Disturbances of Tactile Sensitivity in Patients with Unilateral Cerebral Lesions

DISTURBANCES OF TACTILE SENSITIVITY IN PATIENTS WITH UNILATERAL CEREBRAL LESIONS!

Amiram Carmon

(Department of Neurology, Hadassah-Hebrew University Medical School, Jerusalem)

INTRODUCTION

The contralateral innervation of the somatosensory receptors by the cerebral hemispheres is an accepted tenet. Almost all textbooks of neurology suggest that the expected consequence of damage to the somatosensory projections in one hemisphere is somatosensory impairment restricted to the contralateral side of the body with no appreciable defect on the ipsilateral side. However, a survey of the literature of clinical neurology shows that from time to time excep~ tions to this rule were noted in the form of case reports describing bilateral or ipsilateral somatosensory disturbances in patients with apparently unilateral hemispheric lesions.

Perhaps the earliest clinical contribution of this type was that of Oppenheim (1906) who described bilateral disturbances in stereognosis in a patient with a left hemispheric lesion and who discussed the possible role of the left hemisphere in mediating more complex sensory functions on both the contralateral and the ipsilateral sides of the body. In 1908, Goldstein (d. Goldstein, 1927) described leftsided disturbances in tactile sensitivity in a patient with a lesion of the corpus callosum. He inferred that the left hemisphere subserves sensitivity on both sides of the body, since the blocking of impulses from the right hemisphere to the left by a callosal lesion was a

! Based on a Ph. D. Dissertation, Department of Psychology, University of Iowa_ The investigation was done in the Neurosensory Center and Depiartment of Neurology, University of Iowa College of Medicine, and was supported by Research Grant NS-00616 and Program-Project Grant NS-03354. Neurosensory Center Publication No. 206.

84 A. Carmon

possible explanation for his finding in this case. Later, Goldstein (1927) reported another patient with a lesion in the left hemisphere who showed bilateral disturbances of tactile sensitivity. Discussing these findings, he attributed the mediation of simple tactile sensations on the left s,ide of the body to the right hemisphere but regarded the left hemisphere as controlling the higher tactile sensory functions, especially those of a spatial nature (e.g., sense of position, tactile localization, stereognosis) on both sides of the body.

Similar observations were made by Foix (1922) who descl'ibed patients with not only the expected contralateral sensory deficit in all modalities but also disturbances of position sense and stereognosis on the ipsilateral side. Six out of his seven cases had lesions of the left hemisphere and were aphasic while the remaining non-aphasic patient had a lesion of the right hemisphere. Foix regarded the ipsilateral sensory deficits as disturbances in recognition of the same order as those seen in visual agnosia rather than as basic sensory disturbances. Another case of this type was reported by Guillain, Alajouanine and Garcin (1925), who described a left-handed patient with a .right hemispheric lesion and with astereognosis and loss of position sense on the right side but without impairmentin sensitivity to touch and pin prick on this side.

While all the patients described in these early papers exhibited disturbances complex sensory functions involving spatial cues and object recognition, a series of six cases with bilateral disturbances of sensitivity to simple touch, pressure, pain and vibration stimuli were reported in 1934 by Bychowsky and Eidinow. All six patients had lesions of the right hemisphere and showed disturbances in tactile sensitivity on the ipsilateral as well as on the contralateral side of the body. The authors contrasted their findings with those of the authors who had attributed bilateral control of tactile recognition only to the left hemisphere. To strengthen their contention that the phenomenon could also be observed in right hemisphere lesions, Bychowsky and Eidinow cited (without specific reference) three further cases of bilateral disturbances in tactile sensitivity, all of whom had disease of the right hemisphere, which had been reported by Kraus and Schum.

Korner (1938) attempted to check the validity of the BychowskyEidinow report by testing patients with unilateral hemispheric lesions with somewhat more reliable methods of examination including a graduated series of von Frey hairs which was used for determination

Tactile sensitivity in unilateral brain lesions 85

of the absolute threshold. In her clinical material, she found seven patients, four with lesions in the left and three with lesions of the right hemisphere, who had bilateral sensory disturbances, the deficit being more marked on the side contralateral to the lesion.

Taking all these studies and case reports into account, the number of patients with unilateral lesions who were reported as having bilateral disturbances in tactile sensitivity is rather small. This would create the impression that such disturbances are rare, a view reflected by contemporary textbooks of clinical neurology, which usually mention only the contralateral disturbances. However, it must be borne in mind that the reason for the paucity of such cases may not be due to the rarity of the condition but rather to a methodological bias in the tactile examination of patients with cerebral lesions as well as to the rather inadequate character of the techniques for sensory assessment used in the typical clinical examination.

_ In spite of the early availability of precise instrumentation for measuring tactile sensitivity (d. Carmon and Dyson, 1967), the common practice among clinicians who observed disturbances in tactile sensitivity in cases of hemispheric lesions was to make crude assessments of the sensitivity on one side of the body and to compare them with performance on the other side. This approach was not only technically inadequate, but also was based on a doubtful methodology which defined tI disturbance" on the basis of a difference in sensitivity between the two sides of the body, without regard to overall level of sensitivity.

Head (1920), who used rather precise methods of investigation of tactile sensitivity, did not report bilateral sensory disturbances in any of the 23 patients with unilateral lesions which he studied with great detail. However, his judgements were based only on comparisons of sensitivity on the two sides of the body of the same patient without reference to normal data.

It appears reasonable to assume that the majority of the studies evaluating tactile sensory impairment were based on the assumption that sensitivity on the side ipsilateral to the lesion was normal. Since this was the procedure which supplied most of the data in this area, the claim that ipsilateral as well as contralateral sensory disturbances such as increased threshold may occur, cannot be dismissed.

It is evident that a basic question, namely, the definition of impairment in terms of quantitative deviation of the performance from that of a comparable normal population, was not answered by

86 A. Carmon

the early studies. This problem was solved by the major study of Semmes, Weinstein, Ghent and Teuber (1960) of tactile sensitivity levels in a large sample of patients with traumatic unilateral and bilateral cerebral lesions. They employed an objective and systematic type of measurement and compared the performances of their patients with those of a sample of patients free from cerebral lesions. All patients were given four somatosensory tests applied in a uniform and systematic manner to both hands: a) determination of the threshold to pressure induced by a series of graduated nylon mono@aments; b) two-point discrimination threshold was performed through the use of a manual compass; c) a point-localization test in the form of successive two-point discrimination; and d) sensitivity to passive movement. The results were reported in terms of frequency of impairment, with impairment defined as a score deviating by more than 2.46 S.D. ("moderate deficit") or 3.08 S.D. ("severe deficit") from the mean of the control group. These values correspond to the .01 and .001 levels of probability respectively.

Three findings of the study of Semmes and her co-workers bear directly on the present investigation: (1) 16 patients in the group with left hemisphere lesions and 7 in the group with right hemispheric lesions showed disturbances in tactile sensitivity of the ipsilateral hand (with or without impairment on the contralateral hand); (2) impairment in tactile sensitivity of the right hand were specifically associated with lesions of the sensorimotor area. No such association was found however for the left hand, i,e., the frequency of impairment was not significantly different in lesions in various part of the right hemisphere; and (3) impairment in tactile sensitivity in the right hand was likely to involve all the tests administered, while in the case of the left hand a statistical association was not found between impairments of pressure sensitivity and point localization.

The authors summarized the results in the form of the following conclusions: "The evidence ... suggests that sensation of the left hand is more diffusely represented in the contralateral hemisphere than that of the right hand; that sensation of the left hand is frequently affected by lesions of the ipsilateral sensorimotor region; and that the nature of sensory impairment of the left hand is not the same as that of the right hand" (Semmes et aI., 1960, p. 52).

The present study was designed to investigate the following questions which arose from the clinical and experimental data that have been reviewed:


1. Do bilateral or ipsilateral somatosensory impairments occur in unilateral hemispheric lesions?

2. Are such disturbances differentially associated with damage to one or to the other hemisphere?

3. Do disturbances of tactile sensitivity show different trends of association within the same hand in patients with right and with left hemispheric lesions?

4. Do disturbances in tactile sensitivity show different trends of association between the two hands in patients with right and with left hemispheric lesions?

In order to answer these questions, three tests of tactile sensitivity were applied to both hands of patients with lesions confined to one or the other cerebral hemisphere and to control subjects. The tests were absolute threshold for pressure, differential threshold for pressure and tactile resolution (two-point discrimination).

MATERIAL AND METHOD

Subjects

Two experimental groups were used, a group of patients with lesions localized in the right hemisphere (RH) and a group with lesions localized in the left hemisphere (LH). The patients were drawn from the population of all cases admitted during the period. of the study to the Department of Neurology, University Hospitals, Iowa City, and to the Neurology Service of the Veterans Administration Hospital, Iowa City. All patients in whom the existence of a cerebral lesion apparently confined to one of the hemispheres had been established clinically by neurological examination and by at least one special diagnostic procedure (radioactive brain scan, penumoencephalography, angiography, ventriculography, EEG) were examined, with the exclusion of comatose, aphasic or disoriented patients. In each group there were 27 patients, 18 males and 9 females. Mean age was 49.5 years in the RH group and 48.6 years in the LH group. The cerebral lesions were localized in the frontal region in 8 RH patients and in 7 LH patients, in the temporo-parietal region in 12 RH and 11 LH patients, and involved a large portion of the hemisphere in 7 RH and 9 LH patients. Fourteen patients in each group had a localized vascular lesion (occlusion of artery, infarction or hematoma), 9 had

88 A. Carmon

tumors, while 4 patients in the LH and 3 in the RH group had traumatic injury of the brain. The remaining patient in the RH group had localized loss of brain tissue, presumably due to a degenerative process.

Thirty-eight patients (mean age 45.9 years) who had been admitted for non-neurological disorders or in whom it had been established that they did not suffer from cerebral, upper spinal cord or peripheral nerve disease, constituted a control group. These patients were drawn from the population available during the same period of time as the experimental groups and were divided randomly into two subgroups for control of the order of hands examined.

Procedure

The apparatus used was an electromechanical tactile stimulator which has been described in detail elsewhere (Carmon and Dyson, 1967). In the experimental groups, stimulation was presented in an ABBA order, with the hand ipsilateral to the lesion examined first and last. In the control group the order of testing was right hand first, left second for one subgroup of 19 patients and left hand first, right second for the other subgroup of 19 in an ABBA order.

Test of absolute threshold for pressure

Starting with the ascending order of stimuli (12 weights of .002 to 40.96 gm and an area of 1.77 mm2

), each stimulus was presented four times in a randomized block of 4 stimulations and 4 "nonstimulations" in which the instrument was activated but the stimulator was displaced so as not to touch the hand. The ascending order was terminated whenever a subject responded correctly to all stimulations within a given block. When the ascending order· was completed, a descending order was initiated with stimuli with an intensity two ranks above the one which defined the upper level of the ascending order. This order was continued until the first block of stimuli to which a failure (false negative or false positive) occurred. The locus of stimulation was a 5 X 5 rom area in the second intermetacarpal space, 1 cm proximal from the interdigital fold. The duration of stimulation was 1 sec with a 3 sec interstimulus interval.


Test of successive differential threshold for pressure

The stimuli for comparison were given for each hand in the following order of successive comparisons: ascending, standard stimulus (with weight of 8 gm and area of 12.38 mm2

) first (1), descending, comparison (same area, 6 weights 2-64 gms) first (2), descending, standard first (3), and ascending, comparison first (4). The duration of the stimulation was 1 sec, and the interstimulus interval between standard and comparison stimuli was 1 sec. The interval between successive comparisons was 5 sec. The locus of stimulation was an area of 1 cm2 in the center of the palm, as determined and marked by a concentric-rings grid.

T est of tactile resolution (two-point threshold)

Two stimuli with weight of 20 gm and area of 12.38 mm2 were used. The sequence of stimulation was: ascending order for the ipsilateral hand; ascending order for the contralateral hand; descending order for the contralateral hand; descending order for the ipsilateral hand. Each order was given in the following steps: from 2 to 11 mm in one mm steps, from 11 to 18 mm in 2 mm steps, from 19 to 27 mm in 3 mm steps and from 28 to 35 mm in 4 mm steps. By random assignment, 6 stimulations with a single stimulator were inserted into each mder. A transverse line across the center of the palm was the locus of stimulation. The duration of the stimulation was 1 sec, with 3 sec interstimulus interval.

Scores for all three tests were based on 100% correct responses, averaged for the ascending and descending order.

RESULTS

The mean scores and standard deviations of the scores on the three tests for each hand in each group are shown in Table 1.

The first questions investigated were whether the relatively small differences between the thresholds for the right and left hands of the control patients were significant and whether the order of testing significantly affected performance in these patients. A Type I analysis of variance (Lindquist, 1956) was employed to answer these questions. In no instance did the main within effect of laterality or the effect of order (tested by utilizing the between-subgroups within-hands interac-

90 A. Carmon

TABLE I

Tactile Sensitivity Test Scores

Right hand Left hand Mean SD Mean SD

Absolute threshold (gm) RH group 4.72 13.36 22.85 27.34 LH group 10.97 23.48 1.15 2.29 Controls .435 .356 .612 .519

Differential threshold (gm) RH group 13.29 17.57 31.42 31.26 LH group 25.61 28.20 10.63 6.60 Controls 9.09 6.63 9.49 7.17

Two-point threshold (mm) RH group 13.79 9.82 21.37 13.14 LH group 17.43 13.60 13.75 10.68 Controls 7.85 3.34 7.66 2.64

tion term) approach the .05 significance level. Thus it could be assumed that neither the hand tested nor the order of testing were significantly related to the tactile sensitivity scores in the control patients and that it was valid to compare the performances of the two groups of brain-damaged patients even though a different hand was tested first in each group.

Separate analyses of variance were run to assess and compare the performances of the brain-damaged patients on each test. For both groups combined, the difference between the sensitivity levels of the ipsilateral and the contralateral hand was significant for each test, the respective F's (df 1/52) being 18.4, 20.1 and 11.6. There was no significant interaction between the right and left hemispheric groups with respect to this difference on any of the tests, the respective F's (df 1/52) for interaction being 1.7, 0.2 and 1.5. The two groups did not differ in overall level of sensitivity, the respective F's (df 1/52) being 0.7, 0.6 and 0.5, nor did they differ in respect to level of sensitivity in the ipsilateral hand alone. In summary, the results of these analyses indicate that sensitivity was poorer in the contralateral hand than in the ipsilateral hand on all three tests and that the two groups did not differ in respect to this relationship.

As Table I shows, the variability of the threshold scores of the brain-Iesioned patients was considerably higher than those of the control patients. This difference in variability was particularly large


with respect to the absolute pressure thresholds. In order to make comparisons between the ipsilateral hands of the brain-lesioned patients and the corresponding hands of the controls more meaningful, the scores on the absolute threshold test were transformed by using their natural logarithms. A similar transformation did not appear to be required for the other two tests.

The results of comparisons (in terms of F values) between the ipsilateral hand of the patients and the corresponding hand of the controls are shown in Table II. As will be seen, the ipsilateral hand of the patients in both groups showed a significant impairment in tactile resolution (two-point threshold) as compared to the controls. A similar impairment in the absolute pressure sensitivity in both brain-lesioned groups is also evident. On the other hand, no significant impairment in differential pressure sensitivity of the ipsilateral hand in either group is demonstrable, although a trend toward higher thresholds in the brain-lesioned groups is apparent (Table I).

TABLE II

F-Values (df = 1,63) for Comparisons Between Means of Thresholds of the Ipsilateral Hands of the Patients and the Hands of the Controls

Test

Absolute pressure threshold Differential pressure threshold Tactile resolution

* F < .01 (d£ 1,65) = 7.04 ** F < .05 (d£ 1,65) = 3.99

RH vs. Controls

6.89** 1.48

10.88*

LH vs. Controls

4.84** 0.58

11.07*

A second analysis of the data followed the procedure of Semmes et aI. (1960) in which the number of patients showing significant impairment in relation to the performances of controls is determined. The mean and SD's of the scores of the control patients on each test were computed and two critical values, X + 2.46 SD (.01 probability level) and x: + 3.08 SD (.001 probability level) were derived. The number of brain-lesioned patients whose scores exceeded these values was then determined.

Table III shows the number of patients in the RH and LH groups who showed defects in the ipsilateral hand. It will be noted that, in agreement with the previous analysis, a substantially higher propor-

92 A. Carmon

tion of patients showed impairment in absolute pressure sensitIvIty and tactile resolution than in differential pressure sensitivity. Ten (37 per cent) of the 27 patients in the RH group and 11 (41 per cent) of the 27 patients in the LH group showed ipsilateral impairment on one or more of the three tests as defined by a score exceeding the value of X + 2.46 SD for the control group. In summary, the results of both analyses indicate that ipsilateral impairment of tactile sensitivity was characteristic of a substantial proportion of patients in both the RH and LH groups. However, there are no indications that the two groups differed with respect to the relative frequency of such ipsilateral defects.

TABLE III

Number of Patients with Ipsilateral Defects (Exceeding Semmes et al. Criteria)

Test ExceedingM+2.46 SD* ExceedingM+3.08 SD**

RH LH RH LH


5 3 8

4 1 9

* This SD value corresponds to the .01 level of probability. ** This SD value corresponds to the .001 level of probability.

4 1 6

3 o 7

Table IV shows the number of patients in the RH and LH groups who showed defects in the contralateral hand on each test. As would be expected, the figures are considerably higher than for the ipsilateral

TABLE IV

Number of Patients with Contralateral Defects (Exceeding Semmes et al. Criteria)

Test ExceedingM+2.46 SD* ExceedingM+3.08 SD**

RH LH RH LH


16 9

13

10 9

10

* This SD value corresponds to the .01 level of probability. ** This SD value corresponds to the .001 level of probability.

13 8

13

8 8

10


hand. Moreover, a substantial number of patients showed impairment in differential pressure sensitivity on the contralateral hand while this was rare in the ipsilateral hand. However, it will be noted that the number of such patients was less than the number of patients showing impairment in absolute pressure sensitivity and tactile resolution on the contralateral hand.

The strength of the associations among the three tactile performances was assessed by computing product moment correlation coefficients between pairs of scores for each hand in each group of patients. The results are shown in Table V. It will be seen that in the control group there were no significant correlations among the performances. In both groups of brain-damaged patients, performance levels on the contralateral hand were significantly intercorrelated and to about the same degree. In the RH group, performance levels on the ipsilateral (i.e., right) hand were not significantly intercorrelated. In contrast, the ipsilateral (i.e., left) hand of the LH group showed two significant associations (absolute vs. differential pressure .thresholds and absolute pressure vs. two-point thresholds).

TABLE V

Correlations Between Levels of Sensitivity in the Same Hand

AT vs. DT AT vs. TR DT vs. TR

Control group Right hand .24 -.10 .03 Left hand .15 -.10 -.07

RH group Ipsilateral (right) hand .13 .26 -.01 Contralateral (left) hand .65* .48* .44**

LH group Ipsilateral (left) hand .46* .46* .24 Contralateral (right) hand .51 * .61* .52*

AT = Absolute Threshold; DT = Differential Threshold; TR = Tactile Resolution. * p < .01

** P < .025

The association between deficits (as contrasted to levels of sensitivity) in the same hand was assessed by determinIng the numbers of cases in each group that showed only one deficit or combinations of more than one deficit. In the contralateral hand, 5 LH and 7 RH patients showed impairment on all three tests, 4 LH and 5 RH

94 A. Carmon

patients showed impairment on two tests, and 5 LH and 6 RH patients showed impairment on only one test. In the ipsilateral hand, no patient showed impairment on all three tests, 3 LH and 6 RH patients showed impairment on two tests, and 7 LH and 4 RH patients showed impairment on only one test. In summary, there were no suggestions of a significant difference between the hemispheric groups in respect to the clustering of deficits and the results did not support the indications in the correlational analysis of a closer association of performance levels in the ipsilateral (left) hand of the LH group than in the ipsilateral (right) hand of the RH group.

The relationships between levels of sensitivity in the contralateral and ipsilateral hands of the RH and LH groups (and in the right and left hands of the control group) were similarly assessed. Table VI shows the correlation coefficients for each test across the two hands. All the correlations were positive and significant. The high correlations in the control group are particularly striking. The size of the correlations between the two hands do not appear to be different in the RH and LH groups.

TABLE VI

Correlations Between Levels of Sensitivity ,of the Two Hands

Control group RH group LH group

* p < .01 ** p < .025

Absolute threshold

.61*

.38**

.41*

Differential threshold

.87*

.65*

.45*

DISCUSSION

Tactile resolution

.72*

.59*

.48*

The findings of the study are in accord with the results of Semmes, Weinstein, Ghent and Teuber that bilateral and ipsilateral impairment in tactile sensitivity are shown by a substantial proportion of patients with unilateral cerebral disease. However, there were no indications that the frequency of such bilateral or ipsilateral defects was differentially associated with hemispheric locus of lesion. In the present study, about the same proportion of patients with left or with right hemisphere disease showed impairment on the ipsilateral hand; this result agrees with those reported by Corkin, Milner and Rasmussen


(1964) in their investigation of the sensory effects of cortical excisions in patients with focal epilepsy.

Significant impairment of sensitivity in the ipsilateral hand was found for the absolute pressure threshold and two-point discrimination but not for the differential pressure threshold. With respect to the last measure, ipsilateral thresholds were not significantly higher than those found in control patients. The highest frequency of ipsilateral impairment was found in the two-point discrimination threshold. Corkin, Milner and Rasmussen reported a particularly high frequency of ipsilateral impairment in point localization, a performance which was not investigated in the present study.

Levels of sensitivity on the three tests did not correlate significantly among each other on either hand in the control patients. These findings confirm the previous observations of Semmes et al. In contrast, there were significant positive correlations of substantial magnitude between these performances for the contralateral hand in both hemispherically damaged groups. Performances on the ipsilateral (left) hand of the LH group were positively intercorrelated, significantly so in 2 of the 3 correlations. However, the correlation coefficients among the performances for the ipsilateral (right) hand of the RH group were small and non-significant. Thus the results indicate different patterns of sensory impairment for the ipsilateral hand in left and right hemispherically damaged patients rather than a difference between the right and left hands, as suggested by Semmes and co-workers. A direct comparison with the findings of the Semmes study is possible only for two measures, namely, the absolute pressure and two-point discrimination thresholds. Semmes et aL found a correlation coefficient of .57 between the two measures for the right hand as compared to a correlation coefficient of .36 for the left hand in their total group of brain-injured patients (presumably including those with bilateral lesions). The findings of the present study (Table V) show no bias toward a higher correlation between these measures for the right hand as compared to the left.

Performance on the three tests by the two hands was found to be positively intercorrelated in all three groups of patients. Unexpectedly, the correlation coefficients across hands were somewhat higher for the control patients than for either brain-injured group. This finding was all the more surprising in view of the non-significant within-hand correlations among the sensory measures in the control patients (Table V).

96 A. Carmon

SUMMARY

The primary purposes of this study were to determine the relative frequency with which patients with unilateral cerebral disease show bilateral or ipsilateral defects in tactile sensitivity and to determine whether patients with lesions of the left hemisphere differ from those with lesions of the right hemisphere in this regard as well as with respect to pattern of tactile performance.

The absolute pressure threshold, the differential pressure threshold and tactile resolution (two-point discrimination threshold) on the contralateral and ispilateral hands were measured in patients with unilateral cerebral disease. The same determinations were made for the right and left hands in a group of control patients without evidence of history of cerebral disease.

The major findings of the study were: (1) Bilateral or ipsilateral impairment in tactile sensitivity was shown

by a substantial number of patients with unilateral cerebral disease. (2) Patients with disease of the left hemisphere showed essentially the

same frequency of bilateral or ipsilateral defects as did patients with disease of the right hemisphere.

(3) The three sensory measures showed significant positive correlations for the contralateral hand in both hemispherically damaged patients. However, the two groups differed with respect to performance pattern on the ipsilateral hands; while the three measures were positively intercorrelated for the ipsilateral (left) hand of the patients with lesions of the left hemisphere, the correlation coefficients among the same measure for the ipsilateral (right) hand of the patients with lesions of the right hemisphere were small and non-significant.

( 4) Performance on the sensory tests across the two hands was found to be positively intercorrelated in all three groups of patients.

Acknowledgment. I am greatly indebted to Professors A. L. Benton and H. P. Bechtoldt, who supervised the dissertation, for their encouragement and guidance.

REFERENCES

BYCHOWSKY, G., and EIDINOW, M. (1934) Doppelseitige Sensibilitiitsstorungen bei einseitigen Gehirnherden, "Nervenarzt," 7, 498-506.

CARMON, A., and DYSON, J. A. (1967) New instrumentation for research in tactile sensitivity and discrimination, "Cortex," 3, 406-418.

CORKIN, S., MILNER, B., and RASMUSSEN, T. (1964) Effects of different cortical excisions on sensory thresholds in man, "Trans. Amer. Neurol. Ass.," 89, 112-116.

Forx, C. (1922) Sur une variete de troubles bilateraux de la sensibilite par lesion unilaterale du cerveau, "Rev. neurol.," 29, 322-331.

GOLDSTEIN, K. (1927) Die Lokalisation in der Grosshirnrinde, in Handbuch der normalen und pathologischen Physiologie, ed. by A. Bethe, G. Bergmann, G. Embden and A. Ellinger, Berlin.

GUILLAIN, G., ALAJOUANINE, T., and GARCIN, R. (1925) Un cas d'apraxie ideomotrice


bilaterale co'incidant avec une aphasie et une bemiparesie gauche chez une gauchere. Troubles bilateraux de la sensibilite profonde, "Rev. neurol.," 2, 116-124.

HEAD, H. (1920) Studies in Neurology, London. KORNER, S. C. (1938) Die Beeinflussbarkeit der Sensibilitat an symmetrischen Haut

gebieten bei einseitiger Hirnschadigung und bei Gesunden, "Dtsch. Z. Nervenheilk.," 145, 116-130.

LINDQUIST, E. F. (1956) Design and Analysis of Experiments in Psychology and Education, Boston.

OPPENHEIM, H. (1906) Ober einen bemerkenswerten Fall von Tumor cerebri, "Berl. klin. Wschr.," 13, 1001-1004.

SEMMES, ]., WEINSTEIN, S., GHENT, 1., and TEUBER, H.-1. (1960) Somatosensory Changes After Penetrating Brain Wounds in Man, Cambridge, Massachusetts.

Dr. A. Cannon, Department of Neurology, Hadassah·Hebrew University Medical School, P. O. Box 499, Jerusalem, Israel.

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Disturbances of Tactile Sensitivity in Patients with Unilateral Cerebral Lesions