Attitudes Toward Neurosurgical Procedures for Parkinson's Disease and Obsessive-Compulsive Disorder

The data used in this study were derived from a survey of a stratified random sample of 3,000 individuals conducted between January 1997 and April 1997. Stratification resulted in 1,000 individuals being included as U.S. members of the American Psychiatric Association (APA) and 1,000 being included as U.S. members of the American Academy of Neurology (AAN). The AAN has more than 14,000 U.S. members; 1,000 names were randomly selected with additional geographic and subspecialty stratification. The APA has more than 41,000 U.S. members; 1,000 names were randomly selected with stratification by zip code.

We developed two self-administered, anonymous questionnaires that included sections on demographic characteristics, professional experiences with PD and OCD, and knowledge and attitudes toward stereotactic neurosurgery for PD and OCD (survey instrument available on request). The APA and AAN surveys were identical except for the ordering of questions: the AAN surveys addressed pallidotomy prior to anterior capsulotomy. Most response choices were dichotomous (yes/no). The survey packet included a cover letter (including information on informed consent), a copy of the questionnaire, and a prepaid return envelope. The questionnaire and study procedures were approved by the Institutional Review Board at Baylor College of Medicine. The initial survey and follow-up were conducted by mail and administered by the Center for Medical Ethics and Health Policy and the Department of Psychiatry and Behavioral Sciences of Baylor College of Medicine.

After 1 month, APA and AAN nonrespondents were mailed an additional survey and cover letter requesting participation. After a second month, we attempted to contact every fourth remaining nonrespondent from the APA and AAN lists by telephone, requesting their fax numbers to send another survey to those interested in completing it. This intensive data-collecting effort revealed errors in the original membership listings. Of the 2,000 APA and AAN members in our initial sample, 812 were declared ineligible. Respondents were determined to be ineligible because they were duplicate listings (those who were included in more than one sample), were deceased or retired, were non-M.D.s, failed to meet the deadline, or could not be located (those persons for whom no return mailing was received and who could not be located by telephone follow-up). Of the remaining, eligible 1,188 APA and AAN members, 569 returned valid questionnaires, yielding an overall response rate of 47.9%.

The survey data set was managed by using dBASE software and was analyzed with standard statistical techniques found in the SPSS software. Differences in proportions were tested with two sample proportions tests. Chi-square tests were applied to multilevel categorical data. Logistic regression was used for multivariate analyses, with relaxed statistical criteria for retaining variables in the model (P<0.1). Because of possible bias from multiple comparisons, statistical significance was set at the more conservative P<0.001 level.

Several dependent variables were used to measure attitudes and knowledge of stereotactic neurosurgical procedures. The first dependent variable (awareness) indicated the extent to which psychiatrists and neurologists were aware of neurosurgical procedures for PD and OCD. This parameter was derived from the following questions, which followed a brief introductory paragraph describing stereotactic pallidotomy and anterior capsulotomy: “I am aware of neurosurgical procedures for Parkinson's disease” and “I am aware of neurosurgical procedures for OCD.” The dichotomous response categories for each item were “yes” and “no.”

A second dependent variable (future referral) reflected respondents' plans to refer a patient with disabling PD for pallidotomy and a patient with disabling OCD for anterior capsulotomy. This parameter was measured through the following questions: “I would refer a patient with disabling Parkinson's disease refractory to medications and other interventions for pallidotomy” and “I would refer a patient with disabling OCD refractory to medications and psychosocial interventions for anterior capsulotomy.” An additional, related question began with “I believe colleagues in my state would refer….” The valid responses were again dichotomous, affirmative versus otherwise.

A third dependent variable (assessment) reflected respondents' evaluation of each stereotactic procedure. This variable was derived from the following question: “I consider pallidotomy [question repeated for anterior capsulotomy] to be: an experimental procedure, a medically accepted procedure, I don't know.” A trichotomous coding scheme was allowed here to better reflect respondents' knowledge.

For the APA and AAN surveys, this study investigated the potential association of three groups of independent variables on awareness, future referral patterns, and assessment of stereotactic neurosurgery: personal characteristics, practice patterns, and geography.

Personal characteristics included gender, race, age, academic affiliation (full-time faculty, volunteer or part-time faculty, resident/fellow, none), and board status (certified, eligible, other).

Two variables related to practice patterns: 1) number of patients seen per month with the diagnosis of PD and OCD and 2) degree of professional contact with neurosurgeons. To measure number of patients, the survey asked: “How many patients per month do you see with the diagnosis of Parkinson's [and again for OCD],” with options of 0–1, 2–5, 6–10, and >10 patients per month for both diagnoses. To gauge degree of contact with neurosurgeons, the survey asked: “My degree of professional contact with neurosurgeons is: none, rare, occasional, frequent, daily.”

Geography constituted the third category of independent variables. Respondents were asked to use the two-letter postal code of the state where they practice. We hypothesized that those physicians practicing in Rhode Island or Massachusetts would be more likely to be aware of OCD neurosurgery because of geographic proximity to stereotactic neurosurgery centers.

Of the 1,188 eligible APA and AAN members surveyed, 569 valid physician questionnaires (47.9%) were returned and evaluated (243 from psychiatrists and 326 from neurologists). There were no significant differences in the two physician groups in terms of gender, race, geography, or academic affiliation. Neurologists were significantly younger than psychiatrists (P<0.001). Board status had statistical significance (P=0.00162), although this was likely a secondary effect of age differences (Table 1). Compared with the AAN and APA memberships at large, our sample was representative for both groups in terms of gender, geographic distribution, ethnicity, and academic affiliation, but not for age distribution for the neurologists²⁰ or extent of board certification for the psychiatrists (85.1% in our sample vs. 55.3% nationally; personal communication with APA Office of Membership).

There were notable differences in practice patterns between the surveyed psychiatrists and neurologists (Table 2). As would be expected, a significantly greater proportion of practicing neurologists than psychiatrists saw a moderate to high number of PD patients per month (6 or greater; P<0.001). Likewise, a significantly greater proportion of psychiatrists than neurologists saw a moderate to high number of OCD patients per month (P<0.001). Only 3.2% of neurologists (n=10/312) saw 6 or more OCD patients per month, whereas only 3.3% of psychiatrists (n=8/242) saw 6 or more PD patients per month. For degree of professional contact with neurosurgeons, again there were significant differences: neurologists were much more likely to have a high level of contact than psychiatrists (P<0.001). Notably, 75.4% of psychiatrists (n=181/240) reported no or rare professional contact with neurosurgeons, while only 3.5% of neurologists (n=13/323) reported this low level of contact.

In all, 82.8% of psychiatrists (n=192/232) were aware of neurosurgical procedures for OCD, compared with 27.4% of neurologists (n=86/314; P<0.001; Table 3). Regarding pallidotomy for PD, 84.7% of psychiatrists (n=183/216) were aware of the procedure, compared with 99.4% of neurologists (n=312; P<0.001). In comparing psychiatrists' and neurologists' respective awareness of OCD versus PD neurosurgery, there were no significant differences for psychiatrists (P=0.574), but neurologists were significantly more likely to be aware of neurosurgical procedures for PD (P<0.001) than for OCD. Twenty-five psychiatrists (10.6%) have referred patients for OCD surgery, while 154 neurologists (48.1%) have referred patients for PD surgery (both P<0.001). Significantly more psychiatrists than neurologists (64.9% vs. 17.1%, P<0.001) regarded neurosurgical procedures for OCD as efficacious; conversely, significantly more neurologists than psychiatrists (90.8% vs. 61.9%, P<0.001) considered PD surgery efficacious relative to OCD surgery. The clear majority of both physician groups felt that neurosurgical procedures for OCD or PD did not carry too much risk, since all responses in this category received less than 30% affirmative responses, with nonsignificant P-values between groups.

In addition, 74.1% of psychiatrists (n=146/197) would refer an appropriate OCD patient for anterior capsulotomy, and 67.4% (n=122/181) were willing to refer an appropriate PD patient for pallidotomy (P=0.15). For neurologists, 25.6% (n=56/218) would refer an OCD patient for neurosurgery, while 94.3% (n=297/314) would refer a PD patient for pallidotomy (P<0.001). There were significant specialty differences between psychiatrists and neurologists (P<0.001) for willingness to refer an appropriate patient for these procedures. There was also strong support from both psychiatrists and neurologists for increased federal funding for both OCD and PD neurosurgery.

A large majority of both psychiatrists and neurologists felt that their fund of knowledge for anterior capsulotomy for OCD was inadequate or minimally adequate (89.3% and 96.8%, respectively). Similarly for pallidotomy for PD, psychiatrists overwhelmingly felt that their fund of knowledge was inadequate or minimally adequate (87.2%), although fewer than one-half of the neurologists (49.2%) felt they had a deficient knowledge base regarding pallidotomy for PD. For anterior capsulotomy for OCD, 26.9% of psychiatrists (n=63/234) considered it an experimental procedure, 22.2% (n=52/234) considered it medically accepted, and 50.9% (n=119/234) said they did not know. Neurologists more commonly felt it was an experimental procedure rather than a medically accepted procedure (n=104/287, 36.2%, vs. n=9/290, 3.1%, P<0.01), although 60.6% (n=174/287) said they did not know. In assessing pallidotomy for PD, there was no significant difference between psychiatrists who thought the procedure was experimental and those who thought it was medically accepted (22.1% vs. 29.6%, P=0.116). Neurologists significantly felt that pallidotomy was a medically accepted rather than an experimental procedure (65.3% vs. 27.1%, P<0.0001).

Regarding physician awareness, it has been shown in a study of electroconvulsive therapy (ECT) that the more knowledge and clinical experience a professional has, the more positive his or her attitude will be toward ECT as an effective treatment modality.²⁴ Extrapolating that study to our findings with stereotactic neurosurgery, it is disturbing that 17% of psychiatrists and 73% of neurologists were not aware of OCD neurosurgical procedures. There are several likely reasons for the marked disparity in physician awareness between PD and OCD neurosurgical procedures: better publicity in the scientific and academic communities, including sessions at AAN meetings on pallidotomy; greater number of scientific publications on pallidotomy by neurologists and neurosurgeons in leading peer-reviewed journals; and more publicity of pallidotomy for PD in the lay press.

These explanations, of course, beg the question of why there is more physician interest in performing PD neurosurgery than OCD neurosurgery in the first place. One possible factor for the lower preference for OCD surgery, not explored in this paper, is that it may be unduly associated with past “psychosurgical” techniques used for emotional problems, such as lobotomy. There may be a general reluctance for psychiatrists to enter the area of “psychosurgery” (a highly charged and stigmatized term); the reluctance may be due in part to this past association, coupled with the fact that there are laws in some states, such as California, regulating “psychosurgery” without comparable restrictions for neurosurgery.

Another possible explanation for the disparity in awareness between PD and OCD neurosurgery is the different practice patterns of psychiatrists and neurologists, the latter specialty reporting a much greater degree of professional contact with neurosurgeons. In fact, we found that the only factor positively correlated in multivariate linear regression with likelihood of referring for PD surgery, besides specialty, was degree of contact with neurosurgeons. Psychiatrists' significantly less frequent contact with neurosurgeons would perhaps make them less aware of potential surgical approaches for their patients. However, psychiatrists were significantly more likely than neurologists to be aware of OCD neurosurgery.

One might also suspect that familiarity with the disease would lead to increased awareness of treatment options and thus that neurologists (who seldom see OCD patients) would not know about OCD neurosurgery, and psychiatrists (who seldom see PD patients) would not be aware of PD neurosurgery. However, univariate analysis revealed that the number of patients seen with the diagnosis had no impact on degree of awareness of neurosurgical options, and psychiatrists were actually more aware of PD neurosurgery than of OCD neurosurgery.

A second generalization from this study is that despite data to the contrary, very few neurologists acknowledged the potential efficacy of neurosurgery for OCD, although there were no differences between psychiatrists and neurologists in assessing degree of risk. Conversely, greater than 90% of neurologists stated that pallidotomy for PD was efficacious. The published data for pallidotomy have shown a moderate to large amount of improvement in many subjects, but there are no double-blind controlled trials of pallidotomy at present, so at best one can state that the procedure helps certain specially selected patients who meet specific criteria. Likewise, the data for anterior capsulotomy for OCD are limited, although there are numerous uncontrolled data showing efficacy in the 60% to 70% range.²³ Given the low percentage of neurologists who were aware of neurosurgical intervention in OCD, we can ask why the vast majority would assume that these procedures are not effective. We speculate that this attitude reflects a fundamental bias of practitioners that psychiatric illnesses are conditions of the mind, whereas neurologic illnesses are brain-based and therefore worthy of aggressive, and possibly heroic, intervention in the form of neurosurgery.

A third generalization that can be derived from this study is the relative lack of “cross-talk” between the specialties of psychiatry and neurology. Numerous surveyed physicians responded, “I am a psychiatrist—I know nothing about Parkinson's”; or, “I am a neurologist who never sees any patients with OCD.” We received these typical responses despite evidence of great comorbidities of these two illnesses—PD with depression²⁵ and OCD with tic and neurologic disorders with compulsive features.²⁶ Indeed, both illnesses might best be conceived of as neuropsychiatric illnesses, diseases that the general psychiatrist and general neurologist should be comfortable evaluating. A neuropsychiatric conceptualization⁴ vaults the limiting and misleading demarcations of traditional concepts of illness and recognizes that both illnesses involve dysfunction in subcortical regions. The fact that only one out of four neurologists was even aware of neurosurgical options for OCD suggests the limited knowledge base that our sample of neurologists had about OCD. Similarly, most psychiatrists rated their knowledge base for PD surgery as inadequate, in stark contrast to neurologists, suggesting that many general psychiatrists might benefit from continuing education training in neurology to keep them abreast of therapeutic options. The relevance for the general psychiatrist is more than simply academic: recent data suggest that PD-induced changes in emotional status, such as depression or hypochondriacal complaints, are favorably influenced by pallidotomy.²⁷ Well-run managed care organizations and multispecialty clinics, which include all academic medical centers, are in an especially good position to foster such “cross-talk” as institutional policy and practice.

Several limitations of this study should be acknowledged. First, although our physician samples were largely representative of the national APA and AAN memberships, our results are not necessarily generalizable to non-APA member psychiatrists and non-AAN member neurologists. A recent survey of neurologists suggested that 89.2% of U.S. neurologists are AAN members (C. Keran, personal communication), and we suspect, though we could not confirm, that a similar proportion of U.S. psychiatrists are APA members.

A second potential limitation of our study is that although response rates were quite acceptable for surveys of this type, we cannot exclude the possibility that nonrespondents may have differed from respondents. Third, we relied on self-reports of behavior, which may increase the possibility of response biases. Because there was no independent verification of the data, it is possible that physicians might have overreported their degree of awareness of neurosurgical procedures for fear of appearing ignorant or uninformed. Finally, the questionnaire's brevity encouraged a relatively high response rate but limited our ability to study certain attitudinal dimensions, as well as knowledge, in greater depth. A more robust instrument might have shown additional attitudinal barriers or differences in knowledge between the sampled groups.

Because of these limitations, and the importance these questions have for the practice patterns of neurologists and psychiatrists who treat patients with debilitating OCD and PD, future studies should explore further differences in attitude and knowledge of physicians, including the neurosurgeons who treat these groups of patients. The designers of additional studies might wish to include primary care practitioners' and patients' views toward these two neuropsychiatric illnesses.