Assessment of idiopathic rapid-eye-movement sleep behavior disorder by transcranial sonography, olfactory function test, and FP-CIT-SPECT.

Idiopathic rapid-eye-movement (REM) sleep behavior disorder (iRBD) has been suggested to be a risk factor for subsequent development of neurodegenerative disorders, especially Parkinson's disease (PD) and other alpha-synucleinopathies. At present, it is not possible to predict whether or not an iRBD patient will eventually develop PD. Here, we report 5 iRBD patients who underwent a test battery comprising a neurological examination (including UPDRS rating), mini mental state examination testing, transcranial sonography, olfactory function testing, and presynaptic dopamine transporter imaging with FP-CIT-SPECT. Our preliminary data show the diverse pattern of individual combinations of pathological findings when a multimodal assessment approach is applied in this patient group. Large-size longitudinal studies in iRBD patients are required to evaluate the usefulness of diagnostic tests to identify the subgroup of iRBD patients that is prone to develop PD.