# Aphasia and Cortical Lesion Syndromes

> Aphasia and cortical syndromes for NEET-PG Medicine covering Broca, Wernicke and conduction aphasia with lobar localisation signs and repetition testing.

- Canonical URL: https://prepelephant.com/topics/neet-pg/medicine/aphasia-and-cortical-syndromes
- Exam / course: NEET-PG · Subject: Medicine
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-08
- Last updated: 2026-10-08
- Reference basis: Bradley's Neurology in Clinical Practice; Adams and Victor's Principles of Neurology
- How to cite: "Aphasia and Cortical Lesion Syndromes", PrepElephant, https://prepelephant.com/topics/neet-pg/medicine/aphasia-and-cortical-syndromes

## Direct answer

Aphasia is an acquired language disorder from dominant hemisphere damage, localised by three questions: is speech fluent, is comprehension preserved, is repetition intact. Broca aphasia is non-fluent with preserved comprehension, reflecting an inferior frontal lesion, while Wernicke aphasia is fluent with impaired comprehension, reflecting a posterior superior temporal lesion. Conduction aphasia is fluent with good comprehension but disproportionately poor repetition, from damage to the arcuate fasciculus or adjacent perisylvian cortex.

## What you must remember

- **Broca aphasia:** non-fluent, effortful, telegraphic speech with preserved comprehension and poor repetition, often with right facial and arm weakness from a frontal lesion.
- **Wernicke aphasia:** fluent, paraphasic speech with neologisms, poor comprehension and poor repetition; hemiparesis is usually absent, but a superior quadrantanopia can accompany it.
- **Conduction aphasia:** fluent speech and good comprehension, with repetition impaired out of proportion and phonemic paraphasias; patients often recognise and correct their own errors.
- **Global aphasia:** non-fluent with poor comprehension from a large perisylvian lesion in the middle cerebral artery territory.
- **Anomic aphasia:** word-finding difficulty with fluent speech and intact repetition, a nonspecific sign of temporal or angular lesions.
- **Lobar signs:** frontal lesions cause abulia and gait apraxia, parietal lesions cause neglect and anosognosia, temporal lesions cause a contralateral superior quadrantanopia, and occipital lesions cause homonymous hemianopia with macular sparing.
- **Gerstmann syndrome:** finger agnosia, left-right disorientation, dysgraphia and acalculia from a dominant angular gyrus lesion.

## A worked case: fluent nonsense after a stroke

A right-handed 60-year-old man is found after a stroke speaking fluently but producing nonsensical words, and he does not follow simple commands.

1. **Apply the three questions:** Speech is fluent, comprehension is poor and repetition fails, so the picture is Wernicke aphasia from a posterior left temporal lesion, probably in the middle cerebral artery territory.
2. **Check the visual field:** Look for a superior quadrantanopia from radiation damage; right-sided sensory loss may occur if the lesion extends into the parietal lobe.
3. **Arrange imaging:** Urgent CT or MRI and vascular imaging are arranged.
4. **Contrast Broca aphasia:** A man with right arm weakness whose speech is slow, effortful and telegraphic, yet who understands every question, has Broca aphasia from an inferior frontal lesion.
5. **Recognise conduction aphasia:** A patient with fluent speech, good understanding and a repetition deficit, who repeats "no ifs, ands or buts" as "no if, and, or but", has conduction aphasia and a lesion of the arcuate fasciculus.

## Where the mnemonics mislead

Repetition is the most useful single test, and the usual mnemonic is incomplete.

- **Trap:** trusting the mnemonic that Broca speaks and Wernicke understands. — **Correct:** the real discriminators are fluency together with comprehension, and repetition is what separates conduction aphasia.
- **Trap:** treating dysarthria as aphasia. — **Correct:** dysarthria is a motor speech disorder with normal language content, whereas aphasia affects the language itself.
- **Trap:** assuming a right-sided lesion excludes aphasia. — **Correct:** a left-handed patient may have atypical language localisation, so a right-sided lesion does not exclude aphasia in that patient.
- **Trap:** naming Gerstmann syndrome from a single feature. — **Correct:** the full tetrad of finger agnosia, left-right disorientation, dysgraphia and acalculia, from a dominant parietal lesion, is the expected answer.

## Frequently asked questions

### What distinguishes Broca aphasia from Wernicke aphasia?

Broca aphasia is non-fluent with preserved comprehension, usually from an inferior frontal lesion, while Wernicke aphasia is fluent with impaired comprehension, usually from a posterior superior temporal lesion. Both show impaired repetition, which is why fluency and comprehension must be assessed alongside it.

### What is the key feature of conduction aphasia?

Conduction aphasia is fluent speech with good comprehension but disproportionately impaired repetition, with phonemic paraphasias. It usually results from a lesion of the arcuate fasciculus, and patients often recognise and correct their own errors.

### Which visual field defect follows a temporal lobe lesion?

Damage to Meyer loop fibres in the temporal lobe produces a contralateral superior quadrantanopia, sometimes called a pie-in-the-sky defect. Parietal lesions in the optic radiation produce the opposite inferior quadrantanopia.

### What are the four features of Gerstmann syndrome?

Finger agnosia, left-right disorientation, agraphia and acalculia together make up Gerstmann syndrome, typically from a lesion of the dominant angular gyrus. The tetrad is best remembered as a set, since isolated features occur in other conditions.