Significance of N-isopropyl-[123I] p-iodoamphetamine single-photon emission computed tomography in detection of responsible hypoperfusion in hemichorea

Abstract Hemichorea is relatively an uncommon clinical presentation while its known etiology are vascular, metabolic, neoplastic, infectious, autoimmune, and inherited disorders. In the acquired case of hemichorea, the most common cause is the cerebrovascular insult, which is often diagnosed by the magnetic resonance (MR) imaging. An 84-year-old woman reported a one-week history of involuntary movements in the left side of her face and left limbs. Blood tests were normal and brain MR imaging showed no responsible hyperintense lesion on T1-, FLAIR, and diffusion-weighted imaging. N-isopropyl-[123I] p-iodoamphetamine single-photon emission computed tomography (SPECT) detected hypoperfusion in the right thalamus. Further three-dimensional tomography clearly detected the hypoperfusion in the right subthalamic nucleus. The hypoperfused lesion was MR-negative and remained unchanged in SPECT one year after the onset. After the treatment with 0.35 mg of oral haloperidol was initiated, the hemichorea was gradually decreased and completely disappeared in 9 months. Because the three-dimensional analysis performs voxel-by-voxel analysis, it possibly detects the precise hypoperfusion in a specific region. In conclusion, evaluation of cerebral blood flow using SPECT on patients presenting with acute hemichorea can lead to the detection of responsible lesion when the routine examinations are negative.