Reliability of self-reported diagnoses in patients with neurologically unexplained symptoms

Background: Patients with neurologically unexplained symptoms (NUS) often have a previous history of other medically unexplained symptoms. A past history of such symptoms can help make a positive diagnosis of a somatoform or affective disorder, and enable appropriate management strategies. However, information on past medical diagnoses is primarily obtained from patient interviews and may be inaccurate, particularly in patients with NUS. Objective: To assess the reliability of past medical diagnoses reported by patients with NUS compared with patients with confirmed neurological disease (ND) without suspicion of somatoform illness. Methods: 21 patients with NUS and 16 patients with ND were interviewed about their current and past medical problems and diagnoses. The accuracy of the reported diagnoses was assessed through examination of their complete general practice notes. Results: The median number of previous diagnoses reported by patients with NUS was significantly higher than in controls (7 v 3, p = 0.001). There was no difference in the median number of confirmed diagnoses between the two groups (2 v 2.5); however, the median percentage of reported diagnoses confirmed by investigations was significantly smaller in the NUS group (22% v 80%, p = 0.001). The additional diagnoses reported by patients with NUS not only comprised functional syndromes such as irritable bowel syndrome or non-cardiac chest pain (6% v 0%, p = 0.01), but also organic diagnoses which had either been unequivocally excluded (5% v 0%, p = 0.006), were based on equivocal findings often found after multiple investigations (9% v 0%, p = 0.01), or had not been investigated before a clinical diagnosis was made (50% v 18%, p = 0.04). Conclusion: Reported previous diagnoses should not be taken at face value when the current differential diagnosis includes a functional/somatoform neurological syndrome, particularly if the list of past medical diagnoses is long. Confirmation of previous diagnoses from alternative sources may contribute to a diagnosis of somatoform disorder, allowing appropriate management strategies for the current (and past) complaints to be initiated.