DEEP BRAIN STIMULATION AND
SPEECH PATHOLOGY
Table of Contents
Deep Brain Stimulation 2 Speech Pathology 4 Language 5 Speech 7 Swallowing 9 Voice 11 Definitions 13 References 15
Compiled by Darren Adams-Beutel, Emily Doherty, Kate Houston, Anne Huang, Juanita Mayenco, Caitlin McGrath and Phillipa Thomspon
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Deep Brain Stimulation Deep Brain Stimulation (DBS) is a surgical procedure that specifically targets motor symptoms and can be used to treat some neurological disorders. It has associated risks as well as benefits. DBS involves the placement of electrodes into the brain. The electrodes are connected to a special battery stimulator in the upper chest that can be used to control the strength of the electrical current that stimulates your brain. Neurologists implant the electrodes within specific areas of your brain to modulate the activity of those areas. The electrical current can be used to either suppress or excite activity in the brain depending on what is most suitable for you.
Recently DBS has been successfully used to treat some of the common debilitating motor symptoms of Parkinson’s disease (PD), such as tremor, rigidity, slowed movement, stiffness and walking problems. Research suggests that for some people DBS has significantly helped with these types of gross motor movements to increase quality of life. However, patients can experience varying degrees of benefit.
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Summary The impacts of DBS on communication
While DBS has been seen to help some gross motor aspects of living with PD, there are some areas of body function that DBS is not known to benefit. Research indicates that DBS is mostly ineffective to treat speech and voice problems associated with PD. A large percentage of people with PD report to have speech difficulties after the onset of the disease. Changes in speech due to DBS are variable between patients. As DBS aims to improve motor functioning, some patients may have some improvements in speech, however, the overall effect is not significant. Other patients have experienced a deterioration of speech abilities
with DBS treatment. High stimulation levels may negatively impact speech, with lower settings providing better motor speech control. Voice is one of first difficulties noticed by patients and may continue to be a difficulty noticed by patients after DBS. The effect of DBS on swallowing is more uncertain, although swallowing function should not be negatively affected by DBS. A change you may notice with stimulation is swallowing more slowly. The effect of DBS on your language is another uncertain area in research. Some patients may experience benefits and some may experience a decline. Any changes in language or any of these areas should be discussed with your speech pathologist.
For more information on a specific area please see the chapters on each topic.
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What is a speech pathologist? Speech pathologists are professionals who specialise in communication and swallowing disorders. This includes the assessment and management of areas such as speech, language, fluency, voice and swallowing. Speech pathologists work with a variety of people who have difficulty communicating and swallowing as a result of brain injury, stroke, intellectual disability, hearing loss and dementia, as well as people with Parkinson’s disease (PD). Why see an SLP before and after DBS? You will be required to see a speech pathologist before and after Deep Brain Stimulation (DBS). Before DBS, the speech pathologist will assess your current level of communication and swallowing ability. This will occur about two days before your surgery.
Following your DBS procedure, a speech pathologist will determine if any changes in the areas of speech, language, voice or swallowing have occurred, and whether therapy is required. This review will happen 24-48 hours post surgery.
How can a SP help you in the future? As your PD progresses, you may continue to experience changes in your communication and swallowing. A speech pathologist can work with you to complete assessment on your current skills, to develop goals for treatment and to put treatment options in place to manage difficulties you may be experiencing. By working on these areas of communication and swallowing with evidence-based treatments, the speech pathologist will work to help increase your independence, your participation in society and your quality of life.
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Language
‘Language’ refers to a set of social rules that can tell us: the meaning of words, how to modify words to change meaning, how to put words into appropriate sentences, and how to use those words and sentences for different purposes. Language incorporates writing, reading, listening and speaking.
Language difficulties can occur at any stage of life. Adult language difficulties are usually acquired as the result of head injury, stroke, psychological disorder or degenerative disease, such as dementia or motor neuron disease. People with Parkinson’s disease (PD) may also have difficulties with using or understanding language.
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Deep Brain Stimulation and language Research shows that Deep Brain Stimulation (DBS) can improve motor ability for people with PD, but only a very small amount of research has investigated the effects of DBS on language.
The best available evidence indicates that DBS may have little to no effect on language ability. There is no research evidence to suggest that any level of DBS stimulator strength would cause changes to the way people with PD understand or produce language. Some researchers have noted a decline in verbal fluency (the ability to quickly generate a list of related words) after DBS. However, this may be a result of the implantation surgery, and not the DBS itself. Until more research studies are conducted, the effects of DBS on language are still uncertain.
Possible changes to your language due to the progression of PD Many different parts of the brain have input into language functions. However, many of these functions are monitored by the frontal lobe (the forward-most part of the brain). As PD begins to affect the frontal lobe, secondary language difficulties can occur.
Not all people with PD will experience language problems. However, some people diagnosed with PD, and their loved ones, may notice changes in the person’s ability to understand and use language. For example:
• It may be difficult to find the right words when speaking • The person may have difficulties understanding the non-literal meaning of language, e.g. sarcasm or metaphor • The person may have trouble interacting appropriately or politely with conversational partners A speech pathologist can help to treat any language concerns that you, or your loved ones, have.
• It may become more difficult to understand complex sentences • Longer sentences may be harder to understand than shorter sentences • The person may produce sentences which aren’t always grammatically correct
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Speech Speech is the ability to form the sounds of language to communicate. When a person is unable to produce speech sounds correctly or fluently enough to communicate, then he or she has a speech disorder.
Speech following DBS may show no improvement or may even be reduced for some patients.
After the DBS procedure, the level of stimulation that you receive may also have an effect on the way you speak. In These disorders may arise from a some people, high levels of stimulation number of sources. In Parkinson’s have been found to reduce their ability disease they are often due to stiffness to form words clearly and have had a and reduced movement (hypokinesia) negative effect on their speech. of the muscles and organs involved in speaking. However, this will be different for everyone who undergoes the Deep Brain Stimulation and speech procedure, so it may be necessary to adjust the level of stimulation to find Deep Brain Stimulation (DBS) has the right balance between speech and been successfully used to treat the movement disorders associated with Parkinson’s disease. These symptoms include slowness in execution of movement (bradykinesia), problems with walking, stiffness of muscles and tremor. While there are great benefits to DBS in regard to the reduction of movement disorders the benefits to speech performance are unclear.
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overall movement to suit your own individual lifestyle.
Your doctors will adjust the level of stimulation to work out your optimal stimulator setting.
Possible changes to your speech due to the progression of PD
Speech problems are common in Parkinson’s disease and often increase as the disease progresses. It may become more difficult to articulate
words precisely and as a result words may sound a little slurred. This is called dysarthria and is due to changes to the way the brain controls the muscles needed to make particular sounds. Other symptoms may include short rushes of fluent speech (festinations), hesitations and difficulty starting sentences or getting speech underway.
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Swallowing A person swallows an average of 500 times per day. Effective swallowing involves a complex and coordinated series of muscle movements starting from when food or fluid enters your mouth, to the time it gets to your stomach. A swallow can either be voluntarily or reflexively controlled (automatic). Difficulties experienced when chewing, drinking and swallowing, are known as dysphagia. Deep Brain Stimulation and swallowing Although motor functioning is known to improve with Deep Brain Stimulation (DBS), the effect that DBS could have on your swallowing ability is less well-known. Results may be variable between patients. Changes to your swallow may be different when your DBS stimulator is turned on versus when it is off.
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When the DBS stimulator is on, the speed of movement of your tongue and your swallow in general, may become slower.
Assessments do not typically show any significant effect from the DBS treatment itself, though many PD clients do report a subjective improvement of swallowing function post DBS.
Possible changes to your language due to the progression of PD
PD, however, is commonly associated with a decline in swallowing function. Nearly 90% of individuals with PD suffer from dysphagia (swallowing dysfunction), as it is a common result of the disease progression.
Dysphagia can occur in the early stages of PD, although during this time, symptoms may be mild and less noticeable than other motor symptoms. Dysphagia in patients with PD can range from mild dysphagia through to lifethreatening lung infections (aspiration pneumonia). Changes in swallowing may include:
• Coughing, choking or pain when eating or drinking • Feeling like something is stuck in your throat • Running out of breath while eating or drinking • Having food or fluid left in your mouth after you have swallowed • Trouble with food or fluid spilling out of your mouth (drooling) • Needing a few swallows to get your food or fluid down • Taking a very long time to eat • A dry mouth (xerostomia)
Swallowing difficulties must not be ignored, as aspiration-induced pneumonia can lead to a number of consequences, including lung infections, or in some cases, death. Dysphagia management may warrant minimal intervention in mild cases, or alternative feeding methods in more severe scenarios.
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Voice We rely on our voices every day to communicate with others. When our voices are healthy, the three main parts below work together to produce voice during speech and singing.
enough pressure, they vibrate to produce sound. Muscles in the neck control the pitch of the sound.
• The resonator: Your throat, nose and mouth are part of the resonator system. The shape of the resonators produces your unique voice sound and speech.
Deep Brain Stimulation and voice Studies suggest that some people who undergo Deep Brain Stimulation (DBS) experienced a reduction of voice tremor.
The three main parts of voice production However, there is conflicting evidence are: about the effects of DBS on vocal acoustics in patients with PD. Overall • Breath support: The power for there have been few studies, and the your voice comes from the air in number of patients involved in the your lungs when you breathe out. A stronger airstream equals a stronger studies have been small. voice. Your respiratory system is It is suggested that a combination of very important to support your therapy approaches be considered for voice. voice outcomes resulting from PD. You can talk to your speech pathologist • Your voice box (larynx): This sits about additional options. After the on top of your airway. When air is DBS procedure, the level of stimulation pushed past the vocal folds with that you receive can have an effect on
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your voice. Research suggests that high levels of stimulation may benefit limb movement more than breath and throat control needed for voice production.
Your speech and voice may benefit more from low levels of stimulation than high levels, although outcomes will vary for individuals. Your doctors will adjust the level of stimulation to work out your optimal stimulator setting.
Possible changes to your voice due to the progression of PD
Fifty to ninety per cent of people with PD (with no known cause) will develop speech and voice disorders (known as a motor speech impairment) in the
course of their illness. The term used to describe the type of motor speech impairment most associated with PD is hypokinetic dysarthria. The most common features of hypokinetic dysarthria include:
• Reduced loudness/volume of voice (people may have trouble hearing you talk) • Monotone voice (unable to highlight points in a word or sentence) • Harsh, hoarse or breathy vocal quality • Short rushes of speech (you may find it difficult to say all you need to on one breath) Voice changes tend to occur early in the course of the disease and prosody, fluency, and articulation abnormalities are more likely to occur later. A person with PD may have difficulty monitoring their vocal loudness and quality. This is a result of a sensory problem perceiving their own level of effort and volume for others in conversation.
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Definitions
Aspiration: when food or fluid goes down the wrong way and reaches your lungs Aspiration-induced pneumonia: an infection caused by bacteria from food or fluid present in the lungs Bolus: term used to describe food/fluid in your mouth before it is swallowed Bradykinesia: slowness in execution of movement Delayed swallow: reduced ability to swallow quickly and automatically due to the gradual loss of control over muscles in the mouth and throat Dysphagia: disorder of swallowing function Festinations: short rushes of fluent speech Fluency: smoothness and flow of speech Frontal lobe: the brain is separated into four “lobes�: parietal, temporal, occipital and frontal. The frontal lobe is the forward-most part of the brain, and is involved in many brain functions including: language, motor skills, problem solving, emotion regulation and social behaviour. Hypokinesia: partial or complete loss of muscle movement
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Hypokinetic dysarthria: a condition that is the result of reduced muscle movement, coordination and strength Language: a set of social rules that can tell us the meaning of words, how to modify words to change meaning, how to put words into appropriate sentences, and how to use those words and sentences for different purposes. Language incorporates writing, reading, listening and speaking. Penetration: when food or fluid goes down the wrong way, but does not reach your lungs Prosody: the rhythm and intonation of speech Stroke: an event where the brain experiences a disruption to blood supply from either a blood vessel blockage (ischaemic stroke) or a burst blood vessel (haemorrhagic stroke) Xerostomia: dryness in the mouth. Xerostomia is linked to the progression of PD and is a common side effect of PD medications Verbal fluency: the ability to quickly generate a list of related words.
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The University of Queensland Brisbane QLD 4072 Australia Ph: (07) 3365 1111 Mon - Fri | 8am - 5pm http://www.uq.edu.au/
St Andrew's War Memorial Hospital 457 Wickham Terrace Brisbane QLD 4001 Australia Ph: (07) 3834 4444 http://standrewshospital.comau/
Compiled by Darren Adams-Beutel, Emily Doherty, Kate Houston, Anne Huang, Juanita Mayenco, Caitlin McGrath and Phillipa Thomspon