PRESYNAPTIC AND POSTSYNAPTIC STRIATAL DOPAMINERGIC FUNCTION IN NEUROACANTHOCYTOSIS - A POSITRON EMISSION TOMOGRAPHIC STUDY

Using [F-18]dopa, [C-11]raclopride, (CO2)-C-15, and positron emission tomography, we have assessed striatal dopamine storage capacity, dopamine D2-receptor integrity, and regional cerebral blood flow, respectively, of 6 patients with neuroacanthocytosis. The patients with neuroacanthocytosis all had chorea and variable combinations of seizures, dementia, axonal neuropathy, and orolingual self-mutilation. [F-18]dopa positron emission tomographic findings were compared with 30 normal controls and 16 patients with sporadic, L-dopa-responsive, Parkinson's disease. Caudate and anterior putamen [F-18]dopa uptake were normal in patients with neuroacanthocytosis, but mean posterior putamen [F-18]dopa uptake was reduced to 42% of normal, similar to that in patients with Parkinson's disease. In patients with neuroacanthocytosis, mean equilibrium caudate:cerebellum and putamen:cerebellum [C-11]raclopride uptake ratios were reduced to 54% and 62% of normal, compatible with a 65% and 53% loss of caudate and putamen D2-receptor-binding sites, respectively. Striatal and frontal blood flow was also depressed. The severe loss of D2-receptor-bearing striatal neurons, with concomitant loss of dopaminergic projections from the nigra to the posterior putamen, is consistent with both chorea and extrapyramidal rigidity being features of patients with neuroacanthocytosis.