesions in computed tomography scans of the head. These patients underwent craniotomies for evaluation of mass lesions for possible brain tumors. Granulomatous chronic inflammatory reaction and amebic trophozoites were found in brain biopsies. At autopsy, areas of hemorrhagic encephalomalacia were located in both basal frontal lobes, right parieto-occipital lobes, and, less often, in the brainstem and cerebellum. Angiitis, necrotizing granulomatous encephalitis, and large numbers of amebic trophozoites in perivascular spaces were present. Amebic trophozoites were seen in the left adrenal gland in one of the cases. The amebas in all four cases were identified as Balamuthia mandrillaris (Leptomyxiidae) based on their reactivity with the anti-Balamuthia (Leptomyxiidae) serum in an immunofluorescence test.

Event related brain potentials to semantically incongruent words in children of different ages.

In this study, developmental changes of N400 elicited by a simple paradigm to semantic incongruity were examined. Subjects were divided in three different age groups and educational levels: Group I (first grade) = 7-8 years, n = 10; Group II (third grade) = 9-10 years, n = 10; and Group III (sixth grade) = 11-12 years, n = 10. EEG activity was recorded from 8 monopolar sites referred to linked earlobes. Data showed that the amplitude of the N400 like component did not change significantly from first to sixth grade, although the onset latency appeared to be shorter in older children. No significant latency and amplitude changes were found among groups.