New Perspectives on the Diagnosis and Misdiagnosis in Blackouts

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Abstract

Patients presenting with an abrupt loss of postural control are commonly said to have had ‘collapse?cause’. This is a common presentation, accounting for up to 6% of emergency department cases, and 3% of hospital admissions. However, collapse?cause is a ‘catch-all’ term and there are many different causes which include falls, transient ischemic attacks, cerebrovascular accidents, road traffic accidents, metabolic abnormalities, intoxication, and transient loss of consciousness, (TLOC or ‘blackout’). A majority of patients fall into the latter category. Where TLOC has occurred, the causes are syncope, epilepsy and psychogenic blackouts. The clinical features of these three conditions can often be similar, albeit with subtle differences. A wide variation exists in the way such patients are assessed, investigated and managed, who manages them and where. There is an absence of simple clinical tools for assessment, poor risk stratification, inappropriate and overuse of investigations. Hospitalisation is often unnecessary and misdiagnoses are common. In this thesis, the problem of TLOC has been addressed in four projects. Section 1 (Chapter II): reports a simple new risk stratification scheme for patients presenting with TLOC, assessed in a specialist nurse lead, cardiologist supervised (SP), Rapid Access Blackouts Triage Clinic - RABTC. Frequently, after triage, a patient may be deemed to be at low risk, but blackouts continue, the cause remains unclear, and conventional tests, have been unhelpful. In Chapter III, we describe the option of investigating such patients by long term (up to 3 years) ECG monitoring using an implantable loop recorder (ILR). In order to address the specific question of misdiagnosis of epilepsy where convulsive syncope might be the true diagnosis, the REVISE Study- REVeal in the Investigation of Syncope and Epilepsy was undertaken, which is described in Chapter IV. Lastly, convulsive syncope is the likely explanation for a misdiagnosis in patients diagnosed with epilepsy, but the incidence of cardiac disease in patients with brain injury and epilepsy is unknown. Therefore a cohort of patients in a residential epilepsy centre was studied. In this setting, residents typically had a history of brain injury and suffered from recurrent epileptic seizures. The findings of cardiology assessment are presented in Section 4 (Chapter V).

Keyword(s)

blackouts; diagnosis and misdiagnosis; epilepsy; psychogenic blackouts; syncope; transient loss of consciousness

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