Assessment of nigrostriatal damage in schizophrenia using transcranial sonography and dopamin transporter imaging

There are a some histopathological studies indicating nigrostriatal degeneration in patients with chronic schizophrenia. However, premortem differentiation between neuroleptic-induced parkinsonism and dopmaninergic nigrostriatal impairment in idiopathic Parkinson's disease (IPD) has been difficult.

We report a 63 year old patient with chronic schizophrenia who had developed a slowly progressive hypokinetic-rigid syndrome under neuroleptic medication over 15 years. To evaluate the nigrostriatal dopaminergic innervation transcranial brain parenchyma sonography (TCS) and dopamine transporter (DAT) imaging using I-123-FP-CIT SPECT was performed.

TCS of the midbrain depicted a marked increased echogenicity in both substantia nigra (right: 28 mm2; left: 26 mm2) which is consistent with TCS findings in IPD. FP-CIT SPECT demonstrated a significant decrease of the striatal DAT on both sides (ROI ratios: 1.68 (right), 1.80 (left)). The finding of reduced presynaptic striatal DAT uptake exclude the possibility of a mere drug induced parkinsonism and indicates nigral neurodegeneration as seen in IPD.

This case is the first to demonstrate coexistence of IPD and chronic schizophrenia using two in vivo imaging methods. These findings suggest that DAT-SPECT and TCS may provide a useful diagnostic tool to depict nigrostriatal degeneration in psychiatric patients with parkinsonian symptoms.

In clinical practice, such patients will benefit from the in vivo detection of IPD by applying an optimal pharmacological replacement therapy or potentially deep brain stimulation.