Usefulness of Cardiac MIBG Scintigraphy, Olfactory Testing and Substantia Nigra Hyperechogenicity as Additional Diagnostic Markers for Distinguishing between Parkinson's Disease and Atypical Parkinsonian Syndromes.
BACKGROUND
We aimed to evaluate the utility of the combined use of cardiac 123I-metaiodobenzylguanidine (MIBG) scintigraphy, olfactory testing, and substantia nigra (SN) hyperechogenicity on transcranial sonography (TCS) in differentiating Parkinson's disease (PD) from atypical parkinsonian syndromes (APSs), such as multiple system atrophy (MSA) and progressive supranuclear palsy (PSP).


METHODS
Cardiac MIBG scintigraphy, card-type odor identification testing (Open Essence (OE), Wako, Japan), and TCS were performed with 101 patients with PD and 38 patients with APSs (MSA and PSP). Receiver operating characteristic (ROC) curve analysis was used to assess the sensitivity and specificity of these batteries for diagnosing PD from APSs. The diagnostic accuracy of the three tests was also assessed among patients at the early disease stage (drug-naïve patients with a disease duration of 3 years or less).


RESULTS
In differentiating PD from APSs, the area under the ROC curve was 0.74 (95% CI, 0.65-0.83), 0.8 (95% CI, 0.73-0.87), and 0.75 (95% CI, 0.67-0.82) for TCS, cardiac MIBG scintigraphy, and olfactory testing, respectively. The diagnostic sensitivity and specificity were 53.1% and 91.7%, respectively, for TCS, 70.3% and 86.8%, respectively, for cardiac MIBG scintigraphy, 58.4% and 76.3%, respectively, for OE. Among early-stage patients, sensitivity and specificity were 50.0% and 93.8%, respectively, for TCS, 57.1% and 87.5%, respectively, for cardiac MIBG scintigraphy, and 54.8% and 79.2%, respectively, for OE. At least one positive result from 3 tests improved sensitivity (86.1%) but decreased specificity (63.2%). In contrast, at least 2 positive results from 3 tests had good discrimination for both early-stage patients (50.0% sensitivity and 93.8% specificity) and patients overall (57.8% sensitivity and 95.8% specificity). Positive results for all 3 tests yielded 100% specificity but low sensitivity (25%).


CONCLUSIONS
At least 2 positive results from among TCS, cardiac MIBG scintigraphy, and olfactory testing can support clinical diagnosis in distinguishing PD from APSs.
Department of Neurology, Dokkyo Medical University, Tochigi, Japan.
Hiroaki
H
Fujita
Department of Neurology, Dokkyo Medical University, Tochigi, Japan.
Keisuke
http://orcid.org/0000-0003-0320-8993
K
Suzuki
Department of Neurology, Dokkyo Medical University, Tochigi, Japan.
Ayaka
A
Numao
Department of Neurology, Dokkyo Medical University, Tochigi, Japan.
Yuji
Y
Watanabe
Department of Neurology, Dokkyo Medical University, Tochigi, Japan.|Continence Center, Dokkyo Medical University, Tochigi, Japan.
Tomoyuki
T
Uchiyama
Department of Neurology, Dokkyo Medical University Koshigaya Hospital, Saitama, Japan.
Tomoyuki
T
Miyamoto
Department of Clinical Medicine for Nursing, Dokkyo Medical University School of Nursing, Tochigi, Japan.
Masayuki
M
Miyamoto
Department of Neurology, Dokkyo Medical University, Tochigi, Japan.
Koichi
K
Hirata
D019797:3-Iodobenzylguanidine; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D055696:Olfactory Perception; D010300:Parkinson Disease / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D020734:Parkinsonian Disorders / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D011877:Radionuclide Imaging; D013378:Substantia Nigra / Q000000981:diagnostic imaging*; D017585:Ultrasonography, Doppler, Transcranial
D019797:3-Iodobenzylguanidine