Movement Disorders Vol. 6 , No. 1, 1991, pp. 29-35 0 1991 Movement Disorder Society

Is Focal Hand Dystonia Associated with Psychopathology? Jordan Grafman, “Leonard0 G. Cohen, and *Mark Hallett Cognitive Neuroscience Section and *Human Motor Control Section, Medical Neurology Branch, NINDS, NIH, Bethesda, Maryland, U.S.A.

Summary: The purpose of this study was to determine if patients with focal

hand dystonia have any significant psychopathology. We studied 20 patients with hand cramps who were participating in a therapeutic trial of botulinum toxin injections. Patients were interviewed and administered the Minnesota Multiphasic Personality Inventory (MMPI), Beck Depression Inventory, Spielberger State-Trait Anxiety Scale, a finger tapping test, and a choice serial reaction time test. Behavioral ratings were also obtained. Group statistics indicated that all personality scale scores and performances on motor tasks were within normal limits. Four out of 20 patients demonstrated mild depression. Trait anxiety scores were higher than state anxiety scores, suggesting that receiving medical treatment had a beneficial effect on mood. The number of depressive symptoms endorsed on the MMPI was correlated with reaction time speed but not finger dexterity. None of the 20 patients reported a remarkable psychiatric history. These results indicate that hand cramps are not associated with serious psychopathology. Key Words: Focal dystonia-Psychopathology .

there still persists the clinical suspicion among some that focal dystonia is due to a neurosis or can be thought of as a psychosomatic illness. However, in order to make the diagnosis of a psychiatric disorder, there needs to be positive evidence of psychopathology. Very few controlled studies have claimed a psychiatric etiology for hand cramps. Anxiety has occasionally been proposed as an etiologic factor in the development of hand cramps. Harrington et al. (9) examined whether there was a relationship between writer’s cramp and anxiety. They measured writing speed, observed muscle cramps, and writing behavior, and administered a set of scales designed to assess traits and symptoms associated with neurotic illness and anxiety. Four out of their 22 subjects reported a history of psychiatric disorder (two patients were depressed, and two suffered from anxiety neurosis). The results of their study indicated no difference between controls and patients on the anxiety scales. Overall, writing was slower in

Focal dystonias of the hand, sometimes called “hand cramps,” have a variety of expressions affecting different functional skills (1). In an individual, hand cramps are task specific, involving only a single skill; the most common is writer’s cramp, which affects writing. Recent studies of focal hand dystonia highly suggest that it is a central nervous system disorder (2,3), although some have considered it as having a psychiatric etiology (4-6). Until recently, both behaviorally oriented and medical therapies have generally been ineffective in ameliorating or reducing the severity of the disorder (7). A recent attempt to treat focal dystonias with botulinum toxin injections has been at least partially successful (8). Despite evidence that the focal dystonias are due to a central nervous system disorder, ~~

Address all correspondence and reprint requests to Dr. Grafman at Cognitive Neuroscience Section, Medical Neurology Branch, NINDS, NIH, Bldg. 10, Room 5C422, Bethesda, MD 20892. U.S.A.

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J . GRAFMAN ET AL.

the writer’s cramp patients than in normals. No evidence was found to associate anxiety level with writer’s cramp. Wieck et al. (10) further examined the psychogenic hypothesis by evaluating the effects of relaxation training or “habit reversal” training (a behavioral method) in treating hand cramps in 20 patients. No difference was found between treatments, although both treatments resulted in some minor improvement in the hand cramps. Nevertheless, patients remained substantially handicapped despite the minor improvements. Similar results were found in a prior study by Cottraux et al. (11). A number of other studies have argued that hand cramps either result from an improper habitual grip of an instrument or develop as part of a neurotic disorder and can be successfully treated with behavioral and therapeutic methods (5,12-15). However, when Fahn and Williams (16) reviewed their experience with dystonia, they reported that only 21 of 793 patients seen in their clinic had a documented psychogenic disorder. The general impression from the clinical literature is that psychiatrists and psychologists view hand cramps as a functional disorder, whereas neurologists are convinced that hand cramps are the result of central nervous system dysfunction. Besides neurotic and anxiety disorders, other psychiatric disorders such as conversion disorder, somatization disorder, and factitious disorder have been proposed to account for hand cramps. Since there continues to be some disagreement among clinicians and researchers as to the cause of hand cramps, controlled studies are needed to resolve the dispute. To examine the hypothesis that focal dystonias may be due to a psychiatric disorder, we administered several standardized personality scales to an unselected series of patients being treated for hand cramps with botulinum toxin. An observer rating of each patient’s behavior was also obtained. Two tests of motor performance were also administered: a test of finger dexterity and a test of serial choice reaction time. These tests were chosen to obtain a sample of objective motor performance that could be compared to psychopathology scores. We hypothesized that if psychopathology was responsible for focal hand dystonia, then a strong relationship should exist between objective motor performance and many of the personality scale scores or individual items that represented a patient’s tendencies towards somatization of psychological distress.

Movement Disorders, Vol. 6, No. I , 1991

METHODS Patients Patients participating had a clinical diagnosis of writer’s cramp (or musician’s cramp) in the absence of peripheral nerve or cervical root abnormalities. The mean age of the patients at the time of our examination was 46.7 (SD = 12.17) years, and mean education level achieved was 16.1 (SD = 2.82) years. Other patient characteristics are noted in Table 1 . All patients in our study had an abnormal neurological examination indicative of hand cramps (3). Other central nervous system disorders were ruled out on the basis of the neurological examination, neurophysiological studies, and neuroradiological evaluation. The patients cognitive status was judged to be within normal limits given their work and social history, responses on a self-report questionnaire, and their performance on a mental status evaluation. All patients were currently undergoing treatment with botulinum toxin for their hand cramps. More information about patients with hand cramps and the effectiveness of the botulinum toxin treatment can be found in an earlier article (8). Tests Patients were administered a set of standard personality tests designed to elicit symptoms of depression, anxiety, and subtle personality disorders. Each patient also participated in a brief history interview and were behaviorally rated by the test examiner on the Neurobehavior Rating Scale, an analogue of the Brief Psychiatric Rating Scale. Finally, each patient performed on a finger tapping task (estimating digit dexterity) and a test of serial choice reaction time (estimating response speed and visuomotor learning). All the tests and scales are listed in Table 2 along with a brief description of each. Testing Procedure Patients completed the personality inventories and scales as well as the motor tasks in one session lasting -3 h. The motor tasks were administered after a brief history was taken. Following the motor tasks, the patients filled out the personality inventories and scales. One patient was unable to complete all the tests (he could not take the serial choice reaction time test because of a computer failure).

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HAND DYSTONIA AND PSYCHOPATHOLOGY TABLE 1. Patient characteristics SEX

OCCUPATION

HANDEDNESS

AGE AT ONSET

DURATION

DISABILITY

TYPE OF CRAMP

R

41

6

N

P

WRIT ING

R

51

9

Y

PIANO PLAYING

54

5

Y

S S

20

43

Y

P

3

Y

D

10

Y

D

N

D

WRITING-TYPING WRITING-BUTTONING

2

Y

D

DRUM PLAYING

BOTH

17

Y

D

VIOLIN PLAYING

BOTH

12

Y

D

WRITING-SEWING

R

11

Y

D

WRITING-EATING

R

30

1

Y

S

PIANO PLAYING

R

R

25

5

N

D

WRITING TYPING

R

PATIENT

AGE

A

47

F

HOMEMAKER

B C

60 58

M M

PIANO PLAYER COURT STENOGRAPHER

R

D

63

F

SECRETARY

R

E

26

M

PIANO PLAYER

R

23

F

54

M

SCHOOLTEACHER

R

44

G

62

F

ACCOUNTANT

R

44

18

H

35

M

DRUM PLAYER

R

33

I

44

M

VIOLINIST

R

27

J

58

F

BOOKKEEPER

R

46

K

62

M

ENGINEER

R

51

L

31

M

PIANO PLAYER

R

M

30

F

ACCOUNTANT

TASK

HAND AFFECTED

R BOTH

TYPING

L

WRITING-TYPING PIANO PLAYING-TYPING

R R R

BOTH

N

40

F

BAGPIPE PLAYER

R

34

6

N

S

BAGPIPE PLAYING

L

0

37

M

OFFICER

R

33

4

N

D

WRITING-TYPING

R

P

35

F

COURT STENOGRAPHER

R

0

58

M

EXECUTIVE

R

R

47

F

HOMEMAKER

S

47

F

HOMEMAKER

T

40

M

SALESMAN

R

Y

S

TYPING

L

53

5

N

D

WRITING-TYPING-BANJO

R

L

41

6

N

D

WRITING-TYPING-SEWING

L

R

42

5

N

S

WRITING

R

21

19

N

D

WRITING-GOLF PLAYING

R

~

~

This table emphasizes that the patients entered in our study are quite variable in their presentation. What they have in common is that almost all are right handed and their dystonia primarily appears when playing a musical instrument or writinglusing a keyboard. The answer “Y” to disability indicates that the patient is no longer able to perform the affected task. Type of cramp: P, progressive; S , simple; D, dystonic (1).

RESULTS Personality and Mood State The scores on the personality and mood state inventories and scales are reported in reference to standardized and clinical cut-off scores. Group scale scores from the Minnesota Multiphasic Personality Inventory (MMPI) are plotted in Fig. 1. The group profile indicates that all mean scale scores fell within normal limits. The error bars for scale 2 indicate that four patients achieved t scores of >70, suggesting mild depression. For all the other MMPI scales, only two patients ever had a scale score of >70. Besides individual scale score elevations, the group mean t-score profile was not indicative of psychopathology. The group mean Beck Depression Scale score was 5.4 (SD = 5.33). This score is well under the cut-off score of 15 that indicates a mild clinical depression. The one patient that scored above 15 on this scale was also among the four patients whose t score was >70 on the MMPI depression scale. On the Spielberger State-Trait Anxiety Scale, group mean and individual percentile scores were generally within normal limits. Six patients had percentile scores above the 70th percentile on the trait scale, whereas only three patients had percentile scores above the 70th percentile on the state scale. Patients generally had higher trait than state anxiety

scores, suggesting that their current treatment for dystonia with botulinum toxin had an anxietyreducing effect [t(19) = -2.08; p < 0.021. The scores on the Neurobehavior Rating Scale fell within normal limits. Four patients had scores on this scale that were > I SD from the group mean. Their scores reflected slight test anxiety and depressive affect. No patient reported a significant history of psychiatric disorder. Motor Tasks Group mean scores on the finger tapping test were within normal limits bilaterally. Accuracy and response times on the serial reaction time test across trials were also within normal limits, but response times were slightly slowed. All patients showed procedural learning on this task as evidenced by a slowing of response time from trial six (the last repeated trial) to trial seven (a random trial [t(18) = -3.374; p < 0.0031). A multiple regression analysis designed to determine whether personality scale scores could predict serial reaction time test grand mean reaction times [F(4,14) = 3.21; p < 0.041 indicated that Beck Depression Inventory scores partially predicted response speed (t = 3.42; p < 0.004; r = 0.58). However, no significant correlations were found between any of the mood state scales and finger tapping rate.

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J . GRAFMAN ET AL.

32 TABLE 2. Testsa Tests administered Personality 1 . MMPI 2. Beck Depression Inventory 3. Spielberger State-Trait Anxiety Scales 4. Observers Neurobehavioral Rating Scale Motor tasks 5 . Finger Tapping Test

6. Serial Reaction Time Test

Test description Evaluates personality type and style Evaluates symptoms of depression Evaluates symptoms of anxiety Evaluates test session behavior Evaluates finger dexterity (scoring is the average number of taps recorded for 10 s over three trials for each forefinger) Evaluates choice reaction time and procedural learningb

The MMPI and other mood state inventories were chosen to help us identify whether, as a group, patients with hand cramps displayed psychopathology. In addition, individual patients at risk for personality disorder or mood state changes could be identified. We were especially interested in patients who were at risk for somatization disorder. The finger tapping task and the serial reaction time test were administered to estimate motor dexterity, procedural learning, and reaction time. Administering these tasks also allowed us to look at the relationship between personality scale and mood state inventory scores and objective motor performance. An asterisk can appear in any one of four positions on a computer monitor. When it appears, the subject has to press a key that lies underneath the asterisk position. Seven blocks of 100 trials each are presented. The first two blocks are random and establish a baseline choice reaction time for each subject. The next four blocks each contain 10 sequences composed of 10 trials. Each sequence repeats the spatial order of asterisk presentation of the previous one. The exact sequence is complicated, and subjects generally have trouble retrospectively reproducing it. However, over the four blocks, reaction time tends to be reduced, indicating procedural learning. Block seven is another random block. The difference in reaction time between block six (the last repeated block) and block seven (a random block) is considered a measure of reaction time savings due to procedural learning.

Other Analyses There were no major effects of age, education, gender, or cramp type on the personality scale scores or motor task performance. A multiple regression analysis using age, education, handedness, and gender as independent variables indicated that a higher level of education was associated with higher scores on the MMPI Ego Strength scale. In addition, female patients with hand cramps had significantly higher scale scores on the MMPI Depression scale than male patients with hand cramps. Results of regression analyses indicated that there

Movement Disorders, Vol. 6. No. 1. 1991

FIG. 1. Focal dystonia study: MMPI results. As a group, patients with focal dystonia demonstrated a normal MMPI profile. A few individual patients had scores in the clinically elevated range (>70) on scale 2 (suggestive of a mild depression).

were independent significant effects of affected hand and whether patients were disabled or not on almost all personality scales and reaction time measures with greater psychopathology scores and slowed response times found in patients who were disabled with bilateral hand cramps. Although mean psychopathology scores were greater in the disabled patients or those with bilateral hand cramps, these psychopathology scores never fell in the cliniCallY elevated range. Averaged response time on the Serial Reaction Time Test was 61 ms slower in the disabled group and 250 ms slower when there was bilateral compared to Unilateral Cramps. When duration of illness, cramp type, hand(s) affected, and disability were placed in a step-wise regression analysis, no variable entered the regression analysis on any of the personality scales or motor tasks. Cases with Clinically Elevated Scale Scores Three out of 20 cases had elevated scores on the personality scales and test behavior that were suggestive of a mild clinical disorder. Subject P was a court reporter who described left hand cramps beginning in the fall of 1988. There was no history of psychiatric disorder in her family with the exception of a sister whom she reports had been diagnosed as a manic depressive. She began botulinum toxin treatment in the fall of 1989. Prior to our eval-

HAND D YSTONIA AND PSYCHOPATHOLOGY uation, the patient demonstrated some mild test anxiety and wondered aloud if her hand cramps could be stress related. She described the period surrounding the onset of her cramps as being very stressful at work (i.e., having to meet deadlines) and at home (taking care of her children). Her MMPI scale scores were normal, although she showed a tendency towards suspiciousness and social isolation. Her Beck Depression Inventory score of 23 revealed subject P to be discouraged and disappointed in herself, self-blaming for problems, constantly worried about her physical problems, and claiming that she was completely unable to work. Her anxiety level as estimated by the Spielberger state-trait anxiety scale was within normal limits. During motor testing, she complained about her fingers getting tired, but she persisted on the finger tapping task anyway. Her cognitive testing was well within normal limits. Subject H was a drummer who developed bilateral hand cramps within the past few years. He reported receiving a mild head injury with no loss of consciousness as a child. As a teenager, he reported experimenting with drugs but claimed he no longer uses drugs. He appeared quite anxious during the testing and was constantly fidgeting and moving around. In conversation, he gave the impression that he was acutely concerned with what other people thought of him. He had a clinically elevated MMPI 2-4 profile, which suggested that he was an excessive worrier and easily slips into depression. These patients often are withdrawn and frustrated by a lack of perceived accomplishment. They often are resentful of demands placed upon them and are self-deprecating. His Beck Depression Inventory score of 12 revealed him to be sad with thoughts of killing himself (although he claims he would not act on his thoughts). He did not report feeling anxious on the day of testing, but his Spielberger Trait Anxiety score fell into the elevated range, indicating rather chronic feelings of inadequacy, depression, and anxiety. Subject F reported the onset of writer’s cramp in 1979. At the same time, he indicated he also experienced “ear-ringing. ” He reported an unhappy childhood in which he was placed in a boarding school at the age of 10. He had headaches and felt emotionally distressed as a child, but claimed his physical health was normal. After growing up in a European country, he moved to the United States and eventually was employed as a foreign language and literature teacher. He is now retired and finds

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writing his major problem. About 3 months prior to beginning his botulinum toxin treatment last year, he reported experiencing “heart palpitations.” Prior to beginning the psychological testing, subject F noted to the examiner that he had marked memory difficulties. He had a clinically elevated MMPI 8-2-7 profile, which suggested that he was moderately depressed with elements of tension and anxiety. Somatic delusions occur infrequently in patients with this profile who often have difficulty thinking in a coherent manner. Patients with this profile are often afraid of emotional involvement and experience excessive self-doubt. Finally, they may show a tendency to report periods of dizziness and/or forgetfulness. His Beck Depression Inventory score of 7 was paradoxically within normal limits, suggesting some resistance to admitting psychological distress. His Spielberger State Anxiety score was mildly elevated. Despite memory complaints, his actual performance on objective memory tests was within normal limits. In examining the psychopathology of these three subjects, there was no convincing evidence that their symptomatology was responsible for the hand cramp. In each case, the patient utilized the affected limb in his chosen profession and had to stop working following the onset of the hand cramps. Each person also felt hope that the botulinum toxin would improve their dystonia. It is possible that depressive psychopathology may have exacerbated symptoms or complaints, but there was little evidence in our patients that it led to the development or chronicity of their dystonia or met Diagnostic and Statistical Manual (DSM) 111-R diagnostic criteria for somatization or conversion disorder. Furthermore, only these three out of the 20 patients in our series demonstrated evidence of clinical psychopathology.

GENERAL DISCUSSION We found no statistical relationship between measures of psychopathology and indices of motor performance or characteristics of focal hand dystonia. These results suggest that focal hand dystonia generally is not associated with, nor precipitated by, psychopathology. Although some patients with focal hand dystonia may develop a mild depression or other psychiatric disorder due to the chronicity of their focal hand dystonia (or for other reasons), these psychiatric disorders appear to be independent of the onset and appearance of focal hand dys-

Movement Disorders, Vol. 6,No. 1, 1991

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J . GRAFMAN ET AL.

tonia. However, if a patient is depressed or has a concurrent psychiatric disorder, the severity of their psychiatric disorder may modulate their performance on effort-demanding tasks (e.g., sustained writing) and exacerbate an already affected performance due to the hand cramps. The reported minor improvement in hand cramps, noted in some articles, following psychiatric intervention may be due to an improved psychological status even though the hand cramps remain (10,ll). The exacerbating effects of mood state abnormalities on cognitive and motor functions that require effort are well documented (17). Hand cramps have often been attributed to a psychogenic cause. Hand cramps as a manifestation of somatization, hysterical, or conversion disorder (18) appear unlikely in our patients. There was no evidence in the patients we studied that they received a primary or secondary gain from their illness by avoiding internal conflict or an activity that was noxious to them. We were unable to identify a temporal relationship between the onset of their symptoms and the onset of a conflict in interpersonal or social functioning. Most of our patients first reported their symptoms as adults. The hand cramps in our patients had an insidious onset and slow progression, and were chronic. With one exception, none of the patients in our series reported multiple somatic complaints nor did they report a fluctuating course. Both observation and self-report failed to reveal signs of the histrionic/hysterical or dependent personality found so often in patients with conversion symptoms. All of these observations contrast with the DSM-111-R requirements for diagnosis of somatization, hysterical, or conversion disorder. It is also unlikely that focal hand dystonia is due to an anxiety or neurotic disorder (9). We found no relationship between the medical history, personality scale scores, or patient test behavior and any of the characteristics of focal hand dystonia or motor performance as measured by finger dexterity or reaction times. Thus, our results support the placement of focal hand dystonia at the low end of a continuum of disorders that range from writer’s cramp to torsion dystonia (19). Hand cramps should be considered primarily as a form of focal dystonia that can be exacerbated by concurrent psychiatric disorder. In selected cases, psychiatric treatment may lessen the severity and, perhaps, frequency of the cramps but not eliminate them.

Movement Disorders, Vol. 6 , N o . 1, 1991

Occasionally, a patient may present with pseudo or poorly diagnosed hand cramps as a manifestation of psychological distress (12). Such patients may respond well to psychiatric intervention. However, a psychogenic cause of hand dystonia will remain a rarity. Almost all dystonia patients first come to the attention of neurologists in a movement disorders clinic. Fahn and Williams (16) reported that a small number of patients seen in their dystonia clinic appeared to have a psychogenic dystonia since their symptoms were either relieved by psychotherapy or by the use of psychological suggestion, there was an absence of symptoms when the patient was left alone, or the dystonic symptoms responded to placebo. They also mentioned other less stringent criteria for the diagnosis of psychogenic dystonia and utilized the DSM-111 (18) to clarify their diagnoses. Even if these unusual patients were then referred to a psychiatric clinic and were generally successfully treated, it should not be interpreted that all dystonias are psychogenic in origin and treatable by behavioral methods or psychotherapy. Indeed, this study and others (9) indicate that when patients were psychologically evaluated as part of a neurological evaluation in a dystonia clinic, there was no evidence that psychopathology was associated with the appearance or chronicity of their focal hand dystonia. Acknowledgment: We would like to thank Pat Nelson, M A . , Karen Bressler, B.A., and Vicki Schwartz, B.A. for expertly testing the patients and carefully tabulating the data.

REFERENCES I. Sheehy MP, Marsden CD. Writer’s cramp-a focal dystonia. Brain 1982;105:461-80. 2. Panizza ME, Hallett M, Nilsson J. Reciprocal inhibition in patients with hand cramps. Neurology 1989;39:85-9. 3. Cohen LG, Hallett M. Hand cramps: clinical fedtures and electromyographic patterns in a focal dystonia. Neurology 1988;38:1005-112. 4. Crisp AH, Moldofsky H. A psychosomatic study of writer’s cramp. Br J Psychiafry 1965;111:841-58. 5. Beech HR. The symptomatic treatment of writer’s cramp. In: Eysenck HJ, ed. Behaviour therapy and the neuroses: readings in modern methods of treatment derived from learning theory. Oxford: Pergamon Press, 1960:349-72. 6. Bindman E, Tibbets RW. Writer’s cramp, a rational approach to treatment? Br J Psychiatry 1977;131:143-8. 7 . CritchIey M. Occupational palsies in musical performers. In: Critchley M, Henson RA, eds. Music and the brain. Studies on the neurology of music. London: Heinemann, 1977:36577.

HAND D YSTONIA AND PSYCHOPATHOLOGY 8. Cohen LG, Hallett M, Geller BD, Hochberg F. Treatment of focal dystonias of the hand with botulinum toxin injections. J Neurol Neurosurg Psychiatry 1989;52:355-63. 9. Harrington RC, Wieck A, Marks IM, Marsden CD. Writer’s cramp: not associated with anxiety. Movement Disorders 1988;3:195-200. 10. Wieck A, Harrington R, Marks I, Marsden C. Writer’s cramp: a controlled trial of habit reversal treatment. Br J Psychiatry 1988;153:1 1 1-5. 1 1 . Cottraux JA, Juenet C, Collet L. The treatment of writer’s cramp with multimodal behaviour therapy and biofeedback: a study of 15 cases. Br J Psychiatry 1983;142:180-3. 12, Condrau G. Daseinsanalytic therapy with a patient suffering from compulsion neurosis and writer’s cramp. Am JPsychoanal 1988;3:21 1-20. 13. Osuntokun BO, Bademosi 0, Adeuja AOG. Writer’s cramp: a prospective study of 53 Nigerian Africans. East Afr Med J 1982;59:314-9. 14. Sylvester JD, Liversedge LA. Conditioning and the occupational cramps. In: Eysenck HJ, ed. Behaviour therapy and the neuroses: readings in modern methods of treatment de-

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rived from learning theory. Oxford: Pergamon Press, 1960: 334-47. Liversedge LA, Sylvester JD. Conditioning techniques in the treatment of writer’s cramp. In: Eysenck HJ, ed. Behaviour therapy and the neuroses. Readings in modern methods of treatment derived from learning theory. Oxford: Pergamon Press, 1960:327-33. Fahn S, Williams DT. Psychogenic dystonia. In: Fahn S , Marsden CD, Calne DB, eds. Dystonia 2 (Advances in neurology, vol. 50). New York: Raven Press, 1988:431-55. Weingartner H . Automatic and effort-demanding cognitive processes in depression. In: Poon L, ed. Clinical memory assessment of older adults. Washington, DC: American Psychological Association, 1986:218-25. Diagnostic and statistical manual of mental disorders (3rd ed., rev.). Washington, DC: American Psychiatric Association, 1987. Sheehy MP, Rothwell JC, Marsden CD. Writer’s cramp. In: Fahn S, Marsden CD, Calne DB, eds. Dystonia 2 (Advances in neurology, vol. 50). New York: Raven Press, 1988:45772.

Movement Disorders, Vol. 6 , No. 1, 1991

Is focal hand dystonia associated with psychopathology?

The purpose of this study was to determine if patients with focal hand dystonia have any significant psychopathology. We studied 20 patients with hand...
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