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Manual Approach During Hand Gesture Imitation
Jay C. Kwon, MD;
Sue J. Kang, MS;
Byung H. Lee, MA;
Juhee Chin, MA;
Kenneth M. Heilman, MD;
Duk L. Na, MD
Arch Neurol. 2002;59:1468-1475.
ABSTRACT
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Background Patients' tendency to draw near or into the target when copying figures,
a phenomenon termed closing-in, has been previously
described. That the closing-in could occur when copying hand gestures has
also been noted.
Objectives To study a patient with corticobasal degeneration to quantify his manual
approach behavior and to test a possible working memory hypothesis.
Methods The subject of this study is a patient with severe ideomotor apraxia
from probable corticobasal degeneration. Fluorine 18labeled deoxyglucosepositron
emission tomographic findings revealed a hypometabolism involving the bilateral
parietotemporal and the right frontal lobes. When asked to copy an examiner's
(J.C.K.) hand gesture, the patient approached, touched, or grasped the examiner's
hand, a behavior mostly consistent with the closing-in behavior previously
proposed. To investigate the frequency and severity of closing-in, the patient
was asked to copy 20 meaningless hand gestures (10 simple and 10 complex).
Copying the 20 hand gestures was performed with either the left or the right
hand while the patient was seated opposite the examiner (across condition)
or on the same side of the examiner (lateral condition).
Results Of the 80 trials, closing-in occurred in 43 (53.8%) (35 with approaching,
6 with touching, and 2 with grasping). The closing-in was more frequent and
more severe when gesturing with the left than the right hand, but it did not
differ between the lateral and across conditions and between simple and complex
gestures.
Conclusions Corticobasal degeneration might be associated with aberrant manual approach
behavior. Although our results do not support the working memory hypothesis,
frontal dysfunction might have led to a loss of voluntary control of ontologically
primitive propensity to move the forelimb in the direction to which one attends.
INTRODUCTION
MANY STUDIES have reported phenomena in which the patient's hand unintentionally
approaches or grasps environmental objects or parts of the examiner's body.
These approach phenomena include grasp reflex,1-4
magnetic apraxia,5 utilization behavior,6 and compulsive manipulation of objects associated
with an alien hand.7-10
Recently, we examined and tested a patient with severe ideomotor apraxia associated
with probable corticobasal degeneration (CBD). When asked to copy the examiner's
(J.C.K.) hand gesture, the patient approached, touched, or grasped the examiner's
hand, behaviors consistent with the "closing-in" sign of Mayer Gross.11 In this study, we wanted to quantify this approach
behavior and test a working memory hypothesis that might account for closing-in.
REPORT OF A CASE
Our patient was a 68-year-old right-handed man who was a former bus
driver. The patient had no formal education but was literate in Korean. He
had been healthy until 4 years ago, when he developed clumsiness in the left
hand and an unsteady gait. Three years ago, he became amnesic, misplacing
items in the house and forgetting details of recent events. Two years ago,
he developed bradykinesia and a decreased left arm swing while walking. Around
that time, he also showed occasional twitching (myoclonic jerks) in the left
arm and hand. One year before our examination, he developed dressing apraxia.
For the past few months, the patient's wife occasionally noted that, while
eating with the right hand, the patient's left hand involuntarily hit the
right hand or the dishes. Also, twitching of the left hand increased in severity
and extended to the right hand.
The results of a cranial nerve examination were significant only for
hypometric saccades; his extraocular movements were full. His strength was
normal in all limbs, but a pronator drift was noted in the left arm. Two-point
discrimination was decreased bilaterally, and graphesthesia was decreased
in the left hand. His tendon reflexes were more active on the left than the
right side. There was moderate rigidity in all limbs, more marked on the left
side. Bradykinesia was noted with decreased facial expression. Tremor was
not observed, but intermittent myoclonus was present in both arms, being more
prominent on the left side. His gait was normal in stance and stride, with
no festination, but his left arm swing was decreased. Grasp reflexes were
elicited bilaterally, with repeated tactile stimulation of the palm. Snout,
sucking, and glabellar reflexes were not present.
He scored 18 of a possible 30 on the Mini-Mental State Examination.
On gesture production to verbal command or to imitation, both hands showed
severe ideomotor apraxia, more marked on the left side; the left hand movements
were unrecognizable, and the right hand gestures had severe spatial and content
errors. When asked to imitate nonsense hand gestures with the right hand,
the patient's hand unintentionally approached or touched the examiner's hand.
With an instruction not to touch the examiner's hand, the approaching behavior
stopped temporarily but reappeared after several trials. These unusual behaviors
prompted us to perform an experiment, described later. The results of other
neuropsychological tests were as follows: decreased digit span, forward 4
(27th percentile) and backward 2 (13th percentile); fluent speech with intact
comprehension and repetition but decreased naming (Boston Naming Test score,
31 of 60 [seventh percentile]); reading was intact, but writing showed apraxic
agraphia; Rey-Osterrieth Complex Figure copy score, 3 of 36 (<16th percentile);
Hopkins Verbal Learning Testfree recalls over 3 trials, 6 of 36 (<16th
percentile), and with 20-minute delayed recall, 0 of 12 (<16th percentile);
decreased fluency on a controlled oral word association test (phonemic word
fluency with 3 letters, 0 [<16th percentile]; and semantic word fluency
with animal and supermarket items, 22 [16th percentile]); markedly impaired
at motor set shifting (fist-edge-palm) bilaterally; and perseveration on the
Luria triple loop test. To elicit utilization behavior, the patient was presented
with various objects, such as tissue, cups, and pens, within his reach, but
the patient did not use them.
His vitamin B12 serum level, thyroid function test results,
and serologic results for syphilis were normal. A brain magnetic resonance
imaging scan revealed diffuse atrophy with few white matter ischemic changes;
the right lateral ventricle was larger than the left lateral ventricle. Brain
fluorine 18labeled deoxyglucosepositron emission tomographic
findings revealed a hypometabolism involving both parietotemporal areas and
the right frontal lobe, but the most severe abnormality was located in the
right parietal area (Figure 1).
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Figure 1. Fluorine 18labeled deoxyglucosepositron
emission tomographic scan of the patient. There is hypometabolism involving
the right frontal lobe and the bilateral parietotemporal regions (the right
region is worse than the left region). R indicates right side; L, left side.
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HAND GESTURE COPYING TASK
After obtaining informed consent, a hand gesture copying task was performed.
We used 20 meaningless hand gestures, as illustrated in Figure 2 and Figure 3.
To divide them into 10 simple and 10 complex gestures, we asked 6 healthy
graduate students to rate the complexity of each gesture on a 5-point scale
(1 indicates very easy; 2, easy; 3, moderate; 4, difficult; and 5, very difficult).
According to the mean score of each gesture, the 10 gestures ranked in the
top 10 (mean ± SD of the complexity rating, 3.42 ± 0.89) were
considered complex and the remaining 10 (mean ± SD of the complexity
rating, 1.40 ± 0.51) were considered simple (paired t test, P<.001).
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Figure 2. A and B, results of copying hand
gestures (left hand). The patient's left hand imitated the examiner's (J.C.K.)
left hand (the patient was wearing the multicolored shirt). The procedure
was videotaped, and the still picture with maximum "closing-in" was selected
for presentation. The hand gesture in the left upper corner of each lateral
picture represents the target gesture. The number in the left lower corner
of each picture represents the severity rating of closing-in (0 indicates
no approach; 1, approach but no touch; 2, touch or overlap the examiner's
hand; and 3, grasp the examiner's hand). Pictures were ordered from the simplest
to the most complex gestures (see the "Hand Gesture Copying Task" section
for further explanation). Simple indicates simple gestures; complex, complex
gestures; lateral, the patient was seated on the same side of the examiner
(lateral condition); and across, the patient was seated on the opposite side
of the examiner (across condition).
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Figure 3. A and B, results of copying hand
gestures (right hand). The patient's right hand imitated the examiner's (J.C.K.)
right hand (the patient was wearing the multicolored shirt). The procedure,
hand gesture in the left upper corner of each lateral picture, number in the
left lower corner of each picture, and abbreviations are explained in the
legend to Figure 2. Pictures were ordered from the simplest to the most complex
gestures (see the "Hand Gesture Copying Task" section for further explanation).
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Copying the 20 hand gestures was performed with either the left or the
right hand while the patient was seated opposite the examiner (across condition)
or on the same side of the examiner (side-by-side or lateral condition). Therefore,
there were 4 different test conditions (right vs left hand x across
vs lateral) in which the patient imitated the 20 gestures, a total of 80 trials.
The sequence of the 4 conditions was as follows: acrossright hand,
lateralright hand, acrossleft hand, and lateralleft hand.
For each condition, the 20 gestures were presented in random order. All procedures
were videotaped by a digital videocamera held 1 m above the examining table.
In the lateral and the across conditions, the patient's right hand imitated
the examiner's right hand and the patient's left hand imitated the examiner's
left hand. In the lateral condition, the patient was seated on the left side
of the examiner in the left hand copying condition and on the right side of
the examiner in the right hand copying condition. In each trial, before the
stimulus was presented, the patient was asked to put his right or left hand
on the table with the palm facing the ceiling and all the fingers extended
(neutral hand gesture). The initial positions of the patient's and the examiner's
hands were adjusted such that (1) the intersection of the wrist crease and
the tendon of palmaris longus (called the wrist point) was aligned with each
individual's midaxillary line; (2) in each individual, the distance between
the wrist point and the midsternum was approximately 300 mm; and (3) the distance
between the patient's wrist point and the examiner's wrist point was approximately
350 mm in the across and the lateral conditions. Before the experiment, the
patient was instructed to perform the praxis in the designated place, but
during the experiment, this instruction was not repeated. After each trial,
the patient's hand was relocated to the original position. Before stimuli
were presented, the examiner's hand was covered with white A4 size paper to
prevent the patient from seeing the examiner's hand. Twenty seconds were allowed
for each gesture after removing the white paper from the examiner's hand.
SCORING
Two psychometricians (B.H.L. and J.C.) blinded to the clinical information
rated the patient's response on the videotape. First, the raters assessed
the accuracy of hand gestures as either correct or incorrect. Hand gestures
were considered accurate when the configuration and the orientation were correct.
Second, the raters quantified the severity of closing-in as follows: 0, no
approach; 1, approach but no touch; 2, touch or overlap the examiner's hand;
and 3, grasp the examiner's hand. Interrater reliability was obtained for
the accuracy of gesture copying and the severity of closing-in.
RESULTS
INTERRATER RELIABILITY AND ACCURACY OF PRAXIS
The interrater reliability for the accuracy rating of hand gestures
was 0.88 (P<.001) by correlation; and
for the severity rating of closing-in, 0.85 (P<.001)
by Spearman rank correlation.
The accuracy of gesture copying is presented in Table 1 and in Figure 2
and Figure 3. In the lateral condition,
the patient performed correctly on 12 (7 with the right and 5 with the left
hand) of the 20 (10 left and 10 right) simple gesture trials and on 3 (1 right
and 2 left) of the 20 complex gesture trials (Table 1). In the across condition, correct responses were observed
on 16 (9 right and 7 left) of the 20 simple and on 1 (0 right and 1 left)
of the 20 complex gesture trials. Overall, copying simple gestures was more
accurate than copying complex gestures (P<.001,
McNemar test).
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Results of Accuracy of Praxis and Frequency and Severity of "Closing-in"
on Hand Gesture Copying
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FREQUENCY AND SEVERITY OF CLOSING-IN
The results of the frequency and severity of closing-in are presented
in Table 1 and in Figure 2 and Figure 3.
Closing-in occurred in 43 (53.8%) of the 80 trials. Of the 43 trials with
closing-in, 35 (81.4%) had closing-in of the first degree (approach but no
touch), 6 (14.0%) of the second degree (touch or overlap the examiner's hand),
and 2 (4.6%) of the third degree (grasp the examiner's hand). Closing-in was
more frequent when the gesture copying was performed with the left (frequency,
27 of 40 gestures) vs the right (frequency, 16 of 40 gestures) hand (P = .02, McNemar test). The severity scores of closing-in
were also greater on gesture copying with the left (mean ± SD, 0.88
± 0.79) than with the right (mean ± SD, 0.45 ± 0.60)
hand (P = .01, Wilcoxon signed rank test). There
were no significant differences, however, in the frequency and severity of
closing-in between the across and lateral conditions and between the simple
and complex items. Specifically, in the lateral and the across conditions,
the frequencies of closing-in were 23 of 40 and 20 of 40, respectively (P = .63, McNemar test); the mean ± SD severity scores
of closing-in were 0.75 ± 0.81 and 0.58 ± 0.64, respectively
(P = .24, Wilcoxon signed rank test). With the simple
and complex hand gestures, the frequencies of closing-in were 26 of 40 and
17 of 40, respectively (P = .06, McNemar test); the
mean ± SD severity scores of closing-in were 0.75 ± 0.63 and
0.58 ± 0.81, respectively (P = .28, Wilcoxon
signed rank test).
COMMENT
Our patient had several asymmetrical (left worse than right) abnormal
signs of the forelimbs, including rigidity, bradykinesia, apraxia, myoclonus,
and agraphesthesia. Our patient also had cognitive deficits. A brain magnetic
resonance imaging scan revealed asymmetrical (right worse than left) atrophy
of the cerebral hemisphere, and fluorine 18labeled deoxyglucosepositron
emission tomographic findings showed frontal and temporoparietal hypometabolism
that was also more severe in the right hemisphere. These findings are compatible
with the diagnosis of CBD.
When copying meaningless hand gestures, the patient's hand approached
the examiner's hand. Our patient's approach behavior differs from grasp reflex2-4 and instinctive grasp
reaction,1, 12 which are elicited
only by tactile stimuli of the palm and are not associated with praxis. Behaviors
characterized by manipulation of objects within one's reach have been described
in patients with anarchic hand syndrome7-10
or utilization behavior.6 Neither medical history
taking nor a bedside examination, however, showed such behaviors in our patient.
Our patient's approach behavior may resemble the magnetic apraxia described
by Denny-Brown.5 The original patient of Denny-Brown
grasped bedclothes or objects and had difficulties in relaxation. The use
of the hand was awkward and clumsy even when there was nothing in contact
with the palm. Before grasping, the whole limbs tended to stiffen. For example,
when the patient attempted to write, the hand stiffened and seemed to stick
to the paper. Denny-Brown suggested that magnetic apraxia was driven by the
intact parietal lobe that was disinhibited by frontal lobe dysfunction. Our
patient's behavior may differ from magnetic apraxia in that his approach behavior
was restricted to praxis performance and there was no stiffness or inability
to relax.
There have been a few reports that described approach behavior in patients
with CBD. In the original report of CBD, Rebeiz et al13
noted that 2 of the 3 patients had an aberrant manual approach (ie, one of
their hands would approach the other hand). Recently, Jacobs et al14 described a patient with CBD whose hands, feet, and
mouth were drawn toward the examiner's hands when the examiner's hands passed
close to these areas. These magnetic responses, however, may differ from our
patient's approach behavior because the magnetic response of our patient occurred
exclusively when copying hand gestures.
Our patient's behavior is most compatible with the closing-in phenomenon
described by Mayer Gross,11 who observed a
tendency to come close to the target when drawing.15
He also stated that the closing-in occurred when copying hand gestures. To
our knowledge, however, studies of closing-in when copying hand gestures have
not been performed thereafter.
On bedside examination, we had the impression that our patient had severe
manual approach because even touching and grasping occurred frequently and
consistently. In the experiment, however, touching or grasping occurred only
in 8 (10%) of the 80 trials. This difference might be due to the experimental
methods: before the experiment, the patient was instructed to perform praxis
in the designated place, and after each trial, the patient's hand was relocated
to the original place by the examiner.
Regarding the mechanism of closing-in, Mayer Gross11
postulated that the behavior results from "the fear of empty space." Two years
later, Muncie15(p11) suggested that closing-in
results from "the inability to make an abstract copy from a concrete model."
More recently, by observing the closing-in phenomenon in patients with degenerative
dementia and in 2- to 6-year-old healthy children, Gainotti16
insisted that closing-in is similar to other phylogenetically more primitive
behaviors (grasping, sucking, echolalia, or echopraxia) that normally are
inhibited by higher cortical areas.
We posited that this approach behavior or closing-in might occur as
a strategy to overcome visual-perceptual or working memory deficits. When
copying hand gestures, a patient has to compare his or her own hand with the
examiner's hand. As the distance between the patient's and the examiner's
hands increases, the demands on working memory might become greater. A failure
to correctly imitate hand gestures may be caused by a compromise in visual-kinesthetic
working memory. Therefore, patients with visual-kinesthetic working memory
deficits might move toward the examiner's hand to reduce the demands on working
memory. Based on this hypothesis, we expected that approach behavior would
be more frequent or severe with complex than with simple gestures and in the
across than in the lateral condition because more complex gestures and the
across condition require greater demands on visual-kinesthetic working memory.
Contrary to our expectations and the observations of Mayer Gross,11 the frequency and severity of closing-in did not
vary in terms of the location of the examiner and the complexity of the gesture.
Therefore, our results do not support the working memory hypothesis.
There may be alternative explanations for the manual approach that our
patient demonstrated. While the patient might have touched or grasped the
examiner's hand in an attempt to enhance the copying performance by using
the tactile modality in addition to the visual modality, this explanation
could not account for the predominant response (approach without touch). We
suspect that the manual approach of our patient may be related to directed
spatial attention. When a person attends to a visual stimulus, the person's
eyes automatically move to a position that allows the attended image to fall
on the fovea. For example, when a person is following a moving object, a cortical
area, such as the middle temporal and medial superior temporal areas, computes
the spatial trajectory of this object's movement and provides this information
to the oculomotor system. Although normally people can voluntarily alter the
direction of their gaze so that they do not foveate the object to which they
are attending, with frontal lesions they lose this voluntary control (visual
grasp).17-18 While less robust
than the oculomotor system, humans also have a tendency to move their hands
and head to the region of space to which they are attending.19
Perhaps with the frontal-subcortical dysfunction that is associated with CBD,
voluntary control is diminished and this tendency to act in the direction
to which one is attending becomes manifest, leading to the manual approach
behavior we describe.
AUTHOR INFORMATION
Accepted for publication February 25, 2002.
Author contributions: Study
concept and design (Drs Kwon and Na, and Mss Kang, Lee, and Chin); acquisition of data (Dr Kwon, and Mss Kang and Lee); analysis and interpretation of data (Drs Kwon, Heilman,
and Na, and Mss Lee and Chin); drafting of the manuscript (Drs Kwon and Na); critical revision of the manuscript
for important intellectual content (Drs Kwon, Heilman, and Na, and
Mss Kang, Lee, and Chin); obtained funding (Dr Na); administrative, technical, and material support (Drs Kwon
and Na, and Mss Kang, Lee, and Chin); study supervision (Drs Heilman and Na).
Corresponding author and reprints: Duk L. Na, MD, Department of Neurology,
Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong
Kangnam-ku, Seoul 135-710, Korea (e-mail: dukna{at}smc.samsung.co.kr).
From the Departments of Neurology, Samsung Medical Center, Sungkyunkwan
University School of Medicine, Seoul, Korea (Drs Kwon and Na, Mss Kang, Lee,
and Chin), and the University of Florida and the Veterans Affairs Medical
Center, Gainesville (Dr Heilman). Dr Kwon is now affiliated with the Department
of Neurology, Changwon Fatima Hospital, Changwon, Korea.
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