Posterior Fossa Stroke - Ep.2/2 - SLICE Worldwide 2022

Posterior circulation stroke thrombectomy – (un)answered questions.

Introduction:

Posterior circulation stroke thrombectomy has received some clear answers during the last few years, which should significantly impact clinical practice. Some of them are reviewed here while accompanying the discussion of the Delphi Consensus.

Novelties and questions to be asked:

Type of anesthesia:

• Local/conscious sedation vs. general anesthesia. For a long time, it has been suggested that posterior fossa thrombectomies should be performed under general anesthesia due to the risk of deterioration during the procedure. However, recent data show similar outcomes and safety endpoints regardless of local/conscious sedation in patients with posterior fossa thrombectomy. (1)

Aspiration first vs. stent retriever first:

• The issue is not answered and will probably be answered with the PC-ASTER trial's publication. (2) 
• However, currently available evidence suggests that Aspiration is efficient and should be confidently used as a first-line strategy for posterior circulation stroke. (3,4)

Low NIHSS, what do you do:

• First, decide – what is low NIHSS: 0-5? or 5-10? or 0-10?
• NIHSS 0-10 patients were excluded in the ATTENTION trial following lessons learned from the BASICs registry. Some were present in the BAOCHE trial, which recruited patients with NIHSS 6-10. However, overall numbers were low. (5,6)
• EVT should be performed in patients with a significant deficit and high risk of deterioration. It is reasonable to administer tPA and carefully look for a deterioration in these patients. However, it is imperative to move them to a hospital’s stroke unit with interventional capabilities available.  In a retrospective study, early neurologic deterioration in low NIHSS basilar occlusion patients was seen in up to 30%. (7)

High NIHSS and coma what to do: 

• There is consensus that coma is consistently associated with worse outcomes.
• However, data from the BAOCHE trial shows that the treatment effect was higher in patients with coma at presentation.
• The more severe the patient with basilar artery occlusion, the higher the chance of achieving a favourable functional outcome with endovascular treatment. 
• The severity of the clinical picture is a prognostic marker, but it is not an indicator of no treatment effect. Patients should be selected for treatment based on crucial imaging criteria and not on the severity of clinical symptoms.

Conclusion

There is recently more data available to construct adequate evidenced based local protocols for posterior circulation stroke. In the future, two critical questions remain that need to be resolved in the following years – what to do with mild posterior circulation stroke? What to do with P1, P2, P3 occlusions? 

1.           Liang F, Wu Y, Wang X, Yan L, Zhang S, Jian M, et al. General Anesthesia vs Conscious Sedation for Endovascular Treatment in Patients With Posterior Circulation Acute Ischemic Stroke: An Exploratory Randomized Clinical Trial. JAMA Neurol 2022 Jan 1;80(1):64–72. 

2.           Contact Aspiration Versus Stent Retriever for Recanalisation of Acute Stroke Patients With Basilar Artery Occlusion: The Posterior Circulation ASTER Randomized Trial Protocol - Full Text View - ClinicalTrials.gov 

3.           Gory B, Mazighi M, Blanc R, Labreuche J, Piotin M, Turjman F, et al. Mechanical thrombectomy in basilar artery occlusion: Influence of reperfusion on clinical outcome and impact of the first-line strategy (ADAPT vs stent retriever). J Neurosurg 2018 Jan 12 129(6):1482–91. 

4.           Bernsen MLE, Bruggeman AAE, Brouwer J, Emmer BJ, Majoie CBLM, Coutinho JM, et al. Aspiration Versus Stent Retriever Thrombectomy for Posterior Circulation Stroke. Stroke 2022 Mar 1 29(2):749–57. 

5.           Tao C, Nogueira RG, Zhu Y, Sun J, Han H, Yuan G, et al. Trial of Endovascular Treatment of Acute Basilar-Artery Occlusion. New England Journal of Medicine 2022 Oct 13 387(15):1361–72.

6.           Jovin TG, Li C, Wu L, Wu C, Chen J, Jiang C, et al. Trial of Thrombectomy 6 to 24 Hours after Stroke Due to Basilar-Artery Occlusion. New England Journal of Medicine 2022 Oct 13;387(15):1373–84. 

7.           Raymond S, Rost NS, Schaefer PW, Leslie-Mazwi T, Hirsch JA, Gonzalez RG, et al. Patient selection for mechanical thrombectomy in posterior circulation emergent large-vessel occlusion. Interventional Neuroradiology 2018 Jun;24(3):309–16.