Local cerebral blood flow and its response to intravenous levodopa in progressive supranuclear palsy. Comparison with Parkinson's disease
M. Kobari, Y. Fukuuchi, T. Shinohara, S. Nogawa and K. Takahashi
Department of Neurology, School of Medicine, Keio University, Tokyo, Japan.
The local cerebral blood flow (LCBF) at steady state and after the
intravenous administration of levodopa (1 mg/kg) was measured by the
xenon-enhanced computed tomographic method in six patients with progressive
supranuclear palsy (PSP) and in nine patients with idiopathic Parkinson's
disease. The baseline LCBF values in most brain regions in patients with
PSP were lower than those in patients with Parkinson's disease, and
hyperfrontality of the LCBF was lost. In patients with Parkinson's disease,
the injection of levodopa markedly increased LCBF, especially in the
striatum, thalamus, and internal capsule (approximately 40%). In patients
with PSP, however, levodopa did not increase the LCBF in all brain regions
examined. The LCBF increases after the administration of levodopa in
patients with Parkinson's disease may be secondary to metabolic activation
of the dopaminergic system. The different LCBF responses to levodopa
between patients with PSP and those with Parkinson's disease may reflect
differences in pathologic features, such as in the degree of preservation
of nigrostriatal dopaminergic neurons and the distribution and density of
dopamine receptors, and are also related to the clinical effectiveness of
levodopa therapy.
