Although we currently have two, approved, disease-modifying drugs for the treatment of amyotrophic lateral sclerosis (ALS), we are in disperate need for more efficacious treatment. To aggressively test for newer therapies, we must develop reliable objective biomarkers to supplement clinical outcome measures. Many biomarker candidates have been actively and vigorously investigated. Among neurophysiological biomarkers, transcranial magnetic stimulation (TMS)-based biomarkers show potential in exploring disease mechanisms. Neuroimaging biomarkers have high specificity in diagnosing ALS but are an expensive endeavor and are not sensitive enough to detect changes over time of the disease. Among fluid-based biochemical biomarkers, creatinine (Crn) and uric acids (UA), which have been known for decades, may prove to be highly promising biomarkers that can predict disease progression. They can be easily tested in any clinical trials because the costs are minimal. Although known for some time, neurofilaments (NF), either phosphorylated-NF heavy subunit (pNFH) or NF light subunit (NFL), have emerged as “new” biomarkers using specific antibodies. They appear to be highly specific and sensitive in diagnosing ALS, yet they may be insensitive to assess changes in disease over time. These two NF biomarkers along with Crn and UA should be explored extensively in future clinical trials and any other clinical studies in ALS. Yet, we still need newer, more innovative, and reliable biomarkers for future ALS research. Fortunatley, aggressive investigations appear to be currently underway.

We report an 18 year-old-male, who had been aware of decreased visual acuity for 6 months, newly presented with paresis and sensory disturbance in his right leg. On admission, his critical flicker frequency was reduced bilaterally, and his spinal cord MRI revealed T₂-hyperintense lesions in cervical and thoracic cord with occasional contrast enhancements, but none of them were longitudinally extensive. There was no evidence of T₂-hyperintense in his brain MRI. Anti-aquapolin-4 (AQP4) antibody was negative but the patient was positive for oligoclonal bands in his cerebrospinal fluid. The patient was tentatively diagnosed as opticospinal multiple sclerosis (OSMS). However, he later tuned out to be positive for anti-myelin oligodendrocyte glycoprotein (MOG) antibody. The 2017 revised McDonald criteria don’t take anti-MOG antibody into account in detail as to how clinicians should deal with patients fulfilling the MS criteria when they were also positive for anti-MOG antibody, because of its difficult problem of independence. So, we need to accumulate knowledge about these cases.

We present the unique case of a patient with lumbosacral radiculoplexus neuropathy (LRPN) and a small intramedullary lesion, probably an infarction, in the spinal cord. A previously healthy 58-year-old female developed acute severe pain involving the entire right lower limb, followed by weakness of the right lower limb a few hours later. The patient could not walk and was referred to our clinic. The patient reported no sphincter symptoms. Examination of the cranial nerves and upper limbs revealed no abnormalities. The strength in her right lower limb was reduced to Medical Research Council grade 1–2/5 with depressed tendon reflexes. The muscle power and tendon reflexes were normal in the left lower limb, whereas plantar responses were flexor on both sides. There was moderate sensory loss to light touch, pin-prick, vibration, cold temperature stimulation, and proprioception in the right lower limb. Routine laboratory tests and cerebrospinal fluid were unremarkable as were homocysteine, erythrocyte sedimentation rate, and antinuclear cytoplasmic antibody. The patient was diagnosed with LRPN, and treatment with intravenous immunoglobulin and methylprednisolone elicited favorable effects. After a four-week course of inpatient rehabilitation, the patient regained independent gait with a T-cane. Interestingly, thoracic MRI showed a small area of hyperintensity in the right posterior portion of the spinal cord at the level of T10 spine on diffusion-weighted images. The lesion showed slight hypointensity on the apparent diffusion coefficient map, suggesting acute infarction. Edema in the paraspinal muscles demonstrated by MRI suggested acute denervation caused by a lesion in the posterior rami or anterior roots. Somatosensory evoked potentials demonstrated prolonged N20 peak latency following right posterior tibial nerve stimulation, consistent with a lesion in right S1 and S2 roots. This case illustrates that microvasculitis, a keystone of the LRPN pathophysiology, could involve peripheral perforating arteries of the spinal cord.

A 75-year-old man presented with dysarthria and left facial paralysis. Brain diffusion-weighted MRI revealed a high-signal intensity in the right precentral gyrus, and he was hospitalized under the diagnosis of cerebral infarction. His symptoms worsened and brain MRI findings were consistent with progressive multifocal leukoencephalopathy (PML). Cerebrospinal fluid (CSF) JC virus (JCV) was undetectable in the DNA polymerase chain reaction (PCR) test four times, but brain biopsy revealed typical PML histopathology. He had no human immunodeficiency virus infection and history of immunosuppressive treatment, but he was found to have CD4+ lymphocytopenia. He was treated with mefloquine and mirtazapine, and died 29 months after symptoms onset. In cases whose repeated DNA PCR results are negative for CSF JCV, brain biopsy may be useful for the diagnosis of PML.

We report a 77-year-old man who suffered from Parkinson’s disease for 12 years. Four years after the disease onset, he started to show excessive hobbyism of painting. His painting skills improved along with escalating enthusiasm. He even held a personal exhibition of his paintings. Dopaminergic treatment was increased as he developed wearing-off phenomenon. Six years after the disease onset, he developed dopamine dysregulation syndrome (DDS). In the same year, he underwent surgery for subthalamic deep brain stimulation. DDS did not improve and he did not lose enthusiasm for painting after surgery. Switching from ropinirole to rotigotine improved the DDS, but did not affect the excessive enthusiasm. At the age of 76, he started to have difficulty in completing the paintings. He had an uncontrollable urge to overlay paint strokes until the colors blurred and the paper was torn. In neuropsychological examinations, Mini-Mental State Examination score was above the cutoff, but Frontal Assessment Battery suggested motor perseveration and disinhibition. In summary, the patient’s excessive enthusiasm for painting emerged in association with impulse control disorder (ICD) by dopamine agonist therapy, and subsequent change in his painting style appeared to be related with motor perseveration and/or further escalation of ICD.

We report a case of neuromyelitis optica (NMO) that was diagnosed at the age of 90. After initially developing visual loss in the right eye, a patient was diagnosed with optic neuritis. Although treatment with methylprednisolone therapy provided relief, 3 months later she developed optic neuritis on the other side. Visual activity recovered after further administration of methylprednisolone. At the age of 91, she presented with muscle weakness of her left extremities. A cervical MRI revealed myelitis with a longitudinally extensive spinal cord lesion from the second to fifth cervical vertebrae. Anti-AQP-4 antibody was detected in her serum. She was diagnosed with NMO and treated with methylprednisolone therapy. Subsequently, she repeatedly relapsed within a short period, developing myelitis once and optic neuritis three times within a year. However, during each hospitalization period, methylprednisolone therapy proved to be effective for relieving her symptoms. As NMO patients with onsets over 60 years of the age have been reported, medical practitioners should be aware that disease onset can occur at extremely older ages, such as 90 years old.

We reported a 31-year-old man with recurrent cerebral venous thrombosis caused by congenital protein C deficiency. He was diagnosed with cerebral venous thrombosis before 7 months. He was transferred to our hospital with numbness of right hand and right side of face, and dysarthria. The blood examination showed that his protein C antigen level and protein C activity were decreased than the lower limits of normal. Brain magnetic resonance venography showed poor visualization of the superior sagittal sinus and cortical veins. Genetic analysis revealed a single-base substitution (C>T) at the codon 811 (Arg to Trp) in the 9th exon portion of the protein C gene. Taking those results, he was diagnosed with recurrent cerebral venous thrombosis due to congenital protein C deficiency. Cerebral venous sinus thrombosis that occurred in the absence of an incidents of disease or internal history when there is a juvenile onset, a past history, or a family history, is suspected of congenital thrombophilia and needs blood tests and genetic tests.

A 27-year-old man developed acute encephalitis with headache, fever, seizures, and aphasia. Analysis of cerebrospinal fluid showed elevated levels of cell counts and protein. A brain MRI demonstrated increased FLAIR signals in the left cerebral cortex with cortical swelling. An MRA also showed mild vasodilatation of the left middle cerebral artery branches. After admission, severe psychomotor excitement developed. Immunotherapy with intravenous high-dose steroid and subsequent oral steroid was successful, and the patient returned to premorbid working position. Repeated MRI study showed complete resolution. Serum anti-myelin oligodendrocyte glycoprotein (MOG) antibody was positive, while anti-aquaporin-4 antibody, anti-N-methyl-D-aspartate (NMDA) receptor antibody, and other autoimmune antibodies were all negative. There were no relapses at final follow-up of 8 months after onset. Cerebral cortical encephalitis with unknown etiology can occur associated with anti-MOG antibody, and anti-MOG antibody may play certain role in the pathogenesis.

The case is a 64-year-old male who had a past history of herpes simplex virus encephalitis (HSE) two years prior to his admission. He was admitted to our hospital due to severe pneumonia and sepsis. Several days later, he developed HSE again. It has been known that immunosuppressive state called immune paralysis occurs in the patient with sepsis due to the amplification of anti-inflammatory responses after the initial hyper-inflammatory phase, which increases the susceptibility to various latent viruses including herpes simplex virus. In the present case, we consider that the severe infection may trigger the recurrence of HSE through the viral reactivation due to immune paralysis. When we see a patient suffering from severe infection who had a past history of HSE, we should keep in mind that such a patient may have a risk of the recurrence of HSE.