益子 貴史

BACKGROUND: This case reports aimed to clarify the characteristic MRI findings in GABAA receptor encephalitis. CASE PRESENTATION: We report the cases of two encephalitis patients who had a history of thymoma surgery and in whom anti-GABAAR antibodies and characteristic MRI findings were observed. These patients were clinically diagnosed as having thymoma-associated paraneoplastic encephalitis (TAPE) before the antibodies were identified. TAPE is often associated with antibodies to various neuronal surface antigens, including GABAAR, AMPAR, CASPR2, LGI1, and GlyR. MRI findings of autoimmune encephalitis are extremely variable, but when multiple homogenous high-signal-intensity lesions are observed on FLAIR images, as in these cases, anti-GABAAR antibodies are likely to be involved. We have named here this MRI finding the "cotton-wool-like appearance". CONCLUSION: In cases of encephalitis with such characteristic radiological findings, neurologists should first investigate the presence or a history of thymoma surgery, and then promptly consider testing for anti-GABAAR antibodies.

Only a few reports have generated induced pluripotent stem cells from patients with prion diseases, making it important to conduct translational studies using cells derived from individuals with prion protein (PRNP) mutations. In this study, we established induced pluripotent stem cells from a patient with a glycosylphosphatidylinositol-anchorless PRNP mutation (Y162X), which leads to abnormal deposits of prion protein in various organs. While no abnormal intracellular prion protein deposits were observed in the neurons differentiated from PRNP Y162X induced pluripotent stem cells, extracellular PrP aggregates secretions were significantly increased, and these cells were significantly more sensitive to oxidative stress compared to control cells. Utilizing this PRNP Y162X iPSC-derived neuron model, we discovered that edaravone reduced the sensitivity of PRNP Y162X cells to oxidative stress. Following this finding, we treated a PRNP Y162X patient with edaravone for two years, which successfully suppressed indicators of disease progression. Our study demonstrates that the pathology of the glycosylphosphatidylinositol-anchorless PRNP mutation is associated with oxidative stress and highlights the potential of induced pluripotent stem cell technology in identifying novel treatments for rare prion diseases.

A 69-year-old man was admitted to our hospital because of a sudden gait disturbance. Based on the neurological examination performed upon admission, the patient exhibited ataxic movement in his right lower limb and body lateropulsion toward the right side. Magnetic resonance imaging revealed a lower lateral medullary infarction limited to the lateral surface. A motion analysis revealed ipsilateral lower-limb ataxia. Lower lateral medullary infarction can cause ipsilateral lower limb ataxia, particularly impaired hip joint coordination, resulting in body lateropulsion in dynamic conditions.

Delusional misidentification, a rare syndrome in which a patient displays persistent delusional misidentification of individuals or objects, occurs in several types of dementia. However, the pathology of delusional misidentification is still unclear, and there was no data pertaining to striate-frontal projection. Here, we report a case of delusional misidentification following frontotemporal dementia in which complex striate-frontal and some specific frontal gyrus dysfunction were observed. In our presented case, delusional misidentification progressed following frontal atrophy. Believing that her actual daughter had been replaced by her niece, her symptoms of delusional misidentification and frontal atrophy progressed in the short term, and social arrangement was necessary three months after the onset. There were no abnormal neurological findings including parkinsonism and general cognitive function test scores were preserved. Validated by dopamine transporter single-photon emission computed tomography, right unilateral striatal uptake decreased significantly without parkinsonism or Parkinson's disease. In addition, of specific concern, functional magnetic resonance images showed left opercular inferior frontal gyrus and right superior frontal gyrus dysfunctions. Our case study highlights complex striate-frontal projection and specific frontal gyrus dysfunctions associated with the pathology of delusional misidentification syndrome.