Dysarthria Syndromes in Adult Cerebral Palsy

Journal of Medical Speech-Language Pathology

Volume 20, Number 4, pp. 100–105

Copyright © 2013 Delmar Cengage Learning

Dysarthria Syndromes in Adult Cerebral Palsy

Theresa Schölderle M.A., and Anja Staiger Ph.D.

Clinical Neuropsychology Research Group, Neuropsychological Clinic,

Hospital Bogenhausen München, Germany

Reneé Lampe Prof

Center for Cerebral Palsy München, Germany

Wolfram Ziegler Prof

Clinical Neuropsychology Research Group, Neuropsychological Clinic,

Hospital Bogenhausen München, Germany

Keywords: dysarthria, cerebral palsy, CP type, syndrome classification

Cerebral palsy (CP) is a neurologic disorder that results from damage to the infant brain. The

most common communication impairment in CP is dysarthria. There are inconsistent reports

of different dysarthria syndromes in the CP types (spastic, dyskinetic, and ataxic), and it

remains unclear if dysarthria syndromes of CP can be classified based on a classification

system established for dysarthrias acquired in adulthood.

Twenty-two adult patients with CP participated. Dysarthria was assessed using the

Bogenhausen Dysarthria Scales (BoDyS). Patients were further classified for their

dysarthria syndromes by three experts. The BoDyS profiles of three comparison groups of

spastic (stroke and progressive supranuclear palsy, spastic type), hyperkinetic ( Huntington’s

disease), and ataxic (hereditary ataxias) dysarthria acquired in adulthood underwent a

linear discriminant analysis. The resulting discriminant function coefficients were applied

to the BoDyS profiles of the CP participants to empirically classify their speech disorders.

The observed dysarthric patterns matched the expected syndromes of spastic, hyperkinetic,

and ataxic dysarthria. However, dysarthria syndromes dissociated with CP types in many

cases. The classification of speech impairment should therefore be conducted independently

from CP type.

INTRODUCTION

Cerebral palsy (CP) is a permanent disorder of

movement and posture caused by damage to

the infant brain (Rosenbaum, Paneth, Leviton,

Goldstein, & Bax, 2007). Besides sensory, cogni-

tive, and behavioral dysfunctions, communication

impairment frequently accompanies the motor

disorder, predominantly in the form of dysarthria

(Hunter, Pring, & Martin, 1991).

The neurologic classification of CP type is

based on the primary motor deficit affecting the

extremities. Spastic CP type accounts for 88% of

the cases; the other subtypes are dyskinetic CP

(7%) and ataxic CP (4%). This classification also

includes mixed CP types, in which the predominant

motor syndrome co-occurs with one of the other

two pathologies (Krägeloh-Mann & Cans, 2009).

It is assumed that the different underlying

pathomechanisms of motor disorders in CP types

equivalently inluence speech motor control and

correspondingly manifest in perceptually distinct

dysarthria syndromes. However, this remains

controversial (Ansel & Kent, 1992; Platt, Andrews, &

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DySARTHRIA SyNDRoMeS IN ADuLT CeReBRAL PALSy 101

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Samples were drawn from a larger collection of

speech probes covering different etiologies. These

patients were matched to the CP group by the

overall severity of dysarthria.

DYSARTHRIA ASSESSMENT

All speech samples were elicited using the

Bogenhausen Dysarthria-Scales (BoDyS; Nicola,

Ziegler, & Vogel, 2004). The BoDyS provide a

detailed profile of dysarthric symptoms on the

basis of expert ratings. Four different speech tasks

with varying cognitive and linguistic demands are

included: (1) spontaneous speech, (2) sentence

repetition, (3) reading, and (4) description of a

picture story. The four tasks are administered in

three trials each, resulting in 12 speech samples.

BoDyS offers two scoring levels, the BoDyS scales

and the BoDyS features. The BoDyS scales cover

nine important functional dimensions of speech:

respiration, pitch and loudness, voice quality, voice

stability, articulation, resonance, rate, fluency,

and modulation. each of these scales comprises a

number of BoDyS features representing speciic

dysarthric symptoms. The rate scale, for instance,

comprises the two features, slow and fast. Table 1

provides an overview of the nine BoDyS scales

and, as an illustration, two exemplary sets of

features.

each of the 12 speech samples is analyzed in a

stepwise procedure: First, the perceived features

are checked in a protocol listing the 33 BoDyS

features. Table 2 illustrates this procedure with an

example. In this case, strained-strangled voice was

Howie, 1980). To date, no systematic perceptual

classification of dysarthria syndromes in adult

patients with cerebral palsy (including mixed CP

type) has been made. It is also still unexplored

whether different dysarthria syndromes of CP,

if they occur, are comparable to the correspond-

ing dysarthria syndromes acquired in adulthood.

Because adult CP patients have a history of a

severely compromised motor speech acquisition,

their syndrome patterns could differ from the

patterns described in populations with dysarthria

acquired in adulthood after normal development.

The aims of this study were (1) to classify

dysarthria syndromes in cerebral palsy in relation

to corresponding dysarthria syndromes acquired

in adulthood and (2) to investigate if pathomecha-

nisms of motor disorder affecting the extremities

in different CP types have a comparable impact

on speech, manifesting in corresponding dysar-

thria syndromes.

METHODS

Patients

Twenty-two adult patients with a confirmed

diagnosis of CP participated in the study (18–56

years of age; 12 women and 10 men). All adult

patients who currently received regular treatment

for dysarthria at the Center for Cerebral Palsy,

Munich, Germany, were included. They were

examined for their motor deicit (i.e., CP type) by

a neurologist; patients with mixed CP type were

not excluded.

To empirically classify dysarthria in CP, there

were three comparison groups (n 5 10 each) with

dysarthria acquired in adulthood: group 1 with

spastic dysarthria diagnosed with the spastic form

of progressive supranuclear palsy1 (ages 58–80

years; three men, seven women), group 2 showing

hyperkinetic dysarthria in Huntington’s disease2

(ages 29–68 years; six men, four women),and

group 3 with ataxic dysarthria and Friedreich’s

ataxia3 (ages 16–71 years; six men, four women).

1With S. Lorenzl, Clinic for Neurology, Großhadern, Munich,

Germany and G. Mallien, Neurological Clinic Wandlitz, Germany.2With u. Mannsberger, Clinic for Psychiatry, university Graz,

Austria.3With L. Schöls, H. Ackermann, B. Brendel, Center of

Neurology, university of Tübingen, Germany.

TABLE 1. The BoDyS and the Corresponding Features

of the Scales’ Voice Quality and Fluency

Scales

(Severity, 0–4)

Features

(Frequency of Occurrence, 0–12)

Respiration

Aphonia

Breathy voice

Strained-strangled voice

Fluctuating voice quality

Pitch or loudness

Voice quality

Voice stability

Articulation

Resonance

RatePauses

IterationsFluency

Modulation

BoDyS 5 Bogenhausen Dysarthria Scales.

⎧⎪⎨⎪⎩

⎧⎨⎩

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102 JouRNAL oF MeDICAL SPeeCH-LANGuAGe PATHoLoGy, VoL. 20, No. 4


articulation, intermittent hypo or/ hypernasality,

irregular stress pattern, pitch and loudness

fluctuations, voice tremor, and strained-strangled

voice. The weighted scores of the three compari-

son groups (n 5 30) on these features underwent

a linear discriminant analysis, with the two result-

ing discriminant functions serving as syndrome

classiiers.

Expert Classification

In addition, each participant with CP was classiied

on the basis of samples of the BoDyS tasks

spontaneous speech and sentence repetition, for her

or his dysarthria syndrome by three experienced

listeners who were blinded for the patients’

neurologic diagnoses of CP type. The listeners made

their decisions on the basis of their overall impression

of the patients’ speech. The spastic, laccid, hypoki-

netic, hyperkinetic, and ataxic syndromes were rated

independently for their participation in the dys-

arthric disorder. The listeners also rated the coni-

dence of their classiications. only ratings with high

confidence scores and consistent classifications in

at least two of the three listeners were used for the

analyses. The expert classiications were compared

with the empirical classiications of dysarthria syn-

dromes and with the neurologic classiications of CP

type, which were disclosed after all data analyses

had been completed.

RESULTS

Expert Classification of the Patients

with Cerebral Palsy

Nineteen patients were classified consistently

by at least two experts with high confidence.

The classified syndromes were spastic (n 5 14),

observed in each of the speech samples ( frequency

of occurrence 5 12), and pauses were observed in

eight samples (frequency of occurrence 5 8); the

other features were not observed.

Second, the degree of impairment is scored for

each of the nine BoDyS scales using a 5-point

rating from 0 5 “very severe impairment” to

4 5 “no impairment.” These severity ratings of the

BoDyS scales do not necessarily reflect the fre-

quency of occurrence of the corresponding BoDyS

features. For example, even if strained-strangled

voice can be observed constantly in every speech

sample (frequency of occurrence 5 12; see earlier

example), it can still occur in a mild form with the

average severity of the corresponding voice qual-

ity scale ranging around 3 (“mild impairment”).

For the purpose of this study, we used weighted

features as a measure. Therefore, relative frequen-

cies of occurrence of the BoDyS features (ranging

from 0 5 “not observed” to 1 5 “observed in each

of the 12 samples”) were weighted by the severity

ratings of the corresponding BoDyS scales to

obtain severity scores for all features.4 In the

earlier example, strained-strangled voice has

a weighted score of 1 (relative frequency of

occurrence [1], multiplied with the reverse voice

quality score of 4 – 3 5 1). The weighted features

were used in the analyses reported here.

Classification by Discriminant Functions

To develop an empirically based classiication of the

CP participants, eight of the BoDyS features with

the highest potential to differentiate the expected

dysarthria syndromes (spastic, hyperkinetic, ataxic)

were selected based on common descriptions of the

syndromes. The selected features were involuntary

vocalizations, luctuating voice quality, luctuating

TABLE 2. example of a BoDyS Protocol Including Voice Quality and Fluency Features

Scales Features Frequency of Occurrence (1–12)

Voice quality Aphonia

Breathy voice

Strained-strangled voice X X X X X X X X X X X X

Fluctuating voice quality

Fluency Pauses X X X X X X X X

Iterations

BoDyS 5 Bogenhausen Dysarthria Scales.

4Severity scales had to be reversed in these weightings.

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were stronger and more frequent in hyperkinetic

dysarthria.

Classification of the Patients with Cerebral

Palsy by Discriminant Functions

The discriminant function coeficients were then

applied to the BoDyS features of the CP partici-

pants to empirically map their dysarthria syn-

dromes onto the patterns of the three comparison

groups. The results of the classiication are shown

in Figure 2. A total of 86% (19 of the 22 patients)

were assigned to one of the three groups of dysar-

thria syndromes with a probability greater than

90%. The remaining three patients could not be

classified definitely; they were assigned to one

dysarthria syndrome with a probability less than

80% and to another with greater than 10% prob-

ability. Among the 19 patients classified with a

probability greater than 90%, 10 matched the pat-

tern of spastic dysarthria, six were allocated to

the ataxic group, and three were allocated to the

hyperkinetic group.

Comparison of Expert and Statistical

Classification of Patients with Cerebral Palsy

Sixteen patients were classified definitely by

both the expert ratings (high confidence scores

and agreement in at least two listeners) and the

hyperkinetic (n 5 3), and ataxic (n 5 1), and

one patient was diagnosed with mixed spastic-

hyperkinetic-ataxic dysarthria.

Statistical Reclassification of

the Comparison Groups

In a linear discriminant analysis, 93% of the

patients of the comparison groups were reclassiied

correctly; only two patients with HD were misclas-

siied as having ataxic dysarthria. Among the two

discriminant functions, the irst loaded highest on

the BoDyS features strained-strangled voice, luc-

tuating voice quality, and luctuating articulation

and showed a signiicant canonical correlation of

r 5 0.92 (P < .001). By this discriminant function,

the spastic group was separated from the other two

groups (Figure 1). Whereas the spastic patients

scored high on the feature strained-strangled

voice, the hyperkinetic and ataxic groups scored

high on luctuating voice quality and luctuating

articulation. Regarding the second discriminant

function fluctuating voice quality, fluctuating

articulation and involuntary vocalizations attained

high loadings (canonical correlation r 5 0.69;

P 5 0.01). This function differentiated between

hyperkinetic dysarthria and ataxic dysarthria

(see Figure 1). Whereas luctuating voice quality

and luctuating articulation received higher scores

in the ataxic group, involuntary vocalizations

Spastic

Ataxic

Hyperkinetic

Discriminant function I

Discrim

inant function II

–4 –2 420

–4

–2

0

4

2

6

–6

HD

PSP

FA

Figure 1. Reclassification of the comparison groups by

a linear discriminant analysis. FA 5 Friedreich’s ataxia;

HD 5 Huntington’s disease; PSP 5 progressive supra-

nuclear palsy.

Spastic

Ataxic

Hyperkinetic


Discrim

inant function II

–4 –2 0 42

–4

–2

0

4

2

6

–6

Comparison

groups

CP

Figure 2. Classification of the patients with cerebral

palsy (CP) by discriminant analysis.

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104 JouRNAL oF MeDICAL SPeeCH-LANGuAGe PATHoLoGy, VoL. 20, No. 4


neurologic classiications of CP types agreed in 13 of

the 19 cases. In six patients (three spastic, one dys-

kinetic, one ataxic, and one mixed spastic-dyskinetic

CP type), the dysarthria syndrome did not it with

the CP type (Figure 3). In four of these six cases, the

statistical classiication of the dysarthria syndrome

was in agreement with expert ratings. The two

other cases, both classiied as ataxic dysarthria by

the discriminant analysis, were also rated as ataxic

by the experts yet with low conidence scores.

discriminant analysis (probability .90%). In 13

(81%) of these patients, the two classifications

were consistent.

Comparison of Statistical Classification

of Dysarthria with Cerebral Palsy Type

The classiications of dysarthria syndromes based

on the discriminant analysis (including only

patients classiied with a probability .90%) and the

Spastic

Ataxic

Hyperkinetic


Discrim

inant function II

–4 –2 420 0

–4

–2

0

4

2

6

–6

*

Spastic

Ataxic

Hyperkinetic


Discrim

inant function II

–4 –2 42

–4

–2

0

4

2

6

–6

*


Discrim

inant function II

–4 –2 420

–4

–2

0

4

2

6

–6

Spastic

Ataxic

Hyperkinetic

*

Spastic

Ataxic

Hyperkinetic


Discrim

inant function II

–4 –2 420

–4

–2

0

4

2

6

–6

*

*

*

Spastic CP type

Ataxic CP type

Dyskinetic CP type

Spastic-dyskinetic

CP type

Figure 3. Classification of dysarthria syndromes (by discriminant analysis) as a function of cere-

bral palsy (CP) type; dissociations are marked with asterisks.

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Address Correspondence to Theresa Schölderle, M. A.,

Entwicklungsgruppe Klinische Neuropsychologie Dachauer

Str 164 80992, Muenchen, Germany, PHONE: 149 89

154057, FAX: 149 89 156781

e-mail: [email protected]

REFERENCES

Ansel, B. M., & Kent, R. D. (1992). Acoustic-phonetic

contrasts and intelligibility in the dysarthria

associated with mixed cerebral palsy. Journal of

Speech and Hearing Research, 35, 296–308.

Hunter, L., Pring, T., & Martin, S. (1991). The use of

strategies to increase speech intelligibility in cerebral

palsy: An experimental evaluation. International

Journal of Language & Communication Disorders,

26, 163–174.

Krägeloh-Mann, I., & Cans, C. (2009). Cerebral palsy

update. Brain & Development, 31, 537–544.

Nicola, F., Ziegler, W., & Vogel, M. (2004). Die

Bogenhausener Dysarthrieskalen (BoDyS): ein

Instrument für die klinische Dysarthriediagnostik.

Forum Logopädie, 2/18, 14–22.

Platt, L. J., Andrews, G., & Howie, P. M. (1980).

Dysarthria of adult cerebral palsy: II. Phonemic

analysis of articulation errors. Journal of Speech

and Hearing Research, 23, 41–55.

Rosenbaum, P., Paneth, N., Leviton, A., Goldstein, M., &

Bax, M. (2007). A report: the definition and

classification of cerebral palsy. Developmental

Medicine & Child Neurology, 109, 8–14.

DISCUSSION

Dysarthria in CP can be classiied based on pat-

terns of symptoms similar to dysarthrias acquired

in adulthood. The observed symptoms matched

the predicted dysarthria syndromes (spastic, hy-

perkinetic, ataxic), and the features included in

the two discriminant functions corresponded to

expectations (e.g., strained-strangled voice as an

indicator of spastic dysarthria). The patient clas-

sification obtained in the discriminant analysis

was also conirmed by expert ratings in the major-

ity of cases.

There were dissociations between dysarthria

syndromes and CP types. Accordingly, dysarthria

syndromes do not allow conclusions regarding the

pathomechanisms underlying the motor disorder

of the extremities. This might be attributable to

varying inluences of complex motor pathomecha-

nisms on body and speech motor function or may

indicate compensatory adaptation in speech. As-

sessment of dysarthria in cerebral palsy should

therefore consider aspects beyond syndrome clas-

sification such as functional mechanisms and

communication impairment.

Acknowledgment The irst author was supported

by a PhD fellowship from the German National

Academic Foundation. We would like to thank the

speech-language-therapists at the Center for Cerebral

palsy, München and are grateful to all the participants

of the study. We also thank the ReHa-Hilfe e.V. for their

support.

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Dysarthria Syndromes in Adult Cerebral Palsy

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