J Neurosurg 48:876-882, 1978
Effects on speech of chronic cerebellar stimulation in cerebral palsy DAVID L. RATUSNIK, P H . D . , VIRGINIA I. WOLFE, P H . D . , RICHARD D. PENN, M . D . , AND SHEILA SCHEWITZ, M . S .
Departments of Otolaryngology and Bronchoesophagology (Section of Communicative Disorders) and Neurosurgery, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois Chronic cerebellar stimulation of the anterior lobe is undertaken for relief of motor dysfunction in cerebral palsy, but the effect on speech and vocal ability has been uncertain. The present study evaluated speech before cerebellar stimulation and during the immediate postoperative period in seven severely spastic/athetoid patients with congenital cerebral palsy and one patient with traumatic brain damage. Structured listening tasks were completed in blind fashion by a trained panel of speech pathologists. Group analysis revealed no significant improvement in speech intelligibility or articulatory accuracy after stimulation. With the exception of strain/strangle vocal quality, which improved considerably, vocal characteristics were not affected by cerebellar stimulation. In three of eight patients, however, improvement in certain speech characteristics was noted. KEY WORDS
speech
T
9 cerebellar stimulation
9 voice
RADITIONALLY, disordered speech and voice characteristics of patients with cerebral palsy have been treated by speech and language pathologists. Unfortunately, intervention techniques designed to facilitate oral ~,~,~8-~5,2',25,~7 or nonverbal means 1,6,6,1~176 of communication have met with little success. This is particularly true for oral communication in the patient with severe neuromuscular involvement. Recent reports suggesting that speech is improved by chronic cerebellar stimulation of the anterior lobe deserve close attention. Altering the neurophysiological substrate for speech production through electrical means constitutes a new and radically different mode of treatment. To 9 date only one study ~ and two anecdotal 876
9 cerebral palsy
9 spasticity
9 cerebellum
accounts 1~,2a provide data to support the claim that patients speak more clearly and are less dysarthric after cerebellar stimulation. The report of Cooper, et al.2 suggested that 12 of 25 patients with speech impairment showed " m i l d " to " m o d e r a t e " improvement following stimulation (p. 749), and that dysarthria decreased as judged by patients and families. Other than "ease of speech production" (p. 752), which is difficult to measure, specific speech characteristics, such as articulatory proficiency, pitch control, rate of speech, and voice quality, were not reported. In 1963, Rosentha121 showed conclusively that the unintended influence of the experimenter can determine the outcome of such studies. T o avoid this pitfall, a blind study of patients with cerebellar implants was J. Neurosurg. / Volume 48 / June, 1978
9
Cerebellar stimulation and speech TABLE 1 Clinical data for eight cerebellar stimulation patients at time of surgery Case No.
Sex, Age (yrs)
Cognitive Ability
Preop Speech Proficiency
Type of Neuromuscular Involvement
1
M, 16
normal
2
F, 23
traumatic brain damage, subdural hematoma, left spastic hemiparesis mixed spastic/athetoid quadriplegia
3
F, 15
mild mental retardation normal
4
F, 24
normal
5
F, 11
normal
6
M. 13
normal
7
M, 21
8
M, 30
educable, mentally retarded normal
above group median below group median far above group median below group median above group median below group median far below group median median for group
undertaken. Trained listeners were used to evaluate audio tapes taken before and after chronic cerebellar stimulation.
Clinical Materials and Methods Patient Selection Eight patients, four m a l e s and four females, with severe spastic/athetoid neuromuscular involvement were studied (Table 1). They ranged in age from 11 to 30 years. N o n e was ambulatory, and speech abnormality ranged from m o d e r a t e to severe, secondary to dysarthria. Significantly impaired m o t o r function and relatively n o r m a l intellectual ability characterized t h e group. All patients were from homes in which standard English was spoken. Patients had had extensive speech and physical t h e r a p y with little progress in the last few y e a r s before cerebellar stimulation. Cerebellar stimulation of the anterior lobe was p e r f o r m e d by surgical implantation at our hospital of two sets of platinum electrodes on Silastic sheets via a suboccipital craniotomy. The surgical procedure has been described previously, is T a p e recordings of patients' speech were made in a quiet r o o m on either a Revox Model 77A or Wollensak M o d e l 1500 audio recorder, using a Shure Model S M 10 dynamic microphone maintained at a constant distance (2 inches) f r o m the lips by means of a head holder. J. Neurosurg. / Volume 48 / J u n e , 1978
spastic diplegia severe mixed spastie/athetoid quadriplegia spastic quadriplegia severe mixed spastic/athetoid quadriplegia mixed spastic/athetoid quadriplegia severe mixed spastic/athetoid quadriplegia
Speech S t i m u l i and Elicitation Fourteen speech and voice characteristics were evaluated pre- and postoperatively. The speech c h a r a c t e r i s t i c s assessed were: 1) p e r c e n t a g e intelligibility of w o r d s and sentences, and 2) total words and sentences correctly identified in their entireties. When words were almost correct yet contained an error on one or m o r e speech sounds, a distinctive feature analysis was carried out. W o r d level articulatory proficiency was analyzed according to errors in place of articulation, m a n n e r of a r t i c u l a t i o n , and voicing or nasal/oral articulatory confusion. Furthermore, while m a n y sentence level productions were not completely correct, a satisfactory degree o f accuracy was often apparent. In these instances, sentences were scored according to the n u m b e r of morphemes* judged correct. 3) Voice characteristics assessed on both word and sentence levels included presence of strain/strangle quality, hoarse quality, nasal quality, or vocal clarity. 4) The pitch o f a patients' voice was judged as either within normal limits, too high, or too low. Likewise, *A morpheme is the smallest meaningful unit of language. For example, the word feed (see Table 2) is a morpheme, while the third person singular form s is also a morpheme when used in the word feeds. Free morphemes (e.g., feed) stand on their own while bound morphemes (e.g., s) must be used in conjunction with a free form to be meaningful. 877
D. L. Ratusnik, V. I. Wolfe, R. D. Penn and S. Schewitz TABLE 2 Speech elicitation task words and sentences* Word Level Stimuli 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.
cheese feet chicken fish baby cake bed dress basket black butterfly button
Sentence Level Stimuli 1. 2. 3. 4. 5. 6.
She feeds the three geese. Give Dick the tin dish. James ate the cake. Ted spent ten cents for eggs. The black cat sat on the hat. Run and get some butter.
Morphemes 6 5 4 7 7 5
*Words and sentences chosen from The Phonetic Inventory.8 Speech elicitation stimuli were chosen for representative distribution of speech sound content. The morphemes noted using Brown's criteria)
pitch variation was judged to be within normal limits, too much, or too little. Speech samples were recorded within 2 days before i m p l a n t a t i o n of cerebellar stimulators, and within 1 to 3 months after the surgical procedure. Speech repetition was accomplished by patients in response to presentation of 12 words and six sentences (Table 2). Listeners and Listening Tasks
The patients' productions of words and sentences were evaluated by six graduate speech and language clinicians in structured listening tasks. Twelve word and six sentence p r o d u c t i o n s r e c o r d e d before and after cerebellar stimulation were dubbed in a random order onto master tapes. ~6 Listeners evaluated pre- and postoperative word and sentence samples presented in a blind fashion. Two listening tasks were presented. In the first, the Intelligibility T a s k , listeners were instructed to " W r i t e the word (or sentence) which you hear." The number of words or sentences identified 100% correctly were computed from these responses. During the second task, the Degree of Accuracy Task, the same recordings were presented and samples were evaluated on the basis of articulatory accuracy using a 10-point scale (0 to 100% accuracy). Additionally, judgments of pitch and voice quality were made as listeners indicated whether each sample was clear, strained, hoarse, or nasal; whether pitch level was within normal limits, too high, or too low; 878
and whether pitch variation was within normal limits, too little, or too much. C o m p l e t i o n of the listening tasks required 3 hours. The judgments of the six listeners possessed a high degree of agreement or reliability 7 for words (.80) and sentences (.80). The p r i m a r y goal of study was to determine the effect of cerebellar stimulation on speech and vocal ability in patients with severe spastic/athetoid neuromuscular involvement and speech impairment. W e were also c o n c e r n e d with the feasibility of preoperative prediction of speech and vocal change expected from cerebellar stimulation. Results Initially, the listeners' judgments were analyzed in grouped fashion, c o m p a r i n g perf o r m a n c e b e f o r e to p e r f o r m a n c e a f t e r cerebellar stimulation; t-tests for correlated samples were computed for 12 speech or voice characteristics for words and sentences with mean length of utterance ( M L U ) examined as a sentence level measure, and distinctive feature errors examined in words. A single comparison, strain/strangle voice quality, achieved significance (t = 5.06; df = 7; p = < 0.001). After cerebellar stimulation patients were j u d g e d to use fewer strain/strangle utterances in words. Although speech characteristics, that is, j u d g m e n t s of overall intelligibility, word or sentence identification, m e a n length of utterance, and distinctive feature errors, did not i m p r o v e significantly after cerebellar stimulation, small improvements were noted J. Neurosurg. / Volume 48 / June, 1978
Cerebellar stimulation and speech lar STimulation
Cerebel I I I I
7 F-Is_if) o~: 6
(6.54) ~ (5.94)
~-w
l
e
'
~
Pitch level too I
. o
_ ~
i
(5.46) (4.95) Nasality . pitch variation WNL I (481) Pitch ~evel WNL I (4.45) I I I I I
I.L (.) O0 n~> 3 I.l.I L9 mz
~
(5.79) (575)(~.551. 1525)i5.08 )
(4.90)*
(2.96)
(2.27) ~ (2.08)
z w 2
(I.45) Clear (1.15) _Pitchvariation too much *improved
performance
following
I I I
(I.52)*
(,. ~o)*~
-- (0.89)"
cerebellar stimulation I
PREOPERATIVE L E V E L
POSTOPERATIVE L E V E L
FIG. 1. Summary of the pre- and postoperative speech data for words. WNL = within normal limits. for each characteristic postoperatively. For the group, word (47.96% to 49.80%) and sentence (61.11% to 61.39%) intelligibility improved approximately 2%, words identified (4.16 to 4.50) and sentences identified correctly (2.02 to 2.42) improved by approximately 1%, mean length of utterance of sentences (2.79 to 2.89) improved marginally, while distinctive feature errors (16.71 to 15.94) decreased by approximately 1%. Figures 1 and 2 display the average voice judgments before and after cerebellar stimulation for eight patients for words and six patients for sentences. Sentence level elicitation was not accomplished from Cases 2 and 7 due to the severity of oral neuromuscular involvement. Depending upon the speech or vocal characteristic, improvement (designated by an asterisk in Figs. 1 and 2) is reflected by an increase or a decrease in preponderance of the characteristic. While not to be overemphasized, the trend of changes in mean score may be interpreted as suggesting small voice improvement after J. Neurosurg. / Volume 48 / June, 1978
stimulation. An even split in direction of difference score would be expected purely by chance. That is, of l0 pre- and postoperative comparisons five should improve postoperatively whether or not cerebellar stimulation is effective. For word and sentence level voice characteristics, blind evaluation of seven parameters indicated improvement, although minimally in numerous instances. Figure 1 highlights the significant decrease in strain/strangle vocal quality, improvement in pitch level and variation, and the substantial decrease in words judged too high in pitch. Hoarseness seemed to increase after cerebellar stimulation. Figure 2 displays less change in vocal ability for sentences. While strain/strangle quality lessened postoperatively and nasality apparently increased, no other voice changes were striking after cerebellar stimulation. Again, these speech and voice comparisons were not statistically real effects, with the exception of the strain/strangle comparison, but taken together as an overall characteriza879
D. L. Ratusnik, V. I. Wolfe, R. D. Penn and S. Schewitz Cerebel Ior
Stimulation
I I I I *improved performonce following cerebellor stimulotion
A
u_(.)
or_.
::3E: 6 ol..u o3O (4.47) Pitch voriotion too little
z J4 o3o
(380) ~ (3.08)
(2.66) No_sotity
~~ w 2
(I.97) Pitc_hlevel WNL
(3O0)
(2.80)*
(2 30)* (194)*
(I.55)
z(~
Uj n
(3.36)*
Pijch level too low
n-(.9 LuZ
m~
(402)*
e
I
(I.02) Hoar..__seness
(t.oo) - - - - - - - -
(0.52) Cleor (0.02) Pitch voriotion too much PREOPERATIVE L E V E L
~
I I I I
{0.84)*
~
(0.80)*
(0.47) (0.02)
POSTOPERATIVE L E V E L
FIG. 2. Summary of the pre- and postoperative speech data for sentences. WNL = within normal limits.
tion of verbal behavior, seem to suggest minimal improvement following cerebellar stimulation. Individual patient performance before and after cerebellar stimulation was evaluated for each speech and vocal characteristic with criterion for change set at a difference score (pre- to postoperative levels) level of 5% intelligibility or five words/sentences possessing the speech/voice quality. Of eight patients presenting moderate-tosevere neuromuscular involvement, comparison of listeners' evaluations before and after stimulation revealed improvement for three patients (Cases 1, 3, and 7). Minimal improvement or no change was evident for three patients (Cases 2, 4, and 8). On the other hand, the evaluation for the patients in Cases 5 and 6 was negatively affected after cerebellar stimulation. Although these results are based only on eight patients, it should be noted that approximately 50% failed to improve after stimulation, while 25% actually 880
performed more poorly. The following section reviews the speech and vocal success of three patients changing favorably over the course of cerebellar stimulation. Although he possessed a severe speech impairment, the patient in Case 1 was well above the median for the group. Improvement was noted for nine of 13 word and 10 of 13 sentence level speech and voice characteristics after cerebellar stimulation. Of major importance for communication, intelligibility improved 6.67% in words and 14.73% in sentences, and 13 more words and two more sentences were judged correct after stimulation. Furthermore, the decrease in the number of distinctive features in error (-9.48) and the increase in mean length of utterance (1.09) probably contributed to an improvement in communication for this patient. Marked improvements in vocal characteristics were also noted, as strain quality on word and sentence items decreased after cerebellar stimulation and instances of J. Neurosurg. / Volume 48 / June, 1978
Cerebellar stimulation and speech ranged from moderate impairment for Cases 1 and 3 (both above the group median) to severe impairment for Case 7 (far below median) preoperatively. Speech and vocal performance varied for the three patients after cerebellar stimulation as well. In short, no predictive factors were found that might guide the neurosurgeon in counseling the patient or family regarding the potential for speech improvement following cerebellar stimulation. Cerebellar stimulation apparently facilitates speech ability in patients with a wide range of preoperative abilities. Rather than using perceptual speech data, objective evaluation of anatomical structure and physiological support for speech may offer more useful information for predicting speech and vocal improvement preoperatively. Detailed evaluation of postural tone, trunk support, and air flow measurement may aid in assessing the potential for speech change. For example, the significant decrease in observed strain/strangle quality may have resulted from increased control of proximal musculature due to stimulation. A more upright sitting posture with erect head position after stimulation would also contribute to increased air intake and longer periods of sustained phonation and intraoral breath pressure. If cerebellar stimulation has a positive effect on particular muscle groups, detailed physical and electromusculature evaluation may be indicated to help in judging potential speech improvement. Cerebellar stimulation may also improve nonverbal communication if gains are achieved in distal muscle function. For example, a decrease in primitive reflexes such as the asymmetrical tonic neck reflex and/or improved arm and wrist function could allow access to a communication board or alternative nonverbal means. The quality of life has been enhanced for many children with cerebral palsy through use of manual symbol systems, so this avenue must not be overlooked. The relatively small improvement in speech intelligibility and vocal quality may seem trivial in the three patients. However, even minimal gains may translate into improved Discussion communication in subtle ways. While one Improvement of speech and vocal patient realizes improved speaking ability characteristics was observed after stimula- from only moderately involved preoperative tion in three of eight patients (Cases 1, 3, and levels and may not realize an effect on com7). As shown in Table 1 speech intelligibility munication, a minor increase in a severely and vocal ability in these three patients dysarthric or essentially nonverbal individual 881 J. Neurosurg. / Volume 48 / June, 1978
normal pitch usage and variation increased. The only negative feature to emerge postoperatively was increased nasality. This was not an uncommon finding, as other patients showed limited difficulty in controlling nasality after stimulation. The initial clinical impression was that cerebellar stimulation had had a positive effect on speech and vocal ability. After cerebellar stimulation, the patient in Case 3 possessed the most intelligible speech of the group in words (81.50% intelligible) and sentences (89.44% intelligible). Although she was functioning at moderately impaired speech levels, both intelligibility and voice characteristics improved after cerebellar stimulation. In particular, substantial vocal improvement for word and sentence judgments was noted as pitch level and pitch variation more closely approximated normal limits and fewer instances of monotone (too little pitch variation) productions were observed in sentences. There were fewer nasal words and fewer sentences judged to be strained postoperatively. Also, her mean length of utterance for sentences increased by approximately one morpheme. The initial clinical impression was that cerebellar stimulation had had a positive effect on speech and vocal ability. The patient in Case 7 exhibited the most severely impaired speech and vocal function; a negligible portion of words were intelligible and sentence elicitation was not possible. However, after cerebellar stimulation an improvement in word intelligibility (5.55%) and a decrease in distinctive feature errors were evidenced. While no words were intelligible preoperatively, six were understandable after cerebellar stimulation. Decreased strain and hoarse vocal quality were noted after stimulation. The only negative finding was increased nasal production after cerebellar stimulation. The initial clinical impression was that this patient's speech and vocal ability improved after stimulation. His severely impaired preoperative speech and vocal ability make the improvement for Case 7 the most dramatic of the group.
D. L. Ratusnik, V. I. Wolfe, R. D. Penn and S. Schewitz may generate an entirely different outlook on the communicative process. After stimulation a desire to attempt more oral communication, a change in communicative strategy, and a desire to engage more fully in the therapeutic process m a y ensue. Feffer and Suchotliff ~ defined effective communicators as those who are aware of how they are both perceived by and understood by others. The present study was directed toward the last feature of communication, and therefore was not structured to determine the effectiveness of cerebellar stimulation on the entire communication process. We were unable to assess objectively the importance of increases in speech and vocal proficiency on communication itself. The present study can be considered a stepping-off point, as it concerns perceptual evaluation of word and sentence level intelligibility and vocal characteristics. Long-term follow-up studies are needed, as well as an evaluation of the effect of speech therapy on these patients postoperatively.
Acknowledgments
12. 13. 14. 15. 16.
17.
18. 19. 20.
Aid in manuscript preparation from Carol Melnick Ratusnik, M.A., and Lionel Schewitz, M.D., is gratefully acknowledged.
References 1. Bliss C: Semantography (Biissymbolics), ed 2. Sidney: Semantography (Blissymbolics) Publications, 1965 2. Blumberg ML: Respiration and speech in the cerebral palsied child. Am J Dis Child 89:48-53, 1955 3. Brown R: A First Language: The Early Stages. Cambridge: Harvard University Press, 1973 4. Cooper IS, Riklan M, Amin I, et al: Chronic cerebellar stimulation in cerebral palsy. Neurology 26:744-753, 1976 5. Cruikshank W: Cerebral Palsy. Syracuse: Syracuse University Press, 1976 6. Dixon C, Curry B: Some thoughts on the communication board. Cerebral Palsy J 26:12-13, 1965 7. Ebel R: Estimation of reliability of ratings. Psychometrika 16:407-424, 1951 8. Fairbanks G: Voice and Articulation Drill Book. New York: Harper and Brothers, 1960 9. Feffer M, Suchotliff L: Decentering implications of social interactions. J Pers Soc Psychol 4:415-422, 1966 10. Hagen C, Porter W, Brink J: Nonverbal communication: an alternate mode of communication for the child with severe cerebral palsy. J Speech Hear Dis 38:448--455, 1973 11. McDonald ET: Articulation Testing and
882
21.
22. 23. 24.
25.
26. 27.
Treatment: A Sensory Motor Approach. Pittsburg: Stanwix House, 1964 McDonald E, Schultz AR: Communication boards for cerebral-palsied children. J Speech Hear Dis 38:73-88, 1973 Mysak ED: Organismic development of oral language. J Speech Hear Dis 26:377-384, 1961 Mysak ED: Principles of Reflex Therapy Approach to Cerebral Palsy. New York: Teachers College of Columbia University, 1963 Mysak ED: Significance of neurophysiological orientation to cerebral palsy habilitation. J Speech Hear Dis 24:221-230, 1959 Ontario Crippled Children's Centre Bliss Project Team: Symbol Communication Research Project: 1972-1973. Toronto: Ontario Crippled Children's Centre, 1973 Ontario Crippled Children's Centre Bliss Project Team: Symbol Communication Research Project: 1974. Toronto: Ontario Crippled Children's Centre, 1974 Penn R, Etzel ML: Chronic cerebellar stimulation and developmental reflexes. J Neurosurg 46:506-511, 1977 Richman E: Brain amps for relief of spasms exceed hopes. Med Trib 18:1-12, 1977 Rom P: Developing adjunctive communication techniques and aids for preschool cerebral palsied children. Presented at National Easter Seal Society Convention, Chicago, November 1976 Rosenthal R: On the social psychology of the psychological experiment: the experimenter's hypothesis as unintended determinant of experimental results. Am Sci 51:268-283, 1963 Sayre J: Communication for the non-verbal cerebral palsied. Cerebral Palsy Rev 24:3-8, 1963 Simon R: Delbert gets a brain pacemaker - and a dream is coming true. Today's Health, 1975, pp 18-52 (November) Westlake H: A System for Developing Speech With Cerebral Palsied Children. Chicago: National Society for Crippled Children and Adults, 1951 Westlake H, Rutherford D: Speech Therapy for the Cerebral Palsied. Chicago: National Society for Crippled Children and Adults, 1961 Winer BJ: Statistical Principles in Experimental Design. New York: McGraw-Hill, 1971 Young E: The moto-kinesthetic method as applied to the cerebral palsied. Cerebral Palsy Rev 23:7-8, 1962
Address reprint requests to." David L. Ratusnik, Ph.D., Department of Otolaryngology and Bronchoesophagology (Section Communicative Disorders), Rush-Presbyterian-St. Luke's Medical Center, 1753 West Congress Parkway, Chicago, Illinois 60612. J. Neurosurg. / Volume 48 / June, 1978
Effects on speech of chronic cerebellar stimulation in cerebral palsy DAVID L. RATUSNIK, P H . D . , VIRGINIA I. WOLFE, P H . D . , RICHARD D. PENN, M . D . , AND SHEILA SCHEWITZ, M . S .
Departments of Otolaryngology and Bronchoesophagology (Section of Communicative Disorders) and Neurosurgery, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois Chronic cerebellar stimulation of the anterior lobe is undertaken for relief of motor dysfunction in cerebral palsy, but the effect on speech and vocal ability has been uncertain. The present study evaluated speech before cerebellar stimulation and during the immediate postoperative period in seven severely spastic/athetoid patients with congenital cerebral palsy and one patient with traumatic brain damage. Structured listening tasks were completed in blind fashion by a trained panel of speech pathologists. Group analysis revealed no significant improvement in speech intelligibility or articulatory accuracy after stimulation. With the exception of strain/strangle vocal quality, which improved considerably, vocal characteristics were not affected by cerebellar stimulation. In three of eight patients, however, improvement in certain speech characteristics was noted. KEY WORDS
speech
T
9 cerebellar stimulation
9 voice
RADITIONALLY, disordered speech and voice characteristics of patients with cerebral palsy have been treated by speech and language pathologists. Unfortunately, intervention techniques designed to facilitate oral ~,~,~8-~5,2',25,~7 or nonverbal means 1,6,6,1~176 of communication have met with little success. This is particularly true for oral communication in the patient with severe neuromuscular involvement. Recent reports suggesting that speech is improved by chronic cerebellar stimulation of the anterior lobe deserve close attention. Altering the neurophysiological substrate for speech production through electrical means constitutes a new and radically different mode of treatment. To 9 date only one study ~ and two anecdotal 876
9 cerebral palsy
9 spasticity
9 cerebellum
accounts 1~,2a provide data to support the claim that patients speak more clearly and are less dysarthric after cerebellar stimulation. The report of Cooper, et al.2 suggested that 12 of 25 patients with speech impairment showed " m i l d " to " m o d e r a t e " improvement following stimulation (p. 749), and that dysarthria decreased as judged by patients and families. Other than "ease of speech production" (p. 752), which is difficult to measure, specific speech characteristics, such as articulatory proficiency, pitch control, rate of speech, and voice quality, were not reported. In 1963, Rosentha121 showed conclusively that the unintended influence of the experimenter can determine the outcome of such studies. T o avoid this pitfall, a blind study of patients with cerebellar implants was J. Neurosurg. / Volume 48 / June, 1978
9
Cerebellar stimulation and speech TABLE 1 Clinical data for eight cerebellar stimulation patients at time of surgery Case No.
Sex, Age (yrs)
Cognitive Ability
Preop Speech Proficiency
Type of Neuromuscular Involvement
1
M, 16
normal
2
F, 23
traumatic brain damage, subdural hematoma, left spastic hemiparesis mixed spastic/athetoid quadriplegia
3
F, 15
mild mental retardation normal
4
F, 24
normal
5
F, 11
normal
6
M. 13
normal
7
M, 21
8
M, 30
educable, mentally retarded normal
above group median below group median far above group median below group median above group median below group median far below group median median for group
undertaken. Trained listeners were used to evaluate audio tapes taken before and after chronic cerebellar stimulation.
Clinical Materials and Methods Patient Selection Eight patients, four m a l e s and four females, with severe spastic/athetoid neuromuscular involvement were studied (Table 1). They ranged in age from 11 to 30 years. N o n e was ambulatory, and speech abnormality ranged from m o d e r a t e to severe, secondary to dysarthria. Significantly impaired m o t o r function and relatively n o r m a l intellectual ability characterized t h e group. All patients were from homes in which standard English was spoken. Patients had had extensive speech and physical t h e r a p y with little progress in the last few y e a r s before cerebellar stimulation. Cerebellar stimulation of the anterior lobe was p e r f o r m e d by surgical implantation at our hospital of two sets of platinum electrodes on Silastic sheets via a suboccipital craniotomy. The surgical procedure has been described previously, is T a p e recordings of patients' speech were made in a quiet r o o m on either a Revox Model 77A or Wollensak M o d e l 1500 audio recorder, using a Shure Model S M 10 dynamic microphone maintained at a constant distance (2 inches) f r o m the lips by means of a head holder. J. Neurosurg. / Volume 48 / J u n e , 1978
spastic diplegia severe mixed spastie/athetoid quadriplegia spastic quadriplegia severe mixed spastic/athetoid quadriplegia mixed spastic/athetoid quadriplegia severe mixed spastic/athetoid quadriplegia
Speech S t i m u l i and Elicitation Fourteen speech and voice characteristics were evaluated pre- and postoperatively. The speech c h a r a c t e r i s t i c s assessed were: 1) p e r c e n t a g e intelligibility of w o r d s and sentences, and 2) total words and sentences correctly identified in their entireties. When words were almost correct yet contained an error on one or m o r e speech sounds, a distinctive feature analysis was carried out. W o r d level articulatory proficiency was analyzed according to errors in place of articulation, m a n n e r of a r t i c u l a t i o n , and voicing or nasal/oral articulatory confusion. Furthermore, while m a n y sentence level productions were not completely correct, a satisfactory degree o f accuracy was often apparent. In these instances, sentences were scored according to the n u m b e r of morphemes* judged correct. 3) Voice characteristics assessed on both word and sentence levels included presence of strain/strangle quality, hoarse quality, nasal quality, or vocal clarity. 4) The pitch o f a patients' voice was judged as either within normal limits, too high, or too low. Likewise, *A morpheme is the smallest meaningful unit of language. For example, the word feed (see Table 2) is a morpheme, while the third person singular form s is also a morpheme when used in the word feeds. Free morphemes (e.g., feed) stand on their own while bound morphemes (e.g., s) must be used in conjunction with a free form to be meaningful. 877
D. L. Ratusnik, V. I. Wolfe, R. D. Penn and S. Schewitz TABLE 2 Speech elicitation task words and sentences* Word Level Stimuli 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.
cheese feet chicken fish baby cake bed dress basket black butterfly button
Sentence Level Stimuli 1. 2. 3. 4. 5. 6.
She feeds the three geese. Give Dick the tin dish. James ate the cake. Ted spent ten cents for eggs. The black cat sat on the hat. Run and get some butter.
Morphemes 6 5 4 7 7 5
*Words and sentences chosen from The Phonetic Inventory.8 Speech elicitation stimuli were chosen for representative distribution of speech sound content. The morphemes noted using Brown's criteria)
pitch variation was judged to be within normal limits, too much, or too little. Speech samples were recorded within 2 days before i m p l a n t a t i o n of cerebellar stimulators, and within 1 to 3 months after the surgical procedure. Speech repetition was accomplished by patients in response to presentation of 12 words and six sentences (Table 2). Listeners and Listening Tasks
The patients' productions of words and sentences were evaluated by six graduate speech and language clinicians in structured listening tasks. Twelve word and six sentence p r o d u c t i o n s r e c o r d e d before and after cerebellar stimulation were dubbed in a random order onto master tapes. ~6 Listeners evaluated pre- and postoperative word and sentence samples presented in a blind fashion. Two listening tasks were presented. In the first, the Intelligibility T a s k , listeners were instructed to " W r i t e the word (or sentence) which you hear." The number of words or sentences identified 100% correctly were computed from these responses. During the second task, the Degree of Accuracy Task, the same recordings were presented and samples were evaluated on the basis of articulatory accuracy using a 10-point scale (0 to 100% accuracy). Additionally, judgments of pitch and voice quality were made as listeners indicated whether each sample was clear, strained, hoarse, or nasal; whether pitch level was within normal limits, too high, or too low; 878
and whether pitch variation was within normal limits, too little, or too much. C o m p l e t i o n of the listening tasks required 3 hours. The judgments of the six listeners possessed a high degree of agreement or reliability 7 for words (.80) and sentences (.80). The p r i m a r y goal of study was to determine the effect of cerebellar stimulation on speech and vocal ability in patients with severe spastic/athetoid neuromuscular involvement and speech impairment. W e were also c o n c e r n e d with the feasibility of preoperative prediction of speech and vocal change expected from cerebellar stimulation. Results Initially, the listeners' judgments were analyzed in grouped fashion, c o m p a r i n g perf o r m a n c e b e f o r e to p e r f o r m a n c e a f t e r cerebellar stimulation; t-tests for correlated samples were computed for 12 speech or voice characteristics for words and sentences with mean length of utterance ( M L U ) examined as a sentence level measure, and distinctive feature errors examined in words. A single comparison, strain/strangle voice quality, achieved significance (t = 5.06; df = 7; p = < 0.001). After cerebellar stimulation patients were j u d g e d to use fewer strain/strangle utterances in words. Although speech characteristics, that is, j u d g m e n t s of overall intelligibility, word or sentence identification, m e a n length of utterance, and distinctive feature errors, did not i m p r o v e significantly after cerebellar stimulation, small improvements were noted J. Neurosurg. / Volume 48 / June, 1978
Cerebellar stimulation and speech lar STimulation
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PREOPERATIVE L E V E L
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FIG. 1. Summary of the pre- and postoperative speech data for words. WNL = within normal limits. for each characteristic postoperatively. For the group, word (47.96% to 49.80%) and sentence (61.11% to 61.39%) intelligibility improved approximately 2%, words identified (4.16 to 4.50) and sentences identified correctly (2.02 to 2.42) improved by approximately 1%, mean length of utterance of sentences (2.79 to 2.89) improved marginally, while distinctive feature errors (16.71 to 15.94) decreased by approximately 1%. Figures 1 and 2 display the average voice judgments before and after cerebellar stimulation for eight patients for words and six patients for sentences. Sentence level elicitation was not accomplished from Cases 2 and 7 due to the severity of oral neuromuscular involvement. Depending upon the speech or vocal characteristic, improvement (designated by an asterisk in Figs. 1 and 2) is reflected by an increase or a decrease in preponderance of the characteristic. While not to be overemphasized, the trend of changes in mean score may be interpreted as suggesting small voice improvement after J. Neurosurg. / Volume 48 / June, 1978
stimulation. An even split in direction of difference score would be expected purely by chance. That is, of l0 pre- and postoperative comparisons five should improve postoperatively whether or not cerebellar stimulation is effective. For word and sentence level voice characteristics, blind evaluation of seven parameters indicated improvement, although minimally in numerous instances. Figure 1 highlights the significant decrease in strain/strangle vocal quality, improvement in pitch level and variation, and the substantial decrease in words judged too high in pitch. Hoarseness seemed to increase after cerebellar stimulation. Figure 2 displays less change in vocal ability for sentences. While strain/strangle quality lessened postoperatively and nasality apparently increased, no other voice changes were striking after cerebellar stimulation. Again, these speech and voice comparisons were not statistically real effects, with the exception of the strain/strangle comparison, but taken together as an overall characteriza879
D. L. Ratusnik, V. I. Wolfe, R. D. Penn and S. Schewitz Cerebel Ior
Stimulation
I I I I *improved performonce following cerebellor stimulotion
A
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::3E: 6 ol..u o3O (4.47) Pitch voriotion too little
z J4 o3o
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(2.66) No_sotity
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(3O0)
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(0.52) Cleor (0.02) Pitch voriotion too much PREOPERATIVE L E V E L
~
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{0.84)*
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(0.47) (0.02)
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FIG. 2. Summary of the pre- and postoperative speech data for sentences. WNL = within normal limits.
tion of verbal behavior, seem to suggest minimal improvement following cerebellar stimulation. Individual patient performance before and after cerebellar stimulation was evaluated for each speech and vocal characteristic with criterion for change set at a difference score (pre- to postoperative levels) level of 5% intelligibility or five words/sentences possessing the speech/voice quality. Of eight patients presenting moderate-tosevere neuromuscular involvement, comparison of listeners' evaluations before and after stimulation revealed improvement for three patients (Cases 1, 3, and 7). Minimal improvement or no change was evident for three patients (Cases 2, 4, and 8). On the other hand, the evaluation for the patients in Cases 5 and 6 was negatively affected after cerebellar stimulation. Although these results are based only on eight patients, it should be noted that approximately 50% failed to improve after stimulation, while 25% actually 880
performed more poorly. The following section reviews the speech and vocal success of three patients changing favorably over the course of cerebellar stimulation. Although he possessed a severe speech impairment, the patient in Case 1 was well above the median for the group. Improvement was noted for nine of 13 word and 10 of 13 sentence level speech and voice characteristics after cerebellar stimulation. Of major importance for communication, intelligibility improved 6.67% in words and 14.73% in sentences, and 13 more words and two more sentences were judged correct after stimulation. Furthermore, the decrease in the number of distinctive features in error (-9.48) and the increase in mean length of utterance (1.09) probably contributed to an improvement in communication for this patient. Marked improvements in vocal characteristics were also noted, as strain quality on word and sentence items decreased after cerebellar stimulation and instances of J. Neurosurg. / Volume 48 / June, 1978
Cerebellar stimulation and speech ranged from moderate impairment for Cases 1 and 3 (both above the group median) to severe impairment for Case 7 (far below median) preoperatively. Speech and vocal performance varied for the three patients after cerebellar stimulation as well. In short, no predictive factors were found that might guide the neurosurgeon in counseling the patient or family regarding the potential for speech improvement following cerebellar stimulation. Cerebellar stimulation apparently facilitates speech ability in patients with a wide range of preoperative abilities. Rather than using perceptual speech data, objective evaluation of anatomical structure and physiological support for speech may offer more useful information for predicting speech and vocal improvement preoperatively. Detailed evaluation of postural tone, trunk support, and air flow measurement may aid in assessing the potential for speech change. For example, the significant decrease in observed strain/strangle quality may have resulted from increased control of proximal musculature due to stimulation. A more upright sitting posture with erect head position after stimulation would also contribute to increased air intake and longer periods of sustained phonation and intraoral breath pressure. If cerebellar stimulation has a positive effect on particular muscle groups, detailed physical and electromusculature evaluation may be indicated to help in judging potential speech improvement. Cerebellar stimulation may also improve nonverbal communication if gains are achieved in distal muscle function. For example, a decrease in primitive reflexes such as the asymmetrical tonic neck reflex and/or improved arm and wrist function could allow access to a communication board or alternative nonverbal means. The quality of life has been enhanced for many children with cerebral palsy through use of manual symbol systems, so this avenue must not be overlooked. The relatively small improvement in speech intelligibility and vocal quality may seem trivial in the three patients. However, even minimal gains may translate into improved Discussion communication in subtle ways. While one Improvement of speech and vocal patient realizes improved speaking ability characteristics was observed after stimula- from only moderately involved preoperative tion in three of eight patients (Cases 1, 3, and levels and may not realize an effect on com7). As shown in Table 1 speech intelligibility munication, a minor increase in a severely and vocal ability in these three patients dysarthric or essentially nonverbal individual 881 J. Neurosurg. / Volume 48 / June, 1978
normal pitch usage and variation increased. The only negative feature to emerge postoperatively was increased nasality. This was not an uncommon finding, as other patients showed limited difficulty in controlling nasality after stimulation. The initial clinical impression was that cerebellar stimulation had had a positive effect on speech and vocal ability. After cerebellar stimulation, the patient in Case 3 possessed the most intelligible speech of the group in words (81.50% intelligible) and sentences (89.44% intelligible). Although she was functioning at moderately impaired speech levels, both intelligibility and voice characteristics improved after cerebellar stimulation. In particular, substantial vocal improvement for word and sentence judgments was noted as pitch level and pitch variation more closely approximated normal limits and fewer instances of monotone (too little pitch variation) productions were observed in sentences. There were fewer nasal words and fewer sentences judged to be strained postoperatively. Also, her mean length of utterance for sentences increased by approximately one morpheme. The initial clinical impression was that cerebellar stimulation had had a positive effect on speech and vocal ability. The patient in Case 7 exhibited the most severely impaired speech and vocal function; a negligible portion of words were intelligible and sentence elicitation was not possible. However, after cerebellar stimulation an improvement in word intelligibility (5.55%) and a decrease in distinctive feature errors were evidenced. While no words were intelligible preoperatively, six were understandable after cerebellar stimulation. Decreased strain and hoarse vocal quality were noted after stimulation. The only negative finding was increased nasal production after cerebellar stimulation. The initial clinical impression was that this patient's speech and vocal ability improved after stimulation. His severely impaired preoperative speech and vocal ability make the improvement for Case 7 the most dramatic of the group.
D. L. Ratusnik, V. I. Wolfe, R. D. Penn and S. Schewitz may generate an entirely different outlook on the communicative process. After stimulation a desire to attempt more oral communication, a change in communicative strategy, and a desire to engage more fully in the therapeutic process m a y ensue. Feffer and Suchotliff ~ defined effective communicators as those who are aware of how they are both perceived by and understood by others. The present study was directed toward the last feature of communication, and therefore was not structured to determine the effectiveness of cerebellar stimulation on the entire communication process. We were unable to assess objectively the importance of increases in speech and vocal proficiency on communication itself. The present study can be considered a stepping-off point, as it concerns perceptual evaluation of word and sentence level intelligibility and vocal characteristics. Long-term follow-up studies are needed, as well as an evaluation of the effect of speech therapy on these patients postoperatively.
Acknowledgments
12. 13. 14. 15. 16.
17.
18. 19. 20.
Aid in manuscript preparation from Carol Melnick Ratusnik, M.A., and Lionel Schewitz, M.D., is gratefully acknowledged.
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Address reprint requests to." David L. Ratusnik, Ph.D., Department of Otolaryngology and Bronchoesophagology (Section Communicative Disorders), Rush-Presbyterian-St. Luke's Medical Center, 1753 West Congress Parkway, Chicago, Illinois 60612. J. Neurosurg. / Volume 48 / June, 1978
