Presynaptic and postsynaptic striatal dopaminergic function in neuroacanthocytosis: A positron emission tomographic study

Abstract

Using [¹⁸F]dopa, [¹¹C]raclopride, C¹⁵O₂, 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. [¹⁸F]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 [¹⁸F]dopa uptake were normal in patients with neuroacanthocytosis, but mean posterior putamen [¹⁸F]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 [¹¹C]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.