Linear accuracy of cone beam CT derived 3D images.

OBJECTIVE: To compare the in vitro reliability and accuracy of linear measurements between cephalometric landmarks on cone beam computed tomography (CBCT) 3D volumetric images with varying basis projection images to direct measurements on human skulls. MATERIALS AND METHODS: Sixteen linear dimensions between 24 anatomic sites marked on 19 human skulls were directly measured. The skulls were imaged with CBCT (i-CAT, Imaging Sciences International, Hatfield, Pa) at three settings: (a) 153 projections, (b) 306 projections, and (c) 612 projections. The mean absolute error and modality mean (+/- SD) of linear measurements between landmarks on volumetric renderings were compared to the anatomic truth using repeated measures general linear model (P < or = .05). RESULTS: No difference in mean absolute error between the scan settings was found for almost all measurements. The average skull absolute error between marked reference points was less than the distances between unmarked reference sites. CBCT resulted in lower measurements for nine dimensions (mean difference range: 3.1 mm +/- 0.12 mm to 0.56 mm +/- 0.07 mm) and a greater measurement for one dimension (mean difference 3.3 mm +/- 0.12 mm). No differences were detected between CBCT scan sequences. CONCLUSIONS: CBCT measurements were consistent between scan sequences and for direct measurements between marked reference points. Reducing the number of projections for 3D reconstruction did not lead to reduced dimensional accuracy and potentially provides reduced patient radiation exposure. Because the fiducial landmarks on the skulls were not radio-opaque, the inaccuracies found in measurement could be due to the methods applied rather than to innate inaccuracies in the CBCT scan reconstructions or 3D software employed.

Linear accuracy and reliability of cone beam CT derived 3-dimensional images constructed using an orthodontic volumetric rendering program.

OBJECTIVE: To compare accuracy of linear measurements made on cone beam computed tomographic (CBCT) derived 3-dimensional (3D) surface rendered volumetric images to direct measurements made on human skulls. MATERIALS AND METHODS: Twenty orthodontic linear measurements between anatomical landmarks on 23 human skulls were measured by observers using a digital caliper. The skulls were imaged with CBCT and Dolphin 3D (version 2.3) software used to generate 3D volumetric reconstructions (3DCBCT). The linear measurements between landmarks were computed by a single observer three times and compared to anatomic dimensions using Student's t-test (P < or = .05). The intraclass correlation coefficient (ICC) and absolute linear and percentage error were calculated. RESULTS: The ICC for 3DCBCT (0.975 +/- 0.016) was significantly less than for skull (0.996 +/- 0.007) measurements. Mean percentage measurement error for 3DCBCT (2.31% +/- 2.11%) was significantly higher than replicate skull measurements (0.63% +/- 0.51%). Statistical differences between 3DCBCT means and true dimensions were found for all of the midsagittal measurements except Na-A and six of the 12 bilateral measurements. The mean percentage difference between the mean skull and 3D-based linear measurements was -1.13% (SD +/- 1.47%). Ninety percent of mean differences were less than 2 mm, and 95% confidence intervals were all less than 2 mm except for Ba-ANS (3.32 mm) and Pog-Go(left) (2.42 mm). CONCLUSIONS: While many linear measurements between cephalometric landmarks on 3D volumetric surface renderings obtained using Dolphin 3D software generated from CBCT datasets may be statistically significantly different from anatomic dimensions, most can be considered to be sufficiently clinically accurate for craniofacial analyses.

Application of distance learning to interactive seminar instruction in orthodontic residency programs.

INTRODUCTION: A series of experiments involving 3 orthodontic departments has shown that distance learning can be acceptable to residents and effective in teaching concepts that are fundamental to orthodontic practice. METHODS: Residents in each department participated in distance seminars, clinical conferences, and clinical seminars via high-speed Internet connections. The acceptability of this form of instruction was judged from evaluation forms completed by the residents. Its effectiveness was judged from pretests and posttests on the seminar topics. RESULTS: The improvement from pretest to posttest scores after observing a sequence of distance seminars was similar to that with direct instruction. Orthodontic residents rated the educational experiences positively. Live participation in seminars via video conferencing was preferred to live observation or later observation of a recording, but observation provided similar improvement in test scores. CONCLUSIONS: The acceptability of the distance seminars appeared to be influenced by the instructor's personality and teaching style in facilitating interaction, the seminar subject, the residents' comfort level in dealing with this technology, and the sequence for interaction vs observation. Further development of recorded seminars with live follow-up discussions has the potential to supplement instruction in graduate orthodontic programs and help with the impending shortage of experienced full-time orthodontic faculty.

Accuracy of cone-beam computed tomography imaging of the temporomandibular joint: comparisons with panoramic radiology and linear tomography.

INTRODUCTION: Cone-beam computed tomography (CBCT) is increasingly being used as an imaging modality, particularly in the assessment of the temporomandibular joint (TMJ). A blinded observational cross-sectional in-vitro study was conducted to compare the diagnostic accuracy of observers viewing images made with CBCT, panoramic radiography, and linear tomography. The task was to detect cortical erosions affecting the mandibular condylar head. METHODS: The sample consisted of 37 TMJ articulations from 30 skulls with either normal condylar morphology (n = 19) or erosion of the lateral pole (n = 18). The articulations were imaged by using corrected angle linear tomography (TOMO), normal (Pan-N) and TMJ-specific (Pan-TM) panoramic radiography, and CBCT. Digital images were obtained with photostimulable phosphor plates for all modalities except CBCT. The CBCT detector used an amorphous silicon flat-panel array combined with cesium iodide. Images and 10 rereads were presented to 10 observers on a flat-panel display at a pixel-to-monitor ratio of 1:1. CBCT multi-planar images were presented both statically (CBCT-S) and interactively (CBCT-I). The observers were permitted to scroll through axial (0.4 mm) and para-sagittal (1 mm) sections and then independently rate their confidence about the presence or absence of cortical erosion. Intraobserver reliability was determined by weighted kappa and diagnostic accuracy by the fitted area under the ROC curve. Means were compared by using ANOVA (P < or =.05). RESULTS: Intraobserver reliability was moderate (0.57 +/- 0.22; range, 0.34-0.78). Pan-N (0.72 +/- 0.15), CBCT-I (0.65 +/- 0.21), and CBCT-S (0.65 +/- 0.17) reliability was significantly greater than TOMO (0.44 +/- 0.25). The diagnostic accuracy of CBCT-I (0.95 +/- 0.05) and CBCT-S (0.77 +/- 0.17) was significantly greater than all other modalities (Pan-N [0.64 +/- 0.11], Pan-TM [0.55 +/- 0.11], TOMO [0.58 +/- 0.15]). CBCT-I was also more accurate than CBCT-S, and Pan-N was more accurate than Pan-TM and TOMO. CONCLUSIONS: CBCT images provide superior reliability and greater accuracy than TOMO and TMJ panoramic projections in the detection of condylar cortical erosion.

Accuracy of linear measurements from imaging plate and lateral cephalometric images derived from cone-beam computed tomography.

INTRODUCTION: As orthodontic practice moves toward 3-dimensional cephalometric analyses, a solution is required to ensure sustained availability of well-established projected treatment outcomes based on 2-dimensional analyses. This ex-vivo study was conducted to compare the accuracy of linear measurements made on photostimulable phosphor cephalograms with 3 methods for simulating lateral cephalograms with cone-beam computed tomography (CBCT). METHODS: The linear distances between anatomical landmarks on dentate dry human skulls were measured by observers using digital calipers for S-N, Ba-N, M-N, ANS-N, ANS-PNS, Pog-Go, Go-M, Po-Or, and Go-Co. The skulls were imaged with CBCT with a single 360 degrees rotation, producing 306 basis images and achieving 0.4 mm isotrophic voxel resolution on volumetric reconstruction for making ray-sum reconstructed cephalograms. Two other cephalogram approaches were used with the CBCT system--a single transmission image generated as a scout image designed to check patient positioning before CBCT, and a single-frame lateral basis image. Conventional digital lateral cephalograms (LCs) were acquired with the photostimulable phosphor system. Images were imported into a cephalometric analysis program (Dolphin Imaging Cephalometric and Tracing Software, Chatsworth, Calif) to compute the included linear measurements. Analyses were repeated 3 times and statistically compared with measured anatomic truth with ANOVA (P < or =.05). The intraclass correlation coefficient was determined as an index of intra- and interobserver reliability. RESULTS: The intraclass correlation coefficient for the LCs was significantly less than for the measured anatomic truth and for all CBCT-derived images. CBCT images either produced with individual frames or reconstructed from the volumetric data set were accurate for all measurements except Pog-Go and Go-M. CBCT scout images had the second highest accuracy for all measurements except Pog-Go, Go-M, and Go-Co. Conventional LCs had the least accuracy; they were accurate only for Po-Or and ANS-N. CONCLUSIONS: CBCT-derived 2-dimensional LCs proved to be more accurate than LCs for most linear measurements calculated in the sagittal plane. No advantage was found over single-frame basis images in using ray-sum generated cephalograms from the CBCT volumetric data set.

Childhood obesity and skeletal maturation assessed with Fishman's hand-wrist analysis.

INTRODUCTION: The purpose of this study was to determine whether increased body mass index is associated with accelerated skeletal maturation. METHODS: The skeletal ages of 107 children, aged 9 to 16 years, were determined by using Fishman's hand-wrist analysis. The difference between chronologic age and dental age was analyzed against body mass index, sex, and age. RESULTS: The mean differences between chronologic and skeletal ages for normal weight, overweight, and obese subjects were 0.51 years, 0.44 years, and 1.00 years, respectively. Although there was a trend for obese subjects to have accelerated skeletal maturation compared with overweight and normal-weight subjects, the difference was not statistically significant. Skeletal age differences significantly decreased with increasing age. The mean skeletal age differences were 0.90 year for 9- to 13-year-olds and 0.26 year for 13- to 16-year-olds. Mean skeletal age did not differ significantly by sex. CONCLUSIONS: Overweight or obese children did not have significantly accelerated skeletal maturation after adjusting for age and sex.

Digitized hand-wrist radiographs: comparison of subjective and software-derived image quality at various compression ratios.

INTRODUCTION: The objectives of this study were to compare the effect of JPEG 2000 compression of hand-wrist radiographs on observer image quality qualitative assessment and to compare with a software-derived quantitative image quality index. METHODS: Fifteen hand-wrist radiographs were digitized and saved as TIFF and JPEG 2000 images at 4 levels of compression (20:1, 40:1, 60:1, and 80:1). The images, including rereads, were viewed by 13 orthodontic residents who determined the image quality rating on a scale of 1 to 5. A quantitative analysis was also performed by using a readily available software based on the human visual system (Image Quality Measure Computer Program, version 6.2, Mitre, Bedford, Mass). ANOVA was used to determine the optimal compression level (P < or =.05). RESULTS: When we compared subjective indexes, JPEG compression greater than 60:1 significantly reduced image quality. When we used quantitative indexes, the JPEG 2000 images had lower quality at all compression ratios compared with the original TIFF images. There was excellent correlation (R2 >0.92) between qualitative and quantitative indexes. CONCLUSIONS: Image Quality Measure indexes are more sensitive than subjective image quality assessments in quantifying image degradation with compression. There is potential for this software-based quantitative method in determining the optimal compression ratio for any image without the use of subjective raters.

Correlation between carotid area calcifications and periodontitis: a retrospective study of digital panoramic radiographic findings in pretreatment cancer patients.

OBJECTIVES: The objective of this study was to examine the prevalence of carotid area calcifications retrospectively detected on digital panoramic radiographs of pretreatment cancer subjects, and to correlate the finding of such calcifications with radiographic evidence of periodontal bone loss in the same subjects. STUDY DESIGN: Digital panoramic radiographs of 201 subjects were evaluated for calcifications projected in the carotid artery bifurcation area as well as for alveolar bone loss as a result of periodontal disease. Inclusion criteria were unobscured carotid artery bifurcation regions bilaterally and sufficient index teeth present with a definable cemento-enamel junction and alveolar crest. Radiographs were independently observed for carotid area calcifications and for periodontal status. Image enhancements permitted for detection of calcifications projected in the carotid area included window/level, inverse, and emboss. Periodontal measurements were made on index teeth using proprietary imaging software and a mouse-driven measurement algorithm. A 3-factor analysis of variance was performed with 3 between-subjects comparisons. Percentage of bone loss was the dependent variable. Independent variables were age, subject sex, and the presence or absence of carotid area calcifications. RESULTS: Differences measured in percentage of bone loss between sexes were not statistically significant. While bone loss did increase with age, comparison of the mean bone loss of each age category revealed no statistical significance. There was a highly significant correlation between carotid artery area calcifications visible on panoramic radiographs and percent alveolar bone loss. Radiographs showing unilateral and bilateral calcifications had a mean percent bone loss of 24.2% +/- 12.6% and 25.7% +/- 13.0% respectively, compared to those with no calcification at 10.4% +/- 9.9%. CONCLUSIONS: Nearly 1 in 4 subjects in this study evidenced calcifications projected in the carotid bifurcation region. The finding of such calcifications was significantly related to the calculated percentage of alveolar bone loss.

Orthodontic treatment provided by general dentists who have achieved master's level in the Academy of General Dentistry.

INTRODUCTION: The purposes of this study were to document orthodontic treatment currently provided by general dentists for comparison with past and future studies and to ascertain variables that influence practitioners' orthodontic treatment patterns. METHODS: A 21-item survey was mailed to 750 master's level members of the Academy of General Dentistry. Surveys returned within 8 weeks were included for statistical analysis. RESULTS: The response rate was 62%. Most practitioners spent less than 10% of their practice time providing orthodontic treatment and reported that this would not change in the future. Many provided orthodontic treatment in the permanent dentition, and the most common conditions or malocclusions treated were space maintenance, anterior crossbite, rotation, habits, molar uprighting, and posterior crossbite. The most common orthodontic appliances used were removable Hawley appliances with finger springs, straight wire orthodontic therapy, rapid palatal expanders, and functional appliances. CONCLUSIONS: The number of general dentists providing comprehensive orthodontic treatment has not changed since previous surveys; practitioners also do not expect a change in the next 5 years. Factors that influenced the orthodontic treatment provided included the primary source of orthodontic training, the number of orthodontic continuing education hours earned per year, the practitioner's location, and the proximity to the nearest orthodontist.

Graduate orthodontic education: the residents' perspective.

INTRODUCTION: The purpose of this study was to identify current demographic trends of orthodontic residents, their goals for the future, and their perspectives on orthodontic training. METHODS: A 26-item survey was conducted at the Graduate Orthodontic Residency Program (GORP) at Harvard University in August 2003. Questionnaires were distributed to residents representing 51 orthodontic programs (of 58 in the United States). Surveys were sent to 5 of the 7 programs whose residents did not attend GORP. RESULTS: Of the 380 questionnaires distributed, 295 were completed and returned at the meeting for a 77% response rate. Additionally, 35 of the 50 mailed questionnaires were completed and returned, for a total response rate of 77% (330 completed/430 distributed). Most residents stated that clinical education was the most important factor when choosing a residency. Most residents planned to publish their research, complete American Board of Orthodontics certification requirements, and work 4 days a week after program completion. CONCLUSIONS: Several trends were identified since orthodontic residents were last surveyed in 1992. The most significant change reported was an increase in the number of those who plan to complete American Board of Orthodontics certification requirements.

Do pediatric dentists practice the orthodontics they are taught?

PURPOSE: The purpose of this study was to determine whether the orthodontic treatment provided by pediatric dentists reflects the orthodontic training received in pediatric dental residency programs. METHODS: Five questions from a survey of the American Academy of Pediatric Dentistry (AAPD) diplomates in August 2002 and a survey of pediatric dental residency program directors in June 2002 were statistically analyzed to compare the orthodontic treatment provided by diplomates to that provided within pediatric dental residency programs. RESULTS: Patient populations differed financially between pediatric dental residencies and diplomates of the AAPD. Residents treated significantly more public assistance patients. The residents were more likely than diplomates to use most orthodontic appliances and treat most stages of dental development and most conditions/malocclusions with orthodontics. Diplomates anticipated a decrease in the amount of orthodontic treatment provided in the next 5 years, while program directors anticipated an increase. CONCLUSIONS: The majority of the orthodontic treatment provided by pediatric dental residents and diplomates was similar, although the residents were exposed to more diverse orthodontic treatment modalities than those used by diplomates. The residencies were also more likely than the diplomates to increase the amount of orthodontic treatment provided in the next 5 years.

Solid-state temporomandibular joint imaging: accuracy in detecting osseous changes of degenerative joint disease and determining condylar spatial relations.

The purpose of this study was to evaluate the off-label use of an intraoral charge-coupled device (CCD) for extraoral transcranial radiography of the temporomandibular joint. Corrected linear tomograms and transcranial images made with conventional screen-film combinations and a CCD detector were compared with sectioned cadaver specimens. Radiation dosage, qualitative assessment of condylar degenerative features, and condylar position within the glenoid fossa of the 3 modalities were assessed and compared. The CCD method required special adjustments to achieve adequate quality, and it involved greater exposure than the other methods. This use of this intraoral system for extraoral imaging cannot now be recommended, but future refinements might make it more viable.

Espóndiloartropatía indiferenciada en un paciente con sindrome de inmunodeficiencia adquirida (Sida) / Undifferentiated spondyloarthropathy in a patient with acquired immunodeficiency syndrome (AIDS)

Se comenta el caso clínico de un enfermo en quien una espóndiloartropatía indiferenciada fue la manifestación reveladora de la infección por el virus de la inmunodeficiencia humana (VIH). La sospecha clínica de infección retroviral fue confirmada por estudio serológico. Historicamente el sindrome de Reiter (SR) fue la primera artropatía reportada como asociada a la infección por el VIH y tanto esta entidad como la artritis psoriásica (AP) son más frecuentes en esa población. En el infectado por el VIH ambas entidades suelen tener algunas particularidades: mayor severidad, evolución más prolongada, posible resistencia a los antiinflamatorios habituales, frecuencia relativa de artritis reactiva (AR) en personas HLA-B27 negativas. Debe sospecharse la infección retroviral especialmente cuando el cuadro clínico es atípico, severo o de rápida progresión, la psoriasis es extensa o adquiere formas clínicas poco habituales, hay falta de respuesta al tratamiento convencional, se acompaña de otras afecciones que pueden vincularse a la infección por ese virus o el paciente tiene conductas de riesgo para adquirirlo. Conocer si el enfermo está infectado por el VIH es importante en el momento de decidir el tratamiento. En esta situación los planes terapéuticos están dictados por la severidad de las lesiones cutáneas y musculoesqueléticas y el estado del sistema inmune. Los efectos secundarios y las interacciones medicamentosas pueden limitar las opciones terapéuticas, especialmente el uso de las drogas inmunodepresoras

Cerebral systems in the pathogenesis of endogenous psychoses

Mental process imply a harmonious functioning of psychic systems, assembled into larger units, psychic spheres (Table 1). Their neurophysiological representatives are brain systems of areas and pathways (Figs 1-4). Under functional and/or organic disturbances these systems originate the leading mental symptoms (Table 2) characterizing the diverse endogenous psychoses: hence, the latter's distinctive patterns. Accordingly, understanding and classificatin of psychoses should rest on the pathogenic dynamisms, not on clinical description. This is why Kleist's and Leonhard's conceptions of the endogenous psychoses surpass any other to exist. Kleist standas among the founders of psychiatry, by describing the "degeneration psychoses" and many single psychoses, as well as redefining, isolating and clarifying the progressive ones, later on renamed as schizophrenias (table 3). Such pathogenic criterion may also be useul to define mental conditions other than psychoses, as hysteria, neuroses and psychopathic inferiority (Tables 4 and 5). One should consider here, besides the psychic systems and spheres involved, the way they were caught and the corresponding developmental phase. In Kleist's "degeneration psychoses" - cyclic or episodic (Table 6) the systems and spheres are disturbed by functional transient processes due to latent dispositions, while his and Leonhard's schizophrenias (Table 7) show a rather progressive, deteriorating course. The nature of the disorder is itself genetically determined, as is either its confinement to one sphere or its spreading out. The spread out pattern, while exceptional in schizophrenia, represents a rule for the "degenarion psychoses", in discussant's mind. Both groups may have symptoms alike by involvement of the same sphere (Table 8), but proper diagnosis is reached by taking pathogenesis into consideration.

Uso razonado de los antibioticos / Rational use of antibiotics

En los últimos años ha aumentado enormemente el arsenal terapéutico, por lo que el número de antibióticos disponible es cada vez mayor. Si bien esto resulta beneficioso para el enfermo, el médico puede tener dificultades en el momento de realizar la selección del agente a administrar. Para que el antibiótico prescrito sea el más adecuado para cada situación es necesario que éste tenga en cuenta los datos relacionados con el trípode constituido por: paciente, enfermedad y droga. Con la finalidad de lograr que los antibióticos se apliquen siguiendo directivas lógicas se consideró la necesidad de elaborar bases de "uso razonado de antibióticos", buscando mejorar la relación eficacia-comodidad-beneficio, con el mínimo de toxicidad-desarrollo de resistencias-costo. Para decidir la administración de antibióticos primero hay que contar con la convicción de que se está frente a una patología infecciosa bacteriana que tiene indicación de antibióticos. Siempre hay que tener presente que no toda fiebre es de causa infecciosa, ni que toda infección requiere de antibióticos para curar. Si bien un tratamiento empírico suele iniciarse antes de tener la confirmación etiológica de la enfermedad infecciosa, es esencial que antes de emprenderlo se recojan las muestras necesarias que conduzcan a un diagnóstico etiológico. Ello permite adaptar el tratamiento una vez conocido el agente causal, su sensibilidad y la evolución clínica del caso. Los planes antibióticos se deben seleccionar en forma individualizada para cada enfermo, considerando parámetros relacionados con: la condición del paciente y sus características, la enfermedad y su localización, el agente causal (o los agentes sospechados), la sensibilidad de los mismos a los antibióticos o su patrón en cada medio, las características de la droga en cuanto a espectro, farmacodinamia, farmacocinética, efectos tóxicos e intolerancias. Aunque varios planes terapéuticos pueden ser eficaces para una misma enfermedad infecciosa, se aconseja el que resulte más eficaz para ese caso, retarde la aparición de cepas resistentes que limite el uso posterior de la droga, sea de aplicación más cómoda, provoque menos efectos tóxicos e intolerancias y sea de menos costo económico

Toxoplasmosis encefálica en Sida / Encephalic toxoplasmosis in AIDS

La encefalitis toxoplásmica es la complicación oportunista del SNC que con mayor frecuencia ocasiona manifestaciones neurológicas focales en personas infectadas por el virus de la inmunodeficiencia humana (VIH). Desde 1986, cuando se diagnosticó el primer caso de toxoplasmosis encefálica en el sindrome de inmunodeficiencia adquirida (Sida) en nuestro país, hasta enero de 1997, en la Clínica y Servicio de Enfermedades Infecciosas (CEI-SEIC) se han observado 40 casos de esta enfermedad. La inaccesibilidad a ciertas técnicas diagnosticas y la imposibilidad de realizar autopsias en nuestro medio, hacen que esta complicación esté seguramente subdiagnosticada. La encefalitis toxoplásmica es sospechada por el cuadro clinico-tomográfico y reafirmada por la respuesta favorable al tratamiento. En 1 caso se tuvo la confirmación del diagnóstico por cultivo del germen que fue aislado del LCR. La mayoría de los enfermos tuvieron fiebre y manifestaciones neurológicas focales. Ante la sospecha clínica se realizó tomografía axial computada (TAC) de cráneo, la que se hizo en forma urgente, con la finalidad de iniciar precozmente el tratamiento específico y mejorar el pronóstico. Todos los casos presentaron lesiones características. En 1 sin lesiones tomográficas focales se hizo diagnóstico de encefalitis toxoplásmica difusa. En 27, a los que se les practicó estudio serológico de anticuerpos lgG específicos antitoxoplasma los resultados fueron positivos con títulos variables. En 20 enfermos en quienes se realizó estudio de subpoblaciones linfocitarias todos tenían un estado severo de inmunodepresión. En un alto porcentaje de casos se comprobaron otras infecciones oportunistas concomitantes. Con la sospecha diagnóstica se inició el tratamiento específico. Se observaron reacciones adversas a las drogas en 6 casos. Finalizado el período de tratamiento de la enfermedad activa, se continuó con terapia supresiva, observándose recaídas en 6 enfermos que lo habían discontinuado. Para prevenir esta grave complicación que compromete la vida del enfermo está indicado realizar quimioprofilaxis especialmente en aquellos con serología positiva para toxoplasmosis cuando su estado de inmunodepresión es grave, mientras que no es considerada prioritaria en los seronegativos para toxoplasma, en quienes la frecuencia de neurotoxoplasmosis es escasa

Toxoplasmosis encefálica en Sida / Encephalic toxoplasmosis in acquired immunodeficiency syndrome

La toxoplasmosis encefálica es la más frecuente de las infecciones oportunistas del SNC en el SIDA. Se presentan dos casos de esta afección estudiados en la Clínica Médica "2" de la Facultad de Medicina. Hospital Pasteur. Montevideo. Se destaca la sintomatología inespecífica y focal que orientan al diagnóstico de compromiso del SNC, y principalmente el aspecto tomográfico de las lesiones sugestivas de toxoplasmosis. Cuando se ignora la enfermedad de fondo, como sucedió en ambos casos, el planteo de un SIDA como base patogénica de la inmunosupresión es prioritario para avanzar en el diagnóstico. A falta de una prueba etiológica segura, es adecuado orientarse por la respuesta a la terapéutica específica para la confirmación diagnóstica.