The diagnosis of Parkinson’s disease (PD) requires the exclusion of other diseases using various methods. However, it is difficult to differentiate these diseases based only on clinical symptoms, and information regarding responses to drugs and several imaging examinations are often needed for a diagnosis. In recent years, various neurological signs and symptoms have been reported that are particularly useful in neurological examinations for differentiating PD, progressive supranuclear palsy, and multiple system atrophy. Currently, diagnosis using imaging techniques and artificial intelligence are being developed, but systematic neurological examinations will continue to be important in diagnosing these diseases.

Due to the pandemic of corona virus disease 2019 (COVID-19), the stroke medical care system is unavoidably undergoing major changes such as a decrease in the number of stroke patients receiving consultation, delay in consultation, and a decrease in the number of intravenous thrombolysis and mechanical thrombectomy procedures. Stroke incidence in COVID-19 patients is approximately 1.1%. The features of stroke with COVID-19 have been elucidated: higher incidence in ischemic stroke than hemorrhagic stroke, increasing number of young patients, high D-dimer levels, and higher risk in elderly patients with cardiovascular risk factors such as hypertension and diabetes. In patients with COVID-19, venous thromboembolism is more common than arterial thromboembolism, and stroke is more common than acute coronary syndrome. Protected code stroke (PCS) has been proposed which provides safe, effective and prompt treatment under complete infection control.

An 89-year-old man was admitted because of persistent fever and impaired consciousness. On admission, his consciousness level was E3V3M4 according to the Glasgow Coma Scale. MRI of the brain showed high intensity lesions in the bilateral cingulate gyri. In the cerebrospinal fluid, both cell counts and glucose level were in the normal ranges. He had received antibiotics and intravenous isotonic saline. On the fifth day of hospitalization, blood examination revealed elevation of anti-herpes simplex virus (HSV) immunoglobulin M antibody, and herpes simplex encephalitis (HSE) was diagnosed. Despite treatment with acyclovir, his respiratory function and consciousness level deteriorated rapidly. On the eighth day, he died of respiratory failure. At autopsy, the brain showed multiple softenings of the gray and white matter in the hippocampus, amygdala, and temporal, insular, and cingulate cortices. Some of these lesions were hemorrhagic. Microscopic examination revealed that the lesions were necrotic and associated with perivascular inflammatory cell infiltration in the limbic system, hypothalamus, brainstem tegmentum area, and medulla. Eosinophilic intranuclear inclusions were rarely found in the astrocytes in the medulla. Immunohistochemistry revealed anti-HSV-1 antibody positive neurons in the brainstem tegmentum including reticular formation and the raphe nuclei. HSV-DNA was also detected in the postmortem cerebrospinal fluid. This was a rare case of HSE in which inflammation in the brainstem proved to be the cause of lethal respiratory failure.

Patient 1 was a 55-year-old male with cerebral infarction due to obstruction of the left middle cerebral artery during treatment for bacteremia, along with a verruca of infectious endocarditis harvested from endovascular thrombectomy. Patient 2 was a 59-year-old female suffering from cerebral infarction at the terminal branch during intrahepatic cholangiocarcinoma chemotherapy who thereafter developed cerebral infarction again due to obstruction of the left middle cerebral artery, along with a verruca of nonbacterial thrombotic endocarditis (NBTE) harvested from endovascular thrombectomy. In tumor-bearing patients, while NBTE may be more closely related to the development of cerebral infarctions than previously assumed, we also need pay attention to the onset of infectious endocarditis. We need further studies on the effectiveness and safety of thrombolysis therapy and endovascular thrombectomy for cerebral infarctions due to endocarditis in both patients. The harvested emboli may provide clues to the differentiation thereof.

A 77-year-old man with a history of lung cancer at the age of 71 developed involuntary right leg movement for a month. Neurological examination revealed a right-sided hemi-chorea. Autoimmune disease was suspected owing to the presence of oligoclonal bands and the elevated IgG-index in the cerebrospinal fluid. We detected anti-SRY-Related HMG-Box Gene 1 (SOX1) antibodies, known to be serological markers of Lambert-Eaton syndrome with small cell lung cancer, but not tumors. The results of tests for antiphospholipid, anti-LGI1, and anti-CASPR2 antibodies associated with non-paraneoplastic autoimmune chorea were all negative. This is the first suggestive case of autoimmune chorea in which anti-SOX1 antibodies were detected.

A 63-year-old man was admitted to our hospital with a 2-month history of anxiety. He presented with cognitive impairment and muscle weakness. On MRI, T₂-weighted images showed longitudinally extensive spinal cord lesion (LESCL) from C2 to T6 and gadolinium-enhanced T₁-weighted images showed fan-shaped multiple linear enhancements converging to the lateral ventricles. He was diagnosed as primary central nervous system vasculitis (PCNSV) by brain biopsy. After using high dose corticosteroids, cognitive impairment and muscle weakness were dramatically improved. In patients with cognitive impairment, PCNSV should be included in the differential diagnosis of LESCL.

A 72-year-old man was admitted to our hospital because of right facial muscle weakness and diplopia. He had been treated for aplastic anemia with cyclosporin for 2 years. Thirteen days before admission, a diagnosis of herpes zoster was made and treated with amenamevir. On admission, neurological examination revealed mild cognitive disturbance, mydriasis, weakness of the inferior rectus muscle of the left eye, and right peripheral facial nerve palsy. Cerebrospinal fluid (CSF) analysis showed elevated leukocytes and increased protein levels. Antibody index to varicella-zoster virus (VZV) was elevated in CSF to 25.6, although VZV DNA was negative by PCR. Head CT revealed multiple intracerebral hemorrhages in the left dorsal pons, left ventral midbrain, left thalamus, and left front-parietal lobe. MR angiography detected cerebral artery stenosis. In addition to intravenous acyclovir, the patient was treated with steroid pulse therapy and steroid tapering therapy. One month after admission, his symptoms improved. We diagnosed him with VZV vasculopathy. We believe that multiple intracerebral hemorrhages due to VZV vasculopathy caused facial and oculomotor nerve palsy. Our findings suggest that cerebral hemorrhage induced by VZV vasculopathy must be considered when differentiating cranial nerve palsy after herpes zoster.

A 40-year-old male patient was diagnosed with invasive thymoma and myasthenia gravis in 2015. In 2016 and 2017, he experienced myasthenic crises, with an increase in size of invasive thymoma. In 2018, he received chemotherapy for the invasive thymoma. After 2 months, his symptoms rapidly progressed to myasthenic crisis with severe bulbar and respiratory symptoms, despite the significant effect of chemotherapy for the thymoma. High-dose corticosteroid, multiple plasma exchanges, and intravenous immunoglobulin did not improve the symptoms. Thus, eculizumab was administered, resulting in an improvement in his conditions. To our knowledge, this is the first report showing that eculizumab may improve myasthenic crisis with invasive thymoma.

An 84-year-old man was admitted to our hospital with new-onset refractory status epilepticus of unclear etiology. On the third day, diffusion-weighted brain MRI demonstrated lesions in the right medial temporal and parietal lobes. As a CSF sample showed pleocytosis, paraneoplastic limbic encephalitis (PLE) associated with small cell lung cancer (SCLC) was suspected. The patient was also positive for anti-gamma aminobutyric acid (GABA)_B receptor antibody in the CSF, which has recently been reported in elderly patients with SCLC-related PLE. Methylprednisolone pulse therapy ameliorated the symptoms. It is noteworthy that immune therapy often improves the symptoms of PLE with anti-GABA_B receptor antibody, even though radical therapy for the lung cancer may be difficult.

A 56-year-old man presented to our hospital as he presented progressive hemiplegia of the right upper limb with no other symptoms, including chest pain. Inter-arm blood pressure difference was not observed. Laboratory investigations revealed an elevated D-dimer value (2.4 μg/ml). Chest X-ray study showed normal findings without widened mediastinum. Brain MRI showed acute multiple brain infarcts in the left posterior limb of the internal capsule and right pons on diffusion-weighted imaging. Bilateral internal carotid arteries were non-occlusive in MRA. Carotid duplex ultrasonography revealed normal internal carotid artery flow velocities bilaterally. Because ischemic lesions were found in multiple vascular territories, and D-dimer value was elevated, the patient underwent thoracic contrast-enhanced-CT to exclude malignant tumors. Stanford type A aortic dissection limited to the ascending aorta was detected. As the plaque had accumulated in the false lumen, we suspected that plaque in the false lumen could be an embolic source. After ascending aortic replacement surgery, brain infarction did not recur during hospitalization. In cases of ischemic stroke wherein multiple vascular territories are detected, and D-dimer value is elevated, even in patients without chest pain, the possibility of painless Stanford type A aortic dissection should be ruled out as an embolic source.