Transcranial ultrasound provides a differential diagnosis for parkinsonian syndromes before the disease progresses beyond the very first, nonspecific, clinical signs, according to a new study. Researchers conducting the study say this noninvasive and inexpensive test should become routine, as early diagnosis would allow for disease-specific treatment to start sooner.
Earlier studies used transcranial ultrasound to look for increased echogenicity of the substantia nigra and thereby differentiate between idiopathic Parkinson's disease and atypical parkinsonian syndromes. However, these studies looked at advanced cases with known clinical diagnoses, while the new study focused on early cases.
Dr. Alexandra Gaenslen and colleagues at the Department of Neurodegeneration and Hertie Institute of Clinical Brain Research at the University of Tübingen in Germany, published their research in The Lancet Neurology, which made it available online April 2. They examined 60 patients presenting with early, unclear symptoms of parkinsonism. A baseline transcranial ultrasound exam was conducted, then the patients were tracked for a year to assess the clinical diagnosis. Raclopride PET or SPECT exams provided a diagnosis for those patients for whom clinical examination was not sufficient.
At the beginning of the study, 38 of the 60 patients could not be diagnosed by clinical examination. By the end of the study, 39 of the 60 patients were diagnosed as having idiopathic Parkinson's disease. Researchers were blinded to the exams and diagnoses until the final investigation. The baseline transcranial ultrasound exams turned out to have a sensitivity of 90.7% and a specificity of 82.4%, when compared with the end diagnosis, and a positive predictive value of 92.2%, with a classification accuracy of 88.3%.
The researchers concluded that transcranial ultrasound should be added as a routine test when clinicians are faced with diagnosing early parkinsonian syndromes, pointing out that it's inexpensive, noninvasive, and easy to implement.
