EEG is useful for evaluation of pathophysiology and prognostication of neurocritically ill patients, as it provides non-invasive, real-time monitoring of cerebral function. There have been recently a lot of advances in research on critical care EEG according to the American Clinical Neurophysiology Society’s Standardized Critical Care EEG Terminology. Based on the latest knowledge, this review discusses clinical utilization of EEG in neurocritically ill patients, including critical care continuous EEG monitoring, and key points of interpretation of critical care EEG, classifying main purposes into three points: detection of electrographic and electroclinical seizures, consideration of special encephalopathies, and evaluation and prognostication of cerebral function. Neurologists should have fundamental ability to read and interpret critical care EEG and support treating physicians in terms of therapeutic strategy.

Late-onset hereditary ATTR (ATTRv) amyloidosis in nonendemic areas takes long periods of time to diagnose in many cases because the clinical symptoms are varied and nonspecific with the family history often unidentifiable. In recent years, disease-modifying therapies have been available for ATTRv amyloidosis, and early diagnosis is increasingly needed. The diagnosis of ATTRv amyloidosis usually requires histological confirmation of the amyloid deposition, although the amyloid detection rate largely depends on the experience, knowledge, and skill of the physician who performs the biopsy. It is important to consider ATTRv amyloidosis as a differential disease in idiopathic polyneuropathy. If ATTRv amyloidosis is strongly suspected, it is acceptable to perform TTR genetic testing prior to histological examination after a thorough differential diagnosis has been made.

We studied the clinical features of five Japanese cases with leucine-rich glioma inactivated-1 (LGI1) antibody-positive encephalitis. Their symptoms included seizures, hallucinations, memory impairment, apathy, anxiety, agitation, faciobrachial dystonic seizure (FBDS), and ictal piloerection. All five patients showed hippocampal fluid attenuated inversion recovery (FLAIR) hyperintensity on brain MRI even though their cell counts of cerebrospinal fluid (CSF) were normal range. Four patients had syndrome of inappropriate secretion of antidiuretic hormone. One patient with FBDS also showed basal ganglia lesion on her brain MRI. Sodium channel blockers apparently lowered the frequency of FBDS. One patient had a thyroid cancer and underwent thyroidectomy. Substantial response to immunotherapy was seen in four out of five cases. At follow-up ≥2 years, all five patients had never relapsed. In cases of limbic encephalitis with normal CSF cell counts and hyponatremia, we should consider LGI1 antibody-positive encephalitis and conduct immunotherapy immediately.

A 28-year-old male presented with a sudden, transient visual impairment in the right eye. Brain MRI revealed no obvious ischemic lesions, and he was diagnosed with amaurosis fugax. Physical examination revealed characteristic features of Marfan syndrome, along with a family history of tall stature and valvular heart disease. Further investigation revealed: 1) an ascending aortic aneurysm, 2) a bicuspid aortic valve with fenestration and regurgitation, and 3) a mitral valve prolapse with regurgitation. Genetic testing identified a heterozygous variant c.6905G>A of FBN1, confirming the diagnosis of Marfan syndrome. Bentall operation and mitral valve replacement were performed, resulting in a favorable outcome. Pathological examination showed extensive myxomatous degeneration with thickening of the aortic and mitral valves, suggesting a potential source of embolism.

A 65-year-old man presented to the emergency department with the complaints of left anterior chest and back pain, numbness in the left medial arm, and weakness in the left hand grip. Myocardial infarction was suspected, but later ruled out, and the patient was subsequently referred to our department. Among the intrinsic muscles, the left abductor pollicis brevis was the most severely weakened, and there was a sensory disturbance in the left T1 region and left Horner’s sign. An MRI T₂-weighted image of the cervical spine showed a herniated disc on the left lateral side at the T1/2 level, suggesting compression of the T1 nerve root. Cervical angina is a rare, angina-like anterior chest pain due to cervical spine diseases. It is often reported in patients with C6 and C7 radiculopathy. The most severe weakness in the abductor pollicis brevis muscle in T1 radiculopathy is important to distinguish it from C8 radiculopathy.

An 87-year-old woman receiving aspirin and apixaban with a history of large artery atherosclerotic stroke, and pulmonary embolism presented to the hospital for aphasia and right hemiplegia. A head CT scan showed 18-ml hematoma in the left thalamus. Low-dose Andexanet alfa was administered 84 minutes after the onset of stroke, and 10 hours and 24 minutes after the last dose of apixaban. Three hours later after admission, she had flaccid hemiplegia and became comatose. CT and CT angiography revealed occlusion of left internal carotid artery (ICA) and no evidence of hematoma expansion. Although repetitive mechanical thrombectomy resulted in recanalization (modified TICI 2b), carotid ultrasound revealed the occlusion of left ICA on next day. On day 7, she died of brain herniation following extensive cerebral infarction. It has been reported that some patients did experience thrombotic events after administration of Andexanet alfa. Our case illustrates that even large vessel occlusion might occur after intravenous injection of Andexanet alfa. Thus, careful follow-up, including cerebrovascular imaging, is required immediately after administration of Andexanet alfa.

A 47-year-old man was admitted to our hospital because of sudden-onset motor aphasia and right hemiplegia. His past medical history was notable for left craniotomy and hematoma evacuation following a traumatic brain hemorrhage approximately 40 years earlier, for which dural grafting was performed. He also had a history of three lobar hemorrhages in the left hemisphere since the age of 42 years. Brain CT imaging revealed an acute left frontal lobar hemorrhage. His initial brain MRI conducted at our hospital demonstrated hemorrhagic findings with left hemisphere dominance, including acute and old lobar hemorrhage, cortical superficial siderosis, and cerebral microbleeds. Cerebrospinal fluid analyses demonstrated reduced levels of cerebral amyloid-β 42, and elevated total tau. His apolipoprotein E genotype was ε3/ε3. Whole-exome sequencing did not detect mutations in genes associated with Alzheimer’s disease, including presenilin 1, presenilin 2, and amyloid precursor protein. These findings led to a clinical diagnosis of iatrogenic cerebral amyloid angiopathy (CAA) using recently proposed diagnostic criteria, which do not require pathological evaluation of the brain. Iatrogenic CAA should be considered as a cause of lobar hemorrhage in young patients, especially those with a past history of neurosurgery.

A 67-year-old woman with past medical history of chronic myelomonocytic leukemia (CMML) presented with a chief complaint of headache, diplopia, and hearing impairment in the right ear. Examination revealed impaired ocular movement in the left eye and sensorineural hearing loss in the right ear. Cerebrospinal fluid analysis showed increased cell count and protein, and MRI showed contrast enhancement of hypertrophic dura mater. Since there were no other abnormalities which would have been a cause of hypertrophic pachymeningitis, it was considered as systemic autoimmune/inflammatory disorder (SAID) associated with CMML. Treatment with steroid, cyclophosphamide, and methotrexate led to improvement of the symptoms. SAIDs develop in up to 25% of patients with myelodysplastic syndromes (MDS) or CMML, which may be the only symptoms of MDS/CMML. As a phenotype of SAIDs, systemic vasculitis, connective tissue diseases, and neutrophilic diseases are frequently reported; however, isolated involvement of central nerve system is rarely reported. To our knowledge, this is the first report of hypertrophic pachymeningitis as SAID associated with CMML. To clarify the pathogenesis of neurologic involvement of SAIDs, accumulation of cases is necessary.