Makindo Medical Notes

Related Subjects: |🧠 Acute Stroke Assessment (ROSIER & NIHSS) |⚡ Causes of Stroke

📖 Introduction

Basilar artery thrombosis (BAT) is a rare (<1% of strokes) but highly lethal condition. It results from occlusion of the basilar artery, causing posterior circulation ischaemia. 💀 Untreated, mortality is extremely high. 🔬 Advances in MRA/CTA allow early detection, and mechanical thrombectomy or intra-arterial thrombolysis can be life-saving.

🧩 Anatomy

The basilar artery forms from fusion of the vertebral arteries at the lower pons, running along the brainstem before bifurcating into the posterior cerebral arteries (PCAs).

• AICA: Cerebellum + pons
• Labyrinthine artery: Inner ear
• Pontine arteries: Brainstem perforators → tiny but vital
• SCA: Superior cerebellum + midbrain
• PCAs: Occipital lobes, medial temporal lobes, thalami

🧬 Etiology & Pathophysiology

• ❤️ Cardioembolism: esp. atrial fibrillation
• 🫀 Artery-to-artery embolism: vertebral/basilar atherosclerosis
• 🩸 Thrombus in situ: plaque rupture, local clot
• 🪢 Arterial dissection: vertebral → basilar extension
• 🔥 Vasculitis/Inflammation: arteritis, meningitis

⚠️ Occlusion can evolve gradually → progressive brainstem symptoms, or suddenly → catastrophic collapse ("brainstem stroke syndrome").

⚠️ Risk Factors

• Hypertension, Diabetes, Hyperlipidaemia
• Smoking 🚬
• Atrial fibrillation & cardiac emboli
• Cervical artery dissection
• Substance misuse (cocaine)
• Systemic vasculitis / meningitis
• Inherited arteriopathies

🩺 Clinical Presentation

• 💥 Sudden collapse, coma
• 🦽 Quadriparesis/quadriplegia
• 👀 Diplopia (CN palsies)
• 🗣 Dysarthria, Dysphagia
• 🎯 Cerebellar ataxia
• 🎯 Pinpoint pupils (pons)
• 🧊 "Locked-in syndrome" → conscious, vertical eye movements only

🔎 Early signs can be subtle (dizziness, slurred speech) → high suspicion + CTA/MRA is essential.

🧪 Investigations

• 🩸 Bloods: FBC, U&E, LFT, lipids, coagulation
• 🖼 CT Head: hyperdense basilar sign (HDBA)
• 🩻 CTA: confirms occlusion, assesses collaterals
• 🧲 MRI DWI: acute infarcts
• 📉 ECG & Echo: cardiac embolic source

🖼 Imaging Findings

Hyperdense Basilar Artery sign (HDBA) → direct CT clue of clot

Posterior circulation infarcts → brainstem, cerebellum, occipital lobes

📉 Prognostic Indicators

• 🚬 Poor: age, smoking, high NIHSS, BATMAN <7, delayed therapy
• ✅ Good: rapid recanalisation, bilateral PCOMs, NIHSS ≤4 at 48h

🧮 BATMAN Score (CTA)

Posterior collateral scoring (0–10). <7 = poor prognosis. Includes flow in vertebral, basilar, PCAs + PCOMs.

⚕️ Management

• 🛌 Stabilisation: airway, breathing, ICU admission
• 🖼 Imaging: urgent CTA for eligibility
• 💉 IV Thrombolysis: within 4.5h (select cases up to 6h)
• 🧑‍⚕️ Mechanical Thrombectomy: best option, up to 12–24h if salvageable tissue
• 💊 Antithrombotics: secondary prevention after reperfusion
• ❤️ Supportive: BP, glucose, prevent DVT, manage complications
• 🌅 Palliative: if prognosis grim (locked-in, brainstem necrosis)

📈 Prognosis

❌ Mortality is very high without intervention. ✅ Early recanalisation dramatically improves outcome. ⚡ Survivors often need long-term rehab for motor, swallowing, and cognitive deficits.

📚 References

• Schwartz NE et al. Basilar Occlusion Syndromes. The Neurohospitalist. 2015
• Lindsberg PJ, Mattle HP. Basilar artery occlusion. Lancet Neurol. 2011
• Rangaraju S et al. NIHSS predictors in basilar occlusion. Stroke. 2016
• Kang DH et al. Posterior circulation collaterals & outcome. J Neurointerv Surg. 2016