Extending the clinicopathological spectrum of neurofilament inclusion disease

We describe features of a patient that broadens the clinical and pathological spectrum of neurofilament inclusion disease (NFID). The patient was a 52-year-old man with a 5–6 year history of progressive, asymmetrical spastic weakness of the upper and lower extremities; l-DOPA-unresponsive parkinsonism; and SPECT evidence of asymmetrical frontoparietal and basal ganglia hypoperfusion. The brain had marked frontoparietal parasagittal cortical atrophy, including the motor cortex, with histopathological evidence of neurofilament- and α-internexin-immunoreactive neuronal inclusions. The corticospinal tract had degeneration, but there was minimal lower motor neuron pathology. There was also severe neuronal loss and gliosis in the posterolateral putamen and the substantia nigra, mimicking multiple system atrophy; however, glial cytoplasmic inclusions were not detected with α-synuclein immunohistochemistry. This case extends the clinical and pathological spectrum of NFID to include cases with predominant parkinsonian and pyramidal features.