MM2-thalamic-type sporadic Creutzfeldt-Jakob disease with widespread neocortical pathology

Thalamic-insomnia phenotype in E200K Creutzfeldt-Jakob disease: A PET/MRI study

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gCJD with PRNP E200K mutations frequently manifested as a thalamic-insomnia phenotype.

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Some features of the E200K phenotype are somewhere in between typical CJD and FFI.

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PET is a sensitive approach to help identify the functional changes in prion disease.

Background

Insomnia and thalamic involvement were frequently reported in patients with genetic Creutzfeldt-Jakob disease (gCJD) with E200K mutations, suggesting E200K might have discrepancy with typical sporadic CJD (sCJD). The study aimed to explore the clinical and neuroimage characteristics of genetic E200K CJD patients by comprehensive neuroimage analysis.

Methods

Six patients with gCJD carried E200K mutation on Prion Protein (PRNP) gene, 13 patients with sporadic CJD, and 22 age- and sex-matched normal controls were enrolled in the study. All participants completed a hybrid positron emission tomography/magnetic resonance imaging (PET/MRI) examination. Signal intensity on diffusion-weighted imaging (DWI) and metabolism on PET were visually rating analyzed, statistical parameter mapping analysis was performed on PET and 3D-T1 images. Clinical and imaging characteristics were compared between the E200K, sCJD, and control groups.

Results

There was no group difference in age or gender among the E200K, sCJD, and control groups. Insomnia was a primary complaint in patients with E200K gCJD (4/2 versus 1/12, p = 0.007). Hyperintensity on DWI and hypometabolism on PET of the thalamus were observed during visual rating analysis of images in patients with E200K gCJD. Gray matter atrophy (uncorrected p < 0.001) and hypometabolism (uncorrected p < 0.001) of the thalamus were more pronounced in patients with E200K gCJD.

Conclusion

The clinical and imaging characteristics of patients with gCJD with PRNP E200K mutations manifested as a thalamic-insomnia phenotype. PET is a sensitive approach to help identify the functional changes in the thalamus in prion disease.

Genetic Creutzfeldt-Jakob disease-M232R with the cooccurrence of multiple prion strains, M1 + M2C + M2T: Report of an autopsy case

Genetic Creutzfeldt-Jakob disease (gCJD) with a methionine to arginine substitution at codon 232 of the prion protein gene (gCJD-M232R) is rare and has only been reported in Japan. We report an autopsy case of gCJD-M232R showing alleles of codon 129 that were homozygous for methionine and the presence of multiple strains of the protease-resistant, abnormal isoform of prion protein (PrP^Sc ), M1 + M2C + M2T. The patient, a 54-year-old Japanese man, died after a clinical course of 21 months characterized by slowly progressive dementia and sleep disturbance. At autopsy, the neuropil of the cerebral neocortex showed a widespread and severe spongiform change. Grape-like clusters of large confluent vacuoles were admixed with fine vacuoles. Neuronal loss was moderate, but reactive astrocytosis was mild. The dorsomedial nucleus of the thalamus and the inferior olivary nucleus showed moderate and severe neuronal loss, respectively. Many amyloid plaques were present in the cerebellar molecular layer. PrP^Sc deposition pattern was predominantly the synaptic type in the cerebrum and corresponded to the plaques in the cerebellum. Perivacuolar deposition was also seen. Western blot analysis of PrP^Sc revealed the predominance of type 2. Moreover, by employing Western blot analysis in combination with the protein misfolding cyclic amplification (PMCA) method, which selectively amplifies the minor M2T prion strain, we demonstrated the presence of M2T, in addition to M1 and M2C strains, in the brain of the patient. PMCA was a powerful method for demonstrating the presence of the M2T strain, although the amount is often small and the transmission is difficult.

MM2-type sporadic Creutzfeldt-Jakob disease: new diagnostic criteria for MM2-cortical type

OBJECTIVE

To clinically diagnose MM2-cortical (MM2C) and MM2-thalamic (MM2T)-type sporadic Creutzfeldt-Jakob disease (sCJD) at early stage with high sensitivity and specificity.

METHODS

We reviewed the results of Creutzfeldt-Jakob disease Surveillance Study in Japan between April 1999 and September 2019, which included 254 patients with pathologically confirmed prion diseases, including 9 with MM2C-type sCJD (MM2C-sCJD) and 10 with MM2T-type sCJD (MM2T-sCJD), and 607 with non-prion diseases.

RESULTS

According to the conventional criteria of sCJD, 4 of 9 patients with MM2C- and 7 of 10 patients with MM2T-sCJD could not be diagnosed with probable sCJD until their death. Compared with other types of sCJD, patients with MM2C-sCJD showed slower progression of the disease and cortical distribution of hyperintensity lesions on diffusion-weighted images of brain MRI. Patients with MM2T-sCJD also showed relatively slow progression and negative results for most of currently established investigations for diagnosis of sCJD. To clinically diagnose MM2C-sCJD, we propose the new criteria; diagnostic sensitivity and specificity to distinguish 'probable' MM2C-sCJD from other subtypes of sCJD, genetic or acquired prion diseases and non-prion disease controls were 77.8% and 98.5%, respectively. As for MM2T-sCJD, clinical and laboratory features are not characterised enough to develop its diagnostic criteria.

CONCLUSIONS

MM2C-sCJD can be diagnosed at earlier stage using the new criteria with high sensitivity and specificity, although it is still difficult to diagnose MM2T-sCJD clinically.

Two distinct prions in fatal familial insomnia and its sporadic form

Fatal familial insomnia is a genetic prion disease, which is associated with the aspartic acid to asparagine substitution at codon 178 of the prion protein gene. Although the hallmark pathological feature is thalamic and olivary degeneration, there is a patient with an atypical fatal familial insomnia without the hallmark feature. The cause of the pathological variability is unclear. We analysed a Japanese fatal familial insomnia kindred and compared one atypical clinicopathological fatal familial insomnia phenotype case and typical fatal familial insomnia phenotype cases with transmission studies using multiple lines of knock-in mice and with protein misfolding cyclic amplification. We also analysed the transmissibility and the amplification properties of sporadic fatal insomnia. Transmission studies revealed that the typical fatal familial insomnia with thalamic and olivary degeneration showed successful transmission only using knock-in mice expressing human-mouse chimeric prion protein gene. The atypical fatal familial insomnia with spongiform changes showed successful transmission only using knock-in mice expressing bank vole prion protein gene. Two sporadic fatal insomnia cases with thalamic and olivary degeneration showed the same transmissibility as the typical fatal familial insomnia phenotype. Interestingly, one sporadic fatal insomnia case with thalamic/olivary degeneration and spongiform changes showed transmissibility of both the typical and atypical fatal familial insomnia phenotypes. Protein misfolding cyclic amplification could amplify both typical fatal familial insomnia cases and sporadic fatal insomnia cases but not the atypical fatal familial insomnia phenotype or other sporadic Creutzfeldt-Jakob disease subtypes. In addition to clinical findings and neuropathological features, the transmission properties and the amplification properties were different between the typical and atypical fatal familial insomnia phenotypes. It is suggested that two distinct prions were associated with the diversity in the fatal familial insomnia phenotype, and these two prions could also be detected in sporadic fatal insomnia.

Fatal familial insomnia and Agrypnia Excitata: Autonomic dysfunctions and pathophysiological implications

Fatal Familial Insomnia (FFI) is a hereditary prion disease caused by a mutation at codon 178 of the prion-protein gene leading to a D178N substitution in the protein determining severe and selective atrophy of mediodorsal and anteroventral thalamic nuclei. FFI is characterized by physiological sleep loss, which polygraphically appears to be a slow wave sleep loss, autonomic and motor hyperactivation with peculiar episodes of oneiric stupor. Alteration of autonomic functions is a great burden for FFI patients consisting in sympathetic overactivation, dysregulation of its physiological responses and disruption of circadian rhythms. The cardiovascular system is the most frequently and severely affected confirming the increased sympathetic drive with preserved parasympathetic responses. Sleep loss, autonomic and motor hyperactivation define Agrypnia Excitata (AE), which is not exclusive to FFI, but it has been canonically described also in Morvan Syndrome and Delirium Tremens. These three conditions present different pathophysiological mechanisms but share the same thalamo-limbic impairment of which AE is one of the possible clinical presentations. FFI, and consequently also AE, is a model for the investigation of the essential role of the thalamus in the organization of body homeostasis, integrating both sleep and autonomic function control.

Sporadic Fatal Insomnia in Europe: Phenotypic Features and Diagnostic Challenges

OBJECTIVE

Comprehensively describe the phenotypic spectrum of sporadic fatal insomnia (sFI) to facilitate diagnosis and management of this rare and peculiar prion disorder.

METHODS

A survey among major prion disease reference centers in Europe identified 13 patients diagnosed with sFI in the past 20 years. We undertook a detailed analysis of clinical and histopathological features and the results of diagnostic investigations.

RESULTS

Mean age at onset was 43 years, and mean disease duration 30 months. Early clinical findings included psychiatric, sleep, and oculomotor disturbances, followed by cognitive decline and postural instability. In all tested patients, video-polysomnography demonstrated a severe reduction of total sleep time and/or a disorganized sleep. Cerebrospinal fluid (CSF) levels of proteins 14-3-3 and t-tau were unrevealing, the concentration of neurofilament light protein (NfL) was more consistently increased, and the real-time quaking-induced conversion assay (RT-QuIC) revealed a positive prion seeding activity in 60% of cases. Electroencephalography and magnetic resonance imaging showed nonspecific findings, whereas fluorodeoxyglucose positron emission tomography (FDG-PET) demonstrated a profound bilateral thalamic hypometabolism in 71% of cases. Molecular analyses revealed PrP^Sc type 2 and methionine homozygosity at PRNP codon 129 in all cases.

INTERPRETATION

sFI is a disease of young or middle-aged adults, which is difficult to reconcile with the hypothesis of a spontaneous etiology related to stochastic, age-related PrP misfolding. The combination of psychiatric and/or sleep-related symptoms with oculomotor abnormalities represents an early peculiar clinical feature of sFI to be valued in the differential diagnosis. Video-polysomnography, FDG-PET, and especially CSF prion RT-QuIC and NfL constitute the most promising supportive diagnostic tests in vivo. Ann Neurol 2018;84:347-360.

Fatal familial insomnia and sporadic fatal insomnia

Fatal familial insomnia (FFI) and sporadic fatal insomnia (sFI), or thalamic form of sporadic Creutzfeldt-Jakob disease MM2 (sCJDMM2T), are prion diseases originally named and characterized in 1992 and 1999, respectively. FFI is genetically determined and linked to a D178N mutation coupled with the M129 genotype in the prion protein gene (PRNP) at chromosome 20. sFI is a phenocopy of FFI and likely its sporadic form. Both diseases are primarily characterized by progressive sleep impairment, disturbances of autonomic nervous system, and motor signs associated with severe loss of nerve cells in medial thalamic nuclei. Both diseases harbor an abnormal disease-associated prion protein isoform, resistant to proteases with relative mass of 19 kDa identified as resPrP^TSE type 2. To date at least 70 kindreds affected by FFI with 198 members and 18 unrelated carriers along with 25 typical cases of sFI have been published. The D178N-129M mutation is thought to cause FFI by destabilizing the mutated prion protein and facilitating its conversion to PrP^TSE. The thalamus is the brain region first affected. A similar mechanism triggered spontaneously may underlie sFI.

Clinical findings of a probable case of MM2-cortical-type sporadic Creutzfeldt-Jakob disease with antibodies to anti-N-terminus of α-enolase

We report the case of a 76-year-old woman presenting with 47-month history of progressive dementia and cortical blindness with no family history. Antibodies against thyroid glands and the N-terminus of α-enolase (NAE) were detected in her serum. Neurological examination revealed progressive dementia, frontal signs, visual disturbance, and exaggerated bilateral tendon reflexes in both legs. Diffusion MRI showed cortical hyper-intensities in the bilateral occipital and parietal, and the left frontal and temporal cortices. ^99mTc-ethyl cysteinate dimer-single photon emission computed tomography indicated decreased regional cerebral blood flow throughout the bilateral parietal lobes and partially in the left frontal and temporal lobes. PRNP gene analysis showed no mutations with methionine homozygosity at codon 129 in peripheral blood. Cerebrospinal fluid examination, including 14-3-3 and total tau protein detection, revealed normal levels; however, prion proteins were amplified by the real-time quaking-induced conversion method. Hashimoto's encephalopathy was excluded on the basis of unresponsiveness to corticosteroids. The symptoms progressed slowly. Periodic sharp-wave complexes were observed on electroencephalogram 36 months after the onset of symptoms; the patient reached a state of akinetic mutism at 47 months. This was a probable case of MM2-cortical-type sCJD with anti-NAE antibodies based on the World Health Organization (WHO) diagnostic criteria for sCJD, genetic information, and the slowly progressive course. However, this case did not meet with the probable WHO diagnostic criteria until 3 years after symptom onset, highlighting the difficulty of diagnosing a living case of the MM2-type of sCJD. Therefore, establishment of clinical diagnostic criteria for MM2-type of sCJD is required.

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.

An autopsied case of MM1 + MM2-cortical with thalamic-type sporadic Creutzfeldt-Jakob disease presenting with hyperintensities on diffusion-weighted MRI before clinical onset

A 78-year-old Japanese man presented with rapidly progressive dementia and gait disturbances. Eight months before the onset of clinical symptoms, diffusion-weighted magnetic resonance imaging (DWI) demonstrated hyperintensities in the right temporal, right parietal and left medial occipital cortices. Two weeks after symptom onset, DWI showed extensive hyperintensity in the bilateral cerebral cortex, with regions of higher brightness that existed prior to symptom onset still present. Four weeks after clinical onset, periodic sharp wave complexes were identified on an electroencephalogram. Myoclonus was observed 8 weeks after clinical onset. The patient reached an akinetic mutism state and died 5 months after onset. Neuropathological examination showed widespread cerebral neocortical involvement of fine vacuole-type spongiform changes with large confluent vacuole-type spongiform changes. Spongiform degeneration with neuron loss and hypertrophic astrocytosis was also observed in the striatum and medial thalamus. The inferior olivary nucleus showed severe neuron loss with hypertrophic astrocytosis. Prion protein (PrP) immunostaining showed widespread synaptic-type PrP deposition with perivacuolar-type PrP deposition in the cerebral neocortex. Mild to moderate PrP deposition was also observed extensively in the basal ganglia, thalamus, cerebellum and brainstem, but it was not apparent in the inferior olivary nucleus. PrP gene analysis showed no mutations, and polymorphic codon 129 showed methionine homozygosity. Western blot analysis of protease-resistant PrP showed both type 1 scrapie type PrP (PrP^Sc ) and type 2 PrP^Sc . Based on the relationship between the neuroimaging and pathological findings, we speculated that cerebral cortical lesions with large confluent vacuoles and type 2 PrP^Sc would show higher brightness and continuous hyperintensity on DWI than those with fine vacuoles and type 1 PrP^Sc . We believe the present patient had a combined form of MM1 + MM2-cortical with thalamic-type sporadic Creutzfeldt-Jakob disease (sCJD), which suggests a broader spectrum of sCJD clinicopathological findings.

Sporadic fatal insomnia in a young woman: a diagnostic challenge: case report

Background

Sporadic fatal insomnia (sFI) and fatal familial insomnia (FFI) are rare human prion diseases.

Case Presentation

We report a case of a 33-year-old female who died of a prion disease for whom the diagnosis of sFI or FFI was not considered clinically. Following death of this patient, an interview with a close family member indicated the patient's illness included a major change in her sleep pattern, corroborating the reported autopsy diagnosis of sFI. Genetic tests identified no prion protein (PrP) gene mutation, but neuropathological examination and molecular study showed protease-resistant PrP (PrP^res) in several brain regions and severe atrophy of the anterior-ventral and medial-dorsal thalamic nuclei similar to that described in FFI.

Conclusions

In patients with suspected prion disease, a characteristic change in sleep pattern can be an important clinical clue for identifying sFI or FFI; polysomnography (PSG), genetic analysis, and nuclear imaging may aid in diagnosis.

High-b-value diffusion MR imaging and basal nuclei apparent diffusion coefficient measurements in variant and sporadic Creutzfeldt-Jakob disease

BACKGROUND AND PURPOSE

DWI using a standard b-value of 1000 s/mm(2) has emerged as the most sensitive sequence for the diagnosis of CJD. The purpose of this study was to investigate whether DWI at a high b-value (b = 3000 s/mm(2)) and ADC measurements in the basal nuclei improve the diagnosis of vCJD and sCJD compared with visual assessment of DWI at a standard b-value (b = 1000 s/mm(2)).

MATERIALS AND METHODS

Eight patients with vCJD, 9 patients with sCJD, and 5 healthy volunteers underwent DWI at b = 1000 s/mm(2), and 5 vCJD patients, 4 sCJD patients, and 1 growth hormone-related CJD patient underwent DWI at b = 3000 s/mm(2). Two consultant neuroradiologists performed a visual comparison of the b = 1000 and b = 3000 images. Mean MR SI and ADC values were determined for C, P, and DM thalamus ROIs bilaterally at each b-value. SI ratios for each ROI relative to white matter were calculated.

RESULTS

In 9 out of 10 patients, the higher b-value images were more sensitive to SI change, particularly in cortex and thalamus, with higher SI ratios at b = 3000 in the DM thalamus. For sCJD at b = 1000, we found significantly lower ADC values in the C and P compared with controls (mean C ADC = 587.3 +/- 84.7 mm(2)/s in sCJD patients versus 722.7 +/- 16.6 mm(2)/s in controls; P = .007), and at b = 3000, the differences were more pronounced. In comparison, in vCJD at b = 1000, ADC values were elevated in the Pu (mean Pu ADC = 837.6 +/- 33.0 mm/s(2) in vCJD patients versus 748.0 +/- 17.3 mm/s(2) in controls; P < .001) but failed to reach significance at b = 3000.

CONCLUSIONS

Our results demonstrate that b = 3000 DWI, being more sensitive to slowly diffusing tissue water, is more sensitive to pathology in sCJD than is conventional DWI. High-b-value DWI increases confidence in the radiologic diagnosis of human prion disease.

[Epidemiologic study of Creutzfeldt-Jakob disease from autopsy-confirmed cases]

We investigated epidemiologic data from 61 cases of autopsy-confirmed sporadic Creutzfeldt-Jakob disease (CJD). Dura mater-associated CJD cases and familial CJD cases were excluded. There were 34 male and 27 female cases, with an average age at onset of 66.0 +/- 10.5 years (range 27 to 89). At onset of CJD, 1 case was aged in the 20's and 1 in 30's, but there were no cases aged in the 40's. In 6 cases, age at onset was in the 80's. There was no significant difference in relation to the age at onset between males and females, averaging 66.2 +/- 12.4 years (range 27 to 89), and 65.9 7.5 years (range 53 to 82), respectively. Two cases had been employed as medical workers (a medical technologist and a nurses' aide) but neither had an apparent history of contact with CJD patients. No cases in the study had either family history of CJD or apparent contact with CJD patients. Ten cases had a history of hypertension, 5 cases had a history of diabetes mellitus, 2 cases had a history of malaria and 1 case had suffered from atomic bomb exposure. Twenty-one cases had operation history, including 2 cases of an operation involving the central nervous system. One case had a skull-base fracture operation 19 years before the onset of CJD and the other case had an atlantoaxial subluxation operation 11 years before the onset of CJD; there was no transplantation of dura mater graft in either operation. There was one case with a history of conservative treatment for cerebral hemorrhage; this case had symptomatic secondary epilepsy as a coexisting disease at the onset of CJD. Two cases had Parkinson's disease as a coexisting disease at the onset of CJD. The source hospitals enforcing medical treatment were located in the Aichi (n = 42), Gifu (n = 12) and Mie (n = 7) prefectures of the Tokai region of Japan. Regarding patients' place of residence, 22 cases resided in Nagoya-city. Nagoya University Hospital performed the autopsy in 12 cases, but 10 cases of those were transported after death from the source hospital. Departments of neurology provided clinical treatment in 54 cases. Other departments that provided treatment were Internal Medicine (n = 3), Psychiatry (n = 2), Geriatrics (n = 1), and Neurosurgery (n = 1). In 39 cases, prion protein gene analyses using peripheral blood leukocyte or cryopreserved brain tissue were performed. As for polymorphic codon 129, 36 cases (92%) showed Met/Met, 3 cases showed Met/Val (8%) and no case showed Val/Val polymorphism. Polymorphic codon 219 showed Glu/Glu homozygosity in all of the examined cases. Active autopsy performance of CJD in the Tokai region was suggested from the present study. We estimated that the CJD autopsy rate of the district was more than 50% over the past 7 years.

MM2-cortical-type sporadic Creutzfeldt-Jakob disease with early stage cerebral cortical pathology presenting with a rapidly progressive clinical course

We report the case of a 67-year-old man with MM2-cortical-type sporadic Creutzfeldt-Jakob disease (sCJD) with a rapidly progressive clinical course of 5 months. Initial symptoms were progressive memory disturbance and dementia. MRI revealed high signal-intensity lesions on diffusion-weighted images in the bilateral frontal and occipital cortices. Myoclonus and periodic sharp-wave complexes on the electroencephalogram were observed in the early disease stage. The clinical diagnosis was typical sCJD. Neuropathologic examination at autopsy showed widespread, characteristic cerebral neocortical involvement with large confluent vacuole-type spongiform change. Spongiform degeneration was also evident in the striatum and medial thalamus. In the cerebellar cortex, slight depletion of Purkinje neurons was evident without spongiform change in the molecular layer or apparent neuron loss in the granule cell layer. The inferior olivary nucleus showed slight hypertrophic astrocytosis without neuron loss. Prion protein (PrP) immunostaining showed widespread, characteristic perivacuolar-type PrP deposits with irregular plaque-like PrP deposits in the cerebral neocortex, striatum and medial thalamus. We believe this patient showed early-stage cerebral cortical pathology of MM2-cortical-type sCJD, which may provide clues regarding the pathologic progression of this rare sCJD subtype. Although MM2-cortical-type sCJD generally shows slow progression without myoclonus or periodic sharp-wave complexes, the present patient showed a rapidly progressive clinical course similar to that of MM1-type sCJD.

MM1-type sporadic Creutzfeldt-Jakob disease with unusually prolonged disease duration presenting with panencephalopathic-type pathology

We report an autopsy case of MM1-type sporadic Creutzfeldt-Jakob disease (sCJD) with an unusually prolonged disease duration of 58 months. The initial symptom was progressive mental disorder followed by advanced cognitive impairment. Clinical progression was generally slow; myoclonus appeared at 17 months and periodic sharp-wave complexes on electroencephalogram at 21 months. A state of akinetic mutism occurred 29 months after the onset of symptoms. MRI showed gradually progressive cerebral atrophy. Neuropathologic examination showed widespread severe brain involvement. In the cerebral neocortex, widespread severe tissue rarefaction, hypertrophic astrocytosis and neuron loss (so-called status spongiosus) were observed. The cerebral white matter showed diffuse myelin pallor with intense hypertrophic astrocytosis, numerous foamy macrophages and emperipolesis, indicating panencephalopathic-type sCJD pathology. The brainstem was relatively preserved from sCJD pathology, with the exception of the pontine nucleus and pyramidal tract. This may explain the prolonged disease duration without respiratory insufficiency until the terminal stage. Immunohistochemistry for prion protein (PrP) showed widespread synaptic-type PrP deposits in the cerebral neocortex, hippocampus and thalamus. The striatum and cerebellar cortex showed faint synaptic-type PrP deposition with some areas of small plaque-like PrP deposition. Sparse PrP deposition was also observed in the brainstem. Analysis of the PrP gene showed no mutation but methionine homozygosity at polymorphic codon 129. Western blot analysis of protease-resistant PrP indicated type 1 PrP. To our knowledge, this is the longest reported disease duration of MM1-type sCJD.