Evaluación de la sustancia negra mediante ultrasonografía transcraneal

Abstract

AIM. To describe the prevalence of hyperechogenicity of the substantia nigra in two samples of patients: one group who had been diagnosed with Parkinson's disease (PD) in accordance with United Kingdom Parkinson's Disease Society criteria and a control population, so as to be able to establish the reference values for our neurosonology laboratory. SUBJECTS AND METHODS. Two samples of patients consisting of healthy controls with no neurodegenerative disease and patients with PD were selected. Planimetric measurements of the area of echogenicity in the substantia nigra were performed in both groups. The greatest area of echogenicity measured on each side of each patient was considered. Descriptive statistics of the sample were carried out. The ROC curve was constructed in order to show the overall precision, sensitivity and specificity of transcranial Doppler ultrasonography in comparison to the clinical diagnosis of PD. RESULTS. Altogether 45 patients with PD and 91 controls were analysed. Using our own cut-off point (percentile 90 of the controls = 0.22 cm2), hyperechogenicity of the substantia nigra was observed in 73.33% of patients with PD and 8.79% of the controls (p = 0). An area below the curve of 93% was seen, which represents good overall precision for transcranial Doppler ultrasonography in the diagnosis of PD. CONCLUSIONS. The evaluation of the substantia nigra conducted in our laboratory using ultrasound imaging reveals significant differences between subjects with PD and normal subjects. The values obtained in our laboratory are slightly below those established as an international reference and offer excellent values for specificity and an acceptable level of sensitivity in our locale.