The Japanese clinical guidelines for myasthenia gravis (MG) were revised in 2022. The major revision points in these guidelines are as follows. 1) A description of Lambert-Eaton myasthenic syndrome (LEMS) was included for the first time. 2) Revised diagnostic criteria of both MG and LEMS are proposed. 3) A high-dose oral steroid regimen with escalation and de-escalation schedule is not recommended. 4) Refractory MG is defined. 5) The use of molecular-targeted drugs is included. 6) MG is divided into six clinical subtypes. 7) Treatment algorithms for both MG and LEMS are presented.

To clarify the natural courses, medical conditions, and problems in daily life and medical care of the patients with Charcot–Marie–Tooth disease (CMT) in Japan, we have developed a patient registration system (CMT Patient Registry (CMTPR)). We analyzed data of questionnaires from 303 patients (males: 162, females: 141, mean age: 45.9 years old) who registered for CMTPR. The age of onset was less than 15 years old in 45% and more than 60 years old in 5% of the patients. Genetic testing was performed in 65%, and about half of the patients with genetic testing had a duplication of the PMP22 gene. Seventy-six percent of the patients had regular visits to medical facilities. Five percent of patients had no history of hospital visits. Fifteen percent of all patients needed assistance with daily activities due to motor function impairment in the upper extremities, and 25% required assistance due to lower limb impairment. There were no significant differences in the need for assistance by gender or age. Of the 267 adult patients, 18% had difficulty working due to reasons related to the disease, although none of the junior patients reported any problem attending school. This was the first nationwide epidemiological study with healthcare and welfare information on patients with CMT in Japan. We hope the results of this study will lead to better welfare and medical care in CMT patients.

A 74-year-old woman who presented with a skin eruption involving the left lateral leg along the L5 dermatome and widespread eruptions on the buttocks and trunk was diagnosed with disseminated herpes zoster (HZ). She also had left lower extremity muscle weakness. The pattern of distribution of muscle weakness and gadolinium-enhanced magnetic resonance imaging findings indicated polyradiculoneuritis mainly affecting the L5 spinal root. Moreover, we observed severe weakness of the left tibialis anterior muscle. Weakness of the other L5 myotomes reduced after antiviral treatment; however, left tibialis anterior muscle weakness persisted. We concluded that lumbosacral polyradiculoneuritis was attributable to varicella-zoster virus (VZV) infection, which also caused fibular neuropathy in this case. Retrograde transport of the VZV may have infected the fibular nerve throughout the sites of skin eruption. It is important to be mindful of simultaneous nerve root and peripheral nerve involvement in cases of motor paralysis associated with HZ infection.

The patient, a 58-year-old man, experienced weakness of the proximal muscles in both lower extremities, and Lambert-Eaton myasthenic syndrome and small cell carcinoma of unknown primary origin were diagnosed. He received symptomatic treatment for myasthenia and radiochemotherapy for small cell carcinoma; once this regimen, the myasthenic symptoms improved. However, acute myocardial infarction occurred, after which type II respiratory failure developed, and the patient required ventilator management with tracheal intubation. Acute-phase treatment, such as plasma exchange, intravenous immune globulin therapy, and methylprednisolone pulse therapy, and intensification of symptomatic treatment allowed for extubation, and eventually the patient was able to walk independently. According to electrophysiological examination, compound muscle action potentials were larger at discharge than at the time of exacerbation.

We present a case of internal carotid artery (ICA) stenosis caused by mechanical stimulation by the hyoid bone (HB) and thyroid cartilage (TC). A 78-year-old man with a history of right ICA stenting four years previously was admitted for abrupt onset of dysarthria and left hemiparesis and diagnosed with ischemic stroke by magnetic resonance imaging. Three-dimensional computed tomographic angiography revealed internal carotid in-stent restenosis. Furthermore, the HB and TC contacted with the right ICA. Treatment involved antiplatelet therapy, partial HB and TC resection, and carotid artery restenting. Posttreatmently, the ICA was restored and stenosis improved. Since restenosis may occur posttreatmently in patients with carotid artery stenosis caused by mechanical stimulation of the HB and TC, it is necessary to consider treatments including not only carotid artery stenting but also partial bone structures resection and carotid endarterectomy.

An 87-year-old woman was admitted with acute onset of disturbed consciousness. On neurological examination, both pupils were dilated and non-reactive to light. Decerebrate rigidity was present. Babinski testing was positive. CTA suggested an isolated left P1 segment occlusion. The P2 segment was supplied from the left internal carotid artery via the posterior communicating artery. MRI showed bilateral paramedian thalamic infarctions. Because occlusion of the artery of Percheron was suspected, intravenous thrombolysis was performed. Digital subtraction angiography (DSA) revealed occlusion of the left P1 segment and spontaneous recanalization before endovascular treatment. Her consciousness improved immediately. When acute bilateral thalamic infarction suggests top of the basilar artery syndrome but no basilar artery occlusion is found, occlusion of the artery of Percheron should be considered. Thrombectomy of the affected P1 segment may be needed.

A 50-year-old woman experienced cardiopulmonary arrest. Although the arrest lasted for 4 min, she could not be withdrawn from the mechanical ventilator because of low tidal volume, despite being awake and alert after admission. The results of the anti-acetylcholine receptor antibody and repetitive nerve stimulation tests were negative, and the anti–muscle-specific kinase antibody levels revealed myasthenia gravis. We recommended therapeutic plasma exchange; however, the patient refused the treatment as she did not want to use blood products. Consequently, we initially attempted steroid pulse therapy, which enabled the patient to be withdrawn from the mechanical ventilator. Thus, steroid pulse therapy was beneficial for the crisis associated with the anti–muscle-specific kinase antibody in the absence of therapeutic plasma exchange.

A 73-year-old man, who had been treated for bipolar disorder since he was 39 years old, was admitted because he had developed difficulty in walking and moving his hands for the past 2 months. He was suspected of having Parkinson’s syndrome. On admission, his blood lithium level was at the upper limit of normal (1.34 mEq/l), but his food intake gradually decreased and his communication difficulties worsened. On the sixth day of hospitalization, his blood lithium level was in the toxic range (2.44 mEq/l). His general condition, including motor symptoms, improved after lithium medication was discontinued and infusions (normal saline) were started. On the 24th day of admission, he was transferred to the psychiatry department for a psychotropic medication adjustment. It is important to note that chronic intoxication can occur even at the upper limit of the therapeutic range and that salt reduction at the start of the inpatient diet may be a trigger for intoxication.