Questionnaire survey of Scans without Evidence of Dopaminergic Deficit (SWEDD) in Japan

Abstract

We conducted a questionnaire survey to collect epidemiological information on patients with Scans Without Evidence of Dopaminergic Deficit (SWEDD). We sent questionnaires to 4,970 neurology specialists in Japan in July 2015 and received responses from 933 of them. The total number of patients reported to have Parkinson's disease was 39,532, which included 237 cases of SWEDD in patients (111 males, 125 females, and 1 case without a gender description). The disease duration in patients with SWEDD was short; 127 cases (53.6%) had a duration less than 3 years, and 78 cases (32.9%) had a duration of 3 years or more but less than 7 years. By age, 59 cases (24.9%) occurred in individuals in their 60s, and 106 cases (44.7%) occurred in individuals in their 70s. Sixty-three neurologists stated that they performed dopamine transporter single photon emission computed tomography (DaT SPECT) on almost all patients with Parkinson's disease. They treated a total of 3,600 patients with Parkinson's disease which included 107 cases of SWEDD; therefore, approximately 3.0% of Parkinson's patients were estimated have SWEDD. The causes of SWEDD were unknown (101 cases), essential tremor (22 cases), vascular Parkinsonism (14 cases), and drug-induced Parkinsonism (14 cases). The majority of neurologists had doubts about the diagnosis of Parkinson's disease prior to confirming the diagnosis using DaT SPECT for reasons such as: normal findings on meta-iodobenzylguanidine (MIBG) myocardial scintigraphy, poor responses to anti-Parkinson drugs, lack of true akinesia, unchanged symptoms, and atypical symptoms. Two hundred and nineteen cases included reports on treatment paradigms following the SWEDD diagnosis. Of those cases, patients in 159 cases were maintained on the same treatment following diagnosis.