An 86-year-old woman was diagnosed as having pneumococcal meningitis with fever and disturbed consciousness. She was treated with antibiotics and dexamethasone, and the symptoms of meningitis as well as the biomarkers of inflammation improved. On day 5, quadriplegia was found, and 7 days from the onset, brain MRI revealed multiple ischemic lesions in the bilateral cerebral and cerebellar hemispheres. The D-dimer level was markedly increased to 49.8 µg/ml, whereas there were no findings suggestive of cardioembolic stroke. The cause was speculated to be “diffuse cerebral intravascular coagulation” associated with meningitis. After starting of anticoagulant therapy, recurrence of cerebral infarction, stenosis of the major cerebral arteries, and vascular wall enhancement were not observed. There is no established treatment for cerebral infarction associated with bacterial meningitis. Anticoagulant therapy may be effective for the pathology of diffuse cerebral intravascular coagulation.

A 73-year-old man was brought to our hospital for wake-up right hemiparesis, left conjugate deviation, and global aphasia. We diagnosed him with hyperacute cerebral infarction and performed mechanical thrombectomy. During mechanical thrombectomy, dysgenesis of his left ICA was detected. His left posterior communicating artery (PcomA) was occluded, and his left cerebral hemisphere was judged to be perfused using it as a major collateral pathway. We approached the occluded left PcomA via his left VA and recanalized the artery, resulting in improvement of symptoms. ICA dysgenesis is rare, occurring in less than 0.01% of patients, and is usually asymptomatic, but it becomes apparent when the main collateral vessels are occluded. It is important to confirm the existence or absence of the carotid canal by head CT and to identify the collateral pathway. Guiding devices through unusual pathways may be necessary, and careful device selection and handling are required, paying attention to potential aneurysms and atherosclerotic lesions.

We report a case of early seizure with aphasia that occurred after an ischemic stroke. A 54-year old man who suffered from an ischemic stroke experienced aphasia a day after stroke onset. The patient’s aphasia rapidly improved. Therefore, we first diagnosed the patient with a fluctuating ischemic attack. On day 5 of admission, he developed an aphasia again and convulsion. Electroencephalography during the attack revealed rhythmic delta waves in the left hemisphere, mainly in the left frontotemporal area. Because of the rapid improvement in the electroencephalographic abnormalities and symptoms after administering diazepam, we diagnosed his condition as an early poststroke seizure. Because the seizures recurred, lacosamide was initiated. After starting antiepileptic agents, these symptoms did not recur. Distinguishing between early poststroke seizures with focal signs and transient ischemic conditions is difficult. Therefore, early seizures should be considered when treating patients who have suffered from acute stroke and have fluctuating focal signs.

There are few case reports of thrombectomy via the arterial circle of Willis. We report a case of acute left middle cerebral artery occlusion with chronic left cervical internal carotid artery occlusion, in which thrombus retrieval therapy was performed via the anterior communicating artery and effective recanalization was achieved, with literature review. The patient was an 83-year-old woman. She had been suffering from chronic left internal carotid occlusion for some time and was brought to our hospital with sudden loss of consciousness, aphasia, and quadriplegia. Neuroradiological imaging led to the diagnosis of acute cerebral infarction due to bilateral middle cerebral artery occlusion, and emergency thrombectomy was performed within 5 hours of onset. A guiding catheter was placed in the right internal carotid artery of the neck, and decisive thrombectomy was performed using a stent retriever via the anterior communicating artery, resulting in effective recanalization of the left middle cerebral artery occlusion. Subsequently, thrombectomy was also performed for the right middle cerebral artery occlusion, and effective recanalization was obtained (onset to perfusion times: 6 hours and 37 minutes). Postoperatively, the patient had a poor outcome due to the presence of bilateral scattered cerebral infarction.

Herein, we report a case of stroke with suspected meningovascular neurosyphilis. A 56-year-old man was brought to our hospital due to sudden weakness of the right upper limb and headache during a visit to a sex establishment. Computed tomography and magnetic resonance imaging showed a small amount of subarachnoid hemorrhage in the cerebral convexity and cerebral infarction in the left cerebral perforating branch region; various imaging studies showed stenotic changes in multiple regions of bilateral mainstem cerebral arteries. Blood samples upon admission were positive for syphilis, and cerebrospinal fluid (CSF) examination revealed an elevated cell count of 112/µl, protein levels of 95.0 mg/dl, treponema pallidum antibody level of 149.6 COI, and rapid plasma reagin (RPR) level of 10.6 RU. A diagnosis of meningovascular neurosyphilis was made. After intravenous penicillin infusion and steroid pulse therapy, the RPR level of CSF became negative at 0.1 COI and the stenotic lesion in the main cerebral arteries improved, and the patient was discharged home. Although meningovascular neurosyphilis with intracranial hemorrhage is a rare condition, the number of similar cases may increase as the number of patients with syphilis increases. It is important to distinguish this case from other diseases carefully and administer penicillin promptly.

A thrombus formed within the pulmonary vein stump after pulmonary lobectomy is a rare but noteworthy cause of cerebral embolism. We present the case of a 68-year-old man who underwent a thoracoscopic left lower lobectomy for metastatic lung cancer. The day after the operation, he was found unconscious with left hemiplegia (NIHSS 25 points). Diffusion-weighted brain MRI showed a high-intensity lesion from the right basal ganglia to corona radiata, and MR angiography showed an occlusion in the right internal carotid artery. Mechanical thrombectomy was performed for the hyperacute cerebral embolic infarction, and complete recanalization was achieved. Anticoagulation therapy was commenced with heparin and subsequently changed to warfarin. Contrast-enhanced chest CT revealed the embolic source to be a thrombus in the residual portion of the transected left inferior pulmonary vein. Thrombus regression was monitored using cardiac MRI to reduce radiation risk due to repeated contrast-enhanced CT scans. Cardiac MRI is a useful alternative method for noninvasive serial evaluation of thrombus in the pulmonary vein.

We report the case of a 70-year-old man who was transferred to our department by an ambulance with the chief complaint of disturbed consciousness. Brain magnetic resonance imaging revealed the occlusion of the left horizontal anterior cerebral artery (A1) to the bilateral vertical anterior cerebral artery (A2) as well as acute cerebral infarction in the bilateral anterior cerebral artery region. We performed mechanical thrombectomy therapy and recanalized the right A2 site, although we could not perform the same procedure at the left A2 site. We observed no intracranial hemorrhage during or immediately after the operation. However, 2 days after the operation, subarachnoid hemorrhage, hydrocephalus, and a pseudoaneurysm appeared in the anterior communicating artery. Accordingly, we performed ventricular drainage and maternal vessel occlusion of the left A1. Echocardiography detected a wart on the aortic valve, and blood culture revealed the presence of Enterococcus faecalis, leading to the diagnosis of infective endocarditis. The patient received antibiotic treatment with ceftriaxone, vancomycin, and piperacin; consequently, the symptoms of infection improved. However, he then suffered from sudden cardiac arrest and died. Thrombectomy is challenging in embolisms caused by infections such as infective endocarditis, and arterial rupture might occur at a later stage; thus, caution should be exercised.

The patient is a 73-year-old man. The patient was brought to the emergency room with a chief complaint of dizziness. A head MRI showed multiple infarcts in the cerebral and cerebellar hemispheres. No obvious embolic source could be identified, but the patient had a history of undifferentiated pleomorphic sarcoma of the right humerus and multiple metastases were suspected. So, this case was diagnosed as cerebral infarction due to cancer-associated thrombosis (CAT). After starting subcutaneous injections of heparin calcium, there was no recurrence. However, 2 weeks after switching from heparin calcium to a direct oral anticoagulant, embolic stroke recurred. It is said that adenocarcinoma is the most common cancer causing CAT because mucins secreted by adenocarcinoma cells form microplatelet thrombi. However, it was reported that malignant tumors other than adenocarcinoma also cause CAT. In particular, it is known that the risk of thrombosis increases in cases with distant metastases. When a patient with malignant tumor with metastasis has embolic stroke, it is necessary to consider the possibility of cancer-associated thrombosis, even if it is not adenocarcinoma.

The occurrence of subarachnoid hemorrhage due to internal carotid artery dissection in patients with coronavirus disease 2019 (COVID-19) is rare. A 52-year-old man with impaired consciousness, who was infected with severe acute respiratory syndrome coronavirus-2 five days earlier, was referred to our hospital. Brain computed tomography (CT) and CT angiography revealed subarachnoid hemorrhage but did not show apparent aneurysm. Therefore, we performed external ventricular drainage and medical treatment for COVID-19. Dilatation in the C1 portion of the left internal carotid artery and small aneurysm gradually appeared in a time-series radiological imaging, and the patient was diagnosed with ruptured internal carotid artery dissecting aneurysm. Additionally, we performed clipping on wrapping on the 16th day of admission. He was transferred to a rehabilitation hospital with a modified Rankin Scale score of 4. Considering the pathology and COVID-19 infectious activity, it is important to determine the appropriate time for surgical treatment and strategy for ruptured dissecting cerebral aneurysm for each patient with COVID-19.