A lesson from polybutylene succinate plastisphere to the discovery of novel plastic degrading enzyme genes in marine vibrios.

Polybutylene succinate (PBS) is an eco-friendly green plastic. However, PBS was shown as being non-biodegradable in marine environments, and up until now, only a limited number of PBS-degrading marine microbes have been discovered. We first set up in vitro PBS- and PBSA (polybutylene succinate adipate)-plastispheres to characterize novel PBS-degrading marine microbes. Microbial growth and oxygen consumption were observed in both PBS- and PBSA-plastispheres enriched with natural seawater collected from Usujiri, Hokkaido, Japan, and Vibrionaceae and Pseudoalteromonadaceae were significantly enriched on these films. Further gene identification indicated that vibrios belonging to the Gazogenes clade possess genes related to a PBS degrading enzyme (PBSase). The PBS degradation assay for six Gazogenes clade vibrios identified Vibrio ruber, Vibrio rhizosphaerae, and Vibrio spartinae as being capable of degrading PBS. We further identified the gene responsible for PBSase from the type strain of V. ruber, and the purified recombinant vibrio PBSase was found to have low-temperature adaptation and was active under high NaCl concentrations. We also provided docking models between the vibrio PBSase and PBS and PBSA units to show how vibrio PBSase interacts with each substrate compared to the Acidovorax PBSase. These results could contribute to a more sustainable society through further utilization of PBS in marine environments and plastic recycling.

Type I interferon induced by polyinosinic-polycytidylic acid does not contribute to the efficacy of a formalin-killed cell vaccine against Edwardsiella piscicida in the Japanese flounder (Paralichthys olivaceus).

Polyinosinic-polycytidylic acid (poly I:C) is a type of pathogen-associated molecular pattern that can strongly induce the expression of type I interferon (I-IFN). Our previous study has demonstrated that the combination of poly I:C with a recombinant protein antigen not only stimulated the expression of I-IFN but also conferred protection against Edwardsiella piscicida in the Japanese flounder (Paralichthys olivaceus). In this study, our aim was to develop a better immunogenic and protective fish vaccine, for which we intraperitoneally coinjected P. olivaceus with poly I:C and formalin-killed cells (FKCs) of E. piscicida and compared the efficiency of protection against E. piscicida infection with that of FKC vaccine alone. Results showed that the expression levels of I-IFN, IFN-γ, interleukin (IL)-1ß, tumor necrosis factor (TNF)-α, and the interferon-stimulated genes (ISGs) ISG15 and Mx were significantly increased in the spleen of fish inoculated with poly I:C + FKC. The results of ELISA showed that the levels of specific serum antibodies in the FKC and FKC + poly I:C groups were gradually increased until 28 days postvaccination and were significantly higher than those in the PBS and poly I:C groups. At 3 weeks after vaccination in the challenge test, the respective cumulative mortality rates of fish in the PBS, FKC, poly I:C, and poly I:C + FKC groups were 46.7%, 20.0%, 33.3%, and 13.3% under low-concentration challenge and 93.3%, 46.7%, 78.6%, and 53.3% under high-concentration challenge. This study showed that poly I:C may not provide an effective adjuvant effect with FKC vaccine for intracellular bacterial infections.

Whole-genome analysis of red sea bream iridovirus spread in 2021 in Japan provided epidemiological and viral traits insight.

Red sea bream iridovirus (RSIV) is the pathogen that causes red sea bream iridoviral disease. It causes a huge loss to the Japanese aquaculture industry. In 2021, outbreaks of red sea bream iridovirus occurred in South Japan. This study analysed nine whole-genome sequences of RSIV isolated in Oita and Ehime Prefectures in 2021 using a short-read next-generation sequencer. Nine isolates had highly uniform sequences, and there was no variant depending on locations or host species. Phylogenetic analyses with other reported megalocytivirus isolates showed that RSIV isolated in 2021 was genetically different from RSIV previously isolated in Oita and Ehime Prefectures in 2017-2019. These results suggest that RSIV isolated in Oita and Ehime Prefectures in 2021 might spread from a common ancestor different from the recent one. Additionally, it was found that RSIV isolated in 2021 had sequence mutations on protein-coding sequences that may be involved in viral pathogenicity and infectivity.

Development of single nucleotide polymorphism (SNP) application for detection and genotyping of RSIV-type megalocytiviruses.

Red sea bream iridovirus (RSIV) belonging to the genus Megalocytivirus of the family Iridoviridae is the cause of serious mass mortality of cultured marine fishes. RSIV-type megalocytiviruses show extremely high nucleotide sequence identities. Thus, epidemiological studies on this virus are limited. This study developed two primer sets amplifying the regions possessing single nucleotide polymorphism (SNP) to determine the relationships and divergence of RSIV-type megalocytiviruses isolated from cultured marine fishes in Japan. The two regions were designed according to the genome sequences of the representative RSIV genotype II of megalocytivirus members in GenBank. The SNP 1 and 2 regions have sequences homologous to hypothetical protein ORF 24 and ORF 31, respectively, of RSIV (accession no. AP017456.1). By sequencing the regions, 53 polymorphic sites were identified. The phylogenetic analysis of 25 RSIV-type megalocytivirus isolates, classified into RSIV cluster, was clustered into eight haplotypes (seven haplotypes from Oita, two haplotypes from Ehime, and one haplotype shared between Oita and Ehime). These findings suggested that SNP in the RSIV genome is a powerful application for the detection and identification of RSIV-type megalocytiviruses.

Single-incision laparoscopic full-thickness anterior abdominal wall repair of a Morgagni hernia using a suture-assisting needle in a child: A case report.

Single-incision laparoscopic repair of a congenital Morgagni diaphragmatic hernia using a suture-assisting needle was performed in a 1-year-old boy. Three ports were inserted through a single umbilical incision to repair the 2.5 × 2.3-cm defect. The full-thickness muscle layer of the anterior abdominal wall and the posterior rim of the defect were penetrated with the suture-assisting needle holding a thread, which was then released. The needle tip was pulled back over the muscle layer, shifted laterally, and again passed through the muscle layer and the posterior rim. The thread was then captured by the needle and pulled out through the anterior abdominal wall. Five mattress sutures were placed in this way and tied subcutaneously. The postoperative course was uneventful, and the cosmetic outcome was favorable. A suture-assisting needle is useful for completing full-thickness anterior abdominal wall repair, which is important for preventing the recurrence of a congenital Morgagni diaphragmatic hernia.

A burden of sarcomere gene variants in fetal-onset patients with left ventricular noncompaction.

BACKGROUND: Left ventricular noncompaction (LVNC) is a hereditary cardiomyopathy, associated with high morbidity and mortality, but the role of genetics in cases of fetal-onset has not been fully evaluated. The goal of this study was to identify the genetic background in LVNC fetal-onset patients using next-generation sequencing (NGS). METHODS: Thirty-three fetal-onset Japanese probands with LVNC (20 males and 13 females) were enrolled. In the enrolled patients, 81 genes associated with cardiomyopathy were screened using next-generation sequencing (NGS) retrospectively. RESULTS: Twenty-three patients had congestive heart failure (CHF), and six patients had arrhythmias. Prominent trabeculations were mostly observed in lateral LV, posterior LV, and apex of LV in patients with LVNC. Twelve died; three patients experienced intrauterine death or termination of pregnancy. Overall, 15 variants were found among eight genes in 16 patients. Seven variants were detected in MYH7 and two in TPM1. Sarcomere gene variants accounted for 75.0%. A multivariable proportional hazards model revealed that CHF at diagnosis and a higher ratio of the noncompacted layer/compacted layer in the LV posterior wall were independent risk factors for death in LVNC fetal-onset patients (odds ratio = 4.26 × 106 and 1.36 × 108, p = 0.0075 and 0.0005, respectively). CONCLUSIONS: The present study is the first report focusing on genetic background combined with clinical features in LVNC fetal-onset patients using NGS. Sarcomere variants were most commonly identified in fetal-onset patients, and greater attention should be paid to fetal-onset patients with LVNC having prominent trabeculations in the LV because they are more likely to develop CHF.

[Orbital Compartment Syndrome Perhaps Secondary to Intra-Orbital Fluid Retention and Orbital/Palpebral Emphysema Following Frontotemporal Craniotomy for an Unruptured Cerebral Aneurysm:A Case Report].

A 58-year-old woman underwent left frontotemporal craniotomy for clipping of an unruptured cerebral aneurysm. A small defect was accidentally created in the orbital roof intraoperatively. The patient developed left eyelid edema and ocular pain after recovery from anesthesia. The following day, the eyelid edema worsened, and she had difficulty opening her eyes. On the 9th postoperative day, she noticed diminished visual acuity and diplopia in her left eye when she was able to spontaneously open her eyes. Ophthalmological evaluation revealed mild left visual loss, decreased light reflex, ophthalmoplegia, ptosis, and chemosis. Computed tomography(CT)/magnetic resonance imaging revealed left proptosis, optic nerve stretching, intra-orbital fluid retention, and orbital/palpebral emphysema. She was diagnosed with orbital compartment syndrome(OCS)and received conservative treatment;however, her visual acuity did not improve. OCS observed after cerebral aneurysm surgery is rare;to date, only 24 cases have been reported in the available literature. Although the mechanism of OCS after craniotomy is unclear, it may be attributed to ocular compression by a muscle flap or increased intra-orbital pressure secondary to venous congestion. In the present case, the left superior ophthalmic vein and cavernous sinus were not clearly visualized on CT angiography. Therefore, we concluded that the right superior ophthalmic vein and superficial facial veins underwent dilatation and served as collateral circulation of the left orbital venous system. We speculate that OCS occurred secondary to increased intra-orbital pressure, possibly caused by inflow of cerebrospinal fluid with air into the orbit through a small bone defect that was accidentally created during craniotomy in a setting of orbital venous congestion.

[Anomalous Origin of the Ophthalmic Artery from the Anterior Cerebral Artery Associated with the Paraclinoid Internal Carotid Artery Aneurysm].

The ophthalmic artery usually arises from the supraclinoid portion of the internal carotid artery. Here, we present an extremely rare case of abnormal origin of the ophthalmic artery from the anterior cerebral artery associated with the paraclinoid internal carotid artery aneurysm. As the embryology of the ophthalmic artery is complex, this case provides additional insight into the variation of the ophthalmic artery.

[Two Cases of Late-onset Brain Edema after Craniotomy for Unruptured Intracranial Aneurysms Suspected to be due to an Allergic Reaction to Arachnoid Plasty Material].

We report two rare cases of late-onset brain edema after craniotomy for clipping or coating of unruptured intracranial aneurysms, possibly due to an allergic reaction to topically applied fibrin glue or gelatin sponge used for arachnoid plasty to cover the opened sylvian cistern. Both patients were women in their 60s with an allergic predisposition and both followed a similar clinical course. A slight fever and headache persisted during the postoperative period. Five to six weeks after surgery without complications, MR images showed an extensive T2 prolongated region in the white matter around the operative field, indicative of vasogenic edema, with mass effect and meningeal enhancement around the sylvian fissure that had been covered with gelatin sponge and sprayed fibrin glue. Swelling of the cerebral cortex around the sylvian fissure subjected to arachnoid plasty was also observed. Blood tests showed the absence of an inflammatory reaction and cerebrospinal fluid examination showed lymphocytosis that was considered to be due to an aseptic meningeal reaction or meningitis. Clinical symptoms and imaging findings steadily improved with the administration of steroids and antiallergic agents. Delayed brain edema may occur around the arachnoid plasty area despite an uneventful chronic postoperative period, which could be due to an allergic reaction to locally administered fibrin glue or gelatin sponge. Thus, the application of arachnoid plasty using fibrin glue and gelatin sponge in patients with a predisposition to allergies needs to be carefully considered.

Development of a nanoparticle that releases nucleic acids in response to a mitochondrial environment.

The delivery of nucleic acids targeting mutant mtDNA represent a potential strategy for addressing a variety of mitochondria-related diseases. We previously developed a MITO-Porter, a nano carrier that is capable of delivering nanoparticles of nucleic acids to mitochondria of human cells. Here, we report on an investigation of a series of nanoparticles formed with various poly cationic peptides that can release nucleic acids in response to a mitochondrial environment. A significant relationship was found between the number of and the location of arginine and histidine residues in the peptide sequence and the release of nucleic acids in a mitochondrial environment.

[A Pediatric Case of Clinically Mild Encephalitis/Encephalopathy with a Reversible Splenial Lesion(MERS)with Recurrent TIA-like Symptoms over a Prolonged Period].

We report a rare case of pediatric clinically mild encephalitis/encephalopathy with a reversible splenial lesion(MERS)associated with transient ischemic attack(TIA)-like symptoms. A 13-year-old boy who presented with transient left hemiparesis and dysarthria was transferred to our hospital. He had experienced similar symptoms at the age of nine years and was diagnosed with MERS type 2 due to the typical clinical course and MR imaging findings. His elder brother showed a similar clinical history at the age of eight years. DW-MR images on admission revealed high signal intensity areas in the splenium of the corpus callosum and deep white matter. The territories were depicted as low intensity on apparent diffusion coefficient maps and slightly high intensity on T2-weighted images. Recurrence of MERS type 2 was considered because the symptoms of the patient disappeared within several hours and the abnormal signal intensities markedly decreased on the follow-up DWI performed eight days after initial MR imaging. The abnormal MR imaging findings completely disappeared after five weeks. After discharge, the patient experienced eight TIA-like episodes with a similar clinical course and MR imaging findings over a period of six years. MERS associated with TIA-like episodes is extremely rare, especially MERS associated with recurrent episodes in multiple phases over a long period, as seen in the present case. In addition, the findings in the last two MR imaging scans involving the internal capsule, thalamus, and midbrain were highly unusual and maybe considered to be indicative of an advanced form of MERS type 2, as reported in other familial cases.

Combined Fundal and Segmental Adenomyomatosis of the Gallbladder in a Child: A Rare Case Report.

Adenomyomatosis of the gallbladder (AMG) is characterized by mucosal hyperplasia leading to invagination through the thickened muscle layer, which is relatively common in adults, but is rare in childhood. We report a 12-year-old boy with adenomyomatosis of the gallbladder combined segmental and fundal type. This combined type is rare in adults and is first reported here in childhood. Although initial imaging with computed tomography (CT) suggested the presence of a circular solid mass-like lesion because of its rare morphology, repeated ultrasonography (US) was useful for leading to a correct diagnosis.

[Reversible Cerebral Vasoconstriction Syndrome with Cortical Subarachnoid Hemorrhage due to Acute Cortical Infarction Beneath the Sulcus:A Case Report].

We report a rare case of reversible cerebral vasoconstriction syndrome(RCVS)with cortical subarachnoid hemorrhage(cSAH)associated with a fresh cortical infarction beneath the sulcus with thick cSAH. A 34-year-old woman presented with history of thunderclap headache. She was transferred to our hospital for further examination of a cSAH in the left frontal lobe. Results of the cerebrospinal fluid examination were unremarkable, but three-dimensional rotational angiography revealed multiple instances of narrowing of the cortical branches of the anterior and middle cerebral arteries, suggesting the diagnosis of RCVS. Diffusion weighted imaging(DWI)demonstrated a small cortical area with high-signal intensity around the sulcus , where a thick cSAH clot was observed. This cortical lesion appeared as low-signal intensity on the apparent diffusion coefficient maps, and the follow-up T2-weighted images(obtained 3 months after onset)demonstrated a residual lesion that was smaller than the initial DWI abnormality with high-signal intensity;thus indicating the presence of a coincident fresh cortical infarction. The position of the infarct next to the thickest portion of cSAH suggested that it was the bleeding source of the cSAH. Ten days after onset, the cerebral blood flow and volume in the cortex around the cSAH increased as compared to the same area on the contralateral side. These findings suggested that at least one of the bleeding mechanisms of the cSAH was related to the hemorrhagic infarction or subpial hemorrhage resulting from the "ischemia-reperfusion injury" due to the acute disturbance of the pial vessel microcirculation with subsequent rapid resolution of the blood flow during the early phases of RCVS. These dynamics could not be demonstrated with contemporary angiographic imaging.

Efficacy of the Drip and Ship Method in 24-h Helicopter Transportation and Teleradiology for Isolated Islands.

Our hospital, located on the mainland, serves as a hub center for nine hospitals on the remote islands of Nagasaki Prefecture, Japan. There are no stroke specialists on these islands. We can transfer emergency patients from these islands to our hospital at any time, using a teleradiology system and three types of helicopter transport. We examined the efficacy of the drip and ship (DS) method for treating patients with acute ischemic stroke (AIS) on these islands, in comparison with patients on the mainland. From 2010 to 2017, we reviewed 98 consecutive patients with AIS who received intravenous recombinant tissue plasminogen activator (IV rt-PA) in our hospital or were transported to our hospital after IV rt-PA. Patients were divided into the Islands group (received IV rt-PA on the islands, DS; 31 cases) and the Mainland group (67 cases). The median transport distance from the islands was 112 km. The rate of patients achieving favorable outcomes was 54.8% in the Islands group and 64.2% in the Mainland group, with no significant differences. Multivariate analysis revealed that patients living on isolated islands did not have increased risks of unfavorable outcomes. Endovascular therapy (EVT), as part of the drip, ship, and retrieve method, was performed in 22.6% of patients in the Islands group and EVT in 38.8% of those in the Mainland group. The DS method seems feasible and safe for patients living on isolated islands with the use of 24-h helicopter transportation and teleradiology.

[Unruptured Aneurysm Arising from the Proximal End of the Duplicate Origin of the Middle Cerebral Artery].

We report a rare case of an unruptured aneurysm arising from the junction between the internal carotid artery(ICA)and duplicate origin of the middle cerebral artery(MCA). A 49-year-old man who presented with vertigo was admitted to our hospital. Subsequent MR and CT angiograms revealed an incidental aneurysm arising from the proximal end of the duplicate origin of the left MCA. He underwent clipping via the distal transsylvian approach. The aneurysm projected to the posterior direction and several perforators from the two M1 segments were attached to the neck of the aneurysm, which made neck dissection very difficult. Approaching the space from the posterior/lateral direction to reach the M1 segment, the aneurysm neck was successfully dissected and clipped without sacrificing any perforators or stenosis of parent vessels. The postoperative course was uneventful, and the patient was discharged within 2 weeks. Duplicate origin of the MCA has been confused with a fenestration of the proximal M1 segment or terminal segment of the ICA. In this condition, two MCA branches arise separately from the terminal segment of the ICA and fuse early to form an arterial ring at the proximal M1 segment. An aneurysm originating from this anomaly has never been described. However, some aneurysms associated with this type of origin may have incorrectly been reported as those associated with proximal MCA or terminal ICA fenestrations. We summarize the cases that are similar to our case of duplicate origin of the MCA with an aneurysm, and discuss the precise diagnosis and significant intraoperative problems that were described in the literature.

Antibody-mediated bacterial killing of Ichthyobacterium seriolicida in Japanese amberjack.

Ichthyobacterium seriolicida is the causative agent of bacterial hemolytic jaundice (BHJ) in Japanese amberjack, Seriola quinqueradiata. Fish recovering from BHJ acquire protective immunity against reinfection. In this study, fish were passively immunized to determine whether serum antibody is involved in protection against BHJ. The susceptibility of I. seriolicida to the bactericidal activity of Japanese amberjack serum was also investigated. In passive immunization tests, significantly lower mortality was noted in fish that received convalescent serum. Bacteria were killed when exposed to convalescent serum but not serum from naïve fish. Electron microscopic analyses showed that I. seriolicida cells were morphologically altered by reaction with convalescent serum. Naïve fish serum became bactericidal upon addition of purified IgM from convalescent serum. Involvement of the classical complement pathway in the bactericidal mechanism was confirmed because bactericidal activity was lost upon heating convalescent serum or chelation treatment using EDTA. Convalescent fish serum thus protects against reinfection by I. seriolicida via humoral immunity mediated by activation of the classical complement pathway.

[A Rare Case of a Ruptured De Novo Aneurysm Arising from the Twig-like Networks of an Anomalous Collateral Artery Associated with Hypoplasia of the M1 Segment of the Middle Cerebral Artery 4 Years after the Rupture of an A1 Aneurysm at the Origin of the Collateral Artery].

We report a rare case of a de novo ruptured aneurysm arising from the twig-like networks(TLN)of an anomalous collateral artery associated with an aplastic or twig-like middle cerebral artery(Ap/T-MCA). A 65-year-old woman with a decreased level of consciousness, who had been diagnosed with a right Ap/T-MCA and was treated with coil embolization for a ruptured A1 aneurysm at the origin of the anomalous collateral artery 4 years ago, was transferred to our hospital. Head CT revealed an intracerebral hematoma extending from the right frontal lobe to the caudate nucleus with intraventricular hemorrhage. Subsequent 3D-rotational angiograms revealed a ruptured de novo aneurysm arising from the TLN and regrowth of the residual neck of the coiled aneurysm. The two aneurysms were successfully treated by surgical clipping combined with superficial temporal artery middle cerebral artery anastomosis in the subacute phase. To our knowledge, only 11 cases of this type of aneurysm have been reported, including our case, and this is the first report of a de novo aneurysm within the TLN so far. Although all previously reported aneurysms were small(<5-6mm), 10 of them(91%)ruptured. These data may indicate the vulnerability of this type of aneurysm to rupture despite their small size, probably due to hemodynamic stress and the fragile nature of their immature walls. To prevent recurrence of hemorrhage in these cases, revascularization may be necessary in addition to surgical clipping. Whether this concept is correct is an open question. Further studies are necessary to examine this issue.

[A Rare Case of Ruptured/Unruptured Miniature Aneurysms Originating from the Infundibular Dilatation of the Callosomarginal Artery, Branching from the Infracallosal(A2)Segment of the Azygos Anterior Cerebral Artery].

We report the first case of two de novo miniature aneurysms(ruptured/unruptured)emerging from the infundibular dilatation(ID)of the callosomarginal artery, which branches from the infracallosal(A2)segment of the azygos anterior cerebral artery(AACA), in a 36-year-old woman. The patient had previously been diagnosed with a miniature, unruptured aneurysm, occurring in the A2 segment of the AACA, detected by CT angiography(CTA)at another hospital two years ago, and had been followed up with MR angiography(MRA)every 6 months. Three months after the final check-up with MRA, which did not indicate a significant change in the aneurysm, the patient presented with subarachnoid hemorrhage. Subsequent CTA and digital subtraction angiograms revealed that the right callosomarginal artery, originating from the apex of the aneurysmal bulge, had a maximal diameter of 3mm, indicating an ID of the artery. Additionally, two miniature bleb-like aneurysms emerged from the ID, projecting in opposite directions:one projecting to the right-posterior/superior direction and the other to the left-anterior/inferior direction. Both aneurysms were successfully clipped via a right pterional approach with partial resection of the gyrus rectus, and the right-projecting aneurysm was confirmed to be ruptured during surgery. In the current report, we review previously reported cases of AACA with aneurysms, and discuss their clinical characteristics, and the possible mechanisms underlying the formation of the ID and de novo aneurysms in this extremely rare case.

Production of a novel monoclonal antibody applicable for an immunochromatographic assay for Kudoa septempunctata spores contaminating the raw olive flounder (Paralichthys olivaceus).

Kudoa septempunctata, a myxosporean parasite of the olive flounder (Paralichthys olivaceus), causes foodborne gastroenteritis after ingestion of contaminated raw flounder. Available methods to detect K. septempunctata require expensive equipment, well-trained personnel, and lengthy procedures. Here we generated a novel monoclonal antibody (MAb 15G11) against K. septempunctata and used it to produce a prototype immunochromatographic assay (prototype Kudoa-ICA). Within 15min, the prototype Kudoa-ICA detected ≥1.0×105spores/mL in a spore suspension and ≥2.0×104spores/g of P. olivaceus muscle. The prototype Kudoa-ICA weakly cross-reacted with spores of K. lateolabracis and K. iwatai. cDNA sequence, expression, and western blot analyses revealed that MAb 15G11 detected an approximately 24-kDa protein encoded by a 573bp mRNA. The cDNA nucleotide and predicted amino acid sequences were not significantly similar to any sequence in the GeneBank database. Immunoelectron microscopy revealed that MAb 15G11 reacted with the sporoplasmic cells and mainly with the capsulogenic cells of the K. septempunctata spore. Although the Kudoa-ICA was weakly cross-reactive with two other Kudoa species, it detected >1.0×106spores/g of K. septempunctata in P. olivaceus muscle, which is the criterion used to indicate a violation of the Food Hygiene Law of Japan. We conclude that MAb 15G11 may be suitable for use in an immunochromatographic assay for screening P. olivaceus muscle contaminated with K. septempunctata at food distribution sites such as food wholesalers, grocery stores, and restaurants.

[A Rare Case of Ruptured Internal Carotid-Posterior Communicating Artery Aneurysm Associated with Contralateral Delayed Oculomotor Nerve Palsy].

A 55-year-old man presented with difficulty breathing, chest pain, and disturbance of consciousness, and was transferred to our hospital. Initial whole body CT revealed a diffuse subarachnoid hemorrhage(SAH)with severe pulmonary edema that was considered neurogenic in origin. He received controlled ventilation under sedation and conservative care for the SAH. One day after the onset of the SAH, his left pupil suddenly became dilated to 6mm, with no reaction to light. Head CT showed no new bleeding. Subsequent CT angiogram revealed a right internal carotid-posterior communicating artery aneurysm(IC-PC AN)with a posterior-lateral projection; however, no vessel abnormality was observed in the left anterior or posterior circulations. The aneurysm was successfully treated with coil embolization. We reviewed reported cases of isolated oculomotor nerve palsy(ONP), without direct compression by ruptured aneurysms, and found that only 11 cases exist, including our case. Interestingly, six of them were associated with anterior communicating artery aneurysms. A mass effect, chemical stimulation, and a jet stream of blood were proposed as the mechanisms of this rare type of ONP, in addition to the specific neurovascular relationships between the oculomotor nerve and the posterior cerebral/posterior communicating/superior cerebellar arteries, with abnormal nerve contact or compression. Though rare, ruptured IC-PC ANs could cause contralateral ONP; other types of ruptured aneurysms may also lead to indirect effects on nervous structures without direct compression. This type of rare presentation of ruptured aneurysms should be considered, especially in cases of multiple aneurysms, such as IC-PC ANs.