Verbal perseveration in aphasia

Neuropsychologm. Vol. 19. No. 4. PP 591 ~594, 1981 Prmled I” Great Bnlam

0028 3932,81/040591 04$02.00!0 (‘I 1981 Pergamon Press Ltd

NOTE VERBAL

PERSEVERATION

IN APHASIA

A-rsr,sm YA\IAI>OKI Department

of Neurology

and Psyctualry. Kobe University School of Medicine. Ikutaku, Kobe. 6.50. Japan

12. Kusunokicho,

7-chome.

Abstract--~ Verbal intentlonal perseveration was found in 33 of 38 aphasic patients (86.X”,,) for repetition task. The perseverative error, were dlvlded into stuck, immediate and delayed type according to temporal relation of a response to the original stimulus. The result indicates that perseveration might be related with drsinhibited irrelevant memory trace.

INTRODUCTION PI KSI vt KAIIO\ observed in speech output of aphaulc pattents has been a favourlte topic In neurological htcraturc [I 51. Accordmg to LII I+I~u\‘s classic delinltion 131. perse\eratlon IS divided into three types; tonic. clontc and intentional. Of these three. clonic and Intentional types arc relevant to the lingmstic pathology. CIonlc IS so called because an initiated response is clonically repeated: intentional because perseveration IS only observed when a new movement is Intended. In this sense intentional perseveration involves neurological process which i\ related w’ith spontaneous initlation of action, while clomc per
SUBJECTS

AND METHOD

Thirty eight aphasics wserecxammcd. Ofthem, 37 had left hemlspherlc lesions and one had right hemlrpherc le\lon (left-bander wsith aphasia). Global aphasics were excluded. The age of subJects ranged from 72 to 74 yr with a mean age of 4X. Twenty six were males and 12 were females. Etiologies included 25 ischemic IeGons, fibe haemorrhages.four ruptured aneurgsmv. onesubdural haematoma.one lobectomy and IWO head traumas. Duration of aphasia ranged from 1 month IO day5 to 5 ye- \rlth a mean of 10.X months. Type of aphasia included 24 Hroca’\ aphasia. seven Wernicke’s aphasia. IUO alcxta with agraphla. IUO anomx aphasia. two conduction aphasia and one tranhcortical sensory aphasia. Subjects were ahkcd to repeat four dlffercnt sets of linguistic series. One of them was compo\ed of I7 sentence\ of different syllabic length which are arranged so that a subJect will be presented successively from one syllable to 17 syllabic sentences with the increment of one syllabic at each stimulus presentation The other was composed of I I words ranging from one syllable to I 1 syllables. The remalnlng two sets were composed of non-mcantngful Ilngulstlc series. One of them was composed of eight numerical series ranging from one dtpit to eight dgits. The other- wa\ composed of IO series of syllabic sequence ranging from one ~yllahle IO 10 syllables. The stimulus was glvcn \low1~ and monotonously. Longer syllabic series beyond the subject’s capacity were not presented to avoid catastrophic reactions. In the later analysts. perseveration wah defined a\ any response uhlch had a component of previousresponse and was produced only on presentation of a new task. A task was considered new when the \amc stimulu\ was rcpeatcd anew to a subject.

Regardless oftype ofstimull, perse\cration was detected In 33 5ubJect’r (X6.X”,,) and was absent in live (IK”,,). types of aphasia. all types showed perseveration as Thown in Table I. As for severrty of aphasia, it did not correlate with incidence of peraeveratlon as I$ clear from Table 2. Mild as well as \everc aphnsich showed

As for

591

NOI r

592 Table

I. Relatmn

between aphasia type and perseceration

Aphasia type

Present

Broca Wcrmckc Alcxia with agraphia Anemic ConductIon Tranacortical

Aphasia type

Broca

Wernickc

I I

7 2 2 ,

T

0 0 0

33

5

3x

21

;

between severity of aphasia and pcrsevcratlon

Sevccr1ty

Present

Perseveration Absent

Total

Se\ ere Moderate Mild

5 9 7

I I

6 IO

I

X

Severe Moderate Mild

I

0

I

4 I

I 0

5

77

4

31

Total

Duration I 3 month\ 3 6 months 6 months I yr I2yr 2 yr Total

3

6 7 ,

sensory

Total

71

I

Total

Table 2. Relation

Perseveration Absent

Present

Pcrse\eration Absent

I

Total

5 x 7 6 7

3 ; I

7 9 X

0

I

7 7

33

5

3X

persevcrative errors equally. Duration of aphasia also showed no correlation with Incldcnce of persevcratlon a\ shown in Table 3. Aphasics with shorter duration showed per\everatton as often it\ ones with longer duration.

So far w,c havcconccrned ulth all-or-none mcldence ofperse\eratlon In an indl\Idual and it\ relation with cnriou\ factors. Now \ome quantitative and quulitatl\c aspect\ allI hc dcsxihed. Total number of per\cvcration\ recorded In thizxtudy was76. From thcm,threequnl~tat~velyd~ffcrent subtypcscould hedctccted InType I.“st~l~k”type.t;l\k A (or stimulus A) would bc responded to hy response (A) in which a portion of A or addltlon to A IS Included. I‘hcn this incorrect response (A) would he rrpcsted wjhcn ta\k A wa\ gven agam For instance H stimulu. “FU-TO-KO(nonacnsc). With another prevxtatiun of the RO-GA-TA-NA” (dagger) was reputed ah “FL7‘0.GA-RA-MI” same stimulus, the same “FU-TO-GA-RA-MI” was perscverated. In Type 2,“immediate” type, task A would he rcspondcd to by correct re\ponac A. But for the next task B which 15 one syllable longer than task A, response H(A) would he produced The rcspon\e would Include a portton of the

593

NOTE

previous stimulus A coupled with a portion of the current stimulus B. For instance a stimulus “NU-KA-NI-KU-GI” (a proverb referring to uselessness of a certain action) would be correctly repeated. With the next task “MA-KE-RUGA-KA-CHI” (another proverb whose meaning is irrelevant to the previous one), “MA-KE-RU-KLI-GI-GA” was produced. The perseverate KU-G1 (nail) was incorporated into the new stimulus resulting in nonsense jargon. In Type 3, “delayed” type, stimulus A would be correctly repeated as well as the next stimulus B. Perseveration would appear for the third task C with response C(A). The response would include a portion ofthe old stimulus A which is incorporated with new stimulus C. The stimulus in between, i.e. B, would be correctly repeated. For instance, “NUKA-NI-KU-GI” was correctly repeated. The next step “MA-KE-RU-GA-KA-CHI” was also well repeated without hesitation. Perseveration would appear only at the third stimulus, “MI-KA-RA-DE-TA-SA-BI”, which is a proverb with unrelated meaning from the two previous stimuli. For this a subject responded with “MI-KA-RA-DE-TA-KCTGI” This latency could be as long as nine stimuli. The relation between these subtypes and stimulus types is noteworthy. As shown in Table 4 the delayed type was observed only in response to meaningful stimuli, i.e. sentences and words. The immediate type was seen much more often with meaningful series than with non-meaningful series, i.e. syllables and digits. The stuck type was seen in either group but was more numerous with non-meaningful series,

Table 4. Relation

between

Type of stimulus Meaningful Sentence Word

Stuck

subtype

and stimulus

Perseveration Immediate

subtype Delayed

type

Total

series

Non-meaningful Syllables Digits Total

perseveration

I 6

16 8

7 4

30 18

11 12

3 2

0 0

14 14

36

29

11

76

series

DISCUSSION Incidence

of perseveration

The present incidence of perseveration in single linguistic modality (86.8 0,;) seems to be the highest compared with the previous report [4]. The reason for this is not quite clear but it might be a result of the concentrated use of the test material of similar kind as suggested by Allison. At least it could not be attributed to fatigue or clouded consciousness as had been indicated. In addition our data suggest neither severity nor duration of aphasia influence the incidence. Number of perseverative errors in agiven case might change but the tendency to perseverate seems to be present in every aphasic subject. Even in cases with non-perseveratory subjects in the present study it might very well be detected if an appropriate stimulus was applied. Nature

of perseveration

So far three major

hypotheses as to the nature of perseveration have appeared. The first group as represented by WEPMAN[6] regarded it as manifestation of the impaired attention. Because of occasional closing of an attention shutter to the outside world, a response produced when the shutter is open would be perseverated. The second group considered it as dysfunction of some kind of central mechanism, such as disruption of inhibitory process [7], proactive interference [S]. disrupted recall mechanism [Z] or transmission disturbance in the area of sensory preparation of movement [3]. The third group regarded it as manifestation of disordered motor mechanism, a kind of inertia of the motor apparatus [S]. To help clarify the issue, the phenomenon of delayed perseveration presents a cue. This aspect of perseveration cannot be explained by inertia, for if it is due to inertia, it must cease when the next step is correctly performed. Similarly attention theory is hard to accept. If perseveration is a mechanism to fill the vacuum caused by lapse of attention and no more, why are not more meaningful, so to speak, confabulatory responses produced rather than creating such jargon output? Why has fragmented old material to be mobilized? Furthermore, there have been very interesting clinical observations which contradict the theory of poor attention. Thus a patient of RO(.HFORL) [9] (cited by LEXSER[lo]) failed to name a skull but three items later called a scarecrow a “skull-bound”. Although the

594

NIJIF

phenomenon cannot be labelled as perseveration in the strict sense, it bears close resemblance to it. Actually a stimulus might very well have been perceived. Only the observer has no way to prove it except by chance. Thus it seems more natural to attribute perseveratton to some kind of central process mechanism. Hr~rxoh [2] among others had suggested that perseveration might be related with memory mechanism. He argued that perseveration is uncontrolled augmentation of facilitatory activity that is related to the establishment of new memory. The suggestion is very attractive for the delayed perseveration. When a certain neural mechanism is activated in processing an input. it may remain in state of excitation for a certain period of time and may not disappear even when the task is completed. It is actively inhibtted in order that next stimulus can be processed. It could be this inhibitory process which is disturbed when the brain is injured. Instability of inhibition over a group of neural elements which have recently been put into an activated state would cause confusion in sequencing neural elements in response to a new stimulus. In this way old fragments come to be associated with current components resulting in a chaotic verbal output. If the above speculation is correct, three subtypes of perseveration described in thts study might reflect three different degrees of inhibitory dysfunction. If disinhibitton is strong, stuck type would predominate. Delayed type can be a retlection of the least degree of disinhibition, immediate type being in between. Thus it could be argued that perseveration is really a slip of irrelevant memory trace triggered by subject’s action. Clinically it has to be defined as reoccurrence ofa certam motor response. but in theory an ortginal motor response need not necessarily be reahTed. The initial stimulus is processed but might remain stlent. ~~lirio~~ludgen2rrlrz Patients were examined author is grateful to the staff concerned.

at Hyogo

Prefectural

Tamatsu

Rehabilitation

Center

Hospttal.

The

REFERENCES I. ’ 5: 4. 5.

6. 7. 8. 9. IO.

HI LMIC’K. J. W and BI,KC,. C. B. Perreveratmn m brain InJured adults. J. (‘ornrw~~. Disord 9, I43 156, I Y76 Hr~~xou. A. J. Perseveration. Bruiu 91, 571 582, 196X. LIFPMAYN, H. Uhrr StiG-unqrn drs Ilundrlna hri Gehirnkrcrnhm. Verlag van S. Karger. Berlin, 1905. AI.I.ISON, R. S. and Hunwrr/. L. J. On perseveration in aphasics. Brain 90, 429-448. 1967. LURIA. A. R. Memory disturbances tn local brain lesions. Neurop.s~cho/o(lia 9, 367 375, 1971. WNMAU, J. M. Aphasia therapy: A new look. J. Speech Hrur. Disord. 37, 203 714, 1972. LIWRMI-I II, F. and BI A, vats, M. F. A visual speech disconnexion syndrome. Bruin 96, 695 714. 1973. Fr Owl-KS, C. R. Proactme interference in short-term recall by aphasic, brain-damaged non-aphastc and normal subjects. Nr,uropz~c,ho/ogiu 13. 59 6X, 1975. ROC.IIFORI). Ci. Are jargon dysphasics dyyphaatc? Br. J. Disord. Commute. 9. 35 44. 1974. LI SSI,K, R. Lin~rri.\ric~ In~,r.\ric/cltion.~ of 4plnlai[r. Edward Arnold Ltd., London. 107X

Zusammenfassung Sprachliche Patienten wurden

intentionalc

emgeteilt

entsprechend Ergebnis

Perseveration

fand sich bei 33 van

(86, 8 70) bci Wiederholungsaufgabcn.

zeigt

in Steckenbleiben,

dcr zeitlichen

unmlttelbare

Beziehung

eincr

an, da13 die I’ erseveratmn

Erinnerungsspuren

zu tun

haben kiinnte.

38

aphasischen

Die Perseverationsfelll~r und verzrigerte

Iieaktion

Wiederholung

zum Stimulus.

mit der Enthemmung

Das

irrelevanter