Parasomnia as an occasion for the diagnosis of Parkinson's disease

We report a case of Parkinson's disease (PD) diagnosed by REM sleep behavior disorder (RBD). The patient was a 68-year-old man. On admission, rigidity in the left upper and lower extremities, bradykinesia, and gait disturbance were noted. In addition, polysomnography revealed REM sleep without atonia (RWA), and a diagnosis of untreated PD associated with RED was made. Polysomnographic data showed that REM density decreased and RWA tended to increase after administration of a combination of L-DOPA and DCI (L-DOPA/DCI). Thus, we considered that the pathophysiological mechanism of RED in this case was based not only on the dysfunction of the brainstem mechanism of RWA, but also on the impairment of dopaminergic neuron.