Journal of Occupational Rehabilitation, VoL 4, No. 4, 1994
Prevalence of Psychopathology in Carpal Tunnel Syndrome Patients Lynda B. Mathis, 1 Robert J. Gatchei, 1,2 Peter B. Polatin, 1 H. Jay Boulas, 1 and Regina K. Kinney 1
This study assessed the prevalence rates of psychopathology in acute carpal tunnel syndrome (CTS) and acute low back pain (LBP) patients. Psychopathology was assessed with the Structured Clinical hTterview for the DSM-III-R (SCID). The results showed that the CTS patients had significantly higher rates of anxiety disorders, both current and lifetbne, than the LBP patients. However, LBP patients had significantly higher rates of lifetime substance abuse than the CTS patients, b~ regard to other types of psychopathology, such as depression, current substance abuse, and somatoform pain disorders, CTS patients had similar rates as the LBP patients. It was concluded that alvciety disorders may be a concomitant of carpal tunnel syndrome, and that treating psychological problems along with physical aspects of the syndrome may increase the patient's chance of a successful therapeutic outcome. KEY TERMS: Carpal Tunnel Syndrome, Psychopathology, DSM-III-R, Low Back Pain.
INTRODUCTION It is well recognized that individuals with certain pain/disability syndromes, such as low back pain and temporomandibular disorder, have greater psychopathology than the general population (1-3). It is of interest whether or not these findings hold true for carpal tunnel syndrome (CTS), a neuromuscular pain/disability syndrome of the wrist and hand which has, in recent years, reached almost "epidemic" proportions (4). Carpal tunnel syndrome consists of a number of signs and symptoms generally caused by compression of the median nerve within the carpal tunnel (5). It is characterized by pain and numbness in the thumb, index and long IDepartment of Psychiatry, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75234-9044. 2Correspondence should be directed to Robert J. Gatchel, Ph.D., Department of Psychiatry, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd., Dallas, Texas 75234-9044.
199 1053-o487/94/1200-0199507.0o/0 9 1994 PlenumPublishingCorporation
M a t h i s et aL
200
fingers, and half of the ring finger, especially at night (6). Other symptoms include thenar atrophy, loss of dexterity of the hand, loss of coordination of the thumb, "stiff" fingers, isolated pain in the arm or shoulder, and a combination of neck and wrist pain (7, 8). Patients with CTS tend to have jobs requiring repetitive hand motions, such as typing, playing a musical instrument, wire-stripping, and sign language interpretation (8-10). Other pain/disability disorders of the hand (i.e., reflex sympathetic dystrophy; repetitive strain injury; upper limb pain) have been tenuously linked to such variables as depression, anxiety, feelings of loss or helplessness, and certain premorbid personality traits (11-14). Furthermore, clinical observations of patients with upper extremity disorders including chronic CTS suggest "a pattern of persistent pain, high perceived disability, loss of function, distress, and dysphoria not unlike that observed in the work-disabled low back patient" (15). In spite of such findings and observations, there have been no studies which used operational criteria for diagnosing psychological disorders in CTS patients. The purpose of the current study was to identify possible psychological variables associated with CTS by assessing prevalence rates of psychopathology using the DSM-III-R (16), the official diagnostic and classification system of the American Psychiatric Association. An additional purpose of the study was to compare CTS patients with another group of pain patients. In previous research, the comparison of different groups of pain patients has yielded diverse prevalence rates of psychopathology (17). For example, chronic low back pain patients have higher rates of depression than normal subjects, as well as other groups of pain patients (3, 17). Additionally, while researchers have examined certain epidemiological characteristics of CTS (18, 19), there has been no research comparing CTS patients with other pain patients. For these reasons, prevalence rates of psychopathology in acute CTS patients were compared to those of another group of acute pain patients, specifically, acute low back pain patients.
METHOD Subjects Two groups of subjects were assessed in this study. The first group was a sample of 44 acute CTS patients of an orthopedic hand surgeon. Individuals who had pain or disability in the wrist or hand for 6 months or less (or who first initiated treatment for CTS within the last 6 months), and who received a diagnosis of CTS by the orthopedic hand surgeon, were eligible for participation in the study. The diagnosis of CTS was based on the following criteria: 1) history of symptoms congruent with a diagnosis of CTS, including numbness and tingling in the median nerve distribution, especially when sleeping or driving a car; 2) physical findings of CTS, including altered signs of denervation in the median nerve distribution and/or thenar weakness or atrophy; and 3) positive results from a number of provocative tests, including Tinnel's, Phalen's, and median nerve compression tests. There were
Carpal Tunnel Syndrome
201
4 males and 40 females in the CTS group. Their mean age was 39.45 years, and their mean level of education was 13.61 years. The second group of subjects was a sample of 50 acute low back pain (LBP) patients who presented to a physician in the Dallas area, for treatment of recent back injury specific to the lumbar area. There were 30 males and 20 females in the LBP group. They were matched to the CTS group for age and education: their mean age was 39.54 years, and their mean level of education was 13.86 years.
Procedure Each subject was interviewed by a trained administrator of the Structured Clinical Interview for DSM-III-R (SCID) (20) to determine the presence or absence of DSM-III-R diagnoses. In addition, the specific duration of symptoms and demographic information including gender, age, education, and occupation were obtained. In all cases, the administrator of the SCID was an advanced graduate student of clinical psychology who had a thorough understanding of DSM-III-R diagnostic criteria. Additionally, interviewers had regular conferences with a psychiatrist knowledgeable in SCID administration to review completed SCIDs and clarify any questions with regard to diagnosis. Structured Clinical Interview for DSM-III-R (SCID). The SCID NP and SCID II are standardized, structured clinical interviews designed to determine the presence or absence of DSM-III-R Axis I disorders and Axis II personality disorders (20). The SCID is a two-part structured psychiatric interview for the evaluation of psychiatric disorders. The evaluator reads the questions to the patient and makes differential diagnostic decisions based on the answers elicited. The SCID derives a current and complete past history of psychiatric illness, is standardized, and possesses adequate validity and reliability. In general, the SCID is a reliable instrument, with test-retest correlations in the .60's (21). The SCID also demonstrates good validity, with predictive power ratings ranging from above .60 to .95 (22).
RESULTS
Demographic Information As mentioned above, subjects in both patient groups were matched in terms of age and education. Specifically, the average age of individuals in the CTS group was 39.45 years and the average length of education was 13.61 years. For the LBP group, the average age was 39.54 years and the average length of education was 13.86 years. Occupations possessed by all subjects were categorized into eight groups according to physical requirements and characteristics, as follows: 1) Light clerical, i.e., receptionist, personnel assistant; 2) Heavy clerical, i.e., keyboard operator, word processor; 3) Manufacturing, i.e., stocker, packer, wire-stripper; 4)
202
Mathis et al.
Driver, i.e., truck driver, bus driver; 5) Medical, i.e., dental hygienist, dental assistant; 6) Artistic, i.e., designer, reporter; 7) Light miscellaneous, i.e., nurse, housekeeper, executive; 8) Heavy miscellaneous, i.e., construction worker, forklift operator. Results revealed that the occupation most frequently endorsed by the CTS group was heavy clerical (50%). The occupation most frequently endorsed by the LBP group was light miscellaneous (45%; see Table 1 for a complete listing of percent prevalence of occupation.) There were two significant findings when comparing LBP and CTS groups in terms of occupation. Specifically, occupations categorized as heavy clerical were more frequently endorsed by CTS patients (50%) than by LBP patients (12%; X 2 = 8.97, df = 1, p < .005). Occupations categorized as light miscellaneous were more frequently endorsed by LBP patients (46%) than by CTS patients (16%; X 2 = 9.72, df = 1, p < .005). The duration of the disorder, that is the number of months from the reported origin of symptoms to the date of the evaluation, was also obtained and compared between the two patient groups. Specifically, the CTS patients reported a significantly greater duration of symptoms (X = 3.62 months) than did the LBP patients (X = .88 months; t = 9.13, df = 92, p < .001). Axis I Prevalence Rates: Lifetime The results indicated that 77% of the CTS patients received at least one DSMIII-R Axis I diagnosis. The most frequently diagnosed Axis I disorder in the CTS
Table 1. Percent Prevalence of Occupation in 44 Carpal Tunnel Syndrome Patients and 50 Low Back Pain Patients
Type of occupation
CTS
LBP
(n = 44) %
(n = 50) (%)
Light clerical (receptionist, personnel)
2%
Heavy clerical (keyboards, word processor)
50
12"
Manufacturing (stocker, meat packer)
11
16
Driving (truck driver, bus driver)
5
10
Medical (dental hygienist)
5
0
Artistic (hair stylist, reporter)
5
2
Light miscellaneous (nurse, housekeeper, executive)
16
46*
Heavy miscellaneus (construction, forklift operator)
5
10
"p < .005.
4%
Carpal Tunnel Syndrome
203
g r o u p was anxiety d i s o r d e r s (45%). F u r t h e r , within the anxiety d i s o r d e r category, the m o s t f r e q u e n t l y d i a g n o s e d d i s o r d e r s w e r e p h o b i c d i s o r d e r s (52%, o r 23 p h o b i c d i s o r d e r diagnoses a m o n g 44 patients; see T a b l e 2 for f r e q u e n c i e s o f specific Axis I lifetime d i a g n o s e s a m o n g CTS patients.) W i t h r e g a r d to the L B P patients, 5 4 % received at least o n e D S M - I I I - R diagnosis. T h e most f r e q u e n t l y d i a g n o s e d d i s o r d e r in the L B P g r o u p was substance a b u s e d i s o r d e r s (38%), followed closely by affective d i s o r d e r s (36%). T a b l e 3 p r e s e n t s lifetime p r e v a l e n c e rates o f Axis I clinical diso r d e r s for b o t h g r o u p s o f patients. A n u m b e r o f significant differences w e r e f o u n d b e t w e e n the CTS a n d L B P p a t i e n t s with r e g a r d to lifetime p r e v a l e n c e rates of psychopathology. Specifically, CTS p a t i e n t s h a d a significantly higher rate o f anxiety d i s o r d e r diagnoses ( 4 5 % ) than did L B P p a t i e n t s (12%; X 2 = 13.09, df = 1, p < .001). T o d e t e r m i n e if this finding was an artifact o f g e n d e r , a s e p a r a t e analysis was c o m p u t e d using only the results of the f e m a l e subjects; accordingly, f e m a l e CTS p a t i e n t s had a significantly higher rate o f anxiety d i s o r d e r s (50%) than did f e m a l e L B P p a t i e n t s (20%; X 2 = 5.0, df = 1, p < .05). In r e g a r d to o t h e r clinical diagnoses, L B P p a t i e n t s had a significantly h i g h e r rate o f s u b s t a n c e a b u s e d i s o r d e r s (38%) than did CTS p a t i e n t s (18%; X 2 = 4.5, df = 1, p < .05). H o w e v e r , this did not hold true when male CTS and L B P p a t i e n t s
Table 2. Frequency of Lifetime Axis I Diagnoses in 44 Carpal Tunnel Syndrome Patients
Axis I disorder Somatoform disorders Somatoform pain Somatization Hypochondriasis Undifferentiated somatoform disorder Substance abuse Affective disorders Bipolar Major depression Dysthymia Anxiety disorders Generalized anxiety Phobic disorders Panic disorders Obsessive-compulsive PTSD Agoraphobia WOPD Psychotic disorders Others Organic mood syndrome Adjustment disorder Eating/Impulse control
Men (n = 4) (J')
Women (n = 40) (f)
Total (n = 44) (D
I ---2
3 -3 1 11
4 -3 1 13
----
-18 --
-18 --
------
3 23
3 23
1
1
3 6
3 6
1
3
4
1 ---
4 1 1
5 1 1
204
Mathis et ai. Table 3. Percent Prevalence of Lifetime Axis I Disorders in CTS and LBP Patients CTS Men (n = 4)
Women (n = 40)
LBP Total (n = 40)
Affective disorders
0%
45%
41%
Anxiety disorders
0
50
45
Substance abuse
50
15
Somatoform disorders
25
Psychotic disorders Organic mood syndrome
Men (n = 30) 23%
Women (n = 20)
Total (n = 50)
55%
36%
7
20
12
18
47
25
38
13
14
7
0
4
25
8
9
7
0
4
25
10
11
0
0
0
Adjustment disorder
0
3
2
0
5
2
Eating/impulse control dis.
0
5
5
0
0
0
were analyzed separately from female patients, indicating that substance abuse was frequently diagnosed in all male patients, and that since there were significantly more male LBP patients than CTS patients, gender might be an artifact in this finding. There were no other significant differences in rates of lifetime prevalence of Axis I disorders between CTS and LBP patients.
Axis I Prevalence Rates: Current
Results revealed that 50% of the CTS patients received at least one current Axis I disorder diagnosis. The most frequently diagnosed disorders were anxiety disorders (36%) (See Table 4 for a complete list of current Axis I disorder diagnoses in the CTS group.) Twenty percent of the LBP patients received at least one current Axis I disorder diagnosis. The most common diagnoses among LBP patients were affective disorders (12%). Table 5 presents prevalence of current Axis I disorder diagnoses among both CTS and LBP patients. Carpal tunnel patients had significantly higher rates of current anxiety disorders than LBP patients (36% versus 6%; X 2 = 13.39, df = 1, p < .001). This held true when female CTS and LBP patients were analyzed separately from the males (40% versus 15%, respectively; X 2 = 3.87, df = 1, p < .05). In regard to all other current Axis I disorder diagnoses, there were no significant differences between the CTS and LBP groups of patients.
20S
Carpal Tunnel Syndrome Table 4. Frequency of Current Axis I Diagnoses in 44 Carpal Tunnel Syndrome Patients
Axis I d i s o r d e r Somatoform disorders Somatoform pain Somatization Hypochondriasis Undifferentiated somatoform disorder Substance abuse Affective disorders Bipolar Major depression Dysthymia Anxiety disorders G e n e r a l i z e d anxiety Phobic disorders Panic disorders Obsessive-compulsive PTSD Psychotic disorders Others Organic mood syndrome Adjustment disorder Eating/Impulse control
Men (n = 4) (it)
Women (n = 40) (f)
Total (n = 44) (f)
1 -----
3 -3 1 --
4
----
-7 --
-7
-----1
3 17 -3 3 1
3 17 -3 3 2
----
1 1
1 1
1
1
3 1 --
Table 5. P e r c e n t P r e v a l e n c e o f C u r r e n t Axis I D i s o r d e r s in C T S a n d L B P P a t i e n t s CTS Axis I D i s o r d e r
Men (n = 4)
Women (n = 40)
LBP Total (n = 44)
Men (n = 30)
Women (n = 20)
Total (n = 50)
Affective d i s o r d e r s
0%
18%
16%
7%
20%
12%
Artxiety d i s o r d e r s
0
40
36
0
15
6
Substance abuse
0
0
0
3
0
2
Somatoform disorders
25
13
14
7
0
4
Psychotic disorders
25
5
7
7
0
4
Organic mood syndrome
0
3
2
0
0
0
Adjustment disorder
0
3
2
0
5
2
E a t i n g ] i m p u l s e c o n t r o l dis.
0
0
0
0
0
0
206
Mathis~aL Gender Differences
Within each group of patients, gender analyses were completed in regard to lifetime and current Axis I clinical disorders. There were no significant differences between male and female CTS patients, although this is at least partially due to the overrepresentation of women in the CTS group. In the LBP group, female patients had significantly higher rates of lifetime affective disorders (55%) than did male patients (23%; X ~ -- 5.23, df = 1, p < .05). Female LBP patients also had significantly higher rates of current anxiety (15%) than did male LBP patients (0%; X 2 = 4.75, df = 1, p < .05). Axis II Prevalence Rates
With respect to Axis II personality disorders, the results indicated that 21% of the CTS patients fulfilled diagnostic criteria for at least one personality disorder. This figure is roughly similar to the prevalence rate of at least one personality disorder in the LBP group (24%). The most common personality disorder diagnoses in the CTS group were paranoid personality disorder (9%; defined by the DSMIII-R as a pervasive and unwarranted tendency, beginning by early adulthood and present in a variety of contexts, to interpret the actions of people as deliberately demeaning or threatening) and obsessive-compulsive personality disorder (9%; defined by the DSM-III-R as a pervasive pattern of perfectionism and inflexibility, beginning by early adulthood and present in a variety of contexts). Paranoid personality disorder was also the most common personality disorder diagnosis in the LBP group (18%). Other frequently diagnosed personality disorders in this group include passive-aggressive personality disorder (8%; defined by the DSM-III-R as a pervasive pattern of passive resistance to demands for adequate social and occupational performance, beginning by early adulthood and present in a variety of contexts) and borderline personality disorder (10%; defined by the DSM-III-R as a pervasive pattern of instability of self-image, interpersonal relationships and mood, beginning by early adulthood and present in a variety of contexts).
DISCUSSION
The present results revealed that CTS patients had higher rates of anxiety disorders, both lifetime and current, than did LBP patients. With respect to other forms of psychopathology, prevalence rates for CTS patients were comparable to the LBP patients, with the exception of substance abuse disorders. Here, LBP patients had significantly higher rates of lifetime substance abuse disorders than did CTS patients. For the most part, then, with the exception of anxiety disorders and substance abuse, CTS patients appear similar clinically to LBP patients. Overall, these results suggest that CTS patients may be similar to other acute pain patients in terms of
Carpal Tunnel Syndrome
207
psychopathology; however, unlike other pain patients, CTS patients have significantly greater rates of anxiety disorders, particularly phobias. In an earlier study, Kinney, Gatchel, Polatin, Fogarty, and Mayer (23) reported much lower rates of substance abuse in the sample of acute low back pain patients evaluated relative to those found in the present study. There are a number of potential reasons for this discrepancy, such as a different gender proportion, as well as age differences of patients in the two studies. A replication study will need to be conducted in order to control for these differences. Until then, one must interpret these substance abuse findings with some caution. The finding of a greater prevalence of anxiety disorders in acute CTS patients (nearly one-half of the sample had a lifetime history of some anxiety disorder) is quite compelling. Neither the acute LBP patients in this study, not the acute or chronic LBP patients in the Kinney et al. (23) study, were found to have rates this high. Indeed, these are the first results generated from a systematic assessment of prevalence rates of psychopathology in CTS patients. The fact that anxiety disorder rates were found to be so high suggests that this clinical syndrome may be more of a significant underpinning of CTS than in other musculoskeletal disorders. One might argue that the higher frequency of anxiety in the CTS group might be because the CTS patients reported a longer duration of symptoms than the LBP patients. However, if duration was a factor in these results, we would also expect a greater frequency of depression in the CTS patients, since depression is the most common concomitant of chronic pain (24). This, however, was not the case. Interestingly, Spence (14) found that acute and chronic upper limb pain patients had similar levels of anxiety, and that both acute and chronic upper limb patients had greater anxiety than normal. Spence's (14) finding that chronic upper limb pain patients had no greater anxiety than acute upper limb patients supports the notion that anxiety might be a predisposing factor in upper extremity disorders, as suggested by the current examination of acute CTS patients. One might speculate that the higher level of anxiety found in individuals with CTS is accompanied by a concomitant increased muscle tension level (via an anxiety-muscle tension feedback loop) that predisposes the individual to more neuromuscular fatigue. This fatigue factor, in turn, may increase one's susceptibility to repetitive motion disorders such as CTS. In support of this notion, Feuerstein and Fitzgerald (9) reported that sign language interpreters with upper extremity pain demonstrated a tendency toward a particular "workstyle," characterized by fewer rest breaks, more frequent hand and wrist deviations, and more rapid finger and hand movements than those not experiencing upper extremity pain (9). These researchers suggest that some individuals might be predisposed to respond to work tasks in such a way that leads to greater neuromuscular stress that, in turn, can lead to upper extremity disorders (9). Of course, this is not to say that psychopathology is the primary cause of CTS. Indeed, not all patients in the present study evidenced any psychopathology. Pain is a complex psychophysiological behavior pattern that cannot be broken down into distinct psychological and physical components. The growing acceptance of a
208
Mathis et al.
biopsychosocial conceptual model of pain (24-26), which includes physical, psychological, and social elements, moves away from an overly simplistic physical disease model of pain, and replaces it with an alternative multidimensional model. The present results suggest that one such psychosocial factor----psychopathology--is a potentially important contributory factor for certain patients that will need to be more closely evaluated in future studies of CTS patients. Some patients may have certain premorbid characteristics---specifically anxiety disorder3 that make them more susceptible to CTS. As in other areas of the growing field of health psychology-behavioral medicine, medical personnel will need to be aware of the psychological characteristics of their patients in order to prevent costly effects (both economic and human productivity losses) of prolonged bouts of disability. These results also suggest important implications for treatment of individuals with CTS. Since pain patients with significant levels of psychopathology tend to have less favorable treatment outcomes than those without psychopathology (27), identifying particularly anxious CTS patients could result in more efficient, multidisciplinary treatment of such individuals. More specifically, knowing that anxiety might present a problem for CTS patients could allow the clinician to structure his or her treatment plan with sensitivity to issues of anxiety, perhaps by including treatment modalities that focus on anxiety and tension reduction. This may help prevent the development of chronicity. Moreover, as CTS becomes more chronic, it is especially important to include a multidisciplinary treatment program because of the dramatically increased rates of psychopathology found in chronic pain patients (1, 3, 17). An example of such a multidisciplinary approach was recently used in the treatment of upper extremity disorders by Feuerstein et al. (15). An important issue concerning this study is whether the anxiety found in these CTS patients is a consequence of CTS or whether preexisting anxiety predisposes one to develop CTS. The finding that 45% of the CTS patients received a lifetime diagnosis of anxiety, as well as the acute nature of CTS symptoms in this group of patients, suggests that for many of the patients anxiety may have existed prior to the onset of CTS. We did not address this question specifically, and future research will need to clarify the etiological relationship between psychological disorders and the development of CTS. An additional limitation of the current study is the absence of a nonclinical "healthy" control group with which to compare pain patients. Including such a group in future research would allow for a more stringent comparison between patient and nonpatient groups. Finally, it is important to note that the present investigation focused on CTS only, and that further investigations of other upper extremity pain disorders in terms of identifying prevalence of psychopathology appear warranted.
ACKNOWLEDGMENTS This research was supported by grants to the second author from the National Institute of Mental Health (MH46452 and MH01107).
209
Carpal Tunnel Syndrome REFERENCES
1. Fishbain DA, Goldberg M, Meagher BR, Steele R, Rosomoff H. Male and female chronic pain patients categorized by DSM-III psychiatric diagnostic criteria. Pain 26; 181-197: 1986. 2. Kinney RK, Gatchel R J, Ellis E, Holt C. Major psychological disorders in chronic TMD patients: Implications for successful management. J Am Dent Assoc 123; 49-54: 1922. 3. Polatin PB, Kinney RK, Gatchel RJ, Lillo E, Mayer TG. Psychiatric illness and chronic low-back pain. Spine 18(1); 66-71: 1993. 4. Thompson JS, Phelps TH. Repetitive strain injuries: How to deal with "the epidemic of the 1990s." Postgrad Med 88(8); 143-149: 1990. 5. Schuind F, Venlura M, Pasleels JL. Idiopathic carpal tunnel syndrome: Histologic study of flexor tendon synovium. J Hand Surg 15(A); 497-503: 1990. 6. Fisk GR. The painful wrist: Problems and solutions. In: Perry CBW, ed. The hand and upper limb: Vol. 16. Management of pain in the hand and wrist New York: Churchill Livingstone, 1991, pp. 48-68. 7. Phalen GS. The birth of a syndrome, or carpal tunnel revisited. J Hand Surg 6; 109-110: 1981. 8. Szabol RM, Madison M. Carpal tunnel syndrome. Orthop Clin Am 23(1); 103-109: 1992. 9. Feuerstein M, Fitzgerald TD. Biomecbanieal factors affecting upper extremity cumulative trauma disorders in sign language interpreters. Occup Med 34(3); 257-264: 1992. 10. Hybbinette CH, Mannerfelt L. The carpal tunnel syndrome: A retrospective study of 400 operated patients. Aeta Orthopaed Scand 46; 610-620: 1975. 11. Bruehl S, Carlson CR. Predisposing Psychological factors in the development of reflex sympathetic dystrophy. Clin J Pain 8(4); 287-299: 1992. 12. Houdenhove BV, Vasquez G, Onghena P, Stans L, Vandeput C, Vermaut G, Vervaeke G, lgodt P, Vertommen H. Etiopathogenesis of reflex sympathetic dystrophy: A review and biopsychosocial hypothesis. Clin J Pain 8; 300-306: 1992. 13. Ireland DCR. The Australian experience with cumulative trauma disorders. In Millender LH, Louis DS, Simmons BP, eds. Occupational disorders of the upper extremity. New York: Churchill Livingstone, 1992, pp. 79-88. 14. Spence SH. Psychopathology amongst acute and chronic patients with occupationally related upper limb pain versus accident injuries of the upper limbs. Austr Psychol 25(3); 293-305: 1990. 15. Feuerstein M, Callan-Harris S, Hickey P, Dyer D, Armbruster W, Carosella AM. Multidisciplinary rehabilitation of chronic workrelated upper extremity disorders. J Occup Med 35(4); 396-403: 1993. 16. American Psychiatric Association. Diagnostic and statistical manual of mental disorders (3rd Ed. revised). Washington, D.C.: Author, 1987. 17. Kinney RK. The Assessment of Psychopathology in Three Groups of Pain Patients. Unpublished doctoral dissertation, University of Texas Southwestern Medical Center at Dallas, Texas, 1991. 18. De Krom MCTFM, Kester ADM, Knipschild PG, Spaans F. Risk factors for carpal tunnel syndrome. Am J Epidemiol 132(6); 1102-1110: 1990. 19. Vessey MP, Villard-Mackintosh L, Yeates D. Epidemiology of carpal tunnel syndrome in women of childbearing age: Findings in a large cohort study. Int J Epidemiol 19(3); 655-659: 1990. 20. Spitzer RL, Williams JBW, Gibbon M, First MB. Stnwtured clinical interview for DSM-III-R.New York: New York State Psychiatric Institute, 1988. 21. Williams JBW, Gibbon M, First MB, Spitzer RL, Davies M, Borus J, Howes MJ, Kane J, Hope HG, Rounsaville B, Wittchen HU. The structured clinical interview for DSM-III-R (SCID). Arch Gen Psychiat 49; 630-636: 1992. 22. Skodol AE, Rosnick L, Kellman D, Oldham, JM, Hyler SE. Validating structured DSM-III-R personality disorder assessments using longitudinal data. Am J Psychiat 145; 1297-1299: 1988. 23. Kinney RK, Gatchel RJ, Polatin PB, Fogarty WJ, Mayer TG. Prevalence of psychopathology in acute and chronic low back pain patients. J Occupa Rehab 3; 231-244: 1993. 24. Gatchel RJ. Early development of physical and mental deconditioning in painful spinal disorders. In: Mayer TG, Mooney V, Gatchel R J, eds. Contemporary conservative care forpah~ful spine disorders. 1991. 25. Malone MD, Strube M J. Meta-analysis of non-medical treatments for chronic pain. Pain 34; 231-244: 1988. 26. Polatin PB, Gatchel RJ, Barnes D, Mayer H, Arens C, Mayer TG. A psychosociomedical prediction model of response to treatment by chronically disabled workers with low back pain. Spine 14(9); 956-961: 1989.
210
Mathis et ai.
27. Schwartz RA, Greene CS, Laskin DM. Personality characteristics of patients with myofascial pain-dysfunction (MPD) syndrome unresponsive to conventional therapy. J Dent Res 58; 1435-1439: 1979.
Prevalence of Psychopathology in Carpal Tunnel Syndrome Patients Lynda B. Mathis, 1 Robert J. Gatchei, 1,2 Peter B. Polatin, 1 H. Jay Boulas, 1 and Regina K. Kinney 1
This study assessed the prevalence rates of psychopathology in acute carpal tunnel syndrome (CTS) and acute low back pain (LBP) patients. Psychopathology was assessed with the Structured Clinical hTterview for the DSM-III-R (SCID). The results showed that the CTS patients had significantly higher rates of anxiety disorders, both current and lifetbne, than the LBP patients. However, LBP patients had significantly higher rates of lifetime substance abuse than the CTS patients, b~ regard to other types of psychopathology, such as depression, current substance abuse, and somatoform pain disorders, CTS patients had similar rates as the LBP patients. It was concluded that alvciety disorders may be a concomitant of carpal tunnel syndrome, and that treating psychological problems along with physical aspects of the syndrome may increase the patient's chance of a successful therapeutic outcome. KEY TERMS: Carpal Tunnel Syndrome, Psychopathology, DSM-III-R, Low Back Pain.
INTRODUCTION It is well recognized that individuals with certain pain/disability syndromes, such as low back pain and temporomandibular disorder, have greater psychopathology than the general population (1-3). It is of interest whether or not these findings hold true for carpal tunnel syndrome (CTS), a neuromuscular pain/disability syndrome of the wrist and hand which has, in recent years, reached almost "epidemic" proportions (4). Carpal tunnel syndrome consists of a number of signs and symptoms generally caused by compression of the median nerve within the carpal tunnel (5). It is characterized by pain and numbness in the thumb, index and long IDepartment of Psychiatry, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75234-9044. 2Correspondence should be directed to Robert J. Gatchel, Ph.D., Department of Psychiatry, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd., Dallas, Texas 75234-9044.
199 1053-o487/94/1200-0199507.0o/0 9 1994 PlenumPublishingCorporation
M a t h i s et aL
200
fingers, and half of the ring finger, especially at night (6). Other symptoms include thenar atrophy, loss of dexterity of the hand, loss of coordination of the thumb, "stiff" fingers, isolated pain in the arm or shoulder, and a combination of neck and wrist pain (7, 8). Patients with CTS tend to have jobs requiring repetitive hand motions, such as typing, playing a musical instrument, wire-stripping, and sign language interpretation (8-10). Other pain/disability disorders of the hand (i.e., reflex sympathetic dystrophy; repetitive strain injury; upper limb pain) have been tenuously linked to such variables as depression, anxiety, feelings of loss or helplessness, and certain premorbid personality traits (11-14). Furthermore, clinical observations of patients with upper extremity disorders including chronic CTS suggest "a pattern of persistent pain, high perceived disability, loss of function, distress, and dysphoria not unlike that observed in the work-disabled low back patient" (15). In spite of such findings and observations, there have been no studies which used operational criteria for diagnosing psychological disorders in CTS patients. The purpose of the current study was to identify possible psychological variables associated with CTS by assessing prevalence rates of psychopathology using the DSM-III-R (16), the official diagnostic and classification system of the American Psychiatric Association. An additional purpose of the study was to compare CTS patients with another group of pain patients. In previous research, the comparison of different groups of pain patients has yielded diverse prevalence rates of psychopathology (17). For example, chronic low back pain patients have higher rates of depression than normal subjects, as well as other groups of pain patients (3, 17). Additionally, while researchers have examined certain epidemiological characteristics of CTS (18, 19), there has been no research comparing CTS patients with other pain patients. For these reasons, prevalence rates of psychopathology in acute CTS patients were compared to those of another group of acute pain patients, specifically, acute low back pain patients.
METHOD Subjects Two groups of subjects were assessed in this study. The first group was a sample of 44 acute CTS patients of an orthopedic hand surgeon. Individuals who had pain or disability in the wrist or hand for 6 months or less (or who first initiated treatment for CTS within the last 6 months), and who received a diagnosis of CTS by the orthopedic hand surgeon, were eligible for participation in the study. The diagnosis of CTS was based on the following criteria: 1) history of symptoms congruent with a diagnosis of CTS, including numbness and tingling in the median nerve distribution, especially when sleeping or driving a car; 2) physical findings of CTS, including altered signs of denervation in the median nerve distribution and/or thenar weakness or atrophy; and 3) positive results from a number of provocative tests, including Tinnel's, Phalen's, and median nerve compression tests. There were
Carpal Tunnel Syndrome
201
4 males and 40 females in the CTS group. Their mean age was 39.45 years, and their mean level of education was 13.61 years. The second group of subjects was a sample of 50 acute low back pain (LBP) patients who presented to a physician in the Dallas area, for treatment of recent back injury specific to the lumbar area. There were 30 males and 20 females in the LBP group. They were matched to the CTS group for age and education: their mean age was 39.54 years, and their mean level of education was 13.86 years.
Procedure Each subject was interviewed by a trained administrator of the Structured Clinical Interview for DSM-III-R (SCID) (20) to determine the presence or absence of DSM-III-R diagnoses. In addition, the specific duration of symptoms and demographic information including gender, age, education, and occupation were obtained. In all cases, the administrator of the SCID was an advanced graduate student of clinical psychology who had a thorough understanding of DSM-III-R diagnostic criteria. Additionally, interviewers had regular conferences with a psychiatrist knowledgeable in SCID administration to review completed SCIDs and clarify any questions with regard to diagnosis. Structured Clinical Interview for DSM-III-R (SCID). The SCID NP and SCID II are standardized, structured clinical interviews designed to determine the presence or absence of DSM-III-R Axis I disorders and Axis II personality disorders (20). The SCID is a two-part structured psychiatric interview for the evaluation of psychiatric disorders. The evaluator reads the questions to the patient and makes differential diagnostic decisions based on the answers elicited. The SCID derives a current and complete past history of psychiatric illness, is standardized, and possesses adequate validity and reliability. In general, the SCID is a reliable instrument, with test-retest correlations in the .60's (21). The SCID also demonstrates good validity, with predictive power ratings ranging from above .60 to .95 (22).
RESULTS
Demographic Information As mentioned above, subjects in both patient groups were matched in terms of age and education. Specifically, the average age of individuals in the CTS group was 39.45 years and the average length of education was 13.61 years. For the LBP group, the average age was 39.54 years and the average length of education was 13.86 years. Occupations possessed by all subjects were categorized into eight groups according to physical requirements and characteristics, as follows: 1) Light clerical, i.e., receptionist, personnel assistant; 2) Heavy clerical, i.e., keyboard operator, word processor; 3) Manufacturing, i.e., stocker, packer, wire-stripper; 4)
202
Mathis et al.
Driver, i.e., truck driver, bus driver; 5) Medical, i.e., dental hygienist, dental assistant; 6) Artistic, i.e., designer, reporter; 7) Light miscellaneous, i.e., nurse, housekeeper, executive; 8) Heavy miscellaneous, i.e., construction worker, forklift operator. Results revealed that the occupation most frequently endorsed by the CTS group was heavy clerical (50%). The occupation most frequently endorsed by the LBP group was light miscellaneous (45%; see Table 1 for a complete listing of percent prevalence of occupation.) There were two significant findings when comparing LBP and CTS groups in terms of occupation. Specifically, occupations categorized as heavy clerical were more frequently endorsed by CTS patients (50%) than by LBP patients (12%; X 2 = 8.97, df = 1, p < .005). Occupations categorized as light miscellaneous were more frequently endorsed by LBP patients (46%) than by CTS patients (16%; X 2 = 9.72, df = 1, p < .005). The duration of the disorder, that is the number of months from the reported origin of symptoms to the date of the evaluation, was also obtained and compared between the two patient groups. Specifically, the CTS patients reported a significantly greater duration of symptoms (X = 3.62 months) than did the LBP patients (X = .88 months; t = 9.13, df = 92, p < .001). Axis I Prevalence Rates: Lifetime The results indicated that 77% of the CTS patients received at least one DSMIII-R Axis I diagnosis. The most frequently diagnosed Axis I disorder in the CTS
Table 1. Percent Prevalence of Occupation in 44 Carpal Tunnel Syndrome Patients and 50 Low Back Pain Patients
Type of occupation
CTS
LBP
(n = 44) %
(n = 50) (%)
Light clerical (receptionist, personnel)
2%
Heavy clerical (keyboards, word processor)
50
12"
Manufacturing (stocker, meat packer)
11
16
Driving (truck driver, bus driver)
5
10
Medical (dental hygienist)
5
0
Artistic (hair stylist, reporter)
5
2
Light miscellaneous (nurse, housekeeper, executive)
16
46*
Heavy miscellaneus (construction, forklift operator)
5
10
"p < .005.
4%
Carpal Tunnel Syndrome
203
g r o u p was anxiety d i s o r d e r s (45%). F u r t h e r , within the anxiety d i s o r d e r category, the m o s t f r e q u e n t l y d i a g n o s e d d i s o r d e r s w e r e p h o b i c d i s o r d e r s (52%, o r 23 p h o b i c d i s o r d e r diagnoses a m o n g 44 patients; see T a b l e 2 for f r e q u e n c i e s o f specific Axis I lifetime d i a g n o s e s a m o n g CTS patients.) W i t h r e g a r d to the L B P patients, 5 4 % received at least o n e D S M - I I I - R diagnosis. T h e most f r e q u e n t l y d i a g n o s e d d i s o r d e r in the L B P g r o u p was substance a b u s e d i s o r d e r s (38%), followed closely by affective d i s o r d e r s (36%). T a b l e 3 p r e s e n t s lifetime p r e v a l e n c e rates o f Axis I clinical diso r d e r s for b o t h g r o u p s o f patients. A n u m b e r o f significant differences w e r e f o u n d b e t w e e n the CTS a n d L B P p a t i e n t s with r e g a r d to lifetime p r e v a l e n c e rates of psychopathology. Specifically, CTS p a t i e n t s h a d a significantly higher rate o f anxiety d i s o r d e r diagnoses ( 4 5 % ) than did L B P p a t i e n t s (12%; X 2 = 13.09, df = 1, p < .001). T o d e t e r m i n e if this finding was an artifact o f g e n d e r , a s e p a r a t e analysis was c o m p u t e d using only the results of the f e m a l e subjects; accordingly, f e m a l e CTS p a t i e n t s had a significantly higher rate o f anxiety d i s o r d e r s (50%) than did f e m a l e L B P p a t i e n t s (20%; X 2 = 5.0, df = 1, p < .05). In r e g a r d to o t h e r clinical diagnoses, L B P p a t i e n t s had a significantly h i g h e r rate o f s u b s t a n c e a b u s e d i s o r d e r s (38%) than did CTS p a t i e n t s (18%; X 2 = 4.5, df = 1, p < .05). H o w e v e r , this did not hold true when male CTS and L B P p a t i e n t s
Table 2. Frequency of Lifetime Axis I Diagnoses in 44 Carpal Tunnel Syndrome Patients
Axis I disorder Somatoform disorders Somatoform pain Somatization Hypochondriasis Undifferentiated somatoform disorder Substance abuse Affective disorders Bipolar Major depression Dysthymia Anxiety disorders Generalized anxiety Phobic disorders Panic disorders Obsessive-compulsive PTSD Agoraphobia WOPD Psychotic disorders Others Organic mood syndrome Adjustment disorder Eating/Impulse control
Men (n = 4) (J')
Women (n = 40) (f)
Total (n = 44) (D
I ---2
3 -3 1 11
4 -3 1 13
----
-18 --
-18 --
------
3 23
3 23
1
1
3 6
3 6
1
3
4
1 ---
4 1 1
5 1 1
204
Mathis et ai. Table 3. Percent Prevalence of Lifetime Axis I Disorders in CTS and LBP Patients CTS Men (n = 4)
Women (n = 40)
LBP Total (n = 40)
Affective disorders
0%
45%
41%
Anxiety disorders
0
50
45
Substance abuse
50
15
Somatoform disorders
25
Psychotic disorders Organic mood syndrome
Men (n = 30) 23%
Women (n = 20)
Total (n = 50)
55%
36%
7
20
12
18
47
25
38
13
14
7
0
4
25
8
9
7
0
4
25
10
11
0
0
0
Adjustment disorder
0
3
2
0
5
2
Eating/impulse control dis.
0
5
5
0
0
0
were analyzed separately from female patients, indicating that substance abuse was frequently diagnosed in all male patients, and that since there were significantly more male LBP patients than CTS patients, gender might be an artifact in this finding. There were no other significant differences in rates of lifetime prevalence of Axis I disorders between CTS and LBP patients.
Axis I Prevalence Rates: Current
Results revealed that 50% of the CTS patients received at least one current Axis I disorder diagnosis. The most frequently diagnosed disorders were anxiety disorders (36%) (See Table 4 for a complete list of current Axis I disorder diagnoses in the CTS group.) Twenty percent of the LBP patients received at least one current Axis I disorder diagnosis. The most common diagnoses among LBP patients were affective disorders (12%). Table 5 presents prevalence of current Axis I disorder diagnoses among both CTS and LBP patients. Carpal tunnel patients had significantly higher rates of current anxiety disorders than LBP patients (36% versus 6%; X 2 = 13.39, df = 1, p < .001). This held true when female CTS and LBP patients were analyzed separately from the males (40% versus 15%, respectively; X 2 = 3.87, df = 1, p < .05). In regard to all other current Axis I disorder diagnoses, there were no significant differences between the CTS and LBP groups of patients.
20S
Carpal Tunnel Syndrome Table 4. Frequency of Current Axis I Diagnoses in 44 Carpal Tunnel Syndrome Patients
Axis I d i s o r d e r Somatoform disorders Somatoform pain Somatization Hypochondriasis Undifferentiated somatoform disorder Substance abuse Affective disorders Bipolar Major depression Dysthymia Anxiety disorders G e n e r a l i z e d anxiety Phobic disorders Panic disorders Obsessive-compulsive PTSD Psychotic disorders Others Organic mood syndrome Adjustment disorder Eating/Impulse control
Men (n = 4) (it)
Women (n = 40) (f)
Total (n = 44) (f)
1 -----
3 -3 1 --
4
----
-7 --
-7
-----1
3 17 -3 3 1
3 17 -3 3 2
----
1 1
1 1
1
1
3 1 --
Table 5. P e r c e n t P r e v a l e n c e o f C u r r e n t Axis I D i s o r d e r s in C T S a n d L B P P a t i e n t s CTS Axis I D i s o r d e r
Men (n = 4)
Women (n = 40)
LBP Total (n = 44)
Men (n = 30)
Women (n = 20)
Total (n = 50)
Affective d i s o r d e r s
0%
18%
16%
7%
20%
12%
Artxiety d i s o r d e r s
0
40
36
0
15
6
Substance abuse
0
0
0
3
0
2
Somatoform disorders
25
13
14
7
0
4
Psychotic disorders
25
5
7
7
0
4
Organic mood syndrome
0
3
2
0
0
0
Adjustment disorder
0
3
2
0
5
2
E a t i n g ] i m p u l s e c o n t r o l dis.
0
0
0
0
0
0
206
Mathis~aL Gender Differences
Within each group of patients, gender analyses were completed in regard to lifetime and current Axis I clinical disorders. There were no significant differences between male and female CTS patients, although this is at least partially due to the overrepresentation of women in the CTS group. In the LBP group, female patients had significantly higher rates of lifetime affective disorders (55%) than did male patients (23%; X ~ -- 5.23, df = 1, p < .05). Female LBP patients also had significantly higher rates of current anxiety (15%) than did male LBP patients (0%; X 2 = 4.75, df = 1, p < .05). Axis II Prevalence Rates
With respect to Axis II personality disorders, the results indicated that 21% of the CTS patients fulfilled diagnostic criteria for at least one personality disorder. This figure is roughly similar to the prevalence rate of at least one personality disorder in the LBP group (24%). The most common personality disorder diagnoses in the CTS group were paranoid personality disorder (9%; defined by the DSMIII-R as a pervasive and unwarranted tendency, beginning by early adulthood and present in a variety of contexts, to interpret the actions of people as deliberately demeaning or threatening) and obsessive-compulsive personality disorder (9%; defined by the DSM-III-R as a pervasive pattern of perfectionism and inflexibility, beginning by early adulthood and present in a variety of contexts). Paranoid personality disorder was also the most common personality disorder diagnosis in the LBP group (18%). Other frequently diagnosed personality disorders in this group include passive-aggressive personality disorder (8%; defined by the DSM-III-R as a pervasive pattern of passive resistance to demands for adequate social and occupational performance, beginning by early adulthood and present in a variety of contexts) and borderline personality disorder (10%; defined by the DSM-III-R as a pervasive pattern of instability of self-image, interpersonal relationships and mood, beginning by early adulthood and present in a variety of contexts).
DISCUSSION
The present results revealed that CTS patients had higher rates of anxiety disorders, both lifetime and current, than did LBP patients. With respect to other forms of psychopathology, prevalence rates for CTS patients were comparable to the LBP patients, with the exception of substance abuse disorders. Here, LBP patients had significantly higher rates of lifetime substance abuse disorders than did CTS patients. For the most part, then, with the exception of anxiety disorders and substance abuse, CTS patients appear similar clinically to LBP patients. Overall, these results suggest that CTS patients may be similar to other acute pain patients in terms of
Carpal Tunnel Syndrome
207
psychopathology; however, unlike other pain patients, CTS patients have significantly greater rates of anxiety disorders, particularly phobias. In an earlier study, Kinney, Gatchel, Polatin, Fogarty, and Mayer (23) reported much lower rates of substance abuse in the sample of acute low back pain patients evaluated relative to those found in the present study. There are a number of potential reasons for this discrepancy, such as a different gender proportion, as well as age differences of patients in the two studies. A replication study will need to be conducted in order to control for these differences. Until then, one must interpret these substance abuse findings with some caution. The finding of a greater prevalence of anxiety disorders in acute CTS patients (nearly one-half of the sample had a lifetime history of some anxiety disorder) is quite compelling. Neither the acute LBP patients in this study, not the acute or chronic LBP patients in the Kinney et al. (23) study, were found to have rates this high. Indeed, these are the first results generated from a systematic assessment of prevalence rates of psychopathology in CTS patients. The fact that anxiety disorder rates were found to be so high suggests that this clinical syndrome may be more of a significant underpinning of CTS than in other musculoskeletal disorders. One might argue that the higher frequency of anxiety in the CTS group might be because the CTS patients reported a longer duration of symptoms than the LBP patients. However, if duration was a factor in these results, we would also expect a greater frequency of depression in the CTS patients, since depression is the most common concomitant of chronic pain (24). This, however, was not the case. Interestingly, Spence (14) found that acute and chronic upper limb pain patients had similar levels of anxiety, and that both acute and chronic upper limb patients had greater anxiety than normal. Spence's (14) finding that chronic upper limb pain patients had no greater anxiety than acute upper limb patients supports the notion that anxiety might be a predisposing factor in upper extremity disorders, as suggested by the current examination of acute CTS patients. One might speculate that the higher level of anxiety found in individuals with CTS is accompanied by a concomitant increased muscle tension level (via an anxiety-muscle tension feedback loop) that predisposes the individual to more neuromuscular fatigue. This fatigue factor, in turn, may increase one's susceptibility to repetitive motion disorders such as CTS. In support of this notion, Feuerstein and Fitzgerald (9) reported that sign language interpreters with upper extremity pain demonstrated a tendency toward a particular "workstyle," characterized by fewer rest breaks, more frequent hand and wrist deviations, and more rapid finger and hand movements than those not experiencing upper extremity pain (9). These researchers suggest that some individuals might be predisposed to respond to work tasks in such a way that leads to greater neuromuscular stress that, in turn, can lead to upper extremity disorders (9). Of course, this is not to say that psychopathology is the primary cause of CTS. Indeed, not all patients in the present study evidenced any psychopathology. Pain is a complex psychophysiological behavior pattern that cannot be broken down into distinct psychological and physical components. The growing acceptance of a
208
Mathis et al.
biopsychosocial conceptual model of pain (24-26), which includes physical, psychological, and social elements, moves away from an overly simplistic physical disease model of pain, and replaces it with an alternative multidimensional model. The present results suggest that one such psychosocial factor----psychopathology--is a potentially important contributory factor for certain patients that will need to be more closely evaluated in future studies of CTS patients. Some patients may have certain premorbid characteristics---specifically anxiety disorder3 that make them more susceptible to CTS. As in other areas of the growing field of health psychology-behavioral medicine, medical personnel will need to be aware of the psychological characteristics of their patients in order to prevent costly effects (both economic and human productivity losses) of prolonged bouts of disability. These results also suggest important implications for treatment of individuals with CTS. Since pain patients with significant levels of psychopathology tend to have less favorable treatment outcomes than those without psychopathology (27), identifying particularly anxious CTS patients could result in more efficient, multidisciplinary treatment of such individuals. More specifically, knowing that anxiety might present a problem for CTS patients could allow the clinician to structure his or her treatment plan with sensitivity to issues of anxiety, perhaps by including treatment modalities that focus on anxiety and tension reduction. This may help prevent the development of chronicity. Moreover, as CTS becomes more chronic, it is especially important to include a multidisciplinary treatment program because of the dramatically increased rates of psychopathology found in chronic pain patients (1, 3, 17). An example of such a multidisciplinary approach was recently used in the treatment of upper extremity disorders by Feuerstein et al. (15). An important issue concerning this study is whether the anxiety found in these CTS patients is a consequence of CTS or whether preexisting anxiety predisposes one to develop CTS. The finding that 45% of the CTS patients received a lifetime diagnosis of anxiety, as well as the acute nature of CTS symptoms in this group of patients, suggests that for many of the patients anxiety may have existed prior to the onset of CTS. We did not address this question specifically, and future research will need to clarify the etiological relationship between psychological disorders and the development of CTS. An additional limitation of the current study is the absence of a nonclinical "healthy" control group with which to compare pain patients. Including such a group in future research would allow for a more stringent comparison between patient and nonpatient groups. Finally, it is important to note that the present investigation focused on CTS only, and that further investigations of other upper extremity pain disorders in terms of identifying prevalence of psychopathology appear warranted.
ACKNOWLEDGMENTS This research was supported by grants to the second author from the National Institute of Mental Health (MH46452 and MH01107).
209
Carpal Tunnel Syndrome REFERENCES
1. Fishbain DA, Goldberg M, Meagher BR, Steele R, Rosomoff H. Male and female chronic pain patients categorized by DSM-III psychiatric diagnostic criteria. Pain 26; 181-197: 1986. 2. Kinney RK, Gatchel R J, Ellis E, Holt C. Major psychological disorders in chronic TMD patients: Implications for successful management. J Am Dent Assoc 123; 49-54: 1922. 3. Polatin PB, Kinney RK, Gatchel RJ, Lillo E, Mayer TG. Psychiatric illness and chronic low-back pain. Spine 18(1); 66-71: 1993. 4. Thompson JS, Phelps TH. Repetitive strain injuries: How to deal with "the epidemic of the 1990s." Postgrad Med 88(8); 143-149: 1990. 5. Schuind F, Venlura M, Pasleels JL. Idiopathic carpal tunnel syndrome: Histologic study of flexor tendon synovium. J Hand Surg 15(A); 497-503: 1990. 6. Fisk GR. The painful wrist: Problems and solutions. In: Perry CBW, ed. The hand and upper limb: Vol. 16. Management of pain in the hand and wrist New York: Churchill Livingstone, 1991, pp. 48-68. 7. Phalen GS. The birth of a syndrome, or carpal tunnel revisited. J Hand Surg 6; 109-110: 1981. 8. Szabol RM, Madison M. Carpal tunnel syndrome. Orthop Clin Am 23(1); 103-109: 1992. 9. Feuerstein M, Fitzgerald TD. Biomecbanieal factors affecting upper extremity cumulative trauma disorders in sign language interpreters. Occup Med 34(3); 257-264: 1992. 10. Hybbinette CH, Mannerfelt L. The carpal tunnel syndrome: A retrospective study of 400 operated patients. Aeta Orthopaed Scand 46; 610-620: 1975. 11. Bruehl S, Carlson CR. Predisposing Psychological factors in the development of reflex sympathetic dystrophy. Clin J Pain 8(4); 287-299: 1992. 12. Houdenhove BV, Vasquez G, Onghena P, Stans L, Vandeput C, Vermaut G, Vervaeke G, lgodt P, Vertommen H. Etiopathogenesis of reflex sympathetic dystrophy: A review and biopsychosocial hypothesis. Clin J Pain 8; 300-306: 1992. 13. Ireland DCR. The Australian experience with cumulative trauma disorders. In Millender LH, Louis DS, Simmons BP, eds. Occupational disorders of the upper extremity. New York: Churchill Livingstone, 1992, pp. 79-88. 14. Spence SH. Psychopathology amongst acute and chronic patients with occupationally related upper limb pain versus accident injuries of the upper limbs. Austr Psychol 25(3); 293-305: 1990. 15. Feuerstein M, Callan-Harris S, Hickey P, Dyer D, Armbruster W, Carosella AM. Multidisciplinary rehabilitation of chronic workrelated upper extremity disorders. J Occup Med 35(4); 396-403: 1993. 16. American Psychiatric Association. Diagnostic and statistical manual of mental disorders (3rd Ed. revised). Washington, D.C.: Author, 1987. 17. Kinney RK. The Assessment of Psychopathology in Three Groups of Pain Patients. Unpublished doctoral dissertation, University of Texas Southwestern Medical Center at Dallas, Texas, 1991. 18. De Krom MCTFM, Kester ADM, Knipschild PG, Spaans F. Risk factors for carpal tunnel syndrome. Am J Epidemiol 132(6); 1102-1110: 1990. 19. Vessey MP, Villard-Mackintosh L, Yeates D. Epidemiology of carpal tunnel syndrome in women of childbearing age: Findings in a large cohort study. Int J Epidemiol 19(3); 655-659: 1990. 20. Spitzer RL, Williams JBW, Gibbon M, First MB. Stnwtured clinical interview for DSM-III-R.New York: New York State Psychiatric Institute, 1988. 21. Williams JBW, Gibbon M, First MB, Spitzer RL, Davies M, Borus J, Howes MJ, Kane J, Hope HG, Rounsaville B, Wittchen HU. The structured clinical interview for DSM-III-R (SCID). Arch Gen Psychiat 49; 630-636: 1992. 22. Skodol AE, Rosnick L, Kellman D, Oldham, JM, Hyler SE. Validating structured DSM-III-R personality disorder assessments using longitudinal data. Am J Psychiat 145; 1297-1299: 1988. 23. Kinney RK, Gatchel RJ, Polatin PB, Fogarty WJ, Mayer TG. Prevalence of psychopathology in acute and chronic low back pain patients. J Occupa Rehab 3; 231-244: 1993. 24. Gatchel RJ. Early development of physical and mental deconditioning in painful spinal disorders. In: Mayer TG, Mooney V, Gatchel R J, eds. Contemporary conservative care forpah~ful spine disorders. 1991. 25. Malone MD, Strube M J. Meta-analysis of non-medical treatments for chronic pain. Pain 34; 231-244: 1988. 26. Polatin PB, Gatchel RJ, Barnes D, Mayer H, Arens C, Mayer TG. A psychosociomedical prediction model of response to treatment by chronically disabled workers with low back pain. Spine 14(9); 956-961: 1989.
210
Mathis et ai.
27. Schwartz RA, Greene CS, Laskin DM. Personality characteristics of patients with myofascial pain-dysfunction (MPD) syndrome unresponsive to conventional therapy. J Dent Res 58; 1435-1439: 1979.
