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LSVT Global® Public Webinar Series
Title: Deep Brain Stimulation and LSVT LOUD: Communication Challenges and Treatment Solutions
Presenter: Cynthia Fox, PhD, CCC-SLP
Date Presented: October 23, 2019
Copyright:
The content of this presentation is the property of LSVT Global and is for information purposes only. This content should not be reproduced without the permission of LSVT Global.
Contact Us:
Web: www.lsvtglobal.com Email: [email protected]
Phone: 1-888-438-5788 (toll free), 1-520-867-8838 (direct)
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www.lsvtglobal.com [email protected]
Deep Brain Stimulation and LSVT LOUD: Communication
Challenges and Treatment Solutions
Cynthia Fox, PhD, CCC-SLP
CEO and Co-FounderLSVT LOUD and LSVT BIG Faculty
LSVT Global, Inc.
PLAN FOR
WEBINAR
• Logistics (handouts)
• Presentation of content
• Address your questions
• Survey
Instructor Biography
Cynthia Fox, PhD, CCC-SLPDr. Fox received her doctorate degree in Speech and Hearing Sciences from the University of Arizona, Tucson. Dr. Fox is a research associate at the National Center for Voice and Speech and Co-Founder of LSVT Global. She is an expert on rehabilitation and neuroplasticity and the role of exercise in the improvement of function consequent to neural injury and disease. Dr. Fox is among the world’s experts in speech treatment for people with Parkinson disease. She has multiple publications in this area of focus, as well as numerous national and international research and clinical presentations. She is an expert on rehabilitation and neuroplasticity and the role of exercise in the improvement of function consequent to neural injury and disease.
Disclosures
• Non-financial relationships include a preferencefor the LSVT LOUD as a treatment technique.
• Financial Relationships include Dr. Fox is anemployee of LSVT Global and receives lecturehonorarium. Dr. Fox has ownership interest inthe company.
Information to Self-Report Continuing Education Activity
• This LSVT Global webinar is NOT ASHA or state registered for CEUs, but it may be used for self-reported CEU credit as a non-registered CEU activity.
• If you are a speech therapy professional and would like to self-report your activity, e-mail [email protected] to request a certificate after completion of the webinar which will include your name, date and duration of the webinar.
• Licensing requirements for CEUs differ by state. Check with your state licensing board to determine if your state accepts non-ASHA registered CEU activities.
• Attendance for the full hour is required to earn a certificate.
Learning Objectives
Upon conclusion of this webinar, participants will be able to:
1. Describe voice and speech changes following DBS surgery
2. Explain how LSVT LOUD may improvecommunication post-DBS
3. Outline adaptations that can facilitate and optimize positive outcomes
4. Highlight future adaptations that may improve speechoutcomes
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Poll: Who’s in our audience today?
• Person with Parkinson’s disease
• Family or friend of person with Parkinson’sdisease
• Speech-language pathologist – professional
• Speech-language pathologist – student
• Other
What is Deep Brain Stimulation?
Deep brain stimulation (DBS) uses a surgically implanted medical device to deliver electrical stimulation to a targeted area in the brain. It electrically stimulates specific structures that control unwanted symptoms.
Deep Brain Stimulation in PD
• Placement of electrodes in the Subthalamic Nucleus (STN) or Globus Pallidus Interna (GPi)
Images from Parkinson.org
Deep Brain Stimulation in PD
• Connected to a neurostimulator (~pacemaker) under the clavicle area
• Can be done unilateral or bilaterally
• Consists of multiple surgeries to place electrodes and stimulators
Candidate selection for
DBS
• Diagnosis of idiopathic Parkinson’s disease
• Robust and sustained response to levodopa medications and substantial motor disability
• Absence of dementia or unstable neuropsychiatric symptoms
• Absence of considerable surgical and medical risk factors
• Individual symptoms, needs and goals should be considered in target site selection
Ramirez-Zamora & Ostrem, 2018
How does DBS affect symptoms of PD?
• Can reduce &/or control rigidity, bradykinesia/akinesia, tremor & dyskinesia
• Patient can only return to their best “on time”
• Can reduce amount of meds needed (~30%)
• STN can lead to depression, apathy, impulsivity, worsened verbal fluency, & executive dysfunction
• Not as effective on gait & balance or postural instability
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Potential DBS Complications
Intracranial or intracerebral hemorrhage in 2% of patients
Ischemic stroke in 0-1%
Implantation site infection 3-8%
Seizures in 0-3% of patients
Suicidal ideation may increase after DBS
Declines in cognition in longitudinal follow up have been documented
Possible decline in speech, gait & balance
Duker & Espay, 2013
Dysarthria following DBS of the STN vs. GPI
• Speech function seems to be less compromised under GPi-DBS than under STN-DBS, but further study needed. Skodda, 2012
Pre-existing speech factors to consider pre-DBS
• Lower preoperative speech intelligibility
• Longer disease duration
Tripoliti et al., 2014
• Higher overall motor and speech scores on UPDRS III (higher is worse)
• Preexisting pattern of • Articulatory slurring and hastening• Acceleration of speech
Skodda et al., 2014
Describe voice and speech changes following DBS surgery
Speech characteristics post-DBS
• Neurosurgical interventions do not consistently or effectively improve speech in PD Freed et al., 1992; Goberman, 2005; Pinto et al., 2004; Rousseaux et al., 2004
• While some individual components of speech may improve, e.g., loudness of sustained phonation, oral force control of tongue; Overall speech intelligibility is not improved Kostermann et al., 2008; Pinto et al., 2003
• Speech problems (dysarthria) reported after STN-DBS ranges: 5% - 61% Krack et al., 2003; Guehl et al., 2006
Speech characteristics post-DBS from the patient perspective
• Significant differences in severity of perceived speech disturbance between DBS and non-DBS group
• More severe symptoms reported
• More symptom interference with social interaction and daily experiences relating to functional, physical and emotional issues of a voice disorder
• Low volume was the “most common” speech symptom
• DBS had the greatest adverse impact on “slurred speech.”
Wertheimer et al., 2014
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Medial versus lateral speech profile post-DBSMahlknecht et al., 2017
Medial
• Strained-tight and continuous phonation
• Inaccurate articulation
• Perception of breathing insufficiency
• More dystonic and less responsive to behavioral therapy
Lateral
• Monotone-flat intonation
• Fast rate of speech
• Reduced movement of lips and tongue
• More hypokinetic and respond well to LSVT LOUD, but may have added fatigue and some apathy
Longitudinal Impact on Speech
• 32 patients bilateral STN-DBS at 1 year; 15 at3 years and 12 in medical (no surgery) group
• Speech assessed at baseline, post-DBS 1month, 6 months, 1 and 3 years
• Speech intelligibility deteriorated 1 year afterDBS in 78% of patients in contrast to marked50.7% improvement in parkinsonian motorsymptoms
Tripoliti et al., 2011
Tripoliti et al., 2011
Factors affecting speech outcomes post-DBSSurgical
• Contact placement
• Stimulator settings (frequency, voltage, pulse width)
• Unilateral vs. bilateral stimulation
• Spread of stimulation to other structures
Medical
• Parkinson disease severity
• Severity of speech disorder pre-DBS
• Medication
Methodological
• Selection and number of subjects in studies
• Speech measurement tools vs. UPDRS-III
• Time post surgery studies
Consensus on medical management in PD
Magnitude and consistency of speech improvement with drugs and surgery not the same as limb improvement
Goberman, 2005; Schulz & Grant, 2000; Trail et al., 2005
Explain how LSVT LOUD may improve communication post-DBS
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Speech rehab focus post-DBS
• Maintain and improve physical capacityLoudness, voice quality,
intelligibility, rate
• Maintain vital functions: swallowing safely
• Functional communication is key
• Use of external cueing, devices, augmentative devices
• Address cognitive and/or language deficits
Treat Early and Often!
Our work – LSVT Protocols:Based on 30+ years of NIH funded research
and clinical experience
LSVT LOUD is a speech therapy
Delivered by LSVT LOUD Certified Speech‐
Language Pathologists
LSVT BIG is a physical/occupational
therapy
Delivered by LSVT BIG Certified Physical Therapists or
Occupational Therapists
30+ year LSVT LOUD journey from invention to scale-up
1987-89: Initial invention; Pilot data Lee Silverman Center
1989-91: Treatment development OE-NIDRR
1991-94: Treatment follow-up OE-NIDRR
1990-95: Treatment Efficacy NIH R01 RCT
1995-00: Underlying Mechanism NIH R01 RCT
2002-07: Distributed effects NIH R01
2007-12: Target/mode NIH R01 RCT
2001-02: LSVT Companion Coleman Institute
2002-04: LSVT Companion NIH & MJ FOX Foundation NIH R21
2002-04: LSVT Virtual Therapist Coleman Institute
2004-06: LSVT Virtual Therapist NIH R21
2004: LSVT Down Syndrome Coleman Institute
2006: Technology Enhanced Clinician Training NIH SBIR
2009: Telehealth Delivery of Software Enhanced LSVT NIH SBIR
2010: Independent Delivery of Software Enhanced LSVT NIH SBIR
1993-present: Global LSVT LOUD Training & Certification Courses
Ph
ase
I, II
Inve
nti
on
Ph
ase
III
Re
se
arc
h
Ph
ase
IV, V
Clin
ica
l Im
ple
me
nta
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Evidence for LSVT LOUD3 Randomized Controlled Trials
Change in dB SPL During Reading (50 cm)0cm)
1st RCT; n=45LSVT: Voice/respiratory targetRESP: Respiratory target
Pre, Post, 6 mos, 12 mos, 24 mos
Ramig et al., 1995; 1996, 2001a
2nd RCT; n=30LSVT: Voice/respiratory targetUnTx: No treatment
Pre, Post, 6 mos
Ramig et al., 2001b
3rd RCT; n=64LSVT: Voice/respiratory targetARTIC: Articulatory target UnTx: No Treatment
Pre, Post 6 mos
Ramig et al., 2018
Study Designs• Matched dosage• Matched intensity• Matched homework• Matched therapists’
enthusiasm• Blinded data
analysis• Uncued tasks• Data collected by
someone other than therapist
Spielman, et al., 2003Dumer et al., 2014
Facial expression
El‐Sharkawi, et al, 2002: Miles et al., 2017
Swallowing
Smith, et al., 1995
Adduction
Ramig & Dromey, 1996
Aerodynamics
Baker, 1998; Luschei, 1999
Electromyography (EMG)
Liotti, et al., 2003Narayana, et al., 2010Baumann et al., 2018
Neural Imaging Dromey, 1995; Cannito et al., 2012
Articulation/Intelligibility
Sapir, et al., 2007; 2010
Articulatory acoustics
Smith, A., 2001
Speech Motor Stability
Taskoff, 2001
Perceptual
Beyond Efficacy – numerous studies (over 30) examining distributed effects, neural correlates, mechanism of change
Ramig et al., 1995; 1996; 2001
Intonation (STSD)
Baumgartner et al., 2001
Voice Quality
LSVT LOUD Treatment SessionDaily Exercises
1. Maximum Duration ofSustained Vowel Phonation (Long Ahs) – 15+ reps
2. Maximum Fundamental Frequency Range (High/Low Ahs) – 15 reps each
3. Maximum Functional SpeechLoudness (Functional Phrases) – 5 reps of 10 phrases
Hierarchy Exercises
Structured reading and spontaneous speaking – 25 min
Build complexity across 4 weeks of treatment
Week 1 – words, phrases
Week 2 – sentences
Week 3 – reading
Week 4 ‐ conversation
Homework
Includes all daily exercises and hierarchy exercises. Assigned all 30 days
Carryover Exercises
Use loud voice in real life outside of the treatment room. Assigned all 30 days
Shorter, simple
Longer, complex
Core amplitude rescaling exercises
Translation of amplitude to functional, salient,
individualized goals
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Speech treatment post-DBS in Parkinson’s disease – limited research
• LSVT LOUD case series:Spielman et al., 2011
• LSVT LOUD post STN-DBSsmall groups:Tripoliti et al, 2011
VIDEO – LSVT LOUD POST-DBS
N=4/group
N=4/group
LSVT LOUD pre/post STN-DBS Spielman et al., 2011
Feedback from treating clinicians:
• Subjects had great difficulty producing targetphonations and loud speech during exercises
• Persistent hoarse voice quality, severe slurring,impaired tongue control
• Difficulty with carryover of improved voice intoconversational speech
One possible explanation for this is the high stimulator settings for these three subjects, which has been shown to negatively affect speech intelligibility
Tornqvist et al., 2005; Tripoliti et al, 2008
• 20 participants: medical or surgical groups
• Measured pre, post, and FU
• LSVT LOUD treatment administered
• Examined acoustics, speech intelligibility andperceptual measures LSVT LOUD improved vocal loudness for medical group, but not for STN‐DBS group.
Participants post STN‐DBS were variable in response to LSVT LOUD with minimal sustained improvements.
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LSVT LOUD and CLEAR
• 3 patients with IPD, post bilateral DBS-STN, receiving LSVT followed by a two week (8 sessions) regimen of additional training (“loud and clear”) to improve articulation.
• Loud + Clear. A regimen designed to augment the LSVT effects by proving additional training in high effort oral speech articulation.
Halpern et al., 2010 poster presentation
Vocal Sound Pressure level (dB SPL) for conversation and reading the Rainbow Passage
LSVT_LC dB SPL Pre, Post, 6wk
65
70
75
80
85
90
Pre
1
Pre
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Pre
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Post1
Post2
6wk1
6wk2
Pre
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Pre
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Pre
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Post1
Post2
6wk1
6wk2
Pre
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Pre
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Pre
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Post1
Post2
6wk1
6wk2
DBS-6 DBS-7 DBS-9
CONV
RAINBOW
Interview: Patients’ Responses Regarding Additional Treatment outcome
How would your speech be w/o the additional
Tx
Repeat less?
Easier to use voice strategies
outside Tx?Speech clearer?
Outcome better or
same?Patient
Loud but not as clear
yesyesyesbetterDBS-6
IDKI can’t recallIDKyesbetterDBS-7
Loud but less clear,
mumbled
yesOnce loudness was indoctrinated this allowed me to
improve
articulation of consonants
yesbetterDBS-9
Self Ratings of Communication Effectiveness (CETI-M)
LSVT_LC CETI-M Pre, Post, 6wk
10
20
30
40
50
60
70
80
90
100
Scr
eenin
g
Pre
Post
6wk1
6wk2
Scr
eenin
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Pre
Post
6wk1
6wk2
Scr
eenin
g
Pre
Post
6wk1
6wk2
DBS-6 DBS-7 DBS-9
CE
TI-M
Sco
re (M
ax 1
00)
Outline adaptations that can facilitate and optimize positive outcomes
LSVT LOUD Adaptations
Adaptations ARE:• Increasing repetitions for shorter durations
• Allowing greater rest breaks
• Persisting at phrase/sentence levels of the hierarchy
• Utilizing family and support system for carryover
• Altering materials for visual/language impairments
• Adding additional sessions and more frequent follow-ups
Adaptations are NOT:• Altering core protocol
• Delivering fewer or shorter sessions
• Changing treatment tasks
• Eliminating core elements (target, mode, calibration)
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Adaptation Examples During Treatment• May need to spend more time shaping and modeling good voice
quality during all daily exercises and speech hierarchy exercises
• You may model shorter durations to facilitate better voice quality
• Longer rest periods between repetitions and speech hierarchy exercises
• For medial speech profile, it may be helpful to have shorter duration reps of the “ah” and break up the sequence: 5 short and loud ahs followed by 3 highs/3 lows then speaking then back to 5 short and loud and so on
• Focus on shorter functional phrases for more severe speech impairments
• May take longer for calibration to “kick in” due to cognitive changes post-DBS
• May be increased frustration due to fatigue
Adaptations: General• Repetition, repetition, repetition!!!
• Keep focus simple, even when other communication deficits are present
• Acknowledge a patient’s fatigue within treatment sessions (e.g.,
validate; longer rest periods)
• Frequent and continuous follow-up
• Delayed auditory feedback: http://www.speechvive.com/
• Altered auditory feedback: https://speecheasy.com/speecheasy-pd/?gclid=EAIaIQobChMIpL2zqoSL5QIVjSCtBh1qyAO8EAAYASAAEgLfAfD_BwE
• Augmentative device supplementation
• Pacing – alphabet board, tactile cue, clicking pen
• Additional cues – e.g. “loud and fast”; “loud and clear”
• Don’t discount successful treatment options just because the speech is severe and/or complex
• Do stimulabililty testing and a week of trial treatment
• You can be amazed at some of the outcomes
• FUNCTIONAL oral communication of any kind can dramatically improve quality of life (even ifsupplementation is required)
Give everyone a chance! Multi-disciplinary team is key!
MEDICAL TEAM
• Neurologist
• Neurosurgeon
• General practice physician
• Nurses
• CNP/PA in Neurology
• Physiatrist
• Pharmacist
• Speech therapists
• Physical therapists
• Occupational therapists
• Clinical neuropsychologist
• Social workers
• Nutritionist
Behavioral intervention is the most EFFECTIVE therapy for improving communication!
ALLIED TEAM
Recommendations
Optimize Stimulator Settings for Speech • Have a team approach with the neurologist/neurosurgeon and speech
therapist to adjust stimulation and find the best contact and voltage settings
Behavioral Speech Treatment• LSVT LOUD four weeks – gold standard
• Additional week or more (as needed)
• Additional follow-up 1-3 Months
Severe Speech Impairments from Stimulation• Trials of behavioral speech treatment
• May need addition of augmentative communication devices
Highlight future adaptations that may improve speech outcomes
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• Adaptive DBS - DBS system that uses feedback from the brain itself to fine-tune its signaling versusconstant electrical stimulation to the brain regions Little, Tripoliti, et al., 2016
• Shortening pulse width Dayal et al., 2019
• Low frequency stimulation Fabbri et al., 2019
• Combination of lower frequency, lower pulse width,and higher voltage settings Abeyeskera et al., 2019
Future potential advances to improve speech outcomes post-DBS
• Pre-treat with LSVT LOUD before DBS surgeryTripoliti “With LSVT pre we have had greatimprovement in outcomes.”
• Voice banking pre-DBS• Voice banking to preserve voice for future
augmentative device (if needed)• Voice banking as a speech hierarchy exercise if
receiving LSVT LOUD pre-DBS• https://vocalid.ai/
Future potential advances to improve speech outcomes post-DBS
Summary
• Voice and speech changes can occur following DBS surgery
• Behavioral speech treatment, such as LSVT LOUD, may improve communication post-DBS
• Adaptations can be made that facilitate and optimize positive outcomes
• Future research on adaptations to surgery, stimulationparameters or timing of behavioral treatment have thepossibility of improving speech outcomes
Questions?
1. Type your question into thechat box.
2. Raise your hand and askyour question live.
3. Email additional questions [email protected]
Upcoming Webinar
Deep Brain Stimulation and LSVT BIG: Mobility Challenges and Treatment Solutions
Wednesday, November 13, 2019
2:00 PM - 3:00 PM (EST)
Send your questions in advanceto [email protected]
Thank you!
[email protected] www.lsvtglobal.com
Please complete the survey that will launch when you close the program.
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Application of LSVT LOUD® to Individuals Post Deep Brain Stimulation: Webinar References
Abeyesekera A, Adams S, Mancinelli C, Knowles T, Gilmore G, Delrobaei M, Jog M. (2019). Effects of Deep Brain Stimulation of the Subthalamic Nucleus Settings on Voice Quality, Intensity, and Prosody in Parkinson's Disease: Preliminary Evidence for Speech Optimization. Canadian Journal of Neurological Sciences, 46(3), 287-294.
Dayal V, Grover T, Tripoliti E, Milabo C, Salazar M, Candelario-McKeown J, Athauda D, Zrinzo L, Akram H, Hariz M, Limousin P, Foltynie T. (2019). Short Versus Conventional Pulse-Width Deep Brain Stimulation in Parkinson's Disease: A Randomized Crossover Comparison. Movement Disorders. Sep 30. doi: 10.1002/mds.27863. [Epub ahead of print]
Duker AP, Espay AJ. (2013). Surgical treatment of Parkinson disease: past, present, and future. Neurology Clinics Journal, 31(3), 799-808.
Fabbri M, Zibetti M, Ferrero G, Accornero A, Guimaraes I, Rizzone MG, Romagnolo A, Ferreira JJ, Lopiano L. (2019). Is lowering stimulation frequency a feasible option for subthalamic deep brain stimulation in Parkinson's disease patients with dysarthria? Parkinsonism Related Disorders, 64, 242-248.
Freed CR, Breeze RE, Rosenberg NL, Schneck SA, Kriek E, Qi JX, Lone T, Zhang YB, Snyder JA, Wells TH, et al. (1992). Survival of implanted fetal dopamine cells and neurologic improvement 12 to 46 months after transplantation for Parkinson's disease. New England Journal of Medicine, 327(22), 1549-55.
Goberman AM. (2005). Correlation between acoustic speech characteristics and non-speech motor performance in Parkinson Disease. Medical Science Monitor, 11(3), CR109-16.
Guehl D, Cuny E, Benazzouz A, Rougier A, Tison F, Machado S, Grabot D, Gross C, Bioulac B, Burbaud P. (2006). Side-effects of subthalamic stimulation in Parkinson's disease: clinical evolution and predictive factors. European Journal of Neurology, 13(9), 963-71.
Halpern A, Spielman J, Ramig L, Gilley PM. (2010). Speech treatment for individuals with IPD post deep brain stimulation: LSVT-DBS, Movements Disorders, 25(S2), S452-S453.
Hariz M, Rehncrona S, Quinn NP, Speelman JD, Wensing C. (2008). Multicenter study on deep brain stimulation in Parkinson’s disease: an independent assessment of reported adverse events at 4 years. Movement Disorders, 15, 416-421.
Klostermann F, Ehlen F, Vesper J, Nubel K, Gross M, Marzinzik F, Curio G, Sappok T. (2008). Effects of subthalamic deep brain stimulation on dysarthrophonia in Parkinson's disease. Journal of Neurology Neurosurgery & Psychiatry, 79(5), 522-9.
Krack P, Batir A, Van Blercom N, Chabardes S, Fraix V, Ardouin C, Koudsie A, Limousin PD, Benazzouz A, LeBas JF, Benabid AL, Pollak P. (2003). Five-year follow-up of bilateral stimulation of the subthalamic nucleus in advanced Parkinson's disease. New England Journal of Medicine, 349(20), 1925-34.
Little S, Tripoliti E, Beudel M, et al. (2016). Adaptive deep brain stimulation for Parkinson’s disease demonstrates reduced speech side effects compared to conventional stimulation in the acute setting. Journal of Neurology, Neurosurgery and Psychiatry, 87, 1388-1389.
Mahlknecht P, Akram H, Georgiev D, Tripoliti E, Candelario J, Zacharia A, Zrinzo L, Hyam J, Hariz M, Foltynie T, Rothwell JC, Limousin P. (2017). Pyramidal tract activation due to subthalamic deep brain stimulation in Parkinson's disease. Movement Disorders, 32(8), 1174-1182.
Pinto S, Gentil M, Fraix V, Benabid AL, Pollak P. (2003). Bilateral subthalamic stimulation effects on oral force control in Parkinson's disease. Journal of Neurology, 250(2), 179-87.
Pinto S, Ozsancak C, Tripoliti E, Thobois S, Limousin-Dowsey P, Auzou P. (2004). Treatments for dysarthria in Parkinson's disease. Lancet Neurology, 3(9), 547-56.
(2018). Globus Pallidus Interna or Subthalamic Nucleus Deep Brain Stimulation for Parkinson Disease: A Review. JAMA Neurology, 75(3), 367-372.
Rousseaux M, Krystkowiak P, Kozlowski O, Özsancak C, Blond S, Destée A. (2004). Effects of subthalamic nucleus stimulation on parkinsonian dysarthria and speech intelligibility. Journal of Neurology, 251 (3), 327–334.
Schulz GM, Grant MK. (2000). Effects of speech therapy and pharmacologic and surgical treatments on voice and speech in Parkinson's disease: a review of the literature. Journal of Communication Disorders, 33(1), 59-88.
Spielman J, Mahler L, Halpern A, Gilley P, Klepitskaya O, Ramig L. (2011). Intensive voice treatment (LSVT®LOUD) for Parkinson's disease following deep brain stimulation of the subthalamic nucleus. Journal of Communication Disorders, 44(6), 688-700.
Skodda, S. (2012). Effect of deep brain stimulation on speech performance in Parkinson's disease. Parkinson’s Disease, 850596. doi: 10.1155/2012/850596. Epub 2012 Nov 21.
Skodda S, Grönheit W, Schlegel U, Südmeyer M, Schnitzler A, Wojtecki L. (2014). Effect of subthalamic stimulation on voice and speech in Parkinson’s disease: for the better or worse? Frontiers in Neurology, 4, 1-10.
Trail M, Fox C, Ramig LO, Sapir S, Howard J, Lai EC. (2005). Speech treatment for Parkinson's disease. NeuroRehabilitation, 20(3), 205-21.
Tripoliti E, Zrinzo L, Martinez-Torres I, Frost E, Pinto S, Foltynie T, Holl E, Petersen E, Roughton M, Hariz MI, Limousin P. (2005). Effects of subthalamic stimulation on speech of consecutive patients with Parkinson disease. Neurology, 76(1), 80-6.
Tripoliti E, Strong L, Hickey F, Foltyne T, Arinzo L, Candelario J, Hariz M, Limousin P. (2011). Treatment of dysarthria following subthalamic nucleus deep brain stimulation for Parkinson’s disease. Movement Disorders, 26(13), 2432-2436.
Tripoliti E, Limousin P, Foltynie T, Candelario J, Aviles-Olmos I, Hariz MI, Zrinzo L. (2014). Predictive factors of speech intelligibility following subthalamic nucleus stimulation in consecutive patients with Parkinson's disease. Movement Disorders, 29(4), 532-8.
Wertheimer J, Gottuso AY, Nuno M, Walton C, Duboille A, Tuchman M, Ramig L. (2014). The impact of STN deep brain stimulation on speech in individuals with Parkinson's disease: the patient's perspective. Parkinsonism Related Disorders, 20(10), 1065-70.