Atypical conduction aphasia. A disconnection syndrome

Area of Science:

• Neuroscience
• Neurolinguistics
• Clinical Neurology

Background:

• Conduction aphasia was historically attributed to a disconnection between Wernicke's and Broca's areas, specifically involving the arcuate fasciculus.
• This traditional view is challenged by cases where lesions outside the arcuate fasciculus manifest as conduction aphasia.

Observation:

• The study presents three novel cases of conduction aphasia.
• Two cases involved left-handed patients with left temporoparietal lesions.
• One case involved a right-handed patient with a right temporoparietal infarct, presenting as "crossed" aphasia.

Findings:

• Lesions in these cases were not located within the arcuate fasciculus.
• The findings support the hypothesis that conduction aphasia arises from a disconnection within the language network.
• Damage to specific cortical regions like Wernicke's area alone is not the sole cause.

Implications:

• This challenges the strict arcuate fasciculus theory of conduction aphasia.
• It suggests that the integrity of the circuit connecting language comprehension to speech production is critical.
• Understanding this network disconnection is vital for diagnosing and potentially treating conduction aphasia.