Measurement of global cerebral blood flow (CBF) using extracranial duplex sonography has been described, but normal values are still lacking. In 85 healthy adults (median age 43.4 years, range 20 to 80 years), CBF was determined by duplex sonographic examination of both internal carotid arteries and vertebral arteries. The mean global CBF was 630+/-97 mL/min. Global CBF declined with age; sex did not influence the total CBF. When measurements were repeated, the intraindividual variability was low. This noninvasive sonographic measurement of CBF is reproducible, and values correspond closely to those obtained with positron emission tomography and magnetic resonance imaging.

55Background: Structural abnormality of the substantia nigra can be detected by transcranial sonography in neuropsychiatric disorders such as Parkinson disease and restless legs syndrome. We investigated echogenicity of the substantia nigra as a potential structural marker for dysfunction of the nigrostriatal dopamine system in children with attention-deficit hyperactivity disorder (ADHD). Methods: We used a blinded design and determined echogenicity of the substantia nigra by use of transcranial sonography in 22 children with ADHD and 22 healthy controls matched for age and sex. Results: The echogenic substantia nigra area was significantly larger in ADHD patients than in healthy controls (F 1,42 = 9.298, p = 0.004, effect size = 0.92). We found no effects of age or sex. Limitations: Owing to a lack of dimensional assessment, we could not analyze the correlation between echogenicity and clinical symptoms. Conclusion: Our results support the hypothesis that the nigrostriatal dopaminergic system is abnormal in children with ADHD.