Review Question - QID 217778

This patient with a history of stroke who can comprehend, follow simple commands, and express himself but with the inability to repeat is suffering from conductive aphasia which results from a lesion involving the arcuate fasciculus.

Conduction aphasia is a rare form of aphasia wherein patients have intact expression and comphrension, but cannot repeat simple phrases. The cause is due to an injury to the arcuate fasciculus, which impairs the transmission of information between the Wernicke area and the Broca area. The arcuate fasciculus is located in the supramarginal gyrus or deep parietal matter. Since this may be the only finding in patients with conduction aphasia, the presentation may be subtle. Management is medical optimization of underlying risk factors for stroke and speech therapy.

Acharya et al. describe the classification, identification, and pathophysiology underpinning conduction aphasia.

Figure A/Illustration A depicts that conduction aphasia involves a lesion of the arcuate fasciculus as denoted by the letter D.

Incorrect Answers:
Answer 1: A denotes a lesion to the brain stem in the area of the red nucleus, which could result in “locked-in syndrome”, which is a condition in which patients are conscious and awake, but have no ability to produce movements apart from eye motions. They are unable to speak. However, functionally, they are incapable of anything more than communication via eye movements, unlike this patient who is able to follow commands.

Answer 2: B denotes a lesion Broadmann areas 44 and 45 of the dominant hemisphere of the brain, which controls language. It results in a condition in which the output of spontaneous speech is markedly diminished and there is a loss of normal grammatical structure. Characteristically, patients can become very frustrated as their comprehension is intact.

Answer 3: C denotes a lesion to the Wernicke area (Broadmann area 22), representing a lesion to the inferior division of the left middle cerebral artery. It results in no deficits in fluency, however, patients are unable to comprehend what is being said to them. As such, they are able to speak unhindered but seemingly nonsensically, unlike this patient who is unable to speak but can follow commands.

Answer 5: E denotes a lesion in the cerebellum, which would present with ataxia and dysdiadochokinesia. While motor function is affected with lesions to this region, aphasia is not present.

Bullet Summary:
Conduction aphasia results from a lesion involving the arcuate fasciculus.