La biopsia estereotáctica en el diagnóstico de las lesiones cerebrales focales en sida / Stereotactic brain biopsy in the diagnosis of focal brain lesions in AIDS

Las lesiones cerebrales focales constituyen una complicación frecuente en los pacientes con infección por el virus de la inmunodeficiencia humana (HIV) y síndrome de inmunodeficiencia adquirida (sida). Durante el período comprendido entre enero de 1999 y mayo de 2007 se realizaron un total de 83 biopsias en pacientes con sida y lesiones cerebrales. Se incluyeron aquellos pacientes que no hubiesen respondido al algoritmo habitual de enfoque diagnóstico-terapéutico de estas lesiones. Todas las muestras obtenidas fueron sometidas a evaluación intraoperatoria para asegurar la obtención de material patológico y posterior análisis histopatológico y exámenes microbiológicos. De los 41 pacientes con lesiones cerebrales múltiples, 62 tenían localización supratentorial, en 4 eran infratentoriales y 17 mostraron ambas localizaciones. Cincuenta y un lesiones seleccionadas como blanco estereotáctico tuvieron refuerzo periférico del contraste. Se obtuvo material histopatológico en el 100% de los procedimientos. El diagnóstico más frecuente fue el de leucoencefalopatía multifocal progresiva (LEMP) con 24 casos (29%), seguido del linfoma primario del sistema nervioso central (LPSNC) con 19 diagnósticos (23%) y de toxoplasmosis en 13 pacientes (15.7%). Se comprobó una relación significativa entre los diagnósticos histopatológicos y la localización de las lesiones y entre los diagnósticos histopatológicos y el comportamiento de las imágenes luego de la administración de la sustancia de contraste. El rédito diagnóstico alcanzó el 90.3% (75 biopsias). La morbiletalidad en esta serie fue de 2.4%. La biopsia cerebral estereotáctica permitió alcanzar el diagnóstico etiológico y adecuar el enfoque terapéutico en la mayoría de los pacientes de esta serie.

Focal brain lesions are frequent complications among HIV/AIDS patients. Between January 1999 and May 2007, 83 procedures of stereotactic brain biopsies in HIV/AIDS patients with focal cerebral lesions were carried out. The inclusion criteria were lack of response to current diagnostic and therapeutic guidelines for brain lesions. All the samples underwent microscopic evaluation during surgery to assert valid material and delayed histopathological and microbiological examination. Forty one patient images demonstrated multiple brain lesions. Sixty two cases had supratentorial localization, 4 lesions were located beneath the tentorium and 17 showed both settings. Fifty one lesions presented peripheral enhancement after contrast computed tomography (CT) or magnetic resonance imaging (MRI). A 100% of useful samples recovery was achieved. Progressive multifocal leucoencephalopathy (PML) was the most frequent diagnosis (29%), followed by primary central nervous system lymphoma (PCNSL) (23%), and toxoplasmosis (15.7%). Statistically significant association was observed between histopathological diagnosis and lesion location and between those and peripheral ring enhancement images. The positive diagnostic rate of the invasive procedure was 90.3%. The morbidity/mortality rate was 2.4% in this series. In conclusion, the stereotactic brain biopsy ordered early during the patient’s evolution showed a good performance in order to achieve a prompt and accurate diagnosis and to guide the therapeutic scheme in these AIDS patients with focal brain lesions.

Auditory Brainstem Evoked Potential Responses in Focal Brain Lesions

Brainstem auditory response abnormalities directly reflect disturbance of neural function rather than the underlying anatomic cause of that disturbance. The test has advantage in detecting lesions that alter electrophysiology but do not produce detectable alterations of radiodensity, displace surrounding structures or change vascular supply and permeability. A sequence of seven low-amplitude potentials that occur in the initial 10 msec following click signals can be recorded from scalp electrodes in 44 patient with focal brain lesions using computer averaging techniques. The potentials, termed auditory brainstem responses, are thought to be the far-field reflection of electrical events originating in the auditory pathway during its course through the brainstem. We have studied auditory brainstem evoked potential responses in a variety of focal brain lesions and found them to be of assistance in evaluating the localization of pontomedullary, pons, midbrain, thalamus, subcortical and functional recovery. 1) Distortion of early components (type I) was occured in the brainstem lesions. 2) Distortion of late components (type II) was developed in the diencephalon or subcortical lesions. 3) Distortion of all components (type III) was developed in the brainstem and diffuse brain contusions. 4) Serial recordings provided information about the evolution of brain stem lesions and good functional recovery marker.

Auditory Brainstem Evoked Potential Responses in Focal Brain Lesions

Brainstem auditory response abnormalities directly reflect disturbance of neural function rather than the underlying anatomic cause of that disturbance. The test has advantage in detecting lesions that alter electrophysiology but do not produce detectable alterations of radiodensity, displace surrounding structures or change vascular supply and permeability. A sequence of seven low-amplitude potentials that occur in the initial 10 msec following click signals can be recorded from scalp electrodes in 44 patient with focal brain lesions using computer averaging techniques. The potentials, termed auditory brainstem responses, are thought to be the far-field reflection of electrical events originating in the auditory pathway during its course through the brainstem. We have studied auditory brainstem evoked potential responses in a variety of focal brain lesions and found them to be of assistance in evaluating the localization of pontomedullary, pons, midbrain, thalamus, subcortical and functional recovery. 1) Distortion of early components (type I) was occured in the brainstem lesions. 2) Distortion of late components (type II) was developed in the diencephalon or subcortical lesions. 3) Distortion of all components (type III) was developed in the brainstem and diffuse brain contusions. 4) Serial recordings provided information about the evolution of brain stem lesions and good functional recovery marker.