Imaging in acute basilar artery thrombosis

Congenital and acquired anomalies of the basilar artery: A pictorial essay

INTRODUCTION

The basilar artery is one of the two cases in our body where an arterial vessel is formed by the union of two others - the vertebral arteries. It provides vascular supply to essential structures for the main vital functions; the posterior cerebral arteries originate from it as terminal branches, and form part of the anastomotic circle of Willis.

IMAGING FINDINGS

Congenital and acquired anomalies of the basilar trunk are described. We provide a schematic and detailed representation of normal anatomical variants - mainly represented by the fenestrated basilar artery or the persistence of carotid-basilar anastomosis; course anomalies are also illustrated, with reference to neuro-vascular conflicts and dolichoectasia. Among congenital anomalies, this pictorial review also shows the variants of the basilar origin, such as in the case of basilar trunk arising from only one of the two vertebral arteries, and the calibre changes - which are represented by aneurysm and hypoplasia. The latter appears to be a risk factor for posterior circulation stroke, when associated with a bilateral posterior foetal variant.Among the acquired forms, this pictorial essay describes some clinical cases of dissections, non-congenital aneurysms, thrombosis and tumour with vascular encasing or compression of basilar artery.

CONCLUSION

CT angiography and MRI allow us to study the posterior intracranial circulation in detail, providing useful pre-treatment information. Therefore, knowledge of congenital or acquired anomalies of the basilar artery is essential for radiologists, neuroradiologists and neurosurgeons.

Radiology resident competency in detecting basilar artery occlusion: a simulation-based assessment

PURPOSE

Basilar artery strokes are rare but can have characteristic imaging findings that can often be overlooked. This retrospective study aims to assess radiology residents' ability to identify CT imaging findings of basilar artery occlusion in a simulated call environment.

METHODS

The Wisdom in Diagnostic Imaging Emergent/Critical Care Radiology Simulation (WIDI SIM)-a tested and reliable computer-aided emergency imaging simulation-was employed to assess resident readiness for independent radiology call. The simulations include 65 cases of varying complexity, including normal studies, with one case specifically assessing basilar artery stroke. Residents were presented with a single, unique case of basilar artery occlusion in two separate years of testing and were only provided with non-contrast CT images. Residents' free text responses were manually scored by faculty members using a standardized grading rubric, with errors subsequently classified by type.

RESULTS

A total of 454 radiology residents were tested in two separate years on the imaging findings of basilar artery occlusion using the Wisdom in Diagnostic Imaging simulation web-based testing platform. Basilar artery occlusion was consistently underdiagnosed by radiology residents being tested for call readiness irrespective of the numbers of years in training. On average, only 14% of radiology residents were able to correctly identify basilar artery occlusion on non-contrast CT.

CONCLUSIONS

Our findings underscore a potential gap in radiology residency training related to the detection of basilar artery occlusion, highlighting the potential need for increased educational efforts in this area.

Hyperdense artery sign on computed tomography in acute ischemic stroke

Despite the advent and growing availability of magnetic resonance imaging, the imaging modality of choice in the acute care of stroke patients in many institutions remains computed tomography. The hyperdense artery sign is the earliest marker of acute ischemic stroke. In this short review, we discuss the pathology, incidence, clinical aspects, imaging findings, significance and future questions that need to be addressed concerning this important sign.

Endovascular recanalization of basilar artery occlusion 80 days after symptom onset

BACKGROUND AND PURPOSE

Acute basilar artery occlusion portends high risk of stroke and death. Thrombolysis or endovascular therapy has been limited to patients who present within hours of symptom onset. Without recanalization, acute basilar artery occlusion almost always results in death or severe disability.

SUMMARY OF CASE

We report a case of basilar artery occlusion and successful endovascular recanalization 80 days after symptom onset.

CONCLUSIONS

Endovascular therapy can be feasible and safe for symptomatic basilar artery occlusion at chronic stage.

Complete Nonvisualization of Basilar Artery on MR Angiography in Patients with Vertebrobasilar Ischemic Stroke: Favorable Outcome Factors

BACKGROUND

In vertebrobasilar ischemic stroke, magnetic resonance angiography (MRA) occasionally fails to visualize the basilar artery, but in these patients, little attention has been given to establishing correlations between the clinical and the radiological findings. Our aim was to identify clinical or radiological measures that could assist in predicting a favorable clinical outcome.

METHODS

Risk factors, clinicoradiological features, and functional outcomes were assessed in 40 patients with vertebrobasilar ischemic stroke whose basilar arteries were absent on MRA. The presence of potential feeding arteries to the posterior circulation was recorded from a review of the MRA data. To permit quantitative analysis of the images, a potential feeding artery score (PFAS; range: 0-8) was established. One point was assigned when a signal was seen from an intracranial vertebral artery, a posterior inferior cerebellar artery, a superior cerebellar artery, or a posterior cerebral artery. On MRI, the location of the infarction was classified as involving the proximal, middle, and distal territories of the intracranial posterior circulation. The infarctions were also categorized as single- or multi-sector infarctions, and according to whether more than one penetrating or branch artery was involved. Clinical outcomes were classified as favorable (modified Rankin Scale = 0-2) or poor (modified Rankin Scale = 3-6).

RESULTS

The clinical outcome was favorable in 30% (n = 12) of patients, and poor in 70% (n = 28). A transient ischemic attack preceded the stroke in 48% of patients, especially those with a favorable outcome (67%). Patients with a favorable outcome had a higher PFAS (p = 0.036) and an increased incidence of single-sector infarction (p = 0.049).

CONCLUSIONS

Our study suggests that a higher PFAS, accompanied by a single-sector infarction, is a predictor of improved clinical outcome in patients with vertebrobasilar ischemic stroke in which the basilar artery was absent on MRA.

Basilar artery thrombosis in a trauma patient. Case report and review of the literature

Thrombotic disease of the vertebrobasilar circulation is associated with a poor prognosis. It may occur in trauma patients, especially those with neck injuries and even several months after the initial insult. We report on the case of a young polytrauma patient, victim of a traffic accident, with associated cervical and thoracic spinal injuries resulting in paraplegia. Consciousness was not impaired initially, but during transfer to our hospital he became suddenly unconscious. An occluded basilar artery was found on angiography, but unfortunately we were unable to reopen the vessel with thrombolytic therapy. This case again proves that lesions of the vertebro-basilar system must always be suspected in neck injuries. Even after minor whiplash injuries, fatal basilar thrombosis may occur. A review of all reported cases of traumatic basilar artery thrombosis is given and the use of thrombolytic therapy is discussed.

Basilar artery thrombosis

Basilar artery thrombosis is an infrequent but important neurological emergency requiring early diagnosis and treatment. Of particular relevance to emergency medicine is the recognition and consideration of the unusual signs that may be present in an often previously well patient. It is therefore crucial to expedite investigations, confirm the diagnosis and commence life-saving treatment through the early involvement of a number of disciplines including neurology, radiology and intensive care. This paper confirms the use of magnetic resonance imaging and angiography as the preferred investigative mode and microcatheter directed intra-arterial thrombolysis as the treatment strategy of choice.

Basilar artery occlusion and the dense artery sign in the newborn

A child with basilar artery occlusion in the neonatal period is reported. The occlusion was documented by unenhanced computed tomography performed in the neonatal period demonstrating a "dense" artery at the tip of the basilar artery. The pattern of cerebral damage on MRI scan at 10 years of age confirmed the site of the vascular occlusion. The evidence suggests that embolization was the operating pathogenic mechanism of cerebral vascular occlusion. Neonatal arterial thrombosis involving the carotid circulation has been well documented and may be due to many pathological factors including direct trauma to the carotid artery and embolization from remote sites. Thrombosis of the vertebral artery in the neonate is only rarely reported and only in association with significant cervical trauma. A second child with a similar pattern of cerebral injury demonstrated on neuroimaging is described suggesting that this event may be more common than recognized. The clinical features of basilar artery occlusion as seen in the adult are not apparent in the neonate. Recognition of the neuroimaging characteristics seen in this condition may help to provide the clinician with a reasonable pathogenetic explanation for unexplained cerebral injury.