Loss of dopamine-D2 receptor binding sites in Parkinsonian plus syndromes.

UNLABELLED 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). CONCLUSION 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.

[1]  E. Ciceri,et al.  Magnetic resonance imaging in progressive supranuclear palsy and other parkinsonian disorders. , 1994, Journal of neural transmission. Supplementum.

[2]  A. Rajput,et al.  Accuracy of Clinical Diagnosis in Parkinsonism — A Prospective Study , 1991, Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques.

[3]  J M Links,et al.  Quantification of Neuroreceptors in the Living Human Brain. II. Inhibition Studies of Receptor Density and Affinity , 1986, Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism.

[4]  M. Brin,et al.  Effects of tocopherol and deprenyl on the progression of disability in early Parkinson's disease. , 1993, The New England journal of medicine.

[5]  A. Silman,et al.  Statistical methods for assessing observer variability in clinical measures. , 1992, BMJ.

[6]  B. Snow,et al.  Criteria for diagnosing Parkinson's disease , 1992, Annals of neurology.

[7]  S. Asenbaum,et al.  Dopamine D2 receptor imaging and measurement with SPECT. , 1993, Advances in neurology.

[8]  W. Gibb,et al.  The relevance of the Lewy body to the pathogenesis of idiopathic Parkinson's disease. , 1988, Journal of neurology, neurosurgery, and psychiatry.

[9]  R. Coppola,et al.  Lateralized differences in iodine-123-IBZM uptake in the basal ganglia in asymmetric Parkinson's disease. , 1995, Journal of nuclear medicine : official publication, Society of Nuclear Medicine.