System degeneration in an MM1-type sporadic Creutzfeldt-Jakob disease case with an unusually prolonged akinetic mutism state

Methionine/methionine type 1 (MM1-type) sporadic Creutzfeldt-Jakob disease (sCJD), known as the ‘classic type,’ shows typical clinicopathological sCJD findings. In general, patients reach an akinetic mutism state within a few months of disease onset and die soon after if supportive therapies are not administered. Here, we describe remarkable neuropathologic observations of MM1-type sCJD in a 48-year-old, Japanese man with an unusually prolonged akinetic mutism state. In the early disease stages, the patient exhibited abnormal behaviour with gait disturbance and rapidly progressive cognitive dysfunction. Diffusion-weighted magnetic resonance imaging revealed extensive cerebral cortical hyperintensity. Prion protein (PrP) gene analysis revealed no mutations, and the polymorphic codon 129 exhibited methionine homozygosity. Although the patient remained stable with tube feeding for more than 2 years after reaching the akinetic mutism state, he died because of central respiratory failure 30 months after disease onset. Neuropathologic investigation showed extensive devastating lesions, such as status spongiosus, and typical spongiform changes could no longer be observed in the cerebral neocortex. Conspicuous pyramidal tract degeneration was observed. However, the regions commonly preserved in MM1-type sCJD pathology were still relatively preserved. Immunostaining revealed extensive diffuse synaptic-type PrP deposition in the grey matter. The pathological findings suggested that sCJD is a neurodegenerative disease that shows system degeneration; there are primary and secondary degenerative regions and distinct preserved regions, even in cases with prolonged disease duration. In addition, it is considered that there is a limited survival period for MM1-type sCJD, even if active symptomatic treatment is provided.

Immunohistochemical and ultrastructural evidence for the pathogenesis of white matter degeneration in patients with panencephalopathic-type Creutzfeldt-Jakob disease: Inducible nitric oxide synthase overexpression in bizarre astrocytes

Excessive production of nitric oxide (NO) due to the overinduction of inducible nitric oxide synthase (iNOS) has a severe cytotoxic effect, which may relate to the pathogenesis of neurodegenerative disorders. In this study, we report the novel finding that iNOS is overinduced in a large number of bizarre astrocytes in the white matter of patients with panencephalopathic (PE)-type Creutzfeldt-Jakob disease (CJD). This study was carried out on brain tissue from seven patients with PE-type CJD. As controls, 12 normal individuals and nine patients with cerebral infarction were examined. We identified a large number of bizarre astrocytes in the degenerative cerebral white matter in PE-type CJD. Using immunohistochemistry, only bizarre astrocytes in PE-type CJD showed strong immunoreactivity for both iNOS and superoxide dismutase 1 (SOD1). Ultrastructural examination demonstrated that these bizarre astrocytes contained many free polyribosome-like granules. No significant iNOS immunoreactivity was observed in either the astrocytes of patients with cerebral infarcts or in the normal controls. This study suggests that the iNOS-overexpressing astrocytes, especially iNOS-overexpressing bizarre astrocytes, could play an important role in the development of white matter lesions in PE-type CJD. Our data also suggest that the bizarre astrocytes could be protecting themselves from the cytotoxicity of NO by producing SOD1. These immunohistochemical findings are supported by the ultrastructural observation of numerous polyribosome granules restricted to the cytoplasm of these bizarre astrocytes.

Creutzfeldt-Jakob disease

This review will explore the clinical and pathological findings of the various forms of Creutzfeldt-Jakob disease (CJD). Clinical findings of CJD are characterized by rapidly progressive cognitive dysfunction, diffusion-weighted magnetic resonance imaging (DWI) hyperintensity, myoclonus, periodic sharp-wave complexes on electroencephalogram and akinetic mutism state. Neuropathologic findings of CJD are characterized by spongiform changes in gray matter, gliosis-particularly hypertrophic astrocytosis-neuropil rarefaction, neuron loss and prion protein (PrP) deposition. The earliest pathological symptom observed by HE staining in the cerebral cortex is spongiform change. This spongiform change begins several months before clinical onset, and is followed by gliosis. Subsequently, neuropil rarefaction appears, followed by neuron loss. Regions showing fine vacuole-type spongiform change reflect synaptic-type PrP deposition and type 1 PrP^Sc deposition, whereas regions showing large confluent vacuole-type spongiform changes reflect perivacuolar-type PrP deposition and type 2 PrP^Sc deposition. Hyperintensities of the cerebral gray matter observed in DWI indicate the pathology of the spongiform change in CJD. The cerebral cortical lesions with large confluent vacuoles and type 2 PrP^Sc show higher brightness and more continuous hyperintensity on DWI than those with fine vacuoles and type 1 PrP^Sc . CJD cases showing diffuse myelin pallor of cerebral white matter have been described as panencephalopathic-type, and this white matter pathology is mainly due to secondary degeneration caused by cerebral cortical involvement, particularly in regard to neuron loss. In conclusion, clinical and neuroimaging findings and neuropathologic observations are well matched in both typical and atypical cases in CJD. The clinical diagnosis of CJD is relatively easy for typical CJD cases such as the MM1-type. However, even in atypical cases it seems that clinical findings can be used for an accurate diagnosis.