Brain Advance Access originally published online on September 8, 2009
Brain 2009 132(10):2878-2888; doi:10.1093/brain/awp220
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Symptoms ‘unexplained by organic disease’ in 1144 new neurology out-patients: how often does the diagnosis change at follow-up?
1 School of Molecular and Clinical Medicine, University of Edinburgh, Edinburgh EH16 5SB, UK 2 Institute of Neurological Sciences, Southern General Hospital, Glasgow G51 4TF, UK 3 Aberdeen Royal Infirmary, Aberdeen AB25 2ZN, UK 4 Ninewells Hospital, University of Dundee, Dundee DD1 4HN, UK 5 School of Clinical Sciences and Community Health, University of Edinburgh, Edinburgh EH16 5SB, UK 6 Hairmyres Hospital, East Kilbride G75 8RG, UK 7 Sackler Institute of Psychobiological Research, Division of Community Based Sciences, Faculty of Medicine, University of Glasgow, Glasgow G12 0XH, UK 8 University of Glasgow Dental School, Glasgow G2 3JZ, UK
Correspondence to: Dr Jon Stone, Division of Clinical Neurosciences, Western General Hospital, Edinburgh EH4 2XU, UK E-mail: jon.stone{at}ed.ac.uk
It has been previously reported that a substantial proportion of newly referred neurology out-patients have symptoms that are considered by the assessing neurologist as unexplained by ‘organic disease’. There has however been much controversy about how often such patients subsequently develop a disease diagnosis that, with hindsight, would have explained the symptoms. We aimed to determine in a large sample of new neurology out-patients: (i) what proportion are assessed as having symptoms unexplained by disease and the diagnoses given to them; and (ii) how often a neurological disorder emerged which, with hindsight, explained the original symptoms. We carried out a prospective cohort study of patients referred from primary care to National Health Service neurology clinics in Scotland, UK. Measures were: (i) the proportion of patients with symptoms rated by the assessing neurologist as ‘not at all’ or only ‘somewhat explained’ by ‘organic disease’ and the neurological diagnoses recorded at initial assessment; and (ii) the frequency of unexpected new diagnoses made over the following 18 months (according to the primary-care physician). One thousand four hundred and forty-four patients (30% of all new patients) were rated as having symptoms ‘not at all’ or only ‘somewhat explained’ by ‘organic disease’. The most common categories of diagnosis were: (i) organic neurological disease but with symptoms unexplained by it (26%); (ii) headache disorders (26%); and (iii) conversion symptoms (motor, sensory or non-epileptic attacks) (18%). At follow-up only 4 out of 1030 patients (0.4%) had acquired an organic disease diagnosis that was unexpected at initial assessment and plausibly the cause of the patients’ original symptoms. Eight patients had died at follow-up; five of whom had initial diagnoses of non-epileptic attacks. Seven other types of diagnostic change with very different implications to a ‘missed diagnosis’ were found and a new classification of diagnostic revision is presented. One-third of new neurology out-patients are assessed as having symptoms ‘unexplained by organic disease’. A new diagnosis, which with hindsight explained the original symptoms, rarely became apparent to the patient's primary care doctor in the 18 months following the initial hospital consultation.
Key Words: conversion disorder; neurology; medically unexplained symptoms; misdiagnosis; prognosis
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Received June 19, 2009. Revised July 9, 2009. Accepted July 15, 2009.
*These authors contributed equally to this work.