Neuronal Intranuclear Inclusion Disease Presenting as Juvenile Parkinsonism

Abstract

Diagnostic considerations for juvenile onset Parkinsonism (onset at < 21 years of age) include juvenile Huntington disease, Wilson disease, dentatorubral-pallidoluysian atrophy (DRPLA), storage diseases, and mitochondrial cytopathies. Neuronal Intranuclear Inclusion Disease (NIID) must also be considered. We present a case of juvenile onset NIID with a predominantly Parkinsonian presentation, followed later by corticospinal, cerebellar, and lower motor neuron symptoms. Diagnosis of NIID can be made antemortem through rectal biopsy, however it was missed in this case. Rectal biopsy should be performed in all suspected cases, reviewed by an experienced neuropathologist and repeated if the suspicion for NIID is high. Pathologically, SUMO-1 immunohistochemistry appears to reliably label the neuronal inclusions and abnormal SUMOylation may play a part in the pathogenesis.