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Constructional apraxia and Visuoperceptive Disabilities in Relation to Laterality of Cerebral Lesions
CONSTRUCTIONAL APRAXIA AND VISUOPERCEPTIVE DISABILITIES IN RELATION TO LATERALITY OF CEREBRAL LESIONS R. Arena and G. Gainotti1 (The 2nd Neurological Clinic of the University of Pisa)
Despite the large number of clinical and experimental studies designed to compare the incidence, severity and nature of constructional apraxia re sulting from the lesions of the right and left cerebral hemisphere, several questions still remain unresolved. Incidence and severity of constructional apraxia in patients with unilateral cerebral lesions Both clinical investigations and experimental studies (Piercy, Hecaen and Ajuriaguerra, 1960; Benton and Fogel, 1962; Costa and Vaughan, 1962; Piercy and Smyth, 1962; Arrigoni and De Renzi, 1964; Newcombe, 1969; Black and Strub, 1976) have led to the conclusion that constructional de ficits are more frequent and severe in patients with right hemisphere lesions. However, other well controlled studies (Warrington, James and Kinsboume, 1966; De Renzi and Faglioni, 1967; Dee, 1970; Benson and :Barton, 1970; Gainotti, Miceli and Caltagirone, 1977) have reported that the mean group differences on constructional tasks by subjects with unila teral lesions tend to be negligible. A particular aspect of this problem is the incidence of constructional apraxia in aphasia. Some authors (Hecaen, 1962; Zangwill, 1964; Benton, Levin and Van Allen, 1973) have remarked on the frequent occurrence of constructive disabilities in aphasic patients with posterior lesions of the left hemisphere, but other authors (Warrington et al., 1966; Dee, 1970) have failed to find any relationship, within the left brain-damaged patients, between the incidence of aphasia and of con structional apraxia.
1
Clinic for Nervous and Mental Diseases of the Catholic University ot Rome.
Cortex (1978) 14, 463-473.
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R. Arena and G. Gainotti
Relationships between visuoconstructive and visuoperceptive disabilities in relation to laterality of cerebral lesions Even more open to controversy is the problem of the neurodynamic mechanisms underlying constructional apraxia in right and left hemispheric lesions. Clinical investigations (McFie, Piercy and Zangwill, 1950; Duensing, 1954; Ettlinger, Warrington ad Zangwill, 1957; McFie and Zangwill, 1960; Piercy et al., 1960; Arrigoni and De Renzi, 1964; Warrington et al., 1966; Gainotti and Tiacci, 1970; Gainotti, Messerli and Tissot, 1972; Collignon and Rondeaux, 1974) have stressed the existence of clearcut qualitative differences between the drawing disability of right and left brain-damaged patients, since the former show chiefly an inability to reproduce spatial relationships, whereas the latter tend to give coherent but simplified versions of the model. On the ground of these qualitative differences, the right sided constructive impairment has been regarded as a manifestation of "perceptual" disability, whereas the left-sided constructional apraxia has been conceived as reflecting a "motor-executive" disorder. Experimental studies designed to evaluate this hypothesis have ·given conflicting results. Thus Costa and Vaughan (1962) and Warrington and James ( 196 7) have claimed that the intercorrelations between visuoperceptive and visuocon structive tests are higher in right than in left brain-damaged patients, but this finding has not been confirmed by Piercy and Smyth ( 1962 ), De Renzi and Faglioni (1967), Dee (1970) and Gainotti and Tiacci (1972), who have shown that the basis for visuoconstructive disturbances is a perceptual di sorder, independently of the hemispheric locus of lesion. On the other hand, Warrington et al. ( 1966) and Hecaen and Assai (1970) have obtained data supporting the view that left-sided, but not right-sided apraxia, is due to a planning disorder, but their results have not been confirmed by Gainotti et al. (1977). In our opinion, this confusing situation is due, in part at least, to me thodological reasons. Some authors have studied constructional apraxia or visual-perceptual disabilities, by means of very complex tasks that are ge nerally used to obtain measures of general intelligence and not to assess specific disorders. For example, Costa and Vaughan (1962) and Black and Strub ( 197 6) have used the W AIS Block Designs to measure construc tional apraxia and Costa and Vaughan (1962), Piercy and Smyth (1962) and Gainotti and Tiacci (1972) have used Raven's Progressive Matrices to obtain estimate of the patients' visual perceptual functioning. Since impairment on a complex task may result from a variety of specific deficits (as well as from diffuse mental impariment) such tests do not seem appropriate to study specific visuoconstructive or visuoperceptive disabilities. More ap propriate for this aim are simple tests making only limited demands on
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general intelligence. The first purpose of the present research consisted, therefore, in checking, by means of a simple test of copying drawings (Ben ton's Visual Retention Test, Administration C) the incidence of construc tional apraxia in right and left brain-damaged patients. The second aim was to study the relationships between constructional apraxia and visuopercep tive disabilities in the same groups of brain-damaged patients, by means of two different versions of the same test: one (constructive test) involving graphomotor activity, the other (visuoperceptive test) involving only an activity of visual form discrimination.
MATERIAL AND METHOD
Subjects
Thirty-six control subjects, SO right and 43 left brain-damaged patients were submitted to examination. All patients were drawn from the Neurology and Neurosurgery services of the University Hospital of Pisa. Control subjects had been hospitalized because of psychoneurosis or of neurological lesions situated below the level of the cervical spine. Within the brain-damaged groups, diagnosis of the affected side was made on the ground of the clinical findings supplemented by available EEG, brain scan and neuroradiological data. No selection was made in forming the groups, but left-handed subjects, patients with diffuse of obviously bilateral hemispheric damage and subjects unable to maintain the set necessary to carry out the task were excluded. Furthermore, in order to rule out the effect of diffuse cerebral damage (caused, for example, by brain edema) all patients were studied after the acute phase of illness. No significant differences were found between normal controls and brain damaged patients in relation to age and educational level. Furthermore, no signi ficant difference was found between right and left brain-damaged patients in relation to etiology of illness and presence or absence of visual field defects. The only difference found between the two hemispheric groups consisted in the higher age of left (56.3) compared to right (48.6) brain-damaged patients (t = 2.07; p < .05). Testing procedures Praxis test
The Visual Retention Test (V.R.T.), Administration C (copying), was used as a graphomotor test of constructional praxis (Benton, 1962). Performances on the test were not evaluated on the basis of the usual criteria (which consist in subtracting from an assumed perfect score of 26 the total number of errors) but on the ground of a scoring system analogous to the one proposed by Arrigoni and De Renzi ( 1964 ). Each figure was scored 2 points for essentially correct reproduc tions, 1 point if the reproduction was partly defective (owing to omission of some lines, rotation, distortion or size errors) but not to such an extent as to prevent the identification of the figure, and 0 points for unrecognizable reproductions. In assigning the points we were deliberately liberal in regard to any imperfec tion which did not impair the essential characteristics of the model, and which might be the consequence of the use of the non-dominant hand. In order to rule
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out the effect of unilateral spatial agnosia, the attention of the patients was directed towards possible omissions and the patient was asked to copy figures omitted the first time. The maximum score obtainable with this scoring system was 74.
Perceptual test Perceptual ability was assessed by means of a 15 items, multiple choice version of the V.R.T., Administration M, used as a test of visual form discrimi nation (Benton, 1951). Each item was mounted singly on a card bearing in its upper part the stimulus model and in its lower part 4 more or less similar designs. The patient had to designate which of these 4 designs was the one drawn on the upper part of the card. The score of this test was the sum of the correct choices, the maximum score being 15. Assessment of aphasia In addition to the praxic and the perceptual versions of the V.R.T., left brain-damaged patients received the shortened version of the Token Test recently proposed by De Renzi and Faglioni (1975) in order to assess the presence and severity of aphasia. Cutting scores provided for this version of the Token Test (corrected for educational background) correctly classify more than 90% aphasic patients. On the basis of the results obtained with this version of the Token Test, 23 left brain-damaged patients were considered aphasic. RESULTS
Incidence of constructional apraxia and hemispheric locus of lesion
The incidence of constructional apraxia in right and left brain-damaged patients was assessed by taking as cut-off point between "normal" and "pathological" performances the score of 50, attained or exceeded by all but one the control subjects. Eleven right (37%) and 16 left (37%) brain damaged patients obtained scores lower than the cut-off and were defined as apraxics. In order to obtain a better estimate of the results obtained by right and left brain-damaged patients, the significance of the differences be tween normal controls, right and left brain-damaged patients was estimated by means of the Mann-Whitney's U Test (Table I). TABLE I
Comparison between the Means Obtained by Normal Controls, Right and Left Brain-Damaged Patients on the Test of Constructional Praxis Control subjects (N = 36) 64.03 Controls vs. Right B.D.P.: z = 2.994 (p Controls vs. Left B.D.P.: z = 3.873 (p Right vs. Left B.D.P.: z = 0.560 (p
Right B.D.P. (N = 30)
Left B.D.P. (N = 43)
52.03
48.58
= .0014) = .00007) = n.s.)
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467
Table I shows that both brain-damaged groups score significantly worse than normal controls but that no significant difference is found between patients with lesion of either the right or the left cerebral hemisphere. Visual perceptual disabilities in right and left brain-damaged patients
Again, scores obtained by normal controls were used to discriminate the "normal" from the "pathological" performances of patients with cerebral lesions. Sixteen right (53.3%) and 20 left (46.5%) brain-damaged patients did not exceed the score of 9, attained by the worst control subjects. Their performance was therefore considered pathological. No significant difference was found between the two hemispheric groups (chi2 = 0.11). When the = 13.14) scored means of the three groups were compared, controls significantly higher (p < .001) than both right brain-damaged patients (x = 9.83) and left brain-damaged patients (i = 9.98), while no significant difference between the two hemispheric groups was obtained.
(x
Relationships between constructional apraxia and visuoperceptive disabilities in right and left brain-damaged patients
Given our working hypothesis that constructional apraxia is due to a visual perceptual disorder in right but not in left brain-damaged patients, the following outcomes are predicted: (1) Apraxic right brain-damaged patients should obtain significantly lower scores than non-apraxic right brain-damaged patients on the perceptual test. No such relation should be observed among the patients with lesions of the dominant hemisphere. (2) A close correlation should be found within the right, but not within 1 the left brain-damaged patients, between scores obtained on the "praxic" and scores obtained on the "gnosic" form of the Benton V.R.T. Table II shows that neither of these 2 assumptions was confirmed. In fact, contrary to the hypothesis, the relationship between· praxic and percep tual scores was somewhat higher in left than in right brain-damaged patients. TABLE II
Perceptual Means of Apraxic and Non-apraxic Right and Left Brain-Damaged Patients Left hemisphere
Right hemisphere Non-apraxics 19) {N
=
Apraxics {N = 11)
Non-apraxics
10.58
7.64
11.59
t
= 2.15 {p < .05)
{N
= 27)
t = 4.57 {p
Apraxics
{N
= 16)
7.25
< .01)
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R. Arena and G. Gainotti
The corresponding correlation coefficients (r) were: .69 (p .46 (p < .05), respectively.
< .001)
and
Constructional apraxia and visuoperceptive disabilities in aphasic patients
Benton ( 197 3) has shown, in a recent paper, that a close association exists, within left brain-damaged patients, between constructional apraxia and sensory aphasia. Since an impressionistic analysis of the unexpected results obtained by our left brain-damaged patients seemed to confirm this claim, we undertook a separate analysis of the scores obtained on the gra phomotor and on the perceptual test by the 23 left hemispheric patients considered aphasic on the ground of the results obtained on the Token Test. Incidence and severity of constructional apraxia
On the praxic test a pathological score was obtained by 13 (57%) out of 23 aphasic patients. This incidence was significantly higher than that (15%) found in the group of non-aphasic left brain-damaged patients (chi2 = 6.22; p < .01) although not significantly greater than the incidence ( 37%) found in the right hemispheric group (chi2 = 1.82; p = n.s. ). However, when the mean of aphasic patients (39.00) was compared to the mean of right hemispheric patients (52.03) with the Mann-Whitney's U test, a significant z = 2.36 (p = .0089) was obtained, pointing to the inferior performance of aphasics. Incidence and severity of perceptual disabilities
Similar results were obtained on the perceptual test. The incidence of pathological performances was higher among aphasic subjects ( 16 out of 23 = 70%) than in any other brain-damaged group, but only the compa rison with non-aphasic left brain-damaged patients reached statistical signi ficance (chi2 = 8.33; p < .01). However, .aphasics were found significantly impaired in comparison to right hemispheric patients when a t-test was used (t = 2.33; p < .05). Relationship between results obtained on the graphomotor and the perceptual version of the V.R.T.
Table III reports data relative to the relationships between praxic and perceptual scores in aphasic and non-aphasic left brain-damaged patients. These data show that the significant association between the two disorders, previously found in the left hemispheric group, holds for aphasics only.
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TABLE III
Relationships between Results Obtained on the Graphomotor and the Perceptual Version of the V.R.T. by Aphasic and Non-Aphasic Left Brain-Damaged Patients
Relationships between normal and pathological performances Aphasics (N = 23) Perceptual
Non-aphasics (N=20) Perceptual
+
+
+ 6 4 Graphomotor - - - chP = 7.30 (p
+
2
12
1
Note. The sign
+ 14 3 Graphomotor - - -
<
.01)
1
chi2 = 0.387 (p = n.s.)
means a normal performance; the sign -
a pathological performance.
Means obtained on the perceptual test by apraxic and non-apraxic patients Aphasics Non-apraxics Apraxics (N=10) (N=13) 10.70 6.46 t = 3.29 (p < .01)
Non-aphasics Non-apraxics Apraxics (N
= 17)
(N
= 3)
12.12 10.67 t = 0.86 (p = n.s.)
Correlation coefficients between scores obtained at the graphomotor and at the perceptual test r
Aphasics (p < .001)
= 0.70
Non-aphasics left B.D.P. r = 0.39 (p = n.s.)
Relationship between severity of aphasia and results obtained on the graphomotor and on the perceptual version of the V.R.T.
To further clarify the bearing of aphasia on the performances obtained on the two tests, the correlations between Token Test· scores and scores of the praxic and of the perceptual test were computed in the aphasic patients. Both correlation coefficients were statistically significant (r = 0.59; p < .01 for the graphomotor test and r = 0.66; p < .001 for the perceptual test). There were, however, exceptions to this trend, as shown by the following three aphasics, who were remarkably impaired on the Token Test and, nevertheless, scored in a normal range on the graphomotor test: patient 53 had a Token Test score of 16 and a graphomotor test score of 58, patient 65 had a Token Test score of 15 and a graphomotor test score of 56 and patient 69 had a Token Test score of 20 and a graphomotor test score of 55.
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R. Arena and G. Gainotti DISCUSSION
The main findings of the present research may be summarized as follows: ( 1) No difference was found between right and left brain-damaged
patients, when these groups were compared for incidence and severity of visuo-constructive disabilities. This finding is at variance with the outcome of some previous studies, but in agreement with the results obtained by Warrington et al. (1966), De Renzi and Faglioni (1967), Behson and Barton (1970), Dee (1970), Hecaen and Assai (1970), Gainotti and Tiacci (1972), Benton (1973), Colombo, De Renzi and Faglioni (1976) and Gai notti et al. ( 1977). Two considerations seem in order. First, it is important to stress that we took care to counteract the bearing on the performance of unilateral spatial agnosia which is likely to be at least in part responsible for the poor scores of right brain-damaged patients reported in the literature. Second, our results suggest that most of the contrasting results reported in literature are due to sampling differences from one study to another. This problem had already been raised by Costa and Vaughan ( 1962), Arrigoni and De Renzi ( 1964) and Warrington et al. ( 1966) and has been recently evaluated by Benton (1973), who has shown that: if left brain-damaged patients with severe receptive aphasia are excl~ded from the study (because of their inability to understand the instructions and so on), the performance of the left hemispheric group is likely to be clearly superior to that of patients with right hemispheric damage; if, on the contrary, the left-sided group includes a substantial proportion of aphasic patients, its overall performance is likely to be comparable to that of the right hemispheric group. This claim finds support in De Renzi's (1977) observation that the incidence of constructional apraxia reported by various authors is fairly stable in right brain-damaged patients (ranging from 32 to 40% ). On the contrary, the incidence of visuoconstructive disabilities observed by the same authors in left brain-damaged patients is much more variable (range 14-32% ). In our research, where even the most severe aphasic patients could be examined, because of the elementary nature of the task, the incidence of constructional apraxia was in the expected range ( 37% ) for the right brain-damaged patients, whereas it was higher (37%) than pre viously noticed in the left hemispheric group. (2) No difference was found between the two hemispheric groups on
the test of visual form discrimination. This finding is more surprising, since the greatest part of the neuropsychological literature reports a greater impariment of right brain-damaged patients in tasks involving complex perceptual discrimination. Since the left brain-damaged group was significantly older than the
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right brain-damaged group, we controlled whether age and perceptual scores were correlated in normals: a non significant r = 0.16 was found and, thus, the discrepancy with respect to the literature cannot be accounted for by age. We are inclined to think that also in this case the special care we took not to exclude severe aphasics may explain the impairment of the left brain-damaged group. In fact, since aphasics have been found to score poorly on the visuo-perceptual test, it is apparent that their inclusion in the sample influences the mean score of patients with left hemispheric damage. (3) The relationship between graphomotor and perceptual score was
higher in left than in right brain-damaged patients. This finding is at variance with the claim of Costa and Vaughan (1962) and of Warrington and James ( 196 7) that the intercorrelations between perceptual and praxic tasks are higher in right than in left hemispheric patients. The close correlation found in our research between praxic and perceptual scores in left brain-damaged patients was due chiefly to the poor performances obtained on both tasks by aphasic patients. If we assume that the most severe aphasic patients were probably excluded from the studies accomplished by Costa and Vaughan (1962~ and by Warrington and James (1967), since their n~uro psychological battery included tests demanding sustained attention and understanding on the part of the patients, the difference between their results and our findings can find a satisfactory interpretation. According to our hypothesis, the relationship between perceptual and graphomotor tasks may be expected to be lower in a given group whenever a sampling bias has led to the exclusion of extensive retro-rolandic lesions in that group. The correlation between praxic and perceptual scores should, in contrast, be e<;~.ually significant in both right and left brain-damaged patients, when no sampling bias exists between the two hemispheric groups. , ( 4) Relationship between aphasia and poor performance on the grapho fnotor and petceptual test. Two different interpretations can be advanced to explain the poor performance of aphasic patients on both the praxic and the perceptual version of the V.R.T.: (a) aphasia is not directly responsible for graphomotor and visuopercep tive disabilities, but is simply coincidental with them, owing to the encroachment of the lesion upon the posterior (pariet<>-'temporal) regions of the left hemisphere, which subserve both linguistic and visual-spatial functions; (b) aphasia per se is responsible of the poor performances obtained by aphasic patients both on the praxic and on the perceptual version of the V.R.T. . In the prese~t study we tried to clarify this issue by studying the association between Token Test scores and scores obtained on the praxic and perceptual test, but the outcome of the correlation analysis was not
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R. Arena and G. Gainotti
conclusive. Interest correlations were highly significant in aphasics, but the occurrence in the aphasic group of at least 3 patients who, despite a marked impariment on the Token Test, obtained normal scores on the graphomotor task, argues against a direct bearing of the language deficit upon the praxic and perceptual impairment. In conclusion, the results of the present research support Benton's claim that a significant relationship exists between aphasic and visuo-constructive disturbances (Benton, 1973; Benton et al., 1973), but further investigations are needed to clarify the meaning of this association.
SUMMARY
The main purpose of the present study was to determine whether construc tional apraxia is due to a visual perceptual disorder in right but not in left brain damaged patients. In order to resolve this question, 36 normal controls and 73 brain-damaged patients with lesions restricted to, the right (N = 30) or to the left (N = 43) cerebral hemisphere were given a graphomotor and a multiple choice version of the Benton Visual Retention Test. The graphomotor version of the V.R.T. was used as a test of constructional praxis, whereas tbe multiple choice version of the V.R.T. was used as a test of visual form discrimination. No differences was found between right and left brain-damaged patients with respect to incidence and severity of visuo-constructive and of visuo-perceptive disabilities. Contrary to the hypothesis, the relationship between perceptual and praxic tasks was higher in left than in right brain-damaged patients. The high level of correlation found between graphomotor and perceptual scores within the left hemispheric group· was due chiefly to the poor performances obtained on both tasks by aphasic patients. These findings are interpreted as suggesting that the basis for visuoconstructive disturbances is a perceptual disorder, independently of the hemispheric side of lesion. The contrasting results of our intercorrelational study and of analogous studies reported in neuropsychological literature are interpreted as ·being due to sampling differences, in the absence of clearcut qualitative or quantitative differences between visuo-constructive disabilities of right and left brain-damaged patients. REFERENCES ARRIGONI, G., and DE RENZI, E. (1964) Constructional apraxia and hemispheric locus of lesion, Cortex, 1, 170-197. BENSON, D., and BARTON, M. (1970) Disturbances in constructional ability, Cortex, 6, 19-46. BENTON, A. L. (1951) Manuel du Test de Retention Visuelle. Application Cliniques et Experi mentales, Centre Psycho!. Appl., Paris. (1962) The visual retention test as a constructional praxis task, Confin. Neurol. 22, 141-155. (1973) Visuoconstructive disabilities in patients with cerebral disease: its relationship to side of lesion and aphasic disorder, Documents Ophtalmologica, 34, 67-76. - , and FOGEL, M. L. (1%2) Three-dimensional constructional praxis: a clinical test, Arch. Neurol., Chicago, 7, 347-354. - , LEVIN, H. S., and VAN ALLEN, M. W. (1973) Constructional apraxia and aphasic disorder.
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Communication at the Annual Meeting .of the Academy of Aphasia, Albuquerque, New Mexico, 28-30 october. BLACK, F. W., and STRUB, R. L. (1976) Constructional apraxia in patients with discrete missile wounds of the brain, Cortex, 12, 212-220. CoLLIGNON, R., and RoNDEAUX, J. (1974) Approche clinique des modalites de l'apraxie con structive secondaire aux lesions corticales hemispberiques gauches et droites, Acta Neurol. Belg., 74, 137-146. CoLOMBo, A., DE RENZI, E., and FAGLIONI, P. (1976) The occurrence of visual neglect in pa tients with unilateral cerebral disease, Cortex, 12, 221-231. CosTA, L. D., and VAUGHAN, H. G. (1962) Performance of patients with lateralized cerebral lesions. I: Verbal and perceptual tests, ]. Nerv. Ment. Dis., 134, 162-168. DEE, H. L. (1970) Visuoconstructive and visuoperceptive deficit in patients with unilateral cerebral lesions, Neuropsychologia, 8, 305-314. DE RENZI, E. (1977) L'aprassia costruttiva, in: BISIACH, E., et al., « Neuropsicologia Qinica » Franco Angeli, Milano. - , and FAGLIONI, P. (1967) The relationship between visuospatial impairment and construc tional apraxia, Cortc;x, 3, 327-342. - , - (1975) L'esame dei disturbi afasici di comprensione orale mediante una versione ab breviata del test dei gettoni, Riv. Pat. Nerv. Ment., 96, 252-269. DuENSING, F. (1954) Raumagnostische und ideatorischapraktische Storung des gestaltenden Handelns, Dtsch. Z. Nervenheilk, 170, 72-94. ETTILINGER, G., WARRINGTON, E., and ZANGWILL, 0. L. (1957) A further study of visual-spatial agnosia, Brain, 80, 335-361. GAINOTTI, G., MEssERLI, P., and TISSOT, R. (1972) Troubles du dessin et lesions bemispberi ques retrorolandiques unilaterales gauches et droites, Encephale, 61, 245-264. - , MICELI, G., and CALTAGIRONE, C. (1977) Constructional apraxia in left brain-damaged patients: a planning disorder?, Cortex, 13, 109-118. , - , and TIACCI, C. (1970) Patterns of drawing disability in right and left hemispheric patients, Neuropsychologia, 8, 379-384. - , - (1972) Sui rapporti tra aprassia costruttiva, agnosia visuo-spaziale ed agnosia spaziale unilaterale, Riv. Pat. Nerv. Ment., 93, 103-116. H:EcAEN, H. (1962) Clinical symptomatology in right and left hemispheric lesions, in Interhemi spheric Relations and Cerebral Dominance, ed. by B. V. Mountcastle, Johns Hopkins Press, Baltimore. - , and AssAL, G. (1970) A comparison of constructive deficit following right and left hemi spheric lesions, Neuropsychologia, 8, 289-303. McFIE, ]., PIERCY, M., and ZANGWILL, 0. L. (1950) Visual spatial agnosia associated with lesions of the right hemisphere, Brain, 73, 167-190. - , and ZANGWILL, 0. (1960) Visual-constructive disabilities associated with lesions of the left , cerebral hemisphere, Brain, 83, 243-260. NEWCOMBE, F. (1969) Missile Wounds of the Brain, Oxford University Press, London. PtERCY, M. F., HEcAEN, H., and AJURIAGUERRA, J. (1960) Constructional apraxia associated 1 with unilateral cerebral lesions, Brain, 83, 225-242. -f.., and SMYm, V. (1962) Right hemisphere dominance for certain non-verbal intellectual skills, Brain, 85, 775-790. WARRINGTON, E. K., and }AMES, M. (1967) Disorders of visual perception in patients with localized cerebral lesions, Neuropsychologia, 5, 253-266. - , - , and KINSBOURNE, M. (1966) Drawing disability in relation to laterality of cerebral lesion, Brain, 89, 53-82. · ZANGWILL, 0. L. (1964) Intelligence in aphasia, in Disorders of Language, ed. by A. V. S. De Ruech and M. O'Connors, CIBA Foundation Symposium, Little Brown, Boston.
Guido Gainotti, M.D., Clinica Neurologica, Universita Cattolica, Largo A. Gemelli, 8, 00168 Roma, Italy. Roberto Arena, M.D., 2• Clinica Neurologies dell'Universita di Pisa, Pisa, Italy.
Despite the large number of clinical and experimental studies designed to compare the incidence, severity and nature of constructional apraxia re sulting from the lesions of the right and left cerebral hemisphere, several questions still remain unresolved. Incidence and severity of constructional apraxia in patients with unilateral cerebral lesions Both clinical investigations and experimental studies (Piercy, Hecaen and Ajuriaguerra, 1960; Benton and Fogel, 1962; Costa and Vaughan, 1962; Piercy and Smyth, 1962; Arrigoni and De Renzi, 1964; Newcombe, 1969; Black and Strub, 1976) have led to the conclusion that constructional de ficits are more frequent and severe in patients with right hemisphere lesions. However, other well controlled studies (Warrington, James and Kinsboume, 1966; De Renzi and Faglioni, 1967; Dee, 1970; Benson and :Barton, 1970; Gainotti, Miceli and Caltagirone, 1977) have reported that the mean group differences on constructional tasks by subjects with unila teral lesions tend to be negligible. A particular aspect of this problem is the incidence of constructional apraxia in aphasia. Some authors (Hecaen, 1962; Zangwill, 1964; Benton, Levin and Van Allen, 1973) have remarked on the frequent occurrence of constructive disabilities in aphasic patients with posterior lesions of the left hemisphere, but other authors (Warrington et al., 1966; Dee, 1970) have failed to find any relationship, within the left brain-damaged patients, between the incidence of aphasia and of con structional apraxia.
1
Clinic for Nervous and Mental Diseases of the Catholic University ot Rome.
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Relationships between visuoconstructive and visuoperceptive disabilities in relation to laterality of cerebral lesions Even more open to controversy is the problem of the neurodynamic mechanisms underlying constructional apraxia in right and left hemispheric lesions. Clinical investigations (McFie, Piercy and Zangwill, 1950; Duensing, 1954; Ettlinger, Warrington ad Zangwill, 1957; McFie and Zangwill, 1960; Piercy et al., 1960; Arrigoni and De Renzi, 1964; Warrington et al., 1966; Gainotti and Tiacci, 1970; Gainotti, Messerli and Tissot, 1972; Collignon and Rondeaux, 1974) have stressed the existence of clearcut qualitative differences between the drawing disability of right and left brain-damaged patients, since the former show chiefly an inability to reproduce spatial relationships, whereas the latter tend to give coherent but simplified versions of the model. On the ground of these qualitative differences, the right sided constructive impairment has been regarded as a manifestation of "perceptual" disability, whereas the left-sided constructional apraxia has been conceived as reflecting a "motor-executive" disorder. Experimental studies designed to evaluate this hypothesis have ·given conflicting results. Thus Costa and Vaughan (1962) and Warrington and James ( 196 7) have claimed that the intercorrelations between visuoperceptive and visuocon structive tests are higher in right than in left brain-damaged patients, but this finding has not been confirmed by Piercy and Smyth ( 1962 ), De Renzi and Faglioni (1967), Dee (1970) and Gainotti and Tiacci (1972), who have shown that the basis for visuoconstructive disturbances is a perceptual di sorder, independently of the hemispheric locus of lesion. On the other hand, Warrington et al. ( 1966) and Hecaen and Assai (1970) have obtained data supporting the view that left-sided, but not right-sided apraxia, is due to a planning disorder, but their results have not been confirmed by Gainotti et al. (1977). In our opinion, this confusing situation is due, in part at least, to me thodological reasons. Some authors have studied constructional apraxia or visual-perceptual disabilities, by means of very complex tasks that are ge nerally used to obtain measures of general intelligence and not to assess specific disorders. For example, Costa and Vaughan (1962) and Black and Strub ( 197 6) have used the W AIS Block Designs to measure construc tional apraxia and Costa and Vaughan (1962), Piercy and Smyth (1962) and Gainotti and Tiacci (1972) have used Raven's Progressive Matrices to obtain estimate of the patients' visual perceptual functioning. Since impairment on a complex task may result from a variety of specific deficits (as well as from diffuse mental impariment) such tests do not seem appropriate to study specific visuoconstructive or visuoperceptive disabilities. More ap propriate for this aim are simple tests making only limited demands on
Constructional apraxia and visuoperceptive disabilities
465
general intelligence. The first purpose of the present research consisted, therefore, in checking, by means of a simple test of copying drawings (Ben ton's Visual Retention Test, Administration C) the incidence of construc tional apraxia in right and left brain-damaged patients. The second aim was to study the relationships between constructional apraxia and visuopercep tive disabilities in the same groups of brain-damaged patients, by means of two different versions of the same test: one (constructive test) involving graphomotor activity, the other (visuoperceptive test) involving only an activity of visual form discrimination.
MATERIAL AND METHOD
Subjects
Thirty-six control subjects, SO right and 43 left brain-damaged patients were submitted to examination. All patients were drawn from the Neurology and Neurosurgery services of the University Hospital of Pisa. Control subjects had been hospitalized because of psychoneurosis or of neurological lesions situated below the level of the cervical spine. Within the brain-damaged groups, diagnosis of the affected side was made on the ground of the clinical findings supplemented by available EEG, brain scan and neuroradiological data. No selection was made in forming the groups, but left-handed subjects, patients with diffuse of obviously bilateral hemispheric damage and subjects unable to maintain the set necessary to carry out the task were excluded. Furthermore, in order to rule out the effect of diffuse cerebral damage (caused, for example, by brain edema) all patients were studied after the acute phase of illness. No significant differences were found between normal controls and brain damaged patients in relation to age and educational level. Furthermore, no signi ficant difference was found between right and left brain-damaged patients in relation to etiology of illness and presence or absence of visual field defects. The only difference found between the two hemispheric groups consisted in the higher age of left (56.3) compared to right (48.6) brain-damaged patients (t = 2.07; p < .05). Testing procedures Praxis test
The Visual Retention Test (V.R.T.), Administration C (copying), was used as a graphomotor test of constructional praxis (Benton, 1962). Performances on the test were not evaluated on the basis of the usual criteria (which consist in subtracting from an assumed perfect score of 26 the total number of errors) but on the ground of a scoring system analogous to the one proposed by Arrigoni and De Renzi ( 1964 ). Each figure was scored 2 points for essentially correct reproduc tions, 1 point if the reproduction was partly defective (owing to omission of some lines, rotation, distortion or size errors) but not to such an extent as to prevent the identification of the figure, and 0 points for unrecognizable reproductions. In assigning the points we were deliberately liberal in regard to any imperfec tion which did not impair the essential characteristics of the model, and which might be the consequence of the use of the non-dominant hand. In order to rule
R. Arena and G. Gainotti
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out the effect of unilateral spatial agnosia, the attention of the patients was directed towards possible omissions and the patient was asked to copy figures omitted the first time. The maximum score obtainable with this scoring system was 74.
Perceptual test Perceptual ability was assessed by means of a 15 items, multiple choice version of the V.R.T., Administration M, used as a test of visual form discrimi nation (Benton, 1951). Each item was mounted singly on a card bearing in its upper part the stimulus model and in its lower part 4 more or less similar designs. The patient had to designate which of these 4 designs was the one drawn on the upper part of the card. The score of this test was the sum of the correct choices, the maximum score being 15. Assessment of aphasia In addition to the praxic and the perceptual versions of the V.R.T., left brain-damaged patients received the shortened version of the Token Test recently proposed by De Renzi and Faglioni (1975) in order to assess the presence and severity of aphasia. Cutting scores provided for this version of the Token Test (corrected for educational background) correctly classify more than 90% aphasic patients. On the basis of the results obtained with this version of the Token Test, 23 left brain-damaged patients were considered aphasic. RESULTS
Incidence of constructional apraxia and hemispheric locus of lesion
The incidence of constructional apraxia in right and left brain-damaged patients was assessed by taking as cut-off point between "normal" and "pathological" performances the score of 50, attained or exceeded by all but one the control subjects. Eleven right (37%) and 16 left (37%) brain damaged patients obtained scores lower than the cut-off and were defined as apraxics. In order to obtain a better estimate of the results obtained by right and left brain-damaged patients, the significance of the differences be tween normal controls, right and left brain-damaged patients was estimated by means of the Mann-Whitney's U Test (Table I). TABLE I
Comparison between the Means Obtained by Normal Controls, Right and Left Brain-Damaged Patients on the Test of Constructional Praxis Control subjects (N = 36) 64.03 Controls vs. Right B.D.P.: z = 2.994 (p Controls vs. Left B.D.P.: z = 3.873 (p Right vs. Left B.D.P.: z = 0.560 (p
Right B.D.P. (N = 30)
Left B.D.P. (N = 43)
52.03
48.58
= .0014) = .00007) = n.s.)
Constructional apraxia and visuoperceptive disabilities
467
Table I shows that both brain-damaged groups score significantly worse than normal controls but that no significant difference is found between patients with lesion of either the right or the left cerebral hemisphere. Visual perceptual disabilities in right and left brain-damaged patients
Again, scores obtained by normal controls were used to discriminate the "normal" from the "pathological" performances of patients with cerebral lesions. Sixteen right (53.3%) and 20 left (46.5%) brain-damaged patients did not exceed the score of 9, attained by the worst control subjects. Their performance was therefore considered pathological. No significant difference was found between the two hemispheric groups (chi2 = 0.11). When the = 13.14) scored means of the three groups were compared, controls significantly higher (p < .001) than both right brain-damaged patients (x = 9.83) and left brain-damaged patients (i = 9.98), while no significant difference between the two hemispheric groups was obtained.
(x
Relationships between constructional apraxia and visuoperceptive disabilities in right and left brain-damaged patients
Given our working hypothesis that constructional apraxia is due to a visual perceptual disorder in right but not in left brain-damaged patients, the following outcomes are predicted: (1) Apraxic right brain-damaged patients should obtain significantly lower scores than non-apraxic right brain-damaged patients on the perceptual test. No such relation should be observed among the patients with lesions of the dominant hemisphere. (2) A close correlation should be found within the right, but not within 1 the left brain-damaged patients, between scores obtained on the "praxic" and scores obtained on the "gnosic" form of the Benton V.R.T. Table II shows that neither of these 2 assumptions was confirmed. In fact, contrary to the hypothesis, the relationship between· praxic and percep tual scores was somewhat higher in left than in right brain-damaged patients. TABLE II
Perceptual Means of Apraxic and Non-apraxic Right and Left Brain-Damaged Patients Left hemisphere
Right hemisphere Non-apraxics 19) {N
=
Apraxics {N = 11)
Non-apraxics
10.58
7.64
11.59
t
= 2.15 {p < .05)
{N
= 27)
t = 4.57 {p
Apraxics
{N
= 16)
7.25
< .01)
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R. Arena and G. Gainotti
The corresponding correlation coefficients (r) were: .69 (p .46 (p < .05), respectively.
< .001)
and
Constructional apraxia and visuoperceptive disabilities in aphasic patients
Benton ( 197 3) has shown, in a recent paper, that a close association exists, within left brain-damaged patients, between constructional apraxia and sensory aphasia. Since an impressionistic analysis of the unexpected results obtained by our left brain-damaged patients seemed to confirm this claim, we undertook a separate analysis of the scores obtained on the gra phomotor and on the perceptual test by the 23 left hemispheric patients considered aphasic on the ground of the results obtained on the Token Test. Incidence and severity of constructional apraxia
On the praxic test a pathological score was obtained by 13 (57%) out of 23 aphasic patients. This incidence was significantly higher than that (15%) found in the group of non-aphasic left brain-damaged patients (chi2 = 6.22; p < .01) although not significantly greater than the incidence ( 37%) found in the right hemispheric group (chi2 = 1.82; p = n.s. ). However, when the mean of aphasic patients (39.00) was compared to the mean of right hemispheric patients (52.03) with the Mann-Whitney's U test, a significant z = 2.36 (p = .0089) was obtained, pointing to the inferior performance of aphasics. Incidence and severity of perceptual disabilities
Similar results were obtained on the perceptual test. The incidence of pathological performances was higher among aphasic subjects ( 16 out of 23 = 70%) than in any other brain-damaged group, but only the compa rison with non-aphasic left brain-damaged patients reached statistical signi ficance (chi2 = 8.33; p < .01). However, .aphasics were found significantly impaired in comparison to right hemispheric patients when a t-test was used (t = 2.33; p < .05). Relationship between results obtained on the graphomotor and the perceptual version of the V.R.T.
Table III reports data relative to the relationships between praxic and perceptual scores in aphasic and non-aphasic left brain-damaged patients. These data show that the significant association between the two disorders, previously found in the left hemispheric group, holds for aphasics only.
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469
TABLE III
Relationships between Results Obtained on the Graphomotor and the Perceptual Version of the V.R.T. by Aphasic and Non-Aphasic Left Brain-Damaged Patients
Relationships between normal and pathological performances Aphasics (N = 23) Perceptual
Non-aphasics (N=20) Perceptual
+
+
+ 6 4 Graphomotor - - - chP = 7.30 (p
+
2
12
1
Note. The sign
+ 14 3 Graphomotor - - -
<
.01)
1
chi2 = 0.387 (p = n.s.)
means a normal performance; the sign -
a pathological performance.
Means obtained on the perceptual test by apraxic and non-apraxic patients Aphasics Non-apraxics Apraxics (N=10) (N=13) 10.70 6.46 t = 3.29 (p < .01)
Non-aphasics Non-apraxics Apraxics (N
= 17)
(N
= 3)
12.12 10.67 t = 0.86 (p = n.s.)
Correlation coefficients between scores obtained at the graphomotor and at the perceptual test r
Aphasics (p < .001)
= 0.70
Non-aphasics left B.D.P. r = 0.39 (p = n.s.)
Relationship between severity of aphasia and results obtained on the graphomotor and on the perceptual version of the V.R.T.
To further clarify the bearing of aphasia on the performances obtained on the two tests, the correlations between Token Test· scores and scores of the praxic and of the perceptual test were computed in the aphasic patients. Both correlation coefficients were statistically significant (r = 0.59; p < .01 for the graphomotor test and r = 0.66; p < .001 for the perceptual test). There were, however, exceptions to this trend, as shown by the following three aphasics, who were remarkably impaired on the Token Test and, nevertheless, scored in a normal range on the graphomotor test: patient 53 had a Token Test score of 16 and a graphomotor test score of 58, patient 65 had a Token Test score of 15 and a graphomotor test score of 56 and patient 69 had a Token Test score of 20 and a graphomotor test score of 55.
470
R. Arena and G. Gainotti DISCUSSION
The main findings of the present research may be summarized as follows: ( 1) No difference was found between right and left brain-damaged
patients, when these groups were compared for incidence and severity of visuo-constructive disabilities. This finding is at variance with the outcome of some previous studies, but in agreement with the results obtained by Warrington et al. (1966), De Renzi and Faglioni (1967), Behson and Barton (1970), Dee (1970), Hecaen and Assai (1970), Gainotti and Tiacci (1972), Benton (1973), Colombo, De Renzi and Faglioni (1976) and Gai notti et al. ( 1977). Two considerations seem in order. First, it is important to stress that we took care to counteract the bearing on the performance of unilateral spatial agnosia which is likely to be at least in part responsible for the poor scores of right brain-damaged patients reported in the literature. Second, our results suggest that most of the contrasting results reported in literature are due to sampling differences from one study to another. This problem had already been raised by Costa and Vaughan ( 1962), Arrigoni and De Renzi ( 1964) and Warrington et al. ( 1966) and has been recently evaluated by Benton (1973), who has shown that: if left brain-damaged patients with severe receptive aphasia are excl~ded from the study (because of their inability to understand the instructions and so on), the performance of the left hemispheric group is likely to be clearly superior to that of patients with right hemispheric damage; if, on the contrary, the left-sided group includes a substantial proportion of aphasic patients, its overall performance is likely to be comparable to that of the right hemispheric group. This claim finds support in De Renzi's (1977) observation that the incidence of constructional apraxia reported by various authors is fairly stable in right brain-damaged patients (ranging from 32 to 40% ). On the contrary, the incidence of visuoconstructive disabilities observed by the same authors in left brain-damaged patients is much more variable (range 14-32% ). In our research, where even the most severe aphasic patients could be examined, because of the elementary nature of the task, the incidence of constructional apraxia was in the expected range ( 37% ) for the right brain-damaged patients, whereas it was higher (37%) than pre viously noticed in the left hemispheric group. (2) No difference was found between the two hemispheric groups on
the test of visual form discrimination. This finding is more surprising, since the greatest part of the neuropsychological literature reports a greater impariment of right brain-damaged patients in tasks involving complex perceptual discrimination. Since the left brain-damaged group was significantly older than the
Constructional apraxia and visuoperceptive disabilities
471
right brain-damaged group, we controlled whether age and perceptual scores were correlated in normals: a non significant r = 0.16 was found and, thus, the discrepancy with respect to the literature cannot be accounted for by age. We are inclined to think that also in this case the special care we took not to exclude severe aphasics may explain the impairment of the left brain-damaged group. In fact, since aphasics have been found to score poorly on the visuo-perceptual test, it is apparent that their inclusion in the sample influences the mean score of patients with left hemispheric damage. (3) The relationship between graphomotor and perceptual score was
higher in left than in right brain-damaged patients. This finding is at variance with the claim of Costa and Vaughan (1962) and of Warrington and James ( 196 7) that the intercorrelations between perceptual and praxic tasks are higher in right than in left hemispheric patients. The close correlation found in our research between praxic and perceptual scores in left brain-damaged patients was due chiefly to the poor performances obtained on both tasks by aphasic patients. If we assume that the most severe aphasic patients were probably excluded from the studies accomplished by Costa and Vaughan (1962~ and by Warrington and James (1967), since their n~uro psychological battery included tests demanding sustained attention and understanding on the part of the patients, the difference between their results and our findings can find a satisfactory interpretation. According to our hypothesis, the relationship between perceptual and graphomotor tasks may be expected to be lower in a given group whenever a sampling bias has led to the exclusion of extensive retro-rolandic lesions in that group. The correlation between praxic and perceptual scores should, in contrast, be e<;~.ually significant in both right and left brain-damaged patients, when no sampling bias exists between the two hemispheric groups. , ( 4) Relationship between aphasia and poor performance on the grapho fnotor and petceptual test. Two different interpretations can be advanced to explain the poor performance of aphasic patients on both the praxic and the perceptual version of the V.R.T.: (a) aphasia is not directly responsible for graphomotor and visuopercep tive disabilities, but is simply coincidental with them, owing to the encroachment of the lesion upon the posterior (pariet<>-'temporal) regions of the left hemisphere, which subserve both linguistic and visual-spatial functions; (b) aphasia per se is responsible of the poor performances obtained by aphasic patients both on the praxic and on the perceptual version of the V.R.T. . In the prese~t study we tried to clarify this issue by studying the association between Token Test scores and scores obtained on the praxic and perceptual test, but the outcome of the correlation analysis was not
472
R. Arena and G. Gainotti
conclusive. Interest correlations were highly significant in aphasics, but the occurrence in the aphasic group of at least 3 patients who, despite a marked impariment on the Token Test, obtained normal scores on the graphomotor task, argues against a direct bearing of the language deficit upon the praxic and perceptual impairment. In conclusion, the results of the present research support Benton's claim that a significant relationship exists between aphasic and visuo-constructive disturbances (Benton, 1973; Benton et al., 1973), but further investigations are needed to clarify the meaning of this association.
SUMMARY
The main purpose of the present study was to determine whether construc tional apraxia is due to a visual perceptual disorder in right but not in left brain damaged patients. In order to resolve this question, 36 normal controls and 73 brain-damaged patients with lesions restricted to, the right (N = 30) or to the left (N = 43) cerebral hemisphere were given a graphomotor and a multiple choice version of the Benton Visual Retention Test. The graphomotor version of the V.R.T. was used as a test of constructional praxis, whereas tbe multiple choice version of the V.R.T. was used as a test of visual form discrimination. No differences was found between right and left brain-damaged patients with respect to incidence and severity of visuo-constructive and of visuo-perceptive disabilities. Contrary to the hypothesis, the relationship between perceptual and praxic tasks was higher in left than in right brain-damaged patients. The high level of correlation found between graphomotor and perceptual scores within the left hemispheric group· was due chiefly to the poor performances obtained on both tasks by aphasic patients. These findings are interpreted as suggesting that the basis for visuoconstructive disturbances is a perceptual disorder, independently of the hemispheric side of lesion. The contrasting results of our intercorrelational study and of analogous studies reported in neuropsychological literature are interpreted as ·being due to sampling differences, in the absence of clearcut qualitative or quantitative differences between visuo-constructive disabilities of right and left brain-damaged patients. REFERENCES ARRIGONI, G., and DE RENZI, E. (1964) Constructional apraxia and hemispheric locus of lesion, Cortex, 1, 170-197. BENSON, D., and BARTON, M. (1970) Disturbances in constructional ability, Cortex, 6, 19-46. BENTON, A. L. (1951) Manuel du Test de Retention Visuelle. Application Cliniques et Experi mentales, Centre Psycho!. Appl., Paris. (1962) The visual retention test as a constructional praxis task, Confin. Neurol. 22, 141-155. (1973) Visuoconstructive disabilities in patients with cerebral disease: its relationship to side of lesion and aphasic disorder, Documents Ophtalmologica, 34, 67-76. - , and FOGEL, M. L. (1%2) Three-dimensional constructional praxis: a clinical test, Arch. Neurol., Chicago, 7, 347-354. - , LEVIN, H. S., and VAN ALLEN, M. W. (1973) Constructional apraxia and aphasic disorder.
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Communication at the Annual Meeting .of the Academy of Aphasia, Albuquerque, New Mexico, 28-30 october. BLACK, F. W., and STRUB, R. L. (1976) Constructional apraxia in patients with discrete missile wounds of the brain, Cortex, 12, 212-220. CoLLIGNON, R., and RoNDEAUX, J. (1974) Approche clinique des modalites de l'apraxie con structive secondaire aux lesions corticales hemispberiques gauches et droites, Acta Neurol. Belg., 74, 137-146. CoLOMBo, A., DE RENZI, E., and FAGLIONI, P. (1976) The occurrence of visual neglect in pa tients with unilateral cerebral disease, Cortex, 12, 221-231. CosTA, L. D., and VAUGHAN, H. G. (1962) Performance of patients with lateralized cerebral lesions. I: Verbal and perceptual tests, ]. Nerv. Ment. Dis., 134, 162-168. DEE, H. L. (1970) Visuoconstructive and visuoperceptive deficit in patients with unilateral cerebral lesions, Neuropsychologia, 8, 305-314. DE RENZI, E. (1977) L'aprassia costruttiva, in: BISIACH, E., et al., « Neuropsicologia Qinica » Franco Angeli, Milano. - , and FAGLIONI, P. (1967) The relationship between visuospatial impairment and construc tional apraxia, Cortc;x, 3, 327-342. - , - (1975) L'esame dei disturbi afasici di comprensione orale mediante una versione ab breviata del test dei gettoni, Riv. Pat. Nerv. Ment., 96, 252-269. DuENSING, F. (1954) Raumagnostische und ideatorischapraktische Storung des gestaltenden Handelns, Dtsch. Z. Nervenheilk, 170, 72-94. ETTILINGER, G., WARRINGTON, E., and ZANGWILL, 0. L. (1957) A further study of visual-spatial agnosia, Brain, 80, 335-361. GAINOTTI, G., MEssERLI, P., and TISSOT, R. (1972) Troubles du dessin et lesions bemispberi ques retrorolandiques unilaterales gauches et droites, Encephale, 61, 245-264. - , MICELI, G., and CALTAGIRONE, C. (1977) Constructional apraxia in left brain-damaged patients: a planning disorder?, Cortex, 13, 109-118. , - , and TIACCI, C. (1970) Patterns of drawing disability in right and left hemispheric patients, Neuropsychologia, 8, 379-384. - , - (1972) Sui rapporti tra aprassia costruttiva, agnosia visuo-spaziale ed agnosia spaziale unilaterale, Riv. Pat. Nerv. Ment., 93, 103-116. H:EcAEN, H. (1962) Clinical symptomatology in right and left hemispheric lesions, in Interhemi spheric Relations and Cerebral Dominance, ed. by B. V. Mountcastle, Johns Hopkins Press, Baltimore. - , and AssAL, G. (1970) A comparison of constructive deficit following right and left hemi spheric lesions, Neuropsychologia, 8, 289-303. McFIE, ]., PIERCY, M., and ZANGWILL, 0. L. (1950) Visual spatial agnosia associated with lesions of the right hemisphere, Brain, 73, 167-190. - , and ZANGWILL, 0. (1960) Visual-constructive disabilities associated with lesions of the left , cerebral hemisphere, Brain, 83, 243-260. NEWCOMBE, F. (1969) Missile Wounds of the Brain, Oxford University Press, London. PtERCY, M. F., HEcAEN, H., and AJURIAGUERRA, J. (1960) Constructional apraxia associated 1 with unilateral cerebral lesions, Brain, 83, 225-242. -f.., and SMYm, V. (1962) Right hemisphere dominance for certain non-verbal intellectual skills, Brain, 85, 775-790. WARRINGTON, E. K., and }AMES, M. (1967) Disorders of visual perception in patients with localized cerebral lesions, Neuropsychologia, 5, 253-266. - , - , and KINSBOURNE, M. (1966) Drawing disability in relation to laterality of cerebral lesion, Brain, 89, 53-82. · ZANGWILL, 0. L. (1964) Intelligence in aphasia, in Disorders of Language, ed. by A. V. S. De Ruech and M. O'Connors, CIBA Foundation Symposium, Little Brown, Boston.
Guido Gainotti, M.D., Clinica Neurologica, Universita Cattolica, Largo A. Gemelli, 8, 00168 Roma, Italy. Roberto Arena, M.D., 2• Clinica Neurologies dell'Universita di Pisa, Pisa, Italy.