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.

Total access block time: a comprehensive and intuitive way to measure the total effect of access block on the emergency department

OBJECTIVE

Access block refers to delayed transfer of admitted patients in the ED to wards from lack of an inpatient bed. Existing measures are crude indicators of its impact on ED function. Our aim was to devise measures of the total burden of access block on ED function which better measured the impact on ED function, yet were intuitive and easy to communicate.

METHODS

Current access block measures, reported as percentage of total inpatient admissions, are based upon time intervals and cut points. 'Total access block time' (TABT) is obtained by summing the minutes in excess of 8 h that admitted patients spend in the ED. We describe derivation of TABT with reference to its intuitive comprehensibility and potential to improve understanding and communication of access block issues. Two examples of months with similar traditional measures but different TABT are used to highlight its advantages.

RESULTS

TABT varies over a greater range than traditional measures. High TABT months had higher presentations, higher admissions, more admitted patients with long ED stays and impaired ability to meet triage benchmarks. Differences in these parameters are considered intermediate end-points which reflect the degree of impairment of ED function.

CONCLUSIONS

TABT is a comprehensive, sensitive indicator of total impact of access block on ED function. Unlike current access block measures, TABT is reflective of long-stay ED patients. Descriptive statistics derived from TABT, in terms of effective beds and bed-days lost, will likely improve the communication and comprehension of access block issues.

Therapy of Basilar Artery Occlusion

Background and Purpose— Basilar artery occlusion (BAO) is an infrequent form of acute stroke, which invariably leads to death or long-term disability if not recanalized. A traditional recanalization approach based on historical controls and pathophysiological consideration is local intra-arterial thrombolysis (IAT) in eligible patients. This necessitates diagnostic evaluation and treatment in stroke centers equipped with an interventional neuroradiological service on a 24-hour basis, but its superiority to the technically simple intravenous thrombolysis (IVT) remains unproven.

Methods— We analyzed systematically published case series of substantial size reporting the outcome of BAO after IAT or IVT.

Results— In 420 BAO patients treated with IVT (76) and IAT (344), death or dependency were equally common: 78% (59 of 76) and 76% (260 of 344), respectively ( P =0.82). Recanalization was achieved more frequently with IAT (225 of 344; 65%) than with IVT (40 of 76; 53%; P =0.05), but survival rates after IVT (38 of 76; 50%) and IAT (154 of 344; 45%) were equal ( P =0.48). A total of 24% of patients treated with IAT and 22% treated with IVT reached good outcomes ( P =0.82). Without recanalization, the likelihood of good outcome was close to nil (2%).

Conclusions— Recanalization occurs in more than half of BAO patients treated with IAT or IVT, and 45% to 55% of survivors regain functional independence. Although improved therapy forms for BAO are necessary, hospitals not equipped for IAT may set up IVT protocols. The effect of IVT is probably not much different from the effect of IAT. IVT represents probably the best treatment that can be offered to victims of acute BAO in such hospitals.