Page 165 - ILAE_Lectures_2015

Chapter 17

Non-epileptic paroxysmal neurological and cardiac events: the
differential diagnosis of epilepsy

FERGUS J. RUGG-GUNN

Department of Clinical and Experimental Epilepsy, National Hospital for Neurology and
Neurosurgery, Queen Square, London

An accurate clinical diagnosis requires differentiation between epilepsy and other causes of
transient neurological disturbance and collapse, but the manifestations of epileptic seizures
are diverse and there are many imitators, ranging from convulsive syncope to parasomnias.
Nevertheless, the diagnosis of epilepsy is frequently straightforward, particularly when
precise and detailed personal and eyewitness accounts of the prodrome, onset, evolution and
recovery period after the event are obtained.

Misdiagnosis is common, however, and possibly affects up to 230% of adults with a
diagnosis of epilepsy1,2. For example, 74 patients previously diagnosed with epilepsy were
investigated with tilt-table testing, prolonged electrocardiogram (ECG) monitoring, blood
pressure and ECG-monitored carotid sinus massage and found an alternative, cardiological
diagnosis in 31 patients (41.9%), including 13 taking antiepileptic medication3.

This and other reports highlight the high rate of misdiagnosis of epilepsy, the cause of which
is undoubtedly multifactorial. The reasons for misdiagnosis may include a deficiency of
relevant semiological information obtained during the ascertainment of the clinical history,
lack of understanding of the significance of specific clinical features and over-reliance on the
diagnostic value of routine investigations4. The attainment of a correct diagnosis is of
paramount importance as an erroneous diagnosis of epilepsy has physical, psychosocial5 and
socioeconomic consequences for the patient, and economic implications for the health and
welfare services6.

Syncope

Transient loss of awareness is common, and may affect up to 50% of people at some stage of
life7,8,9. Elucidating the aetiological basis for an episode of loss of awareness is challenging.
Typically, the episode is transient, patients are generally unable to provide an accurate
description of the event and there may be a lack of reliable witnesses, particularly in the
elderly who, more frequently, live alone. The difficulty in establishing an accurate diagnosis
is further hampered by systemic and neurological examinations and subsequent investigations
frequently being normal after an episode or between habitual attacks when the patient is seen
in the hospital ward or clinic10.

Transient loss of awareness has three main underlying mechanisms:
1. Transient global cerebral hypoperfusion, i.e. syncope
2. Epilepsy
3. Dissociative (psychogenic, non-epileptic) seizures (discussed in Chapter 19).

Syncope, derived from the Greek ‘syn’ meaning ‘with’ and ‘kopto’ meaning ‘I interrupt’,
may be defined as transient, self-limited loss of consciousness, usually leading to collapse,
due to cerebral hypoperfusion11.