Medical scientists are asked to make various judgments when new diseases emerge, such as COVID–19, but even for these experts, their judgments are often incorrect. Experts always attempt to convince the public using a term “science–based evidence” but, in many cases, without real solid evidence. There are massive of unexplained diseases and pathogenicity in neurology. In order to discover and elucidate new diseases and their pathophysiological conditions, it is important to carefully examine and investigate each patient, followed by a persistent tracing sincerely and deeply. Medicine is still developing, and to make the neurology more practical and useful for the world, I would like to expect flexibility, innovation, and conscience from doctors with neurological expertise.

Nutrition therapy is extremely important for neurological diseases in order to improve patients' prognosis and quality of life. In the recent years, nutritional therapy has been recommended in the treatment guidelines for several disorders, including stroke and amyotrophic lateral sclerosis. Nutritional disorders in patients with neurological diseases vary depending on the background disease and pathological conditions. Furthermore, because of the wide range of lesions (including those in the central nerves, peripheral nerves, and muscles), several disorders such as dysphagia, respiratory disorders, motor paralysis, muscle rigidity, involuntary movements, and ataxia often coexist in patients. Moreover, patients may also have other complications such as constipation, diarrhea, pressure ulcers, and aspiration pneumonia. In order to provide appropriate nutritional therapy, each patient must be provided tailor–made interventions and support ; sharing of knowledge among multidisciplinary experts would aid the development of such interventions.

Older adults are at a high risk of developing malnutrition and sarcopenia because of various factors, including diseases, aging, unfavorable living conditions, hormonal changes, and inadequate dietary intake. It is important to screen for malnutrition and sarcopenia using appropriate diagnostic criteria. Malnutrition in older adults should be assessed using the Global Leadership Initiative on Malnutrition criteria rather than serum albumin or prealbumin levels. Meanwhile, the Asian Working Group for Sarcopenia 2019 criteria are preferred for the diagnosis of sarcopenia. These criteria may be useful in identifying the etiology of malnutrition and sarcopenia.

Individualized nutritional therapy can be effective in preventing poor outcomes. Providing effective nutritional therapy requires understanding the effects of energy, protein, and vitamins on malnutrition and sarcopenia. Therefore, it is important to clarify the etiology of malnutrition and sarcopenia when developing nutritional therapy for older adults. Moreover, attention to and individualization of nutritional therapy (energy, protein, and vitamin intake) and exercise intervention may improve these conditions.

In the nutrition therapy for stroke patient, it is important to carry out appropriate the nutritional management with understanding of the pathophysiology of each stroke types, cerebral infarction, cerebral hemorrhage, and subarachnoid hemorrhage. In addition, the nutrition management according to the severity and stage in each patient should be performed.

In the acute stage of stroke, shorten the fasting period and start the enteral nutrition as soon as possible. In cases without dysphagia, oral intake should be started promptly, and in cases with severe dysphagia or with comatose, the nutritional management by tube feeding should be performed. In severely stroke cases, a hyperglycemia condition might be likely to occur, because the catabolism may be accelerated by the invasive stress. The energy dose and the nutritional composition must be set in consideration of glycemic variability.

On the other hand, the energy consumption would be increasing during recovery stage. The appropriate nutrition therapy should be practiced for the elderly patient coexisting with frailty or sarcopenia, who make up the majority of the hospitalization on the recovery rehabilitation floor.

The basic concept of nutrition therapy in stroke is the early initiation of enteral nutrition managed by an appropriate protocol. These practices may help improve outcomes in stroke patients.

Weight loss is frequently observed in early–stage amyotrophic lateral sclerosis (ALS) and is considered an independent predictor of survival. Weight loss observed in ALS is associated with multifactorial etiology, including muscle wasting and dysphagia ; however, recent studies have implicated disease–specific hypermetabolism in weight loss and disease progression in ALS. The pathophysiology of hypermetabolism as a contributor to weight loss in ALS remains unclear ; however, hypothalamic involvement is considered an early extra–motor manifestation of ALS. TDP–43 protein aggregates detected in the hypothalamic subnuclei may be associated with weight loss or abnormalities of eating behavior in patients with ALS. Weight loss from diagnosis up to tracheostomy also predicts functional prognosis during the long–term period with ventilator. In fact, patients with ALS who survive with prolonged mechanical ventilatory support often develop significant brain and brainstem atrophy, including atrophy of the limbic motor system and the hypothalamus. Nutritional intervention to maintain body weight may be a useful disease–modifying therapeutic approach, and recent studies have reported that slowing of weight reduction rate after diagnosis may be associated with better survival and that a high–calorie diet improves survival in patients with rapidly progressive disease. Nutritional education regarding a high–calorie diet, weight control, and early gastric tube placement are important after diagnosis. Researchers from the USA, Europe, and Japan have established formulas to estimate the recommended daily energy intake. Although a lipid shift in energy metabolism might occur in the brain and muscles in patients with ALS, the effectiveness of high–fat diets requires further investigation.

The amount of weight loss in patients with Parkinson disease (PD) documented in the literature varies from 52 to 65%. As reduced energy input, hyposmia, cognitive impairment, depression, gastrointestinal dysfunction, and dysphagia are thought to be causally related to weight loss. On the other hand, weight loss and malnutrition are also the result of a negative energy balance, which means that energy expenditure exceeds intake caused by tremor, rigidity, and dyskinesia. To predict total energy expenditure, a calculation method to multiply basal energy expenditure by 1.1–1.3, or PD coefficient which is appropriate to the degree of rigidity and tremor has been proposed. For nutrition therapy to replenish energy in PD patients, functional food including medium–chain triglyceride supplements may be helpful.

Nutritional impairment in multiple system atrophy (MSA) can be divided into early and advanced stages. In the early stage, nutritional impairment due to dysphagia can develop. In the advanced stage, body fat could accumulate after the introduction of a ventilator or the placement of a gastrostomy. Nutritional impairment may be progressive in MSA patients, even if body weight is maintained. The serum albumin level is a useful indicator of nutritional status. Leptin resistance due to autonomic neuropathy may be related to the accumulation of body fat. In the early stages, sufficient nutrition should be administered to prevent the progression of nutritional disorders. In the advanced stage, the amount of administered energy is reduced to prevent fat accumulation. Further research is needed to establish the evidence for the nutritional management of MSA.

The symptoms of Parkinson's disease are improved by oral administrations of levodopa. In several years following the start of levodopa treatment, however, wearing–off may appear and disturb the quality of life of patients with Parkinson's disease. We applied levodopa suspension therapy with frequent administrations in a case of 52–year–old man who developed Parkinson's disease at the age of 39 and suffered from marked wearing–off symptoms. He took 2 tablets of levodopa/DOPA decarboxylase inhibitors/COMT inhibitor every 3 hours a day with 12 tablets a day. However, he could not continue his work at the office because of marked wearing–off symptom. The daily dose of levodopa was suspended in two bottles together with 1000mg of vitamin C and he took it every hour between 6 o'clock in the morning and 9 o'clock in the evening. Then his symptom of wearing–off improved and he was able to continue his job. Levodopa suspension therapy with frequent administrations may contribute in stabilizing fluctuation of blood concentration of levodopa. Levodopa suspension therapy is easy to prepare at home and might be effective to release the symptoms in cases with Parkinson's disease showing marked wearing–off symptom.

A 39–years–old woman presented with generalized seizures after 7 days of fever. Generalized seizures did not stop despite administration of several anti–epileptic drugs and sedatives. We diagnosed new–onset refractory status epilepticus (NORSE). Immunotherapy was started from the early stage and thiamylal coma therapy was performed for a few weeks. As seizures declined, we decreased thiamylal sodium and succeeded in stopping use of sedative agents. Tetany–like symptoms were identified in the hands and toes.

The etiology and optimal treatment of NORSE remain unclear, and accumulation of more cases is needed.