Loss of dopamine-D2 receptor binding sites in Parkinsonian plus syndromes.
This study analyzed temporal changes of striatal dopamine-D2 receptor binding during the course of different extrapyramidal movement disorders using 123I-iodobenzamide (IBZM) SPECT.


METHODS
Eighteen patients (9 with Parkinson's disease, 9 with parkinsonian plus syndrome) were followed for 11-53 mo. Dopamine-D2 receptor binding was assessed using 123I-IBZM SPECT at the beginning and at the end of the follow-up period. SPECT data were acquired 120 min postinjection of 3-5 mCi 123I-IBZM. A semiautomated algorithm was applied to the raw data for semiquantitative evaluation of regional cerebral receptor binding.


RESULTS
Intraobserver (r = 0.992) and interobserver (r = 0.930) variance was low for the semiautomated interpretation of the SPECT examination of the dopaminergic D2 receptor binding, reflecting a highly reproducible SPECT algorithm. Mean specific dopamine-D2 receptor binding was lower in patients with parkinsonian plus syndrome compared to patients with Parkinson's disease on the initial (p < 0.001) as well as the follow-up study (p < 0.001). In patients with Parkinson's disease, we observed an unaffected receptor binding compared to a reduced binding of radiotracer in patients with parkinsonian plus syndrome during the course of the disease (p < 0.001).


CONCLUSIONS
During the follow-up, patients with Parkinson's disease showed a constant dopamine-D2 receptor binding. In contrast, patients with parkinsonian plus syndrome revealed a decline of the binding of dopamine-D2 receptor. These findings are in agreement with histopathological data that demonstrated a preserved dopamine-D2 receptor status in patients with Parkinson's disease and a decline of the dopamine-D2 receptors in patients with parkinsonian plus syndrome. SPECT examinations using 123I-IBZM are useful for assessing dynamic changes of dopamine-D2 receptors in extrapyramidal movement disorders. Semiquantitative SPECT evaluations may provide valuable information for clinical management and prognosis of the patient with extrapyramidal movement disorders.
Hierholzer
J
J
Strahlenklinik und Nuklearmedizinische Klinik der Charité der, Humboldt-Universität zu Berlin, Germany.
Cordes
M
M
Venz
S
S
Schelosky
L
L
Harisch
C
C
Richter
W
W
Keske
U
U
Hosten
N
N
Mäurer
J
J
Poewe
W
W
Felix
R
R
D000328:Adult; D000368:Aged; D001549:Benzamides; D001665:Binding Sites; D003287:Contrast Media; D003342:Corpus Striatum / Q000000981:diagnostic imaging / Q000378:metabolism*; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D019578:Multiple System Atrophy / Q000378:metabolism; D015588:Observer Variation; D009849:Olivopontocerebellar Atrophies / Q000378:metabolism; D010300:Parkinson Disease / Q000000981:diagnostic imaging / Q000378:metabolism*; D011759:Pyrrolidines; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D015203:Reproducibility of Results; D013494:Supranuclear Palsy, Progressive / Q000378:metabolism; D013577:Syndrome; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon
D001549:Benzamides; D003287:Contrast Media; D007457:Iodine Radioisotopes; D011759:Pyrrolidines; D017448:Receptors, Dopamine D2; C055743:3-iodo-2-hydroxy-6-methoxy-N-((1-ethyl-2-pyrrolidinyl)methyl)benzamide