Aqueductal developmental venous anomaly causing obstructive hydrocephalus: A case report and review of the literature.

A developmental venous anomaly (DVA) is a venous drainage of the associated parenchyma that is normally asymptomatic. However, a DVA located adjacent to the aqueduct can cause obstructive hydrocephalus by blocking the flow of cerebrospinal fluid. We describe a rare case of obstructive hydrocephalus due to aqueductal stenosis secondary to a DVA. A 43-year-old man presented with sudden bilateral temporal pain during weight training. Using a 3-Tesla scanner, cranial magnetic resonance imaging (MRI) was performed, and hydrocephalus was found with mild enlargement of the lateral and third ventricles. Susceptibility-weighted imaging and postcontrast MRI revealed that the DVA from the bilateral thalami narrowed the orifice of the aqueduct on its drainage route towards the vein of Galen. We assumed that force exerted during weight training may have caused dilation of the anomalous veins, leading to his symptom. A review of the relevant English-language literature yielded only 19 cases of aqueductal stenosis due to DVA. In comparison to these cases, the duration of symptom in our case was extremely short because the patient had a history of ventriculomegaly detected on plain computed tomography and was diagnosed quickly based on the characteristic finding of DVA: the caput medusae appearance.

Posterior cerebral artery (PCA)-accessory PCA (hyperplastic anterior choroidal artery) anastomosis detected on magnetic resonance angiography.

PURPOSE: To describe a case of posterior cerebral artery (PCA)-accessory PCA (hyperplastic anterior choroidal artery) anastomosis detected on magnetic resonance angiography. METHODS: A 76-year-old man with a history of cerebral infarction underwent cranial magnetic resonance (MR) imaging and MR angiography of the intracranial region for the evaluation of brain and vascular lesions. The MR machine was a 3-Tesla scanner. MR angiography was performed using a standard three-dimensional time-of-flight technique. RESULTS: There were two right PCAs. The parieto-occipital and calcarine arteries of the right PCA arose from the right ICA, indicative of accessory PCA, and there were three stenotic lesions at the proximal segment of this artery. The temporal artery of the right PCA originated from the basilar artery. A small anastomotic channel between these two arteries was identified on partial maximum intensity projection (MIP) images. Computed tomography angiography was additionally performed and the findings were confirmed. CONCLUSION: We speculated that the pressure gradient between the PCA and the accessory PCA enlarged the anastomotic channel. Partial MIP images are useful for diagnosing small arterial variations using MR angiography.

Accessory posterior cerebral artery (hyperplastic anterior choroidal artery) associated with contralateral accessory middle cerebral artery incidentally diagnosed by magnetic resonance angiography.

PURPOSE: To describe a case of accessory posterior cerebral artery (PCA) [hyperplastic anterior choroidal artery (AChA)] associated with contralateral accessory middle cerebral artery (MCA) incidentally diagnosed by magnetic resonance (MR) angiography. METHODS: A 71-year-old man with paroxysmal atrial fibrillation underwent cranial MR imaging and MR angiography of the intracranial region using a 1.5-T scanner for the evaluation of brain and vascular lesions. RESULTS: On MR angiography, two right PCAs of equal size arose from the internal carotid artery instead of the basilar artery. Additionally, a small left MCA branch arose from the proximal A2 segment of the anterior cerebral artery (ACA). CONCLUSION: One of the branches of the PCA rarely arises from the AChA. This variation is referred to as a hyperplastic AChA or accessory PCA. The latter name was recently proposed and may be more appropriate than the former name. An MCA branch arising from the ACA is called an accessory MCA. It is a frontal branch of two types: proximal-origin and distal-origin. The distal-origin accessory MCA arises from the distal A1 segment, A1-A2 junction or proximal A2 segment. Distal-origin accessory MCAs are rare. Our patient had two rare variations: an accessory right PCA and a distal-origin accessory left MCA. To identify cerebral arterial variations, especially accessory MCA, volume-rendering images are more useful than maximum-intensity projection images on MR angiography.

Thyrolinguofacial trunk arising from the common carotid artery and diagnosed by computed tomography angiography.

PURPOSE: Various variations in the head and neck vasculature have been reported. The purpose of this report is to describe an extremely rare case of thyrolinguofacial trunk (TLFT) arising from the common carotid artery (CCA). METHODS: A 66-year-old woman with vertigo, dizziness, and heaviness in the head underwent computed tomography (CT) angiography of the neck and head region for evaluation of cerebrovascular diseases. RESULTS: The TLFT originated from the anterior wall of the right CCA and was divided into the superior thyroid artery and linguofacial trunk (LFT). The LFT was divided into lingual and facial arteries. In addition, we observed fusiform dilatation of the intracranial right vertebral artery, which might have caused these symptoms. CONCLUSION: The presence of a common trunk of the external carotid artery (ECA) branches increases the risk of complications such as bleeding and ischemia during treatment of the head and neck region, including chemoradiotherapy for oral bleeding and tongue cancer. Therefore, this is an area of significant interest across various medical specialties, including surgery, otolaryngology, and radiology. Understanding the diverse variations in the neck vasculature is expected to lead to a reduction in complications associated with various procedures.

Persistent trigeminal artery variant and presumed ophthalmic artery simultaneously arising from the inferolateral trunk incidentally diagnosed by magnetic resonance angiography.

PURPOSE: To describe a case of persistent trigeminal artery variant (PTAV) and presumed ophthalmic artery (OA) simultaneously arising from the inferolateral trunk (ILT). METHODS: A 53-year-old woman with an initial episode of convulsion underwent cranial magnetic resonance imaging (MRI) and MR angiography (MRA) of the intracranial region for the evaluation of brain and vascular lesions. The MR machine was a 3-T scanner. RESULTS: MRI revealed no pathological brain lesions. On MRA, the left anterior inferior cerebellar artery (AICA) arose from the cavernous segment of the internal carotid artery (ICA), indicative of the PTAV. The arising point was more distal than the usual point, and the presumed OA also arose simultaneously from the short common trunk, which was considered the ILT. CONCLUSION: There are two types of PTA: lateral (usual) and medial (intrasellar) PTA. The lateral-type PTA and PTAV arise from the ICA of the distal precavernous-proximal cavernous segment and take a course similar to that of the posterior fossa. The medial type arises slightly more in the distal cavernous segment than in the lateral type. The OA rarely arises from the cavernous segment of the ICA and enters the orbit via the superior orbital fissure. The origin of this type of OA is considered to be the ILT. We herein report a case of a PTAV and presumed OA arising simultaneously from an ILT. No similar case has been reported in the relevant English language literature.

Syntenic analysis of ACCase loci and target-site-resistance mutations in cyhalofop-butyl resistant Echinochloa crus-galli var. crus-galli in Japan.

BACKGROUND: Recently, suspected cyhalofop-butyl-resistant populations of allohexaploid weed Echinochloa crus-galli var. crus-galli were discovered in rice fields in Aichi Prefecture, Japan. Analyzing the target-site ACCase genes of cyhalofop-butyl helps understand the resistance mechanism. However, in E. crus-galli, the presence of multiple ACCase genes and the lack of detailed gene investigations have complicated the analysis of target-site genes. Therefore, in this study, we characterized the herbicide response of E. crus-galli lines and thoroughly characterized the ACCase genes, including the evaluation of gene mutations in the ACCase genes of each line. RESULT: Four suspected resistant lines collected from Aichi Prefecture showed varying degrees of resistance to cyhalofop-butyl and other FOP-class ACCase inhibitors but were sensitive to herbicides with other modes of action. Through genomic analysis, six ACCase loci were identified in the E. crus-galli genome. We renamed each gene based on its syntenic relationship with other ACCase genes in the Poaceae species. RNA-sequencing analysis revealed that all ACCase genes, except the pseudogenized copy ACCase2A, were transcribed at a similar level in the shoots of E. crus-galli. Mutations known to confer resistance to FOP-class herbicides, that is W1999C, W2027C/S and I2041N, were found in all resistant lines in either ACCase1A, ACCase1B or ACCase2C. CONCLUSION: In this study, we found that the E. crus-galli lines were resistant exclusively to ACCase-inhibiting herbicides, with a target-site resistance mutation in the ACCase gene. Characterization of ACCase loci in E. crus-galli provides a basis for further research on ACCase herbicide resistance in Echinochloa spp. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Fenestration of the superior cerebellar artery diagnosed by magnetic resonance angiography.

We herein report a case of fenestration of the superior cerebellar artery (SCA), which was incidentally diagnosed by magnetic resonance (MR) angiography. A 65-year-old woman was referred to our hospital for unruptured cerebral aneurysms. MR angiography revealed 2 unruptured aneurysms. It also showed fenestration of the left SCA near its origin from the basilar artery, as well as several other vascular variations: a left common carotid artery arising from the brachiocephalic trunk, and a right vertebral artery terminating to the right posterior inferior cerebellar artery. Yearly observation was chosen as a treatment strategy due to the small size of the cerebral aneurysms. According to previous reports, SCA fenestration is an extremely rare variation. This is the second case of SCA fenestration diagnosed by MR angiography in the relevant English-language literature.

Medial-type persistent trigeminal artery and ipsilateral posterior communicating artery supplying bilateral posterior cerebral arteries combined with an aberrant right subclavian artery and bicarotid trunk.

PURPOSE: To describe a case of a medial-type persistent trigeminal artery (PTA) associated with multiple arterial variations. METHODS: A 34-year-old woman with multiple sclerosis underwent cranial magnetic resonance (MR) angiography from the aortic arch to the neck region and intracranial region for the evaluation of an unruptured cerebral aneurysm that was previously detected on MR imaging. The MR machine was a 3-T scanner. RESULTS: There was an aberrant right subclavian artery and bicarotid trunk, medial-type left PTA and ipsilateral posterior communicating artery (PCoA) supplying bilateral posterior cerebral arteries (PCAs). The unruptured aneurysm was located at the paraclinoid segment of the left internal carotid artery and was treated successfully by coil embolization via a transfemoral approach. CONCLUSION: Only 10% of PTAs are classified as the medial type. The association with extremely large ipsilateral PCoA, which supplies the bilateral PCAs, has not been previously reported. Aberrant right subclavian arteries are common and are frequently associated with a bicarotid trunk. Before catheterization of the cerebral arteries, the aortic arch and its branches must be evaluated by MR angiography or computed tomography angiography to prevent catheterization failure via the right transradial approach.

A nonbifurcating cervical carotid artery with a remnant of the proximal internal carotid artery that mimicked an aneurysm on magnetic resonance angiography.

PURPOSE: To describe a case of a nonbifurcating cervical carotid artery with remnant of the proximal internal carotid artery (ICA). METHODS: A 47-year-old man with unruptured cerebral aneurysm underwent magnetic resonance (MR) angiography of the neck region and intracranial region. The MR machine was a 3-T scanner. Catheter angiography was performed for the treatment of the aneurysm by coil embolization. RESULTS: The proximal main trunk of the left external carotid artery (ECA) was absent, and branches arose separately, indicative of a nonbifurcating cervical carotid artery. At the level of the ICA origin, aneurysmal protrusion was found on MR angiography. On catheter angiography, this protrusion was not an aneurysm but a remnant of the proximal ICA. CONCLUSION: The configuration of the nonbifurcating cervical carotid artery lacks the proximal ECA; however, segmental agenesis of the proximal ICA forms this rare cervical arterial variation. The present case had remnants of the proximal ICA. We speculate that the ICA channel, except for the origin, was occluded after the development of EC-ICA anastomosis, and a nonbifurcating cervical carotid artery with a remnant of the ICA may have formed. Including our patient, only four cases have been reported in the relevant English-language literature.

Wallerian degeneration of the ipsilateral middle cerebellar peduncle after lower pontine paramedian infarct diagnosed by magnetic resonance imaging.

We reported a case of Wallerian degeneration of the unilateral middle cerebellar peduncle (MCP) that developed after ipsilateral paramedian lower pontine infarction. The patient was a 70-year-old woman with right hemiparesis and dysarthria. Using a 3-Tesla scanner, cranial magnetic resonance imaging was performed, and an infarct was found at the left paramedian lower pons. Seven months later, an abnormal signal was found at the central portion of the left MCP, indicative of Wallerian degeneration of the pontocerebellar tract (PCT). There was no abnormality at the contralateral MCP. Usually, Wallerian degeneration of the bilateral MCPs may develop after unilateral paramedian pontine infarction, because bilateral PCTs cross each other at the midline of the basis pontis. In the present case, however, Wallerian degeneration was found at only the ipsilateral MCP. The contralateral PCT was not affected because the PCT runs in the craniocaudal direction, and our patient had a lower pontine infarct. The location of the pontine infarct (affected PCT) and the Wallerian degeneration of the side of the MCP were well correlated.

Congenital external carotid-internal carotid artery anastomosis: a report of three cases and literature review.

PURPOSE: Congenital external carotid-internal carotid artery (EC-ICA) anastomosis is a cervical arterial variation that was initially reported, based on anatomic dissection, from Japan in 2000. The purpose of this report is to show the characteristic radiological findings of this extremely rare cervical arterial variation. METHODS: We analyzed nine cases, including six previously reported cases and three cases that we recently experienced. Three of the six previously reported cases were from Japan, and the remaining three cases were from Korea. MR angiography (4), CT angiography (2), catheter angiography (2) and autopsy (1) were used as diagnostic modalities. RESULTS: The study population included eight men and one woman. Anastomosis was seen on the left side in seven cases and the right side in two cases, and it was located at the level of the C1/2-C2/3 intervertebral space. In all cases, ECA was larger than the ICA at the level of their origins. In four cases, the ICA was extremely small in caliber. In one case, the ICA may have been occluded postnatally, and its configuration was similar to that of the nonbifurcating cervical carotid artery (CCA). With the exception of this occluded case, the carotid bifurcation and EC-ICA anastomosis formed a large arterial ring in all cases. CONCLUSION: EC-ICA anastomosis can be regarded as a variant of the nonbifurcating CCA because if the most proximal segment of the small ICA is occluded, nonbifurcating CCA may form. EC-ICA anastomosis is located between the C1/2-C2/3 intervertebral space and may be formed by the remnants of the proatlantal artery I.

Persistent trigeminal artery-superior cerebellar artery segmental fusion diagnosed using magnetic resonance angiography.

PURPOSE: To describe a case of persistent trigeminal artery (PTA)-superior cerebellar artery (SCA) segmental fusion incidentally diagnosed on magnetic resonance (MR) angiography. CASE REPORT: A 53-year-old woman with a history of facial pain underwent cranial MR imaging and MR angiography. MR angiography showed a left lateral-type PTA arising from the precavernous portion of the left internal carotid artery (ICA). PTA branched into the left distal SCA and showed segmental fusion with the proximal SCA at the distal part of the PTA. We also diagnosed an unruptured cerebral aneurysm at the junction between the left ICA and PTA. DISCUSSION: PTA is the most frequent type of carotid-vertebrobasilar anastomosis. The reported prevalence rate is 0.2% by angiography and 0.34% by MR angiography. There are two types of PTA-lateral (usual) and medial (intrasellar). SCA arising from the lateral-type PTA has rarely been reported. Further, a PTA from which the distal SCA branches and segmentally fuses with the proximal SCA at the distal part of the PTA has not been reported. CONCLUSION: Using MR angiography, we diagnosed a rare type of PTA that fused segmentally with SCA. No similar case has been reported in relevant English-language literature.

Transcriptionally linked simultaneous overexpression of P450 genes for broad-spectrum herbicide resistance.

Broad-spectrum herbicide resistance (BSHR), often linked to weeds with metabolism-based herbicide resistance, poses a threat to food production. Past studies have revealed that overexpression of catalytically promiscuous enzymes explains BSHR in some weeds; however, the mechanism of BSHR expression remains poorly understood. Here, we investigated the molecular basis of high-level resistance to diclofop-methyl in BSHR late watergrass (Echinochloa phyllopogon) found in the United States, which cannot be solely explained by the overexpression of promiscuous cytochrome P450 monooxygenases CYP81A12/21. The BSHR late watergrass line rapidly produced 2 distinct hydroxylated diclofop acids, only 1 of which was the major metabolite produced by CYP81A12/21. RNA-seq and subsequent reverse transcription quantitative PCR (RT-qPCR)-based segregation screening identified the transcriptionally linked overexpression of a gene, CYP709C69, with CYP81A12/21 in the BSHR line. The gene conferred diclofop-methyl resistance in plants and produced another hydroxylated diclofop acid in yeast (Saccharomyces cerevisiae). Unlike CYP81A12/21, CYP709C69 showed no other herbicide-metabolizing function except for a presumed clomazone-activating function. The overexpression of the 3 herbicide-metabolizing genes was also identified in another BSHR late watergrass in Japan, suggesting a convergence of BSHR evolution at the molecular level. Synteny analysis of the P450 genes implied that they are located at mutually independent loci, which supports the idea that a single trans-element regulates the 3 genes. We propose that transcriptionally linked simultaneous overexpression of herbicide-metabolizing genes enhances and broadens the metabolic resistance in weeds. The convergence of the complex mechanism in BSHR late watergrass from 2 countries suggests that BSHR evolved through co-opting a conserved gene regulatory system in late watergrass.

A posterior inferior cerebellar artery of C2 transverse foramen level origin that entered the spinal canal via the C1/2 intervertebral space demonstrated by computed tomography angiography.

PURPOSE: To describe a case of a posterior inferior cerebellar artery (PICA) of C2 transverse foramen level vertebral artery (VA) origin that entered the spinal canal via the C1/2 intervertebral space. CASE REPORT: A 48-year-old man with posterior neck pain underwent computed tomography (CT) angiography and selective left vertebral angiography. Arterial dissection was found at the distal V2 segment of the left VA on subtracted CT angiography. The left PICA arising from the VA at the level of C2 transverse foramen was identified on CT angiography with bone imaging. This PICA of extracranial origin entered the spinal canal via the C1/2 intervertebral space, just like a PICA of C1/2 level origin. DISCUSSION: The origins of PICAs show several variations. PICAs originating at the extracranial C1/2 level VA are relatively rare, with a reported prevalence of approximately 1%. Our patient had a left PICA arising from the VA at the level of the C2 transverse foramen. No similar cases have been reported in the relevant English-language literature. We speculated that the proximal short segment of the PICA arising from the C1/2 level VA regressed incidentally and that the distal segment of the PICA was supplied by the muscular branch of the VA arising from the level of the C2 transverse foramen. CONCLUSION: We reported the first case of PICA arising from the C2 transverse foramen level VA. CT angiography with bone imaging is useful for identifying a PICA arising from the extracranial VA.

Clostridium folliculivorans sp. nov., isolated from soil samples of an organic paddy in Japan.

Two Gram-stain-negative, terminal endospore-forming, rod-shaped and aerotolerant bacterial strains designated D1-1T and B3 were isolated from soil samples of an organic paddy in Japan. Strain D1-1T grew at 15-37 °C, pH 5.0-7.3, and with up to 0.5 % (w/v) NaCl. Phylogenetic analysis of the 16S rRNA gene revealed that strain D1-1T belonged to the genus Clostridium and was closely related to Clostridium zeae CSC2T (99.7 % sequence similarity), Clostridium fungisolvens TW1T (99.7 %) and Clostridium manihotivorum CT4T (99.3 %). Strains D1-1T and B3 were whole-genome sequenced and indistinguishable, with an average nucleotide identity value of 99.7 %. The average nucleotide identity (below 91.1 %) and digital DNA-DNA hybridization (below 43.6 %) values between the two novel isolates and their corresponding relatives showed that strains D1-1T and B3 could be readily distinguished from their closely related species. A novel Clostridium species, Clostridium folliculivorans sp. nov., with type strain D1-1T (=MAFF 212477T=DSM 113523T), is proposed based on genotypic and phenotypic data.

Large persistent trigeminal artery variant that supplied the subtotal cerebellar hemisphere and caused trigeminal neuralgia, which was diagnosed by magnetic resonance (MR) angiography and MR cisternography.

PURPOSE: To describe a case of large persistent trigeminal artery (PTA) variant that caused trigeminal neuralgia, which was diagnosed by magnetic resonance (MR) angiography and MR cisternography. CASE REPORT: An 82-year-old woman with left trigeminal neuralgia underwent cranial MR imaging, MR angiography and MR cisternography. MR imaging revealed no significant abnormality. MR angiography showed that a relatively large artery arose from the precavernous segment of the left internal carotid artery (ICA) without connection to the basilar artery, which is indicative of a PTA variant. This artery supplied the left cerebellar arteries, except for the rostral branch of the superior cerebellar artery. MR cisternography showed that the inferior surface of the left trigeminal nerve was compressed by the PTA variant. She was treated by microvascular decompression surgery and her symptoms disappeared. DISCUSSION: According to a meta-analysis, the prevalence of the PTA variants is reported to be 0.2%. The majority of PTA variants are small arteries and are classified as the anterior inferior cerebellar artery type. The present case involved a relatively large artery that supplied large territories of the cerebellar hemisphere. PTA and PTA variants rarely cause trigeminal neuralgia. CONCLUSION: Using MR angiography and MR cisternography, the author diagnosed a case of large PTA variant that caused trigeminal neuralgia. No similar case has been reported in the relevant English language literature.

Duplicated superior cerebellar arteries, one of which was supplied by a persistent trigeminal artery variant diagnosed by magnetic resonance angiography.

PURPOSE: The purpose of the study was to describe a case of duplicated superior cerebellar arteries (SCAs), whose caudal branch was supplied by a persistent trigeminal artery (PTA) variant, diagnosed by magnetic resonance (MR) angiography. CASE REPORT: A 74-year-old woman with a history of cerebral infarction underwent cranial MR imaging and MR angiography. MR imaging revealed chronic-stage left cerebellar and right basal ganglionic infarctions. MR angiography showed no steno-occlusive lesions in the intracranial arteries; however, duplicated left SCAs were observed and the caudal branch arose from the precavernous segment of the left internal carotid artery, which is indicative of a PTA variant. DISCUSSION: Variations of the SCA (e.g., duplication, early bifurcation, and common trunk of the posterior cerebral artery and SCA) are frequently seen. A cerebellar artery arising from the precavernous segment of the internal carotid artery without connection to the basilar artery is regarded as a PTA variant. According to a meta-analysis, the prevalence is reported to be 0.2%. The majority of PTA variants are classified as the anterior inferior cerebellar artery type. PTA and PTA variants are frequently associated with other cerebral variations. A case of duplicated posterior inferior cerebellar artery, in which one of the branches was supplied by a PTA variant, was reported previously. However, the combination of duplicated SCA and PTA variants has not been reported. CONCLUSION: Using MR angiography, the author diagnosed a case of duplicated SCA, whose caudal branch was supplied by a PTA variant. No similar case has been reported in the relevant English-language literature.

Newly developed twisted carotid bifurcation on the left side incidentally diagnosed by magnetic resonance angiography.

We herein report a case of left twisted carotid bifurcation (TCB) that newly appeared on follow-up examination. The patient was a 71-year-old woman with neck bruit and hyperlipidemia underwent neck magnetic resonance angiography. The left carotid bifurcation showed a normal branching pattern. Two years later, a follow-up examination was performed, and the left internal carotid artery (ICA) ran medial to the external carotid artery (ECA), indicating TCB. On the right side, the ICA ran dorsal to the ECA. The prevalence of TCB is reported to be 3.6%-15.1%. According to a review of the relevant literature, >80% of TCBs were found on the right side. TCB is generally considered to be a result of excessive lateral migration of the ECA during embryogenesis, and age-related atherosclerotic elongation and tortuosity of the carotid arteries may be another cause. In the case of TCB, carotid endarterectomy (CEA) is slightly difficult and slightly dangerous, because the affected ICA lies behind the ECA, and superior laryngeal nerve injury rarely occurs. TCB is not uncommon, but there is greater frequency on the right side. It may also newly develop. It is important to conduct a radiological evaluation of TCB before performing CEA.

An extremely short posterior communicating artery diagnosed by magnetic resonance angiography.

PURPOSE: To describe a case of an extremely short posterior communicating artery (PCoA) incidentally diagnosed by magnetic resonance (MR) angiography. CASE REPORT: A 48-year-old woman with Parkinson's disease underwent cranial MR imaging and MR angiography. MR imaging revealed no abnormality. After creating partial maximum-intensity-projection (MIP) images, MR angiography showed an extremely short right PCoA, only 4 mm long. The P1 segment of the right posterior cerebral artery (PCA) took an anterior course, and at the junction with the PCoA, the PCA made a hairpin turn and ran posteriorly. The length of the P1 segment was approximately 20 mm, which was relatively long. DISCUSSION: According to an anatomical study using 170 cadaveric brains, the length of the PCoA ranged 5 to 26 mm (mean: 15 mm). Another 2 anatomical studies reported that the shortest PCoA was 7 mm. The present case had an extremely short right PCoA connecting with a hairpin turn at the P1-P2 junction, a unique configuration. CONCLUSION: To identify this variation by MR angiography, creation of partial MIP images was useful.

Ophthalmic artery arising from the presumed meningohypophyseal trunk of the cavernous internal carotid artery diagnosed by magnetic resonance angiography.

PURPOSE: The purpose of the study is to describe a case of ophthalmic artery (OA) arising from the presumed meningohypophyseal trunk (MHT) of the cavernous internal carotid artery (ICA). CASE REPORT: A 63-year-old woman suspected of having cerebral infarctions underwent cranial magnetic resonance (MR) imaging and MR angiography. MR angiography showed a right OA that was found to arise from the superolateral aspect of the proximal cavernous ICA. This OA entered the orbit via the superior orbital fissure (SOF). DISCUSSION: Rarely, an OA arises from the inferior aspect of the middle cavernous ICA at the level of the inferolateral trunk (ILT) and enters the orbit via the SOF. This OA variation was traditionally regarded as a persistent primitive dorsal OA but is now believed to be due to the persistence of the lateral branch of the primitive maxillary artery. The present case had an OA arising from the superolateral aspect of the more proximal cavernous ICA than the origin of the ILT, which was suggested to be the origin of the MHT. Persistence of the proximal segment of the trigeminal artery may play an important role in the formation of this extremely rare variation. CONCLUSION: To identify this extremely rare OA variation, careful observation of source images and the creation of volume-rendering MR angiography images are important.