Objective: A case of encephalitic Parkinsonism due to bilateral substantia nigra lesion showing reversible course with preserved nigrostriatal dopaminergic activities.

Background: A few cases have been described with pathology isolated to the substantia nigra, documented on magnetic resonance image (MRI). However it is difficult to predict whether the encephalitic Parkinsonism is reversible in the early phase of infection.

Method: A 31-year-old female patient visited our hospital due to dysarthria accompanied by akinetic-rigid syndrome. On arrival, her vital signs were stable except for a fever of 37.8℃..United Parkinson Disease Rating Scale (UPDRS) motor score was 38/108 at admission. Serum chemistry was unremarkable except for an increased the C-reactive protein (15.9 mg/l). A cerebrospinal fluid (CSF) examination performed at admission showed 56 white blood cells with 93% lymphocytes and 51.1 mg/dl proteins.

Results: The brain MRI scans performed on admission showed symmetrical hyperintensity lesions involving bilateral substantia nigra on T2-weighted and Fluid attenuated inversion recovery (FLAIR) images. ¹²³I-labeled 2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl)-nortropane (¹²³I-FP-CIT) PET imaging performed on the second day after admission showed preserved dopamine transporter radiotracer uptake in bilateral striatum . After admission her Parkinsonism showed progressive course. She had difficulty in swallowing and had to be fed via a nasogatric tube and her bradykinesia and rigidity more severely affected then bed-ridden state 7 days after admission (UPDRS motor score : 55/108). After two week of treatment for encephalitis, her extrapyramidal symptoms gradually improved, especially her gait (UPDRS motor score : 25/108)

A 3-month follow-up, her response and movement further improved and her facial expressions were more varied than before (UPDRS motor score : 10/108). A repeated MRI after 3 months, the lesions in high-signal intensity observed in bilateral substantia nigra were disappeared and neurological abnormalities were all disappeared (UPDRS 0/108)

Conclusion: Our observation suggested that the clinical symptoms of the patient due to viral invasion of dopaminergic cells seemed to be well correlated to the radiological topography in brain MRI and the prognosis of the patient seemed to be well correlated to the ¹²³I-FP-CIT PET imaging

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MDS Abstracts - https://www.mdsabstracts.org/abstract/reversible-encephalitic-parkinsonism-due-to-bilateral-substantia-nigra-lesion-showing-preserved-nigrostriatal-dopaminergic-activity/