Transcranial ultrasound in the diagnosis of Parkinson's disease

Abstract

This Practice Point commentary discusses a prospective study by Gaenslen et al. regarding the diagnostic value of transcranial ultrasound in patients with early features of parkinsonism. Reference diagnoses were obtained on the basis of repeated clinical examination over the course of 1 year and by the performance of functional imaging in uncertain cases. Ultrasound at baseline had a sensitivity of 91% with a specificity of 82% for a diagnosis of idiopathic Parkinson's disease; the positive predictive value for idiopathic Parkinson's disease was 93% with a classification accuracy of 88%. While application of this technique in carefully selected patients may improve diagnostic accuracy, it is important to note that nigral changes similar to those observed in patients with Parkinson's disease occur in approximately 10% of healthy individuals and have been reported in depression and essential tremor. The diagnosis of parkinsonian disorders continues to be based primarily on demonstration of characteristic neurological features.