TACS versus PACS: counting anterior circulation features
Anterior circulation strokes (internal carotid artery and its branches) are total (TACS) with all three features, partial (PACS) with two, or with a lone disturbance of functions such as language.
Remember
Count the three features: unilateral weakness or sensory loss, a homonymous hemianopia (loss of the same half of the visual field in both eyes) and higher cerebral dysfunction (a disturbance of functions such as language). All three make a TACS, while two make a PACS, as does higher cerebral dysfunction alone.
The Bamford (Oxford) classification is a way of naming an ischaemic stroke from its symptoms, without waiting for imaging. For strokes in the anterior circulation (the internal carotid artery and its branches, which feed the front and sides of the brain), the job is to count the three features.
- Unilateral weakness and/or sensory loss of the face, arm or leg.
- A homonymous hemianopia (loss of the same half of the visual field in both eyes).
- Higher cerebral dysfunction: a disturbance of the functions of the cortex (the outer layer that carries out thinking, language and conscious movement), such as dysphasia, a disturbance of language.
Weakness or sensory loss counts as one feature, and having both is still one feature.
A TACS, a total anterior circulation stroke, has all three features together. It is the most extensive anterior circulation syndrome, affecting a large proportion of the cortex, and it carries a high mortality.
A PACS, a partial anterior circulation stroke, is the milder form, where part of the area supplied by the anterior circulation is affected. It needs two of the three features, or higher cerebral dysfunction on its own. Think of it as a TACS with one feature missing, or a lone higher cerebral dysfunction. For example, arm weakness with dysphasia but no visual field defect makes two features, so it is a PACS. The early risk of another stroke is relatively high in a PACS.
The T in TACS is for Total, with all three features, and the P in PACS is for Partial, with part of the full set.
Key facts
- TACS
- all three features together: unilateral weakness or sensory loss, homonymous hemianopia and higher cerebral dysfunction
- PACS
- two of the three features, or higher cerebral dysfunction alone
- Weakness and sensory loss
- they count as one feature, so having both is still one feature
- Basis
- the Bamford (Oxford) classification uses the symptoms, not imaging
- TACS outlook
- the most extensive anterior circulation syndrome, with a high mortality
- PACS recurrence
- the early risk of another stroke is relatively high
Exam traps
- Weakness with dysphasia and full visual fields does not make a TACS, because a TACS needs all three features and with full visual fields there is no hemianopia.
- Dysphasia does not fit a lacunar stroke (a small, deep stroke), because language is processed in the cortex and a lacunar stroke causes syndromes without cortical signs.
- Weakness that resolves fully does not make a TACS, because a TACS also needs homonymous hemianopia and higher cerebral dysfunction.
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