Stroke is a neurological disorder caused by cerebral circulation disorder leading to a decreased supply of oxygen and nutrients to brain tissue. They can be both ischaemic and haemorrhagic. Ischaemic strokes occur when an artery is clogged and blood flow is prevented, and haemorrhagic strokes are caused by a ruptured blood vessel bleeding into surrounding tissue.
Some consequences of strokes can significantly affect speech and language skills as well as swallowing and feeding. Aphasia, dysarthria (anarthria) and/or dyspagia have been reported.
Aphasia is a disorder caused by damage to brain cells by strokes, traumatic brain injuries, tumours, infections and the like. The two best-known types of aphasia are Broca’s and Wernicke’s Aphasia.
If a stroke occurs in the language processing area of the brain (the Wernicke’s area at the back of the upper temporal limb of the left hemisphere), it is called Wernicke’s Aphasia. This is basically characterised by a disrupted understanding of language while language production remains unaffected. People with Wernicke’s Aphasia often speak a lot, create new, meaningless words, replace words and letters, and often their speech in incomprehensible. This presents significant problems with naming, reading, writing and repetition. Difficulties in understanding depend on the severity of the injury itself.
Broca’s Aphasia is caused by damage to the back of the lower temporal limb of the brain’s left hemisphere. Understanding of language is preserved and production of language is impaired, so it is also known as motor aphasia. A person with Broca’s Aphasia cannot repeat words, speak spontaneously or read out loud and has difficulties in naming.
Dysarthria is a motor speech disorder that is caused by damage to the peripheral or central nervous system that results in poor muscular control of the organs of speech. This can take the form of weakness, a lack of coordination or paralysis or paresis of speech muscles and a lack of power, speed or tone in muscle movements. Articulation, phonation, resonance and production can also be distorted.
Apraxsia is a motor dysfunction that results in an inability to perform intentional movements, despite the desire and the existing ability to carry out movements. Symptoms include articulation errors (often requiring the proper position of the organs of speech to pronounce a word) and disrupted speech. Strength, range of movement and coordination are normal for non-verbal oral movements.
Disphagia implies difficulty in swallowing, food chewing problems, preparation of swallowing, initiation of swallowing, swelling of the throat and transfer and acceptance of from the oesophagus to the stomach.
In cases of dysphagia a speech and language therapist should evaluate oral-pharyngeal and respiratory functions related to nutrition and provide education, counselling and training for dysphagic persons and those close to them.