A complex integration of physical and cognitive abilities that produces an articulation of language using sounds. On the cognitive end, the frontal and temporal lobes of the cerebrum that regulate language recognition and processing translate thought processes into the language concepts. This activity takes place primarily in two regions, called Broca’s area and Wernicke’s area. These are functionally, rather than physically, defined regions in the brain and usually are located in the dominant side of the cerebrum (the left hemisphere in most people; some left-handed people have these regions in the right hemisphere).
Wernicke’s area processes incoming language; Broca’s area formulates outgoing language.
Outgoing language becomes speech when the cerebral cortex, in coordination with the activities of Broca’s area, sends signals to initiate movement of the structures that make speech possible the lips, mouth, tongue, throat, and vocal cords as well as of the structures of the chest involved in breathing. In turn, the signals activate the structures of the basal ganglia, the clusters of nerves that regulate voluntary movement, which send the neuron communications that direct the specific actions of the muscles involved. Signals from the cerebellum coordinate all of this movement, making it smooth and sequential. Interruptions along any part of this pathway disrupt speech.
In Parkinson’s disease such interruptions most commonly take place in the basal ganglia, where insufficiency of the level of dopamine causes nerve signals to become jumbled. Muscles on the receiving end of these incomplete or chaotic neuron communications may be slowed (bradykinesia) or fail to respond (akinesia). The lips and tongue incompletely shape the appropriate formations for making the sounds of words; the vocal cords do not adjust for the quality of sound the words require; breathing may be inadequate to produce the volume of air necessary to produce adequate sound through the vocal cords. These dysfunctions result in the speech difficulties characteristic of Parkinson’s disease such as soft, monotone voice; slowed hesitant, speech; or rapid stuttering speech. When cognitive impairment is a feature of the Parkinson’s as well, the cerebrum’s language centers also are affected, as manifested by dysphasia (difficulty in finding the right word). Clinicians refer to these difficulties as dysfunctions in phonation, res-onation, and articulation.
Speech difficulties generally occur in the later stages of Parkinson’s, although in some people a soft, almost whispery voice is one of the earliest signs of the disease (usually recognized in retrospect). swallowing problems often coexist with speech difficulties, as swallowing and speech share common structures and physiological processes. Speech therapy often can help people handle both developments by teaching methods of compensating for diminished functions. Voice volume is a factor of generating enough breath and sometimes the person with Parkinson’s is not able to do so. bradykinesia (slowed muscle response and movement) also can affect the muscles of the chest, the abdomen, and particularly the diaphragm. Although the person’s pace and depth of breathing may increase with physical activity as the body demands more oxygen, he or she may have difficulty intentionally taking deep breaths to improve speech. breathing exercises, including yoga breathing, help to maintain maximal breath control. hypomimia, or the “masked face” of Parkinson’s, tends to contribute to communication problems for people who have speech difficulties, as it eliminates the facial expressions that help to give context to spoken communication. This condition affects the response of others more than the speech of the person with Parkinson’s but contributes to the overall challenge of verbal communication. Loved ones can help by being patient when the person with Parkinson’s is attempting to articulate the right word. Some people appreciate prompting or filling in elusive words; others find this reaction intrusive and frustrating. It often is worthwhile to ask the person with Parkinson’s what he or she prefers. Often speech improves when anti-parkinson’s medications are at their peak in relieving other motor symptoms and deteriorates during off-states.