What is the initial treatment for a patient with a posterior circulation stroke?

Initial Treatment for Posterior Circulation Stroke

Administer intravenous alteplase 0.9 mg/kg (10% bolus over 1 minute, remainder over 59 minutes) within 4.5 hours of symptom onset if eligible, followed by immediate consideration for endovascular thrombectomy in patients with basilar artery occlusion. 1, 2, 3

Immediate Recognition and Diagnostic Pitfalls

Posterior circulation strokes are frequently missed because they present with non-specific symptoms rather than the classic anterior circulation findings of limb weakness and aphasia. 2, 3 Critical presentations include:

• Dizziness, vertigo, nausea, vomiting, and headache without motor weakness 2, 3
• Loss of consciousness, double vision, hearing loss, and imbalance 3
• Ataxia (especially truncal), nystagmus, visual field defects, and cranial nerve palsies 2, 3

The NIHSS score dramatically underestimates severity because it focuses on limb weakness and speech rather than cranial nerve deficits and ataxia—a patient can have an NIHSS of 0 with only headache and vertigo yet harbor life-threatening basilar artery occlusion. 2, 3 This diagnostic challenge leads to significantly longer door-to-needle times compared to anterior circulation strokes. 2, 3

Rapid Imaging Protocol

• Complete non-contrast CT within 25 minutes of arrival for thrombolysis candidates 2, 3
• Look for the hyperdense basilar artery sign (sensitivity 71%, specificity 98%; optimal density 40-42 Hounsfield units), which predicts poor 6-month outcome (mRS >2, OR 5.6) 3
• Perform CTA immediately at time of brain CT from aortic arch to vertex to assess both extracranial and intracranial circulation 2, 3
• Do not delay IV tPA for vascular imaging in patients within the treatment window—begin tPA before transport for additional imaging or endovascular therapy 3

Blood Pressure Management Before Thrombolysis

Target systolic ≤185 mmHg and diastolic ≤110 mmHg for thrombolysis candidates. 2, 3 If blood pressure exceeds these thresholds:

• Labetalol 10-20 mg IV over 1-2 minutes (may repeat once) OR 3
• Nitropaste 1-2 inches OR 2, 3
• Nicardipine drip 5 mg/h, titrate up by 2.5 mg/h at 5-15 minute intervals (maximum 15 mg/h) 3

Do not administer tPA if blood pressure cannot be reduced and maintained at target levels. 2, 3 For non-thrombolysis candidates, lower blood pressure only when systolic >220 mmHg or diastolic >120 mmHg. 2

Intravenous Thrombolysis

Administer IV alteplase 0.9 mg/kg within 4.5 hours of symptom onset (10% bolus over 1 minute, remainder over 59 minutes). 2, 3 The 2024 ESO-ESMINT guideline suggests using IVT up to 24 hours unless otherwise contraindicated based on expert consensus. 1

Do not withhold thrombolysis for mild or rapidly improving symptoms—a substantial proportion of these patients have poor outcomes and cannot be discharged home. 1, 2 Approximately one-fifth of ischemic strokes occur in the posterior circulation, and while randomized trials focused on anterior circulation, open studies indicate that intravenous alteplase may be equally beneficial for posterior circulation strokes, including basilar artery occlusion. 1

Thrombolysis in posterior circulation stroke appears to have similar benefits and lower hemorrhage risks compared to anterior circulation strokes. 4, 5

Endovascular Thrombectomy

The 2024 ESO-ESMINT guideline suggests EVT plus best medical treatment over BMT alone for basilar artery occlusion within 6 hours and 6-24 hours from last seen well, particularly in patients with NIHSS ≥10. 1 The recent ATTENTION and BAOCHE trials demonstrated that thrombectomy benefits strokes with basilar artery occlusion. 4

For patients with NIHSS <10, there is no evidence to recommend EVT over BMT—in fact, BMT was non-significantly better and safer than EVT in this subgroup. 1

The guideline further suggests IVT plus EVT over direct EVT when both are being considered. 1 Suction thrombectomy (ADAPT) and stent retriever thrombectomy are both reasonable approaches, with ADAPT achieving higher rates of complete reperfusion and lower periprocedural complications in some series. 1

Prognostic Awareness

Mortality in basilar artery occlusion ranges from 45% to 86% without recanalization. 2, 3 Predictors of poor outcome include:

• Older age and higher NIHSS score 2, 3
• Lack of recanalization 2, 3
• Atrial fibrillation and intracranial hemorrhage 2, 3
• pc-ASPECTS ≤8 2, 3
• Presence of intracranial atherosclerotic disease 6

Younger age (<70 years) and absence of intracranial atherosclerosis are independently associated with good outcomes after endovascular treatment. 6

Post-Treatment Management

• Perform repeat CT or MRI at 24 hours after thrombolytic therapy regardless of clinical stability 2
• This 24-hour scan is required before starting anticoagulants or antiplatelet agents for secondary prevention 2
• Assess swallowing ability before allowing oral intake—consider water swallow test or videofluoroscopic modified barium swallow if indicated 2
• Monitor for brain edema, which peaks at 3-5 days but can occur within 24 hours with large cerebellar infarctions 2