Involvement of nigrostriatal pathway in japanese encephalitis with movement disorders: Evidence from ^99mTc-TRODAT-1 and ¹²³I-IBZM SPECT imagings

Purpose: The purpose of this study was to evaluate molecular evidence of nigrostriatal pathway involvement in Japanese encephalitis (JE) survivors with movement complications. Methods: Three JE patients were recruited. All had cranial magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT) studies with ^99mTc-TRODAT-1 and ¹²³I-IBZM. Results: Cranial MRI revealed involvement of bilateral thalami, substantia nigra, and medial temporal lobes in all three patients, but only case 1 had additional bilateral basal ganglia involvement. The ^99mTc-TRODAT-1 SPECT for presynaptic dopamine transporter imaging disclosed asymmetrical decreases in bilateral striatal uptake in all three patients. However, the ¹²³I-IBZM SPECT imaging for postsynaptic D2 dopamine receptors (D2Rs) revealed inconsistent abnormalities including asymmetrical bilateral decreases (case 1), unilateral decrease (case 2), and bilateral increases (case 3) in striatal uptakes. Conclusion: Data have suggested that presynaptic dopaminergic neurons in JE patients are more susceptible to JE virus than postsynaptic striatal neurons. The degree of movement impairment was more closely correlated to the degree of D2Rs disruption seen in ¹²³I-IBZM SPECT imaging.