Current status of a helicopter transportation system on remote islands for patients undergoing mechanical thrombectomy.

BACKGROUND: Mechanical thrombectomy (MT) is standard treatment for acute ischemic stroke (AIS) with large-vessel occlusion within 6 h of symptom onset to treatment initiation (OTP). Recent trials have extended the therapeutic time window for MT to within 24 h. However, MT treatment remains low in remote areas. Nagasaki Prefecture, Japan has many inhabited islands with no neurointerventionalists. Our hospital on the mainland is a regional hub for eight island hospitals. We evaluated clinical outcomes of MT for patients with AIS on these islands versus on the mainland. METHODS: During 2014-2019, we reviewed consecutive patients with AIS who received MT at our hospital. Patients comprised the Islands group and Mainland group. Patient characteristics and clinical outcomes were compared between groups. RESULTS: We included 91 patients (Islands group: 15 patients, Mainland group: 76 patients). Seven patients (46.7%) in the Islands group versus 43 (56.6%) in the Mainland group achieved favorable outcomes. Successful recanalization was obtained in 11 patients (73.3%) on the islands and 67 (88.2%) on the mainland. The median OTP time in the Islands was 365 min. In both the Islands and Mainland groups, the OTP time and successful recanalization were associated with functional outcome. The modified Rankin Scale (mRS) score at 90 days ≤2 was obtained in two patients and mRS = 3 in four patients among eight patients with OTP time >6 h. CONCLUSIONS: Few patients with AIS on remote islands have received MT. Although patients who underwent MT on the islands had longer OTP, the clinical outcomes were acceptable. OTP time on remote islands must be shortened, as this is related to functional outcome. In some cases with successful recanalization, a favorable outcome can still be obtained even after 6 h. Even if OTP exceeds 6 h, it is desirable to appropriately select patients and actively perform MT.

Concurrent Ossification of the Posterior Atlantoaxial Interlaminar Membrane and Atlas Hypoplasia: A Case Report.

An onset of cervical myelopathy due to ossification of the posterior atlantoaxial membrane (PAAM) is extremely rare in older patients, and its clinical characteristics are still unclear. We report an onset of ossification of PAAM with congenital atlas hypoplasia in an 81-year-old man who presented with a 2-year history of progressive cervical myelopathy. Cervical computed tomography (CT) revealed canal stenosis secondary to a hypoplastic posterior arch of the atlas with a diameter of 20.3 mm between the anterior and posterior process. Magnetic resonance imaging showed marked spinal cord compression at the level of C1-2 secondary to atlas hypoplasia as well as ossification of PAAM. The patient underwent laminectomy of C1 and partial C2, as well as removal of the ossification, without atlantoaxial fusion. His neurological status improved 1 year postoperatively. In older patients, cervical myelopathy secondary to PAAM ossification, in the absence of trauma and atlantoaxial instability, may be induced by age-related pathophysiology associated with congenital atlas hypoplasia.

[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.

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.

[A Case of Dural Arteriovenous Fistula Involving the Superior Sagittal Sinus that Presented as a Primary Intraventricular Hemorrhage].

We report an extremely rare case of dural arteriovenous fistula(DAVF)involving the superior sagittal sinus(SSS)that presented as a primary intraventricular hemorrhage(PIVH). A 79-year-old man who presented with disturbance of consciousness and vomiting was transferred to our hospital. The initial head CT revealed an intraventricular hemorrhage in the lateral, third, and fourth ventricles, predominantly involving the right lateral ventricle associated with obstructive hydrocephalus. CT angiography and three-dimensional rotational angiography(3D-RA)revealed SSS-DAVF with retrograde venous drainage from the cortical venous system to the subependymal venous system through engorged superficial/anastomotic/deep medullary or transcerebral veins, showing a pseudophlebitic pattern. A severe stenosis of the SSS was observed at the site just proximal to the shunting point. A varix of the right transvers caudate vein(TCV)was observed within the thickest portion of the hematoma in close contact with the wall of the right lateral ventricle. A stenosis of the branching point of the right TCV was detected on the 3D-RA image. The DAVF was completely cured after transarterial embolization. The varix gradually shrank and finally disappeared after 2 months. This is the first report of a case of PIVH due to SSS-DAVF with a subependymal varix considered as the bleeding point. Serial gadolinium-enhanced MR images clearly showed the shrinking of the varix. Our case is the second reported case of spontaneous resolution of the varix after embolization of the DAVF. The obstructive changes of the two venous outflow pathways(SSS/TCV)might further worsen the state of venous congestion in the deep medullary venous system and eventually lead to formation and rupture of the varix.

[A Rare Case of Spontaneous Thrombosis and Recanalization of a Ruptured Small Aneurysm in the Distal Posterior Inferior Cerebellar Artery].

The incidence of spontaneous thrombosis of intracranial aneurysm ranges from 1% to 2% of ruptured aneurysms. Most of them are giant or large aneurysms, and various factors have been discussed in previous literatures. Recanalization of thrombosed aneurysms may be rare, but its mechanism is poorly understood. Reports on recanalization of small aneurysms after spontaneous thrombosis are rare, and the natural history is still unknown. We describe a rare case of spontaneous thrombosis and recanalization of a ruptured small aneurysm of the distal posterior inferior cerebellar artery. Spontaneous aneurysmal thrombosis should not always be considered as a good or safe sign, as it may recanalize in a short time, resulting in re-rupture. In the acute stage, periodic follow-up of patients with a spontaneously thrombosed aneurysm is important.

[A Rare Case of an Unruptured Aneurysm Arising from the Proximal End of the Fenestration of the Infracallosal Segment(A2)of the Anterior Cerebral Artery].

We report an extremely rare case of a fenestration in the infracallosal(A2)segment of the right anterior cerebral artery(ACA)associated with an unruptured aneurysm at the proximal end of the fenestrated portion. A 70-year-old man was referred to our hospital for further examination and treatment of unruptured aneurysms at the A1/A2 junction of the right ACA and the distal end of the right vertebral artery that were incidentally detected on MR angiography. CT angiography and 3D-rotational angiography revealed a fenestration in the proximal A2 segment of the right ACA with a small(3.6×3.8mm)aneurysm arising from the proximal end of the fenestration. The dome of the aneurysm projected to the left anterior/inferior direction. He underwent aneurysm neck clipping surgery via the right pterional approach without complications, while the vertebral artery aneurysm was managed conservatively. An extensive review of the literature revealed that only a small number of cases of A2 fenestration have been reported to date. To our knowledge, this is the first report of an A2 fenestration associated with an aneurysm at the fenestrated segment. Embryologically, the A2 fenestration may represent a remnant of plexiform arterial channels that constitute the primitive ACA system including the primitive olfactory artery, median artery of the corpus callosum and anterior communicating plexus.

[Open Surgery Following Transarterial Embolization for Cavernous Sinus Dural Arteriovenous Fistula].

Cavernous sinus(CS)dural arteriovenous fistula with cortical venous drainage often have a malignant presentation and require urgent treatment. Endovascular embolization is the primary treatment of choice, but failure to catheterize the CS may occur due to vessel tortuosity, hypoplasia, or stenosis. In the absence of venous access to the lesion, a careful surgical approach should be considered. Here we describe a patient who underwent open surgery following an unsuccessful transvenous embolization due difficulties in venous access.

[A Rare Case of an Unruptured Aneurysm Arising from the Proximal End of the Fenestration of the Cavernous Segment of the Internal Carotid Artery].

We report an extremely rare case of a fenestration in the cavernous segment of the left internal carotid artery(ICA)associated with an unruptured aneurysm at the proximal end of the fenestrated portion. A 44-year-old woman with a dull headache was referred to our hospital for further evaluation of a suspected aneurysm in the right ICA on MR angiography(MRA). CT angiography and 3D-rotational angiography revealed no aneurysm in the right ICA;however, an intracavernous fenestration with an incidental aneurysm was observed in the left ICA. The aneurysm was small(5×3mm)with a wide neck arising from the origin of the ventral limb of the duplicated vessels, in association with a tiny bulge projecting medially. She requested conservative management and periodic follow-up with MRA. After 18 months, no structural change in the aneurysm was observed. To our knowledge, including our patient, only three cases of this type of ICA fenestration have been published, and this is the first report of an ICA fenestration with an unruptured aneurysm at the fenestrated segment. It is presently unknown whether the intracavernous fenestration has the potential to form an aneurysm within the proximal end of the duplicated segment, as reported in cases of supraclinoid ICA fenestrations.

[A Mirror Image of a Tiny Distal Anterior Cerebral Artery Aneurysm that Ruptured].

Distal anterior cerebral artery(DACA)aneurysms have a low incidence. Particularly, DACA mirror aneurysms are extremely rare, although DACA multiple aneurysms are not rare. Generally, it is said that tiny aneurysms have a low risk of rupture. However, we sometimes encounter cases of ruptured tiny aneurysm. We describe a rare case of a mirror image of DACA ruptured tiny aneurysm. A tiny aneurysm can rupture if the aneurysmal wall is fragile. Detection of the aneurysm may often be difficult with a single modality, even if the modality is digital subtraction angiography. Moreover, the distribution of subarachnoid hemorrhage may not be typical. It might be important to capture a slight change of aneurysm in follow-up imaging to detect a ruptured aneurysm over multiple iterations of imaging.

[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.

[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 Case of Segmental Dysgenesis at the Terminal Portion(C1)of the Internal Carotid Artery with an Anomalous Collateral Vessel Containing Plexiform(Twig-like)Networks as a Possible Cause of Intracerebral Hemorrhage].

A 65-year-old woman was transferred to our hospital because of loss of consciousness along with a right hemiplegia due to an intracerebral hematoma(ICH)that extended from the left temporal lobe to the lateral part of the basal ganglia. CT angiograms(CTA)and 3D-rotational angiograms showed an absence of the distal C1 segment of the left internal carotid artery(ICA), and an anomalous collateral vessel arising from the proximal end of the left A2 with plexiform(twig-like)arterial networks, supplying antegrade blood flow to the left middle cerebral artery territory. The caliber of the left carotid arterial system decreased from the origin to the terminal end. The source images of CTA revealed that the plexiform arteries were very close to the ICH, suggesting that the vessels might have caused the bleeding. Because a hypoplastic left carotid canal was observed, the segmental dysgenesis of the C1 portion of the left ICA seemed to have occurred during the early embryonic period. T2-weighted DRIVE images of MRI demonstrated the presence of a cord-like rudimentary structure corresponding to the distal C1 and proximal M1 portions. The patient was managed conservatively and was transferred to another hospital for subsequent rehabilitation. Segmental dysgenesis of the C1 portion is extremely rare. To our knowledge, only a single report has been published. The present findings suggest that 1)an anomalous collateral vessel corresponding to Heubner's artery evolved with residual primitive plexiform(twig-like)arterial networks and 2)this anomalous structure has not been proposed as a type of collateral systems for ICA dysgenesis.

[A Very Rare Case of Diffuse Subependymal Metastases from Small Cell Lung Carcinoma].

While parenchymal metastases are common in solid systemic cancers, subependymal metastases are rare. Approximately half of the reported cases of intraventricular metastases originate from renal carcinoma. A 65-year-old man presented with general fatigue, appetite loss, nausea, and disorientation. Radiological examination revealed diffuse periventricular tumors. The patient underwent an open biopsy via right frontotemporal craniotomy. The patient was diagnosed with metastatic small cell lung carcinoma after histopathological examination. Although subependymal metastases from solid systemic cancer are very rare, this ventricular wall abnormality in the cancer patients must not be overlooked. Many small subependymal metastases might be missed on routine examination.

[A Case of Intracranial Localized Castleman's Disease Mimicking Convexity Meningioma].

A 68-year-old man presented with abnormal behavior and Todd's paralysis on the right side after having taken a bath. Computed tomography and magnetic resonance imaging revealed a tumor mimicking convexity meningioma that had a perifocal edema, although its mass was not very large. The patient underwent surgery, and full recovery was achieved following a total removal of the lesion. Pathohistological examination demonstrated an intermediate type of Castleman's disease. The final diagnosis was intracranial localized Castleman's disease because the results of the full physical examination and laboratory analyses were normal. Castleman's disease is a rare lymphoproliferative disorder of unknown etiology. Moreover, intracranial involvement is very rare. In cases of intracranial meningeal tumors with perifocal edema, we should take this disease into consideration in the differential diagnosis.

[Internal Carotid Artery Stenosis Associated with Hyoid Bone:Can Hyoid Bone be a Risk Factor for Acute Cerebrovascular Syndrome?]

Eagle syndrome is a well-known disease caused by elongation of the styloid process and/or calcification of the stylohyoid ligament, which interferes with adjacent anatomical structures, giving rise to acute cerebrovascular syndrome(ACVS)and/or pain. Although hyoid bone is also a stylohyoid complex, its association with ACVS is not well known. Thus, we investigated the anatomical relationship between the internal carotid artery(ICA)and the hyoid bone. Between January 2014 and December 2015, three-dimensional computed tomographic angiography(3D-CTA)of the neck was performed for 218 patients. Of the patients, an abnormal anatomical relationship was noted in 10(4.6%)cases. In 5 cases, the ICA was entrapped by the hyoid bone. In 3 cases, the ICA was in contact with or adjusted to the hyoid bone. In 2 cases, the ICA was compressed by the hyoid bone, causing ACVS. In 7 cases, the position and course of the ICA were inward. In 4 of these cases, the hyoid bone was repositioned back to its normal location. Moreover, in 1 case, the course of the ICA was repositioned back to its normal location beside the hyoid bone. The anatomical position of the hyoid bone may vary more than expected and can be a risk factor for ACVS. In particular, in cases of ACVS where the ICA has an inward course, the relationship between the ICA and the hyoid bone should be proactively examined.