Marked reduction of striatal dopamine D2 receptors as detected by 123IBZM‐SPECT in a Wilson's disease patient with generalized dystonia

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Abstract
[123I]iodobenzamide‐single photon emission computed tomography (IBZMSPECT) was employed to study the distribution of dopamine D2 receptors in a patient with biochemically proven Wilson's disease presenting with generalized dystonia. IBZM is a dopamine D2 receptor antagonist with high affinity and specific binding to basal ganglia detectable by SPECT. IBZM‐SPECT in this patient (age, 20 years) displayed a striatum to frontal cortex ratio of 1.2 compared to 1.55 ± 0.05 (mean ± SD) in normal controls (n = 7; mean age, 53.3 years). In parallel with this finding, MRI with heavily T2‐weighted sequences showed atrophy and low signal intensity changes of the basal ganglia. There was no improvement of dystonia after a subcutaneous injection of apomorphine. In contrast, IBZM‐SPECT of a neurologically asymptomatic Wilson's disease patient (age, 21 years) displayed a striatum to frontal cortex ratio of 1.6. The MRI scan of this patient was normal. It is suggested that the observed apomorphine‐unresponsive generalized dystonia in this Wilson's disease patient is related to striatal lesions proven by IBZM‐SPECT and MRI.