Management of dissecting aneurysms of the posterior circulation

Morphological changes in vertebral artery dissections observed on 4D flow magnetic resonance images: case report

The morphology of vertebral artery (VA) dissections can change in the clinical course. A 58-year-old female with a 2-week headache was diagnosed with left VA dissection. Hemodynamic stress on the right VA detected on 4D flow MRI scans resulted in increased wall shear stress but the vessel was morphologically unchanged. Subsequent MRA revealed right VA dissection. Her bilateral dissections were treated conservatively and no neurological abnormality developed. Serial 4D flow MRI may be useful for observing morphological changes in VA dissections and help to clarify the mechanism(s) underlying VA dissections.

Posterior Circulation Aneurysms

Posterior circulation aneurysms have a higher tendency to rupture and become symptomatic in comparison to anterior circulation aneurysms. Current treatment modalities for aneurysms in these locations vary widely including microsurgical clipping, trapping with bypass, wrapping, and various endovascular methods such as coiling, balloon or stent-assisted coiling, flow diversion, and vessel sacrifice, among others.Overall, surgical versus endovascular treatment of posterior circulation aneurysms continue to be a controversial topic in cerebrovascular neurosurgery. At our center, multi-disciplinary assessments including surgeons capable of both endovascular and microsurgical treatments of these aneurysms are employed to guide the treatment strategies. As advancements in both fields are made, this will continue to be a topic for debate. Anatomy and individual patient's characteristics will dictate the correct approach and therefore proficiency in the microsurgical techniques required to treat these aneurysms will continue to be both relevant and important.

A Juvenile Case of Bow Hunter's Syndrome Caused by Atlantoaxial Dislocation with Vertebral Artery Dissecting Aneurysm

BACKGROUND

Bow hunter's syndrome (BHS) is caused by posterior circulation insufficiency that results from the occlusion or compression of the vertebral artery (VA) during neck rotation. Owing to its rarity, there is no guideline to support the decision of selecting a conservative or a surgical approach. Management of BHS is dependent on each patient.

CASE DESCRIPTION

A 13-year-old girl presented with transient visual disturbance, hypoesthesia, and paralysis of the left side of the body. Magnetic resonance imaging revealed an acute cerebral infarction in the right thalamus, and magnetic resonance angiography demonstrated occlusion of the right posterior cerebral artery and dilation of V3 of the left VA. Digital subtraction angiography revealed a left VA dissecting aneurysm at V3 and left VA occlusion at the level of C1-C2 during neck rotation to the right. A dynamic x-ray suggested atlantoaxial joint instability, and three-dimensional computed tomography revealed aplasia of C1 lamina and atlantoaxial rotatory dislocation. BHS with left VA dissecting aneurysm caused by atlantoaxial rotatory dislocation was diagnosed. We performed C1-C2 posterior fusion by the Goel-Harms technique. Stroke did not recur, and computed tomography angiography obtained 8 months postoperatively demonstrated a decrease in the dissecting aneurysm.

CONCLUSIONS

To our knowledge, this is the first case of BHS with VA dissecting aneurysm and aplasia of C1 lamina. Based on this case, we suggest that C1-C2 posterior fusion is effective for BHS with VA dissecting aneurysm.

Clinical and Radiological Characteristics of Intracranial Artery Dissection Using Recently Proposed Diagnostic Criteria

BACKGROUND

Data on the clinical and radiological characteristics of intracranial artery dissection (IAD) have remained limited. Our purpose was to reveal the clinical and radiological characteristics of IAD according to diagnostic criteria for IAD as recently reported by a group of international experts.

METHODS

Patients were retrospectively enrolled using a prospective single-center stroke registry between 2011 and 2016. Baseline characteristics and radiological findings including conventional magnetic resonance imaging (MRI) sequences, magnetic resonance angiography (MRA), high-resolution 3-dimensional T1-weighted imaging (HR-3D-T1WI), and digital subtraction angiography were reviewed. We performed statistical comparisons to determine which findings from which modalities are useful.

RESULTS

We identified 118 patients with suspected artery dissection, with 64 patients (median age, 51 [interquartile range, 45-56) years; 16 women) finally meeting the criteria for definite (n = 47), probable (n = 15), or possible (n = 2) idiopathic IAD. Ischemic stroke alone was found in 31 patients (48%) on admission. There were 36 patients (56%) suffering from hypertension and 39 (61%) with smoking history. The vertebral artery alone was the most affected in 42 patients (66%). Intramural hematoma (IMH) was more frequently detected on HR-3D-T1WI than on conventional MRI/MRA (odds ratio, 4.72; 95% confidence interval, 1.71-13.00). In 54 patients (84%), the modified Rankin Scale score after 3 months was 0-1.

CONCLUSIONS

Male dominance and age at IAD onset were similar to previous studies, and more than half had hypertension and smoking history. We confirmed that HR-3D-T1WI is useful for detecting IMH in the diagnostic criteria.

State-of-art in surgical treatment of dissecting posterior circulation intracranial aneurysms

Vertebrobasilar (VB) intracranial dissecting aneurysms (IDAs) pose difficult therapeutic issues and are especially among the most difficult to manage surgically. There are, however, some cases where selective aneurysm obliteration by endovascular approach is impossible or is associated with an unacceptable risk of morbidity. This is particularly true when the aneurysm is dissecting, giant, or has a large neck. In such cases, surgical treatment may be the only alternative. Optimal management of these lesions is therefore challenging and treatment decisions have to be made on a case-by-case basis. Ideal treatment should be a complete surgical excision of the lesion; however, this procedure might only be possible after distal and proximal vessel wall occlusion which might not be tolerated by the patient depending on the location of the aneurysm. Therefore, formulation of recommendations concerning the surgical strategy remains still difficult due to inconsistency of surgical outcomes. The literature describing surgical strategy of VB IDAs is varying in quality and content, and many studies deal with only a few patients. In the presented review, the authors summarize the current knowledge on the incidence, pathogenesis, clinical presentation, and diagnostic procedures with special emphasis on surgical treatment of IDAs in posterior circulation.

Usefulness of four-dimensional computed tomographic angiography in a vertebral artery dissection case

Discrimination of intramural hematoma from intra-aneurysmal blood flow is a critical issue for determining the necessity of treatment in vertebral artery dissection (VAD) cases. We describe modified four-dimensional computed tomographic angiography (4D-CTA) that is useful for evaluating blood flow in a dissected vertebral artery in a 41-year-old man who was diagnosed as VAD. Magnetic resonance angiography (MRA) showed a growth of intramural hematoma, which was confusingly similar to intra-aneurysmal blood flow. Modified 4D-CTA enabled us to discriminate the intramural hematoma from blood flow because of its fine time and spatial resolution. Modified 4D-CTA may be a substitute for angiography in VAD cases.

Stent-assisted Coiling for Ruptured Basilar Artery Dissecting Aneurysms: An Initial Experience of Four Cases

No treatment strategy has been established for subarachnoid hemorrhages due to basilar artery (BA) trunk dissecting aneurysms. Our aim was to report our initial experience performing stent-assisted coiling (SAC) for ruptured BA dissecting aneurysms to validate the effectiveness of this treatment. We experienced four consecutive cases of ruptured dissecting BA trunk aneurysm treated with SAC between 2008 and 2014 at three institutions. Aneurysm rebleeding was prevented without causing severe brainstem ischemia in all cases. In our opinion, both the blockage of the inflow to aneurysms and the preservation of the antegrade flow of the BA can be achieved by SAC, although controversies regarding long-term stability and appropriate antiplatelet therapy remain.

Endovascular Treatment in Ruptured Middle Cerebral Artery Dissection Preservation of Arterial Continuity

Rupture of spontaneous dissecting aneurysms of the middle cerebral artery (MCA) is rare and its etiology remains obscure, although the risk of rebleeding is greater than with saccular aneurysms. Most reports concerning the treatment of a ruptured dissecting aneurysm of the anterior circulation involve surgical trapping or wrapping. Here, we report on a case of an MCA dissecting rupture treated with endovascular procedures. A 22-year-old female presented with sudden stuporous mental change following severe headache and left side hemiparesis. A computed tomography scan showed a diffuse subarachnoid hemorrhage and diffusion MR showed diffusion restriction at the right putamen and internal capsule. A 3-hour follow-up digital subtraction angiography (DSA) showed a dissecting aneurysm, which was not seen on an initial DSA. A stent assisted coil embolization was performed and double stents were applied to achieve flow diversion effects. A small remnant area of the dissecting aneurysm had disappeared at 60-day and was not observed on 12-month follow-up DSA.

Top of the basilar syndrome in a young adult initially presenting with a convulsive seizure

A 23-year-old man was admitted to our hospital due to loss of consciousness and a generalized convulsive seizure. He was diagnosed as having primary epilepsy and treated with antiepileptic drugs. Emergency CT scan of the head showed no abnormality. However, MRI scan of the head several days after admission revealed fresh infarctions caused by occlusion of the basilar artery, i.e., "top of the basilar" syndrome. This case indicates the need for precise differential diagnosis of convulsive seizure in an emergency situation. It should also be borne in mind that basilar occlusion with 'onset seizure' can occur even in young adults who have no risk factors for stroke.

Dissecting aneurysms limited to the basilar artery: report of two cases and review of the literature

Spontaneous dissecting aneurysms limited to the basilar artery are rare. We describe two patients who presented to our institution with different clinical problems, one with brain stem infarction and the other with subarachnoid hemorrhage. We describe the clinical and imaging features in these patients, their treatment, and outcome. We also reviewed the literature concerning this entity, and we have identified 32 patients (including our two patients) with angiographically confirmed dissecting aneurysms limited to the basilar artery. Of these, 40.6% presented with brain stem infarction, 50.0% presented with subarachnoid hemorrhage, and 9.4% presented with both infarction and subarachnoid hemorrhage. Patients who presented with basilar artery dissecting aneurysms and brain stem infarction tended to be younger (mean age, 38 +/- 7 years) than those who presented with subarachnoid hemorrhage (48 +/- 12 years) and were more likely to be male. We discuss the natural history of this entity and suggest an approach to clinical management for these patients.

3T MRI - 3D DSA Fusion Technique on Posterior Cerebral Artery Dissecting Aneurysm: Understanding a Potential Pathophysiologic Mechanism

SUMMARY

We aimed to show the anatomical relationship between a dissecting aneurysm of the posterior cerebral artery (PCA) and tentorial free edge to understand the pathophysiologic mechanism. A 52-year-old woman with a history of head trauma presented with dizziness and numbness in her left fingers. 3D DSA showed a dissecting aneurysm of the right P2-P3 segment of PCA. The fusion of 3D DSA and 3T MRI was performed at the dedicated workstation using three pairs of landmarks including the ICA termination, MCA bifurcation and A1-A2 junction of the right ACA. Fusion of 3D DSA and 3T MRI clearly demonstrated the dissected segment of PCA crossed the tentorial free edge twice. The fusion images support the direct trauma hypothesis of dissecting aneurysm of the P2-P3 segment of PCA. This novel imaging technique shows future potential to be used to understand the anatomical relationships between various vascular lesions and surrounding structures.

Successful treatment of a ruptured dissecting basilar artery aneurysm

✓ Dissecting basilar artery (BA) aneurysms in patients presenting with subarachnoid hemorrhage are life threatening, especially in those who experience subsequent bleeding or progressive dissection, and immediate surgical or endovascular intervention may be necessary. The authors report on a 52-year-old woman whose dissecting BA aneurysm was treated successfully with proximal occlusion and flow reversal. Clipping of the proximal BA above the level of the anterior inferior cerebellar arteries facilitated retrograde flow from a radial artery graft placed between the left vertebral artery and the left posterior cerebral artery, thereby providing continuous perfusion of the BA and its branches. Postoperative angiograms obtained 1 year later revealed good retrograde flow through the BA and dilation of the radial arterial graft. There were no episodes of recurrent hemorrhage.

Ischemic Basilar Artery Dissecting Aneurysm Treated by Stenting Only-Case Report-

A 45-year-old man presented with enlargement of basilar artery dissecting aneurysm 10 months after suffering brain stem infarction. Combined stenting and placement of Guglielmi detachable coils (GDCs) was planned to obliterate the aneurysm sac. Stent deployment was performed but the procedure was halted to avoid overdosing with contrast material. Cerebral angiography 10 days later showed thrombosis of the aneurysm sac and normalization of the blood flow in the basilar artery. The patient has been followed up for 2 years and showed good clinical and angiographic outcome. Stenting results in obliteration of the aneurysm sac, so a two-stage procedure is recommended.

Isolated dissections and dissecting aneurysms of the posterior inferior cerebellar artery: topic and literature review

Isolated dissections of the posterior inferior cerebellar artery (PICA) are rare. Thus, no large series of cases have been reported in the literature. Due to limited knowledge regarding the natural history of these lesions and the lack of high-quality evidence supporting various treatment options, management is controversial and practice parameters are ill defined. In order to offer a comprehensive reference for the diagnosis and management of isolated PICA dissections, the authors reviewed the National Library of Medicine from 1966 to October 2001. Twenty-seven patients averaging 43.6 years of age and including 14 males and 13 females were reported. Subarachnoid hemorrhage occurred in 20 patients, and two died. Dissections were located in the proximal PICA in 22 patients and were three times more common on the left side (left:right=3:1). Six patients were managed conservatively, and four with endovascular techniques. Seventeen had open surgery: five underwent resection, two went through trapping, and two had proximal clipping. Wrapping with muscle was performed in two patients, encasement with Sundt clips in two, and four had occipital artery (OA)-PICA bypass surgery. A meticulous analysis of reported cases with regard to clinical and pathological features, management strategies, and outcomes is presented.

Fatal rupture following intra-aneurysmal embolization for the distal posterior inferior cerebellar artery aneurysm with parent artery preservation

This 70-year-old female was admitted to our hospital 1 day after a sudden consciousness disturbance. Computed tomography (CT) showed subarachnoid hemorrhage (SAH), and angiogram revealed an irregular-shaped aneurysm at the lateral medullary segment of the left posterior inferior cerebellar artery (PICA). The patient was treated by intra-aneurysmal embolization with Guglielmi detachable coil (GDC) with parent artery preservation. Post-operative angiogram showed obliteration of the aneurysm except for the neck remnant, but she presented with rerupture 19 days after the onset and died 3 days later. Postmortem examination revealed massive hematoma around the aneurysm, which compressed medulla oblongata from behind. Histological assessment showed the 'entry' where the aneurysmal wall lacked internal elastic lamina, providing evidence of dissecting aneurysm. The present case suggests that embolization of distal PICA aneurysm with parent artery preservation should be avoided because radiological evaluation may fail to rule out the possibility of dissection, where the aneurysmal wall is affected not only at the 'entry' but also in the adjacent region.

Dissecting basilar artery aneurysm growing during long-term follow up--case report

A 58-year-old male presented with a dissecting aneurysm of the basilar artery manifesting as dysarthria, left hemiparesis, and numbness of the left side. Angiography revealed a double lumen at the midportion of the basilar artery which was consistent with a diagnosis of dissecting basilar artery aneurysm. The patient was treated conservatively, and remained neurologically stable for a 5-year period following initial presentation, but serial magnetic resonance imaging revealed growth of the aneurysm compressing the brain stem. His condition then worsened. Computed tomography revealed obstructive hydrocephalus. Ventriculoperitoneal shunting was performed and the patient's symptoms improved. However, he died of subarachnoid hemorrhage. Autopsy showed the patient had had a type 3 "dolichoectatic dissecting aneurysm." Surgical treatment should be seriously considered for treating the patients with dissecting basilar artery aneurysm causing brain stem ischemia, especially if the aneurysm is growing. High-flow bypass and proximal occlusion may be the choice in patients with poor collateral circulations.

Vertebrobasilar dissection: a possible role of whiplash injury in its pathogenesis

We reviewed 29 patients with vertebrobasilar dissections (VBD) to investigate the correlation between minor trauma and VBD and the clinical features of this trauma-related condition. Mean age was 43 years, with a male predominance (male/female ratio was 25/4). Seventeen patients presented with subarachnoid hemorrhage (SAH), and 12 with ischemic symptoms. Two patients presenting with ischemia had extracranial VBD (V3 segment). Angiographically, aneurysmal dilatation was observed in most SAH patients (13 patients) in contrast to narrowing or occlusion in most ischemic patients (10 patients). Among the 12 SAH patients treated with coil embolization or conservatively, five died, whereas all ischemic patients recovered well with anticoagulation and/or antiplatelet therapy. Seven patients had received minor or trivial head/cervical trauma, due to whiplash injury, minor fall, or during exercise, which were identified to precede with the lapse of some time (a few minutes or days) the onset of symptoms. All of these patients presented with ischemic symptoms, and they were younger than the other ischemic or SAH patients. The site of vertebral artery dissection was intracranial in four cases, extracranial in one case, and combined in two cases at the level of the V3 segment and the origin of the posterior inferior cerebellar artery. However, no SAH occurred. These clinicopathological findings, i.e. ischemia and angiographic narrowing/occlusion, suggest that dissections were subintimal. Therefore, it is believed that this minor or trivial trauma may primarily cause subintimal dissection with luminal compromise, leading to ischemic symptoms, rather than subadventitial or transmural dissection with aneurysmal dilatation, leading to SAH. This lesion may also occur in younger patients with a favorable outcome. Careful note should be made of patient for the early recognition of this disorder.

Subarachnoid hemorrhage from vertebrobasilar dissecting aneurysm treated with staged bilateral vertebral artery occlusion: the importance of early follow-up angiography: technical case report

OBJECTIVE AND IMPORTANCE

Vertebrobasilar dissecting aneurysms are an uncommon but increasingly recognized cause of subarachnoid hemorrhage (SAH). We describe a patient with SAH caused by a dissecting aneurysm involving both vertebral arteries as well as the basilar trunk. The patient was treated successfully with proximal occlusion of the vertebral arteries using endovascular balloon occlusion in two stages. The importance of early follow-up angiography to document progression or resolution of untreated dissections is emphasized. This approach is suggested as definitive treatment for vertebrobasilar dissection in appropriate circumstances.

CLINICAL PRESENTATION

A 41-year-old man presented with SAH from spontaneous vertebrobasilar dissection. Angiography revealed aneurysmal dilation of the right vertebral artery and basilar trunk and occlusion of the left vertebral artery.

INTERVENTION

The dissecting aneurysm was treated with balloon occlusion of the right vertebral artery. Repeat angiography 2 weeks later demonstrated resolution of the left vertebral occlusion, with restoration of antegrade flow in the basilar trunk and increased filling of the right vertebral and basilar dissecting aneurysms. Balloon occlusion of the left vertebral artery led to aneurysm thrombosis and excellent clinical outcome.

CONCLUSION

Bilateral vertebrobasilar dissecting aneurysms are an uncommon cause of SAH. If unilateral proximal vertebral artery occlusion is chosen as the initial treatment, it is essential to document the status of the contralateral vessel using follow-up angiography. Staged bilateral vertebral artery occlusion should be considered in the event of recurrent or progressive aneurysm enlargement. Endovascular balloon occlusion has advantages over proximal clipping of the parent vessel: cranial nerve manipulation is avoided, test occlusion in the awake patient can be performed at the site of permanent occlusion, and therapeutic levels of anticoagulation can be maintained throughout and after the procedure, thus diminishing the likelihood of thromboembolic complications.