What’s our child’s physical system like? Considerations about structure, biology, biomechanics

K. Verdolini Abbott, Ph.D., CCC-SLP University of Pittsburgh 2010

Discussion in three parts

• (1) General developmental information • (2) Information pertinent to “indirect therapy” • (3) Information pertinent to “direct therapy” Image from http://fit.bethlin.com/wp-content/uploads/2009/04/funny-pictures-cat-is three-steps-into-an-epic-journey.jpg

Developmental issues

• Very young children (< 2 3 yr) appear to have phonotrauma infrequently Image from http://supermon.files.wordpress.com/2010/01/baby.jpg

Developmental issues

• More broadly – Babies/infants low risk – Children high risk – Adults • Males low risk • Females high risk (Percent; approximate) 8 6 4 2 0 16 14 12 10 0 to 2 2 to 3 3 to 13 15 to 60 60 to 90 males females

Developmental issues

• We will try to figure out if there are physical changes over time that might help to explain these shifts in risk (special interest is increased risk in children) • If so, maybe we can use the information to shed light on prevention and treatment of phonotrauma in children http://technology.amis.nl/blog/wp-content/images/data_miner_collage_10gr2.jpg

•

Laryngeal macrostructure (and vocal tract)

Neonatal vs adult – Pharynx short – Cricoid cartilage is high (C4) – Tip of the epiglottis is high (C1) – Approximation of epiglottis and soft palate thought to allow sucking and simultaneous respiration – Hyolaryngeal area is compact • Possible implication: Source filter interactions may vary with age; details not well studied for children. Relevance for phonotrauma???

– Age 2: Lower border of larynx descends to C5 – Age 6: Lower border of larynx descends to C6 – Age 15: Lower border of larynx descends to final position C6-7; thyroid cartilage and hyoid bone separate during descent – Epiglottis: Increases curvature until age 3, then gradually flattens • Isaacson, 1996

Laryngeal macrostructure

• Neonatal vs adult – Aryepiglottic folds thick and bulky – Arytenoids appear prominent – Glottis is 7 mm AP and 4 mm lateral – Isaacson, 1996 • Possible implication: Mostly relevant for swallowing; epiglottis squashed against the VFs in infants. Relevance for phonotrauma???

Laryngeal macrostructure

• Child vs adolescent • Prepubertal vs pubertal larynx, male and female (ages 9-18; Kahane, 1978) • Angle of the thyroid cartilage decreases in boys with age; therefore the relative posterior glottal gap is reduced, compared to the relative gap in females • Possible implication: PGG is thought to contribute to phonotrauma (e.g. Morrison & Rammage, 1993); may help explain risk of phonotrauma in children and decreased risk in adult males infants???) (but decreased risk in

Laryngeal macrostructure:

Membranous vs Cartilaginous Vocal Folds Infant vocal fold Membrane: Cartilage 1.5:1 at birth with relative growth of membranous folds Adult vocal fold Membrane: Cartilage (5.5:1 male and 4:1 female) (images courtesy Christopher Hartnick, p.c.)

Laryngeal macrostructure

• Possible implication – Reduced motor control of voice in infancy and childhood?

– Small changes in control parameters should produce large proportional changes in tissue • Possible implication – High frequency of VF vibration due to small mass of membranous folds should also

increase

the risk of phonotrauma in infants (more vibrations per unit time) – Poor control might somehow

increase

risk of injury in infancy?

Laryngeal macrostructure

• So far how are we doing in trying to find a physical basis to explain changes in risk of phonotrauma with age and gender?

• Mostly poorly.

• Batting 0.001 at best.

http://education.baseballhalloffame.org/experience/thematic_units/science/assets/Gill_ Batting.jpg

Laryngeal microstructure

• Neonatal vs adult – Hyaluronic acid (cushioning in adults): Minimal in infants. Speculatively actively produced in maculae flavae of infants from phonation (Sato et al., 2001). – Collagen: About 51% of the collagen found in adults (Hammond et al., 2000) – Elastin: About 23% of the elastin found in adults (Hammond et al., 1998) – Image from Gray, 1996 • Possible implication (especially for HLA): Less cushioning in the vocal folds in babies. Should have

higher

risk for injury.

• Batting 0.00 here.

Laryngeal microstructure

• Differentiated tri-layered structure of the lamina propria not present at birth • Gradually develops over first 17 yr of life – Monolayer --> – Bilaminar structure  – Trilaminar structure • Hartnick CJ et al. Development and maturation of the pediatric human vocal fold lamina propria. Laryngoscope. 2005 Jan; 115(1):4-15.

• Next slides courtesy C. Hartnick, p.c

.

2 day 3 year 2 month 7 year

13 year old

Laryngeal microstructure

• Possible implication: Maybe “harder striking surface” with increasing age, increasing risk of injury ?

• But what about decreased risk in adult males ? (Possibly attributable to another factor, i.e. sharp increase in hyaluronic acid .) • (Batting 0.001 again, barely?)

Laryngeal microstructure

• Neonatal vs adult, cont’d – Fibroblasts: Inactive in producing fibers in newborn. – (Speculation that fibroblasts and macula flavae may contribute to development of ligament over time.) – Hirano et al., 1999 • Possible implication: Maybe infants don’t have the biological machinery to produce a lot of fibrous tissue that are the physical basis of chronic phonotrauma.

• Batting 0.002?

Laryngeal macro- and microstructure

• Summary : – What is the physical basis for changes in risk for phonotrauma with gender and age (for now focus is decreased risk in infants and increased risk in children)? – For now we have to admire the question without a lot of good answers • Biology/biomechanics:

Infant Child C/w decreased risk in infant C/w increased risk in infant

No hard striking surface (LP) Limited capacity for fiber production High Fo Reduced cushion

Laryngeal structure

• The situation is more complex than we’d like • Biomechanically: – –

Maybe infant crying isn’t the same as adult screaming Maybe it’s relevant babies use voice less or differently than older children and adults

Laryngeal microstructure

• Aside: Much of current knowledge about laryngeal microstructure is based on pathology model in cadavers (see Hartnick) • Tissue processing concerns – Prolonged tissue fixation – Prolonged intubation pre mortem – Dessication • Functional approach to be taken in coming years with novel technology (Optical Coherence Tomography; Hartnick, p.c.; image courtesy Hartnick)

Vocal tract structure

• Dimensions increase • Formant frequencies decrease • Possible implications: Source-filter interactions may change quantitatively (NB: Such interactions affect (a) adduction; and (b) amplitude of VF vibration; see Titze) • Details not well worked out specifically for children http://users.uom.gr/~toutios/assets/vocal-tract.gif

Vocal tract/articulatory function

• Ages 1-6: Changes in coordinative relationships of articulators – Young children: Jaw predominated – Older children: Increasing independence of upper and lower lip; increasing use of lip movement for bilabial closure – Green et al., 2000; Green et al., 2002 http://www.orthodontics.org/lipbumper.jpg

Vocal tract/articulatory function

• Possible implication: Evidence is seen of increasing differentiation in motor control – Is one implication that very young children may have difficulty differentially altering voice independent of articulation, meaning we might want to manipulate both together in therapy “en bloc?” – I.e. laryngeal function might benefit from articulatory manipulations?

• http://www.speech-solutions.com/images/prompt.JPG

Respiratory structure/function

• • Decreasing compliance of rib cage Changes in general shape and orientation of rib cage • Papastamelos et al., 1995; Sharp et al., 1970 • • Toddlers – Rest breathing: • Paradoxing in inspiration (collapse of chest), probably due to high rib compliance (Gaultier et al., 1987) Toddlers to children – Rest versus speech breathing (15 mo): • Rest: Relative

synchrony

between rib and abdomen • Speech: O

ppositional (paradoxical)

breathing movement between rib and abdomen in speech – Variability: • Large intra- and intersubject

variability

(5 wk to 1 yr; 1 yr to 3 yr) » Moore et al., 2001; Boliek et al., 1996, 1997) http://www.luxfitness.com/Figures/muscles_of_the_abdomen.jpg

Respiratory function

• Toddlers and children (9 48 mo) – Increasing

independence

of rib and abdomen during speech (not rest) breathing (coupling decreased 15% over 3 yr) – Increasing

rib expansion

in speech (7% over 3 yr) – Increase in

oppositional movement

(paradoxing) of rib and abdomen, abdomen possibly decreasing dissipation of air and this limiting speech Ps (my speculation) – Changes were gradual, suggesting attribution to structural changes, not motor control changes » Moore et al., 2001; 2004 • Possible implication: With age, increased capability to limit dissipation of air during speech, and thus limit Ps – which should limit VF impact stress?

(e.g. Jiang & Titze, 1994) • Doesn’t help to explain increased risk of phonotrauma from infancy to childhood.

So far

• A tiny bit of heat and not much light

Indirect therapy

• “Voice hygiene” • Adventures in Voice hygiene differs from traditional hygiene education programs – Adventures in Voice hygiene understood as care of tissue mostly independent of phonation – Adventures in Voice hygiene program

is lean and mean:

(a) hydration; (b) exogenous inflammation control; (c) yelling and screaming – Adventures in Voice hygiene program is tailored to individual child http://www.bigmusclesbuilding.com/image-files/anabolicsteroids-1.jpg

Vocal hygiene: Dehydration (bad)

• Increases the subglottic pressure required to oscillate the vocal folds Fisher et al., 2001; Jiang et al., 2000; Titze, 1988; Verdolini-Marston et al., 1990; Verdolini et al., 1994; Verdolini et al., 2002 • May increase the risk of phonotrauma Titze, 1981 http://web.hcsps.sa.edu.au/projects/deserts/projects/group13/namib%20des ert%201.jpg

Vocal hygiene: Hydration (good)

• Reduces the subglottic pressure required to oscillate the vocal folds Jiang et al., 2000; Verdolini-Marston et al., 1990; Verdolini et al., 1994 • May diminish phonotraumatic lesions Verdolini-Marston et al., 1994 http://lomophilly.files.wordpress.com/2009/09/water-drop-a.jpg

Vocal hygiene: Inflammation (bad)

Laryngopharyngeal reflux • LPR could increase the risk of phonotraumatic lesions and other conditions (e.g. cancer; paralysis) • According to some data, effective treatment of LPR may improve vocal fold condition and voice (Koufman, 1991; Shaw et al., 1996, 1997) http://science.nayland.school.nz/SimonPa/Webpage/Year11/Acid_and_base _image/Acid_med.jpg

Vocal hygiene: Inflammation (bad)

Laryngopharyngeal reflux • However – Scary (next page) http://images.icanhascheezburger.com/completestore/2009/4/5/1288346177 68108870.jpg

Laryngoscope. 2006 Jan;116(1):144-8. Links

Empiric treatment of laryngopharyngeal reflux with proton pump inhibitors: a systematic review.

Karkos PD

,

Wilson JA

.

Department of Otolaryngology, The Freeman Hospital, Newcastle upon Tyne, UK.

OBJECTIVE: The objective of this study was to define the outcome of empiric treatment of suspected laryngopharyngeal reflux (LPR) symptoms with proton pump inhibitors (PPIs). DESIGN: The authors conducted a systematic review of the English and foreign literature. Studies that used PPIs as an empiric treatment modality for suspected LPR, whether alone or in combination with other acid suppressants and/or placebo, were included. Studies that did not include PPIs as a treatment option were excluded. MAIN OUTCOME MEASURES: A lack of common outcome measures was evident in the uncontrolled studies. In the randomized, controlled trials, outcome measures included symptom questionnaires and videolaryngoscopy. Only one study used computerized voice analysis. RESULTS: Fourteen uncontrolled studies together with one unblinded, nonrandomized study with a control group of healthy volunteers and six double-blind, placebo controlled randomized trials were identified from 1994 to 2004. Selection bias, blinding of the results, and lack of common outcome measures were some of the problems preventing a formal metaanalysis. Although uncontrolled series reported positive results, randomized, controlled trials demonstrated no statistically significant differences for changes in severity or frequency of symptoms associated with suspected reflux between PPIs and placebo. CONCLUSIONS: Recommendations for empiric treatment of suspected LPR with PPIs, by far the most common ear, nose and throat practice in the United Kingdom, are based on poor levels of evidence from uncontrolled studies. The few randomized, controlled trials have failed to demonstrate superiority of PPIs over placebo for treatment of suspected LPR.

Vocal hygiene: Inflammation (bad)

Smoking and other • Don’t do it! • Consider also other environmental issues (petrol pollution, allergies, chemicals, etc.) – E.g. Richter et al.

http://i.treehugger.com/images/2007-2-28/smoking.jpg

• Don’t do it!

Vocal hygiene:

Screaming like crazy (bad) •

Unless

you have specialized training in screaming by a knowledgeable theatre trainer (use of epiglottis as noise source; vocalization in falsetto) –

E.g. Ufema & Montequin, unpublished data

http://thepeoplebrand.com/blog/wp-content/uploads/2007/03/holler2.jpg

Vocal hygiene:

Screaming like crazy (bad) • A trick: Earplug in one ear in background noise • Increases bone conduction; you hear yourself better and don’t scream • Two earplugs even better than one (hear others’ speech better too) http://www.activevibrant.com/catalog/images/hearing/Reusable%20Ear%20 Plug%201260.jpg

Voice hygiene

• But wait!

• There’s a 64,000 lb elephant in the driveway • All of the foregoing data and observations were based on adults • Do they apply to children?

• Give it up???

Voice hygiene

• Evidence-based practice and all….

• Nooooo: There’s the principle of

first principles!

http://www.mathhelpforum.com/math-help/attachments/calculus/6661d1212778861 first-principles-calculus-1.12.jpg

Direct voice therapy

Switching gears • Voice work • Adventures in Voice differs from traditional voice work for children – Emphasis is vocal

function

rather than conservation

Biomechanics

• Basic question: Is there an ideal biomechanical set-up to optimize voice across a range of people?

Biomechanics

• What do we mean by “biomechanical set up?” – In this case we mean amount of VF adduction • What do we mean by “optimizing voice?” • Implicit goal for most people: – Intense voice – Clear voice – Limited potential for injury – Limited effort

Biomechanics

How do we operationalize these desired outcomes?

• (a.) – Voice intensity and clarity are interrelated, so we can collapse them into one variable – We can operationalize that variable as “dB • (b.) – Perpendicular VF impact stress is the factor thought most directly causal to VF injury – We can thus operationalize that variable as SI (force/area) • (c.) – A chief factor predicting vocal effort is phonatory PL – We can thus operationalize that variable as PL

Biomechanics

• Going at the issues sequentially – First question: What VF configuration (adduction) will give us the greatest ratio of dB/SI?

– Second question: What VF configuration (adduction) will give us the least PL?

– Third question: Will the ideal configuration to optimize dB/SI be similar to the configuration to minimize PL? http://www.hellowood.com/images/Steps3WR.jpg

Biomechanics

• Question approached from converging studies – Simulation – Excised – Human Berry et al., 2001 http://www.ust.ucla.edu/ustweb/Homepage_imgs/ucla_04.jpg

Biomechanics

• Methodology (excised) Jiang, J.J, Zhang, Yu, & Ford, C.N. (2003). Nonlinear dynamics of phonations in excised larynx experiments J. Acoust. Soc. Am. 114, 2198 (2003)

Biomechanics

• Results for output: excised studies

Biomechanics

• Results for output: excised + simulation studies

Biomechanics

• Results for impact stress: excised studies

Biomechanics

• Results for ratio of output/impact intensity (“vocal economy) (combined excised/simulation)

• Summary:

Biomechanics

• Vocal fold posturing yielding best ratio of output to impact intensity involves barely separated vocal folds (~0.6-0.7 mm), for conditions tested •

Precisely

replicated results for independent human study • Generally similar results expected for other fundamental frequencies, possibly with slight shifts (existing studies run with Fo ~ 155 – 196 Hz) http://www.stammeringlife.com/Images/Vocal%20Folds%20(vf)%20Opening%20and% 20Closing.JPG

Biomechanics

• Problem: We wanted best ratio of – Strong output – Limited impact

and

effort • Pick 2 out of 3???

• Nope.

Biomechanics

• PL > 2k/T B c w/2 – Titze, 1988

• Summary

Biomechanics

• Barely touching or barely separated VF posture gives us biomechanical target relevant for wide sector of population with voice disorders • Glossing over vocal tract for the moment http://www.stammeringlife.com/Images/Vocal%20Folds%20(vf)%20Opening%20and% 20Closing.JPG

Biomechanics

• As chance would have it • Performing arts, classical singing technique, “resonant voice” – produced with this general posturing – Peterson et al., 1994 – Verdolini et al., 1998 http://api.ning.com/files/vlzj-gWGwag4ns0bp0kF-GRoztWyRSrxo78oTwyb9rO3 28SsjXn5aOOtT9C0j*clTfJTE8-SiaRPWY0pByJ7xMTTK-adcrj/singer.jpg

Biomechanics

• Resonant voice • Voice produced with perceptible anterior oral vibrations, in the context of “easy” voice – Verdolini-Marston et al., 1995 – Verdolini, 2000 – Video

Biomechanics

• Link between perception and production

Complete vocal fold closure

Incomplete vocal fold closure

Biomechanics

• Summary to this point • Barely ad/abducted vocal folds optimize relation between voice output intensity (strong) and impact stress (small). Same configuration relatively minimizes vocal effort as well.

• Target configuration corresponds to percept of “resonant voice” (anterior oral vibrations, easy voice) http://www.stammeringlife.com/Images/Vocal%20Folds%20(vf)%20Opening%20and% 20Closing.JPG

• But wait!

Biomechanics

• Tentatively, no reason to think they don’t apply to children • Oops. All the foregoing data refer to

adults.

• But data are sorely lacking

Biomechanics

• Data forthcoming • Initial observations indicate the data appear to apply to children as well (D. Berry, p.c.)

Biomechanics

• But wait!

• There’s another little guy in the yard • The SI involved in resonant voice might be relatively small, but it’s still “non-zero” • Is it sufficiently small not only to hopefully help

prevent

phonotrauma, but also to help

heal existing phonotrauma?

Biology

• Stated differently: What about value of resonant voice (“tissue mobilization”) for

recovery

from injury?

http://ramanathan.files.wordpress.com/2007/12/lifesaver.jpg

Biology

• First study showed we detect (presumably) VF inflammatory mediator concentrations in vocal fold secretions 140 120 100 80 60 40 20 0 Pre

Interleukin-1beta (pg/mg protein)

2 1.5

1 0.5

0 10 Min.

Time

20 Min

Tumor Necrosis Factor-alpha (pg/mg protein)

Pre 10 Min.

Time

20 Min.

Matrix Metalloproteinase-8 (pg/mg protein)

Verdolini et al., 2003 30 25 20 15 10 5 0 Pre 20 Min 10 Min

Time

Biology

• A next study showed vocal fold mobilization in the form of “resonant voice” exercises (large-amplitude low-impact VF vibrations) reduced inflammation • (Scream study; Verdolini et al., in preparation) http://s3.hubimg.com/u/337798_f260.jpg

• Scream study

Biology

Verdolini et al., in preparation

IL-1beta

14.00

12.00

10.00

8.00

6.00

4.00

2.00

0.00

Spontaneous Speech Voice Rest

Treatment Condition

Resonant Voice

IL-6

70.00

60.00

50.00

40.00

30.00

20.00

10.00

0.00

Spontaneous Speech Voice Rest

Treatment Condition

Resonant Voice IL-1beta baseline IL-1beta post-loading IL-1 beta 4-hr post-treatment IL-1beta 24-hr post-treatment IL-6 baseline IL-6 post-loading IL-6 4-hr poast-treatment IL-6 24-hr post-treatment

MMP-8

16.00

14.00

12.00

10.00

8.00

6.00

4.00

2.00

0.00

Spontaneous Speech Voice Rest

Treatment Condition

Resonant Voice MMP-8 baseline MMP-8 post-loading MMP-8 4-hr post-treatment MMP-8 24-hr post-treatment

Biology

• Summary so far for biology of resonant voice: – Low VF impact, helping to minimize (further) tissue damage =

biological prevention factor

– Large-amplitude VF oscillations (tissue mobilization) =

biological healing factor

http://www.creatingpositivelives.co.uk/assets/Healing%20Hands%20Larger%201.jpg

Biology

• Branski et al. (2007; Best Basic Science paper,

J Voice

)

Biology

• Branski et al. (2007; cont’d)

Biology

• Li: ABM simulation in phonotrauma Based on Li et al., 2005

Biology

• One last wait!

• We‘ve talked about value of resonant voice for

acute

injury • Phases of healing – Inflammation (several days) • What about

chronic

injury, which is most of what we see?

– Protein synthesis (a few weeks) – Tissue remodelling (year or longer)  proteins align according to force vectors applied during healing

•

Question

How

do we get people to acquire the target vocal fold configuration???

• See motor learning!