High prevalence of amyotrophic lateral sclerosis (ALS) in Kii Province (Kii) located in southern Kii Peninsula was first pointed out by Kinnosuke Miura in 1911, and epidemiological studies by Kiyoshi Kimura et al. verified extremely high incidence after World War II. In 1970s, Yoshiro Yase pointed out that “endemic paraplegia of Koza in Kii” in Honcho Koji Innen Shu published in 1689 would mean the same disorder as that of ALS and be the earliest description of Kii ALS although he gave no clear grounds. In this study, the original of the article was presented with an English translation, and factuality of it was investigated from the viewpoints of geography, geology, culture and history of Kii. As a result, it was shown that the article was probably written based on historical events and that the “endemic paraplegia” meant the same disorder as Kii ALS. The author has concluded that “endemic paraplegia of Koza in Kii” is likely to be the earliest description of Kii ALS since ALS is included in the causes of paraplegias of these kinds.

Anti-IgLON5 diseases were first reported in 2014 as sleep disorders such as parasomnia and obstructive sleep apnea. The pathological findings were suggestive of tauopathies and eight clinical subtypes have been reported so far. Serum and cerebrospinal fluid anti-IgLON5 antibodies should be measured in patients with sleep-related disorders with parasomnia as well as in patients with movement disorders, motor neuron disease or dementia with characteristic parasominia. The prognosis is generally poor, but some patients have been reported to improve with immunotherapy. Early diagnosis and early immunotherapy may improve the prognosis.

Progressive multifocal leukoencephalopathy (PML) is a rare opportunistic infection caused by JC virus (JCV) activation. We report an 85-years old man who had been diagnosed to have rheumatoid arthritis (RA) 1.5 years prior to diagnosis of PML, and had been treated with salazosulfapyridine (SASP). He developed weakness of the left upper limb, which progressed gradually for two months. A neurological examination on admission revealed severe palsy of the left upper limb without sensory disturbance, cognitive decline or gait disturbance. Brain MRI revealed white matter lesions in the right frontal lobe around the precentral gyrus. Cerebrospinal fluid (CSF) examination and peripheral lymphocyte counts were normal. HIV was ruled out serologically. There were no findings suggestive of malignancy. We suspected PML and stopped SASP. JCV-DNA was detected in CSF. There were enlarged nuclei positive with VP-1 immunostaining in the brain biopsy materials. Thus, the diagnosis of PML was definitive. Paralysis of the left upper limb began to improve one week after discontinuing SASP. Treatment with mefloquine and mirtazapine was initiated, but he developed severe interstitial pneumonia, which might be caused by mefloquine. Therefore, he underwent rehabilitation without medication. JCV-DNA became undetectable and white matter lesions decreased 6 months later. Paralysis improved and he had no problem with activities of daily living a year later. The risk factor for PML has changed over the last decade, and drugs such as biologics became significant risk factors for patients with autoimmune diseases. There are reports suggesting that systemic lupus erythematosus (SLE) and RA themselves might be independent risk factors for PML. Although there is no previous report of SASP inducing PML, SASP might be the culprit in our case. However, there is another possibility that SAPS and RA worked synergistically for the onset of PML.

We report an 80-year-old man with IgG4-related pleuritis who had been treated with a low dose oral steroid for two years and developed recurrent myelitis. He was admitted to our hospital with gradually worsening numbness in the lower body and difficulty in walking due to mild weakness and loss of proprioception in the legs. T₂-weighted MR images of the spinal cord showed a high signal intensity lesion, located centrally in the spinal cord at the Th2–4 spine levels. Laboratory data revealed an elevated serum IgG4 level and cerebrospinal fluid protein level. Anti-aquaporin 4 antibody, anti-myelin oligodendrocyte glycoprotein antibody and other autoantibodies were negative. He showed a good response to the administration of steroid pulse therapy with almost resolution of the neurological symptoms and MRI findings. He was followed with the maintenance therapy with a low dose oral steroid. After one year, he developed recurrence of myelitis in the lower end of the medulla oblongata and in the central to dorsal area at the C2 spine level. Each lesion of recurrent myelitis was located within 3 vertebral segments length and improved without focal spinal atrophy. Recently, IgG4-related disease (IgG4-RD)-associated inflammation involving brain parenchyma and spinal cord were reported. Further investigations are needed to elucidate the relationship between IgG4-RD and seronegative recurrent myelitis.

Neurocutaneous melanosis is caused by postzygotic NRAS mutations in neural crest cells, resulting in large or multiple nevi in the skin and proliferation of leptomeningeal melanocytes in the central nervous system. The onset of neurological symptoms is usually before the age of 2 years, but it can also occur in adults. A 35-year-old male had been asymptomatic for a long time after excision of a large congenital melanocytic nevus, but he developed headache, disturbance of consciousness, and seizure. Methotrexate was ineffective, cerebral pressure was decreased by spinal drainage, and steroid pulse therapy was temporarily effective. Seizures and disturbance of consciousness worsened and the patient died on the 92nd day. Cerebrospinal fluid human melanin black-45 immunostaining and serum 5-S-cysteinyldopa (5-S-CD) were useful in diagnosing melanocytic proliferation, and serum 5-S-CD may be useful in predicting prognosis.

A 76-year-old woman with a 1-month history of headache, jaw claudication, scalp tenderness, and blurred vision was admitted to our hospital. Erythrocyte sedimentation rate was highly elevated. Brain MRI showed marked perineural optic nerve enhancement and superficial temporal artery enhancement bilaterally. Neuro-ophthalmic examination detected left dominant decline in critical fusion frequency whereas visual acuity, visual fields, and ophthalmoscopy were normal. Intravenous pulse methylprednisolone was administered for 3 days to treat suspected giant cell arteritis (GCA); however, visual acuity in the left eye declined and horizontal hemianopia developed. Ophthalmoscopy revealed pallid optic disc edema on the left. Histopathologic examination of a right temporal artery biopsy specimen showed intimal thickening, mild mural inflammation consisting predominantly of lymphocytes with occasional giant cells, and focal disruption of the internal elastic lamina, consistent with GCA. Perineural optic nerve enhancement on contrast-enhanced MRI may be a valuable clue for diagnosing ischemic optic neuropathy and may indicate the need for urgent treatment.

An 82-year-old man presented with subacute bilateral lower limb paralysis, deep sensory disturbance, and vesico-rectal disturbance. MRI of the spinal cord revealed a large gray matter-dominant lesion extending from the medulla oblongata to the lower thoracic spinal cord. The patient was treated with steroid-pulse therapy for myelitis, but without symptomatic improvement. A spinal cord biopsy was performed for treatment-resistant myelopathy, and histopathology revealed a diffuse large B-cell lymphoma, that was diagnosed as a primary intramedullary spinal cord lymphoma because systemic examination didn’t show any other findings suggestive of malignant lymphoma. A spinal cord biopsy is necessary for the definitive diagnosis of this disease, but in the case of poor response to treatment and a progressive course, intramedullary malignant lymphoma should be considered if there is a persistent elevation of CSF IL-10 or a prolonged contrast effect.

A 35-year-old man was admitted to our department for loss of consciousness. CT and MRI revealed diffuse enhancement of the subarachnoid space surrounding the brainstem and the cerebellar sulci, without any parenchymal lesions in the brain or the spinal cord. Furthermore, gadolinium-enhanced MRI revealed a nodular lesion with heterogeneous enhancement in the right prepontine cistern, at the site from which a biopsy was obtained via right lateral suboccipital craniotomy on the day following admission. Histopathological examination of the resected specimen revealed glioblastoma multiforme. Based on the radiological and histopathological findings, the patient was diagnosed with primary leptomeningeal gliomatosis (PLG). The patient received temozolomide chemotherapy with concurrent radiotherapy and showed radiological remission, 12 months after diagnosis. However, he developed local recurrence 6 months later and died 23 months after diagnosis. Autopsy findings showed tumor cell infiltration of the leptomeninges, as well as the brain and spinal parenchyma. PLG should be considered in the differential diagnosis in patients with diffuse leptomeningeal enhancement even without parenchymal lesions on radiological imaging. A surgical biopsy is recommended for prompt and accurate diagnosis in such cases.

An 81-year-old man presented with limb weakness and dysesthesia approximately 10 days after eating pork liver. His neurological examination revealed muscle weakness predominantly centered in the lower limbs and absence of deep tendon reflex, and cerebrospinal fluid analysis showed elevated proteins with normal cell counts. Furthermore, his nerve conduction studies revealed distal motor latency prolongation and decreased motor nerve conduction velocities in the bilateral median, ulnar, tibial, and peroneal nerves. Lastly, serological analysis was performed for hepatitis E virus markers, resulting in a positive result for hepatitis E virus (HEV)-IgA antibody and HEV-RNA. Given all these findings, the patient was diagnosed with acute HEV-associated Guillain–Barré syndrome (GBS), and intravenous immunoglobulin treatment was administered for five days. Following this, muscle weakness and dysesthesia gradually improved. As observed in this report, the number of HEV-associated GBS cases has been increasing over the past several years. Therefore, HEV infection should be considered in GBS patients who have a history of pork consumption or have been suffering from liver dysfunction.

A 72-year-old man presented with two episodes of migratory left-sided paresthesia lasting 10 min. At the first episode, diffusion-weighted imaging hyperintense lesions (DWIHLs) were seen in the right parietal lobe, suggesting an initial diagnosis of acute ischemic stroke, for which we administered antiplatelet therapy for secondary prevention. Four months later, he again developed transient migratory left-sided paresthesia. Gradient-echo T₂*-weighted imaging at this time showed disseminated cortical superficial siderosis (cSS) and strictly cerebral microbleeds around the DWIHLs in the right parietal lobe. These findings led to a diagnosis of cerebral amyloid angiopathy and its related findings, including transient focal neurological episodes (TFNE) and DWIHLs, and antiplatelet medication was stopped. In clinical settings, although it is challenging to distinguish TFNE of hemorrhagic origin from cerebral ischemic symptoms, including transient ischemic attacks, this case suggests that even when elderly patients with transient neurological symptoms present with cortical DWIHLs, paramagnetic-sensitive MRI should be performed to check for cSS around the DWIHLs.