Ischaemic Strokes in the Pons

🧠 Note: Anatomical diagrams of the pons are often displayed inverted compared to radiological (CT/MRI) orientation — except as shown below. This distinction is important when correlating anatomy with clinical findings or interpreting imaging.

🌉 Introduction

• 🩸 Pontine strokes are most often lacunar infarcts due to occlusion of small penetrating arteries from the basilar trunk.
• 📈 Common risk factors include age, hypertension, diabetes, and atherosclerosis.
• ⚠️ Bilateral lesions are uncommon but can occur with basilar artery occlusion — potentially devastating with “locked-in” presentation.

🧬 Aetiology

• 🎯 Usually small-vessel occlusion of penetrating branches of the basilar artery → unilateral pontine infarcts.
• 🫀 Basilar occlusion at the origins of perforators → possible bilateral pontine infarction.
• 🔄 Shared risk factors with other small-vessel strokes: hypertension, diabetes, ageing, and lipohyalinosis.
• 🚫 Large-vessel infarcts (basilar atherothrombosis, embolism) → wider territory infarction ± coma.
• 💧 Oedema near 4th ventricle may obstruct CSF flow → acute hydrocephalus requiring ventricular drainage.

🧩 Clinical Features

• ⚡ Contralateral hemiparesis or hemisensory loss — corticospinal and medial lemniscus involvement.
• 🚫 No cortical signs (e.g., aphasia, neglect, hemianopia) — helps differentiate from cortical stroke.
• 🙂 Ipsilateral facial palsy (LMN type) — facial nucleus or fascicle lesion.
• 👀 Diplopia or lateral gaze palsy — due to abducens (VI) nerve involvement.
• 🔒 Locked-in syndrome: Quadriplegia + anarthria but preserved consciousness and vertical eye movement.
• 🌀 Vertigo, nystagmus, ataxia — if cerebellar peduncles affected.
• 🔥 Pyrexia & autonomic instability — involvement of reticular or hypothalamic pathways.
• 🗣️ Dysarthria–clumsy hand syndrome or pure motor stroke presentations (lacunar syndromes).
• 🔁 Fluctuating symptoms — “pontine warning syndrome”, similar to capsular warning episodes.

🖼️ Anatomical & Imaging Examples

📍 Pontine infarcts typically respect the midline and may extend posteriorly toward the cerebellum.

🧪 Investigations

• 🩸 Routine bloods: FBC, U&E, LFTs, glucose, lipid profile.
• 🧠 CT ± CTA: To confirm acute stroke, rule out haemorrhage, and assess basilar patency.
• 🧲 MRI brain: More sensitive for small infarcts — DWI highlights acute ischaemia early.
• 🔍 MRA / CTA: Evaluate for vertebrobasilar stenosis or occlusion.

🩺 Management

• 💉 Reperfusion therapy: IV thrombolysis (within window) or thrombectomy for basilar occlusion — improves survival in selected patients.
• 🏥 Stroke Unit care: Multidisciplinary monitoring, oxygenation, and early rehab initiation.
• 💊 Antiplatelet: Aspirin 300 mg ± Clopidogrel after imaging confirms ischaemia.
• ⚖️ Risk factor control: Optimize BP, glucose, and address AF or dyslipidaemia.
• 🧠 Statins: Start high-intensity statin (e.g., atorvastatin 80 mg) for secondary prevention.
• 🗣️ Rehabilitation: Physiotherapy, occupational therapy, and speech therapy for motor/speech recovery and swallow safety.

💡 Teaching tip: Pontine strokes are often clinically silent or subtle initially but may deteriorate rapidly. Always assess eye movements, facial symmetry, and bulbar function in any suspected brainstem event. Locked-in syndrome is the hallmark of extensive bilateral pontine infarction — preserved awareness but paralysis below the eyes.