3H-spiperone binding to lymphocytes fails in the differential diagnosis of de novo Parkinson syndromes.

In order to investigate the diagnostic value of 3H-spiperone binding capacity to lymphocytes in the differential diagnosis of de novo Parkinson's disease (idiopathic Parkinson syndrome, PD), we performed a double blind prospective study of spiperone binding capacity of 123 patients and 23 healthy control persons, belonging to different diagnostic groups (PD, Parkinsonian syndrome due to vascular lesions, multiple system atrophy [MSA], essential tremor). Diagnoses were based on medical history, clinical examination, CT or MRI scan, acute response to dopamimetic drugs, one year follow up, and long term response to L-DOPA treatment. Spiperone binding was assayed using ten different concentrations (0.03-3 nmol) in absence or presence of 1 mumol (+)-butaclamol to determine nonspecific binding. There was no significant difference in spiperone binding between patients with PD not treated with L-DOPA, and patients with other basal ganglia disorders including parkinsonian syndrome due to vascular lesions, multiple system atrophy, or progressive supranuclear palsy, and age matched controls. Binding was significantly higher in parkinsonian patients with PD treated with L-DOPA and patients with essential tremor. It is concluded that at present 3H-spiperone binding gives no further information in the differential diagnosis of de novo Parkinson's disease.