ATTRv amyloidosis is an autosomal-dominant disorder characterized by mutations in the transthyretin (TTR) gene, systemic deposition of transthyretin amyloid fibrils, and progressive polyneuropathy. Current scoring systems developed for ATTRv amyloidosis to measure the severity of polyneuropathy are not sufficiently sensitive or are difficult to implement in daily practice. Results of phase 3 trials for oligonucleotide therapeutics and real-world evidence have shown that neurofilament light chain (NfL), a key structural component of axons, is a reliable blood biomarker for assessing disease progression and treatment response in patients with ATTRv amyloidosis with polyneuropathy. Because blood NfL levels can be affected by factors such as age, body mass index (BMI), and renal function, its significance in patient monitoring needs to be assessed carefully while considering the clinical characteristics of each patient.

The term organic disease has been used as the antonym of functional neurological disorder (FND), which was once called hysteria. Recently, the term “structural” is proposed instead of “organic”. This is because the English word “organic” has two meanings: “related to the living organism” and “related to the organ, a part of the body”. When the first meaning is thought of, the traditional usage of the “non-organic” seems strange since even FND takes place within the human body. There has been two Japanese translations for the word “organic”, “yuki” and “kishitsu”. Ogata Koan used the term “kishitsu-henseibyou” as the translation for a German word “desorganisationen” in 1857. Kawamoto Komin is known to have established the term “yuki kagaku” as the translation of organic chemistry in 1861, at the end of the Edo era. Kuwata Kohei used the term “kishitsu” as the translation for “structural” in 1872. In 1875, Tsuboi Ishun used “kishitsu” as the translation of “organic”. He also used the term “yuki” in another book, and it is noteworthy that he used the two words as the translations of “organic” in two different meanings depending on the contexts. Thereafter, the lectures of Erwin von Bälz, Jean-Martin Charcot’s “Tuesday Lessons”, and other foreign texts were translated using the term “kishitsu” as the antonym of hysteria. Kawahara Hiroshi and Miura Kinnosuke also used “kishitsu”, and the term was established as the standard. It is surprising and worth praise that the pioneers in late Edo and Meiji periods invented two Japanese terms translating “organic” corresponding to the two meanings of this foreign word. Considering these backgrounds, we would like to argue that the term “kishitsu (sei)” continues to be an appropriate term in Japanese used for the antonym of FND, and we need not to change the Japanese term to “kozo (sei)” in response to the change of the term in English.

Anti-myelin associated glycoprotein (MAG) neuropathy typically progresses slowly, but rare cases exhibit rapid deterioration. We report an 83-year-old man with a two-year history of paresthesia in both feet and recent-onset gait ataxia who developed rapidly progressive muscle weakness in all four limbs over several days. Nerve conduction studies and positive anti-MAG antibodies confirmed the diagnosis of anti-MAG neuropathy. The patient's muscle weakness improved with intravenous immunoglobulin (IVIg) therapy. This case highlights the existence of atypical anti-MAG neuropathy mimicking chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) with a rapid deterioration course and suggests the potential efficacy of IVIg in such presentations.

The patient was a 78-year-old woman. She underwent foramen magnum decompression for syringomyelia associated with Chiari type I malformation, which had developed with difficulty in raising the left upper limb and muscle weakness in both upper limbs. One year after surgery, weight loss of 20 ‍kg, progressive muscle atrophy and weakness in the extremities, paralytic dysarthria, and fasciculation in the bilateral anterior thighs were observed, and needle electromyography showed acute denervation and chronic denervation in the medial vastus muscle. The rapid postoperative progression of symptoms and lower motor neuron symptoms in the lower extremities could not be explained by syringomyelia associated with Chiari type I malformation and were considered a possible complication of amyotrophic lateral sclerosis (ALS). It is possible that the surgery may have caused ALS progression, and attention to the rate of progression of neurologic symptoms may be important in the diagnosis of ALS complications.

A 63-year-old woman, previously diagnosed with multiple sclerosis (MS) and treated with IFNβ-1b, developed asymptomatic lesion expansion surrounding the thalamus and basal ganglia. However, an AQP4 autoantibody ELISA was negative. The patient was subsequently hospitalized due to drowsiness, lethargy, and difficulty in managing housework. During lumbar puncture, the patient lost consciousness. Electroencephalography (EEG) revealed rapid eye movements, and a multiple sleep latency test (MSLT) indicated narcolepsy. Cerebrospinal fluid (CSF) orexin levels were normal, and no cataplexy was observed. The patient was thus diagnosed with narcolepsy type 2. The patient tested positive for AQP4 antibody, and was diagnosed with neuromyelitis optica spectrum disorder (NMOSD). Sleep physiology testing is crucial because some patients with NMOSD do not exhibit hypothalamic lesions or decreased CSF orexin levels.

A 67-year-old man who was on medication for hypertension and unstable angina pectoris developed mild left hemiparesis on day X−1. He made an emergency call at 4 am on day X due to persistent symptoms. Brain magnetic resonance imaging performing following admission showed multiple acute cerebral infarcts, resulting in the initiation of treatment by continuous intravenous heparin was started. One hour later, after initial heparinization, he developed generalized seizure and stopped breathing on echocardiography. Emergency tracheal intubation was performed, and contrast-enhanced brain computed tomography showed hypoperfusion of the right middle cerebral artery; consequently, we performed mechanical thrombectomy. During emergency thrombectomy, multiple new thrombi were observed on cerebral angiography. We suspected heparin-induced thrombosis (HIT), and therefore changed heparin treatment to argatroban, following which the thrombi disappeared immediately. The diagnosis of HIT was comfirmed by complete blood count and serological examination, which revealed thrombocytopenia and anti-HIT antibodies, respectively. As was observed in our patient, spontaneous HIT without recent exposure to heparin can occur in rare circumstances; as such, heparin treatment should be administered with caution. As mechanical thrombectomy is usually performed under heparinization, it is important to consider the risk of HIT in cases of new thrombi during thrombectomy.

Although disruption of basal ganglia loops due to reduced cortical blood flow has been postulated as a possible mechanism for chorea after cortical infarction, detailed studies have not been conducted. We report a case of cardiogenic cerebral embolism of the right frontal to insular cortex due to occlusion of the right M2 branch, followed by the appearance of chorea in the left upper limb on the next day, recanalization of the occluded vessel, and hyperperfusion detected in the same area of brain via single-photon emission computed tomography (SPECT). Interestingly, the blood flow to the right striatum, which was not infarcted, was increased; however, this was not observed after the disappearance of chorea. We speculated that hyperperfusion after cortical infarction affected the striatum, which resulted in the emergence of chorea. In addition to cortical infarction, increased cortical blood flow due to recanalization should be considered as a possible mechanism for chorea development due to cortical infarction.