Transcranial sonography on Parkinson's disease and essential tremor

The study on transcranial sonocraphy (TCS) as a diagnostic test for Parkinson’s disease (PD) has been neglected in some hospitals. The current study was conducted as the first study to investigate the utility of TCS for diagnosis of PD and its ability to distinguish PD from essential tremor (ET) in an Iranian population. TCS of substantia nigra (SN) was performed on 50 PD, 48 ET, and 50 healthy controls by two blinded investigators. Bilateral SN margin over 0.20 cm2 was found in 39 (90%) and 7 (15%) in PD and ET patients, respectively. Furthermore, 4 (8%) of healthy control displayed this particular echo feature as well (false positives). SN hyperechogenicity ≥0.20 cm2 was considered as a cut-off point to detected PD. Accordingly, TCS proved 90% (95% confidence interval [CI]: 77.85-97.35) sensitive and 92% (95% CI: 80.75-97.73) specific for the detection of PD by visualizing the SN. SN hyperechogenicity ≥20 cm2 is a specific feature of PD. Since, the symptoms of PD and ET might be overlapping; this method seems to be reliable to confirm PD diagnosis in doubtful clinical cases. Further studies in years to come are warranted to shed light on standardized data for Iranian to enhance the validity of TCS.