Organic syndromes diagnosed as conversion disorder: identification and frequency in a study of 85 patients
Introduction
The percentage of patients initially diagnosed with a conversion disorder [1] and later identified as having an organic disorder, in most cases a neurological disorder (i.e., a so-called false positive), has changed from the early days of Slater and Glithero [18], who considered the incidence to be high, to rather lower levels in more recent studies. Table 1 provides an overview of the most relevant studies.
Comparison of these studies is difficult for a number of reasons. First, some studies that find a high percentage of organic disorder, are quite dated. Since these works, major developments have occurred in the technical diagnosis of patients and advanced diagnostic techniques have become available 2, 3, 4, 5, 6. The studies are also difficult to compare due to differences in descriptions of the symptoms and delineation of the relevant symptom patterns (both pseudoneurological symptoms and pain symptoms or vomiting are mentioned). The fact that the diagnostic categories are often not mutually exclusive further complicates comparison 7, 8. In such a manner, Weintraub [9] cited a high false-positive rate of 63.5% in a study by Whitlock [10], but his patient group consisted of patients with coexisting neurological or organic disease.
Considerable differences between these studies also exist in the duration of the symptoms, the frequency of repeated physical examination, the thoroughness and care with which the diagnosis was performed, the research setting, and the time of follow-up. It appears that, with increased follow-up time, there is an increased probability of encountering neurological disease that can, in retrospect, explain the initial symptoms.
Finally, in a number of studies, diagnoses were determined by exclusion of an organic disease without further positive confirmation on the basis of psychiatric examination. In contrast, there are indications that patients with a previous psychiatric history are at a greater risk of having their neurological symptoms attributed to a psychiatric syndrome [5].
The aim of the present study was to explore the following questions:
- 1.
What incidence of neurological disorder is revealed by neurological reassessment, and by which diagnostic technique is the final diagnosis established?
- 2.
What differences can be observed between the organic or false-positive group and the conversion or true-positive group on the basis of the available information?
Section snippets
Method
Neurological reassessments and psychiatric examinations were undertaken on consecutive patients with a prior diagnosis of conversion disorder upon their referral to a Dutch psychiatric hospital (De Grote Rivieren) for examination and treatment during 1991 to 1996 11, 12, 13.
Inclusion criteria for the study were:
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A diagnosis of motor-type conversion disorder (i.e., paresis or paralysis, gait disturbances, coordination problems, abasia–astasia, aphonia, fits or pseudoepileptic seizures with motor
Subject characteristics
Our sample consisted of 85 patients (21.2% men and 78.8% women). Upon referral, their mean age was 38 years (sd = 12.7, range 17 to 65) with a mean onset at the age of 33.5 years (sd = 12.6; range 15 to 67). The duration of the symptoms was an average of 4.3 years (sd = 6.0, median 3.8 years, range 2 months to 34 years). In 27 (32.1%) patients, the onset of the symptoms had been acute (within 1 week). Forty (47.6%) patients had reported the same or other conversion symptoms in the past.
Discussion
In this study, we found that 11.8% of the sample consisted of false-positive conversion disorder patients. Compared with the conversion group, the organic group needed a surplus of supplemental examinations before the final diagnosis could be made. Comparison of both groups revealed that they differed significantly with respect to prior suspicion of neurological disorder, age at onset of symptoms, duration of symptoms, age at referral, and use of medication. The first three of these five
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