What is the Difference between dysarthria and expressive aphasia?

Answer 1

Both dysarthria and aphasia are abnormalities of speech. The chain of speech and abnormalities are as follow:
i. Hearing
ii. Understanding -- Aphasia
iii. Thought & word finding -- Aphasia
iv. Voice production
v. Articulation -- Dysarthria

Aphasia refers to the abnormalities in understanding, thought and word finding.

Dysarthria refers to the difficulties in speech at any level such as breathing, vocal cord, larynx, palate, tongue and lips.

The common types of aphasia are Wernicke's aphasia and Broca's aphasia.

Wernicke's area (Broadmann's area 22) in cerebral cortex receives visual input from occipital lobe and auditory input from temporal lobe, it permits the understanding of spoken and written language and enable a person to interprete it. Destruction of Wernicke's area in dominant hemisphere cause receptive aphasia. The patient is unaware of the speech by others and also himself. So, he speaks long and meaningless speech. Since the Broca's area is intact, he can produce smooth speech.

Broca's area (Broadmann area 44, 45) in cerebral cortex is motor speech area. It is connected to the Wernicke's area by arcuate fasciculus. It receives impuls from Wernicke's area and converted it into the motor command and sends to cerebral cortex to be converted into action of muscles involved in speech.If destructed, the patient retains the ability to think. The patient speaks short but meaningful speech with great effort. The sentence is not complete. This is expressive aphasia.

For dysarthria, lesions of upper motor neuron, lower motor neuron, basal ganglia, cerebellum or extrapyramidal system leads to disturbance of the intergration of speech production and the speech rhythm. The speech of the patient is not clear but very complete and meaningful. Patient can interprete other's speech and respond to it correctly.