Related Subjects:
|Subarachnoid Haemorrhage
|Perimesencephalic Subarachnoid haemorrhage
|Haemorrhagic stroke
|Cerebellar Haemorrhage
|Putaminal Haemorrhage
|Thalamic Haemorrhage
|ICH Classification and Severity Scores
๐ง Thalamic strokes can mimic sleepiness rather than coma. They arise from disruption of the thalamus, a key relay for sensory and motor pathways. Early recognition is crucial as prognosis depends on rapid imaging and management.
๐ Introduction
Thalamic strokes involve an interruption of blood flow to the thalamus, a deep-seated structure acting as a relay centre for motor and sensory signals. They can be ischaemic or haemorrhagic and represent a small but important group of strokes. Clinical manifestations are varied โ ranging from sensory loss and hemiparesis to visual field defects, memory impairment, and movement disorders.
๐ฉธ Anatomy & Vascular Supply
- The thalamus is supplied by small penetrating arteries from the posterior cerebral artery (PCA) and posterior communicating artery (PComA).
- Paramedian arteries: from PCA (sometimes via a single artery of Percheron โ bilateral thalamic infarcts).
- Tuberothalamic (polar) artery: from PComA โ anterior thalamus.
- Thalamogeniculate arteries: from PCA โ lateral thalamus.
- Posterior choroidal arteries: posterior thalamus & adjacent structures.
โ ๏ธ Etiology
- Ischaemic infarction: small vessel disease (hypertension, diabetes), emboli, artery of Percheron occlusion.
- Haemorrhage: hypertensive bleeds, amyloid angiopathy, vascular malformations.
- Other: venous infarction (deep cerebral vein thrombosis), neoplasm, inflammatory lesions.
๐งฉ Clinical Features
- Sensory loss: contralateral hemianesthesia (all modalities).
- Motor weakness: contralateral hemiparesis from internal capsule involvement.
- Thalamic pain syndrome: chronic burning/aching pain weeks after stroke.
- Visual field defects: contralateral homonymous hemianopia/quadrantanopia.
- Oculomotor signs: vertical gaze palsy, light-near dissociation.
- Consciousness: drowsiness/coma in bilateral infarcts (esp. artery of Percheron).
- Cognitive & behavioural changes: memory impairment, apathy, disorientation.
๐ Vascular Territories & Syndromes
Artery | Clinical Syndrome |
Paramedian (incl. artery of Percheron) | โฌ๏ธ Consciousness, vertical gaze palsy, memory impairment |
Tuberothalamic (polar) | Language disturbance, memory issues, apathy |
Thalamogeniculate | Contralateral sensory loss, hemiparesis, movement disorders |
Posterior choroidal | Visual field defects, ataxia, hemisensory loss |
๐จ Artery of Percheron infarct: Rare cause of sudden coma with bilateral thalamic and midbrain infarcts. Look for vertical gaze palsy + memory loss โ a high-yield exam favourite!
๐ผ๏ธ Imaging
- CT head (non-contrast): first-line to exclude haemorrhage.
- MRI DWI: best for small acute infarcts.
- CTA/MRA: shows PCA/PComA anatomy, can detect artery of Percheron occlusion.
- DSA: gold standard if vascular malformation suspected.
๐งช Investigations
- Bloods: FBC, U&E, glucose, lipids, clotting.
- ECG ยฑ Holter: atrial fibrillation, arrhythmias.
- Echocardiogram: cardiac embolic source.
- Risk factors: BP monitoring, HbA1c.
๐ Acute Management
- Ischaemic: IV thrombolysis โค4.5h (if eligible), mechanical thrombectomy up to 6h (โค24h in selected cases), start antiplatelets once haemorrhage excluded.
- Haemorrhagic: strict BP control, neuro ICU, manage ICP, neurosurgical opinion.
๐ Secondary Prevention
- Antiplatelets (aspirin, clopidogrel) or anticoagulation if cardioembolic.
- Statins (LDL reduction + plaque stabilisation).
- Risk factor control: BP, diabetes, smoking cessation, exercise.
๐งโ๐ฆฝ Rehabilitation
- Physio: motor recovery, gait training.
- OT: daily living adaptations.
- SLT: dysarthria, dysphagia.
- Pain team: for thalamic pain syndrome (antidepressants, anticonvulsants).
- Psychological support for depression, fatigue, cognitive issues.
๐ Prognosis
- Many recover function, but persistent sensory loss and pain are common.
- Haemorrhagic strokes carry higher mortality.
- Bilateral thalamic infarcts have poor outcomes if coma persists.
๐ References
- Schmahmann JD. Vascular syndromes of the thalamus. Stroke. 2003.
- Adams HP Jr et al. Guidelines for early management of adults with ischaemic stroke. Stroke. 2007.
- Guenego A et al. Artery of Percheron infarct. Neuroradiology. 2015.
๐ผ๏ธ Images