Page 190 - ILAE_Lectures_2015

Chapter 19

Diagnosis and management of dissociative seizures

JOHN D.C. MELLERS

Department of Neuropsychiatry, Maudsley Hospital, Denmark Hill, London

Up to one in five people diagnosed with epilepsy will turn out to have dissociative seizures
(DS)  psychologically mediated episodes of altered awareness and/or behaviour that may
mimic any type of epilepsy1,2. These patients are typically treated with antiepileptic
medication for a number of years before the correct diagnosis is made. During this time they
are exposed to significant iatrogenic risks including drug toxicity, teratogenic risk (most
patients are young women) and the risk, in approximately 10%, of receiving emergency
treatment for ‘status’3,4. By the time the correct diagnosis is made many patients and their
families have already adapted their lives to chronic disability. For some, a medical ‘sick role’
seems preferable to a psychiatric one from the start. For the majority, however, years of
inappropriate medical interventions will have reinforced the patients’ view of themselves as
medically disabled. The one factor consistently associated with a better prognosis in this and
other functional disorders is a short duration of illness at the time of diagnosis: in other words,
prompt diagnosis5. How to recognise and treat DS is therefore an important subject for all
clinicians working in the field of epilepsy.

Definitions and terminology

A review in 1997 found no less than 15 synonyms for this disorder6. Some terms
(pseudoseizures, hysterical fits) are clearly pejorative and have been abandoned. Others (non-
epileptic seizures, non-epileptic events, non-epileptic attack disorder) define the condition by
what it is not and may well be interpreted by the patient as suggesting that ‘the doctor doesn’t
know what’s wrong with me’7. Furthermore, some of these terms are ambiguous. Non-
epileptic seizures (NES), for example, is used by some to describe conditions, both medical
and psychiatric, that may be mistaken for epilepsy, while on other occasions NES is used as
a form of shorthand for the psychogenic attacks alone. The debate about terminology is likely
to continue, but in the meantime ICD 108 does in fact provide a perfectly acceptable and
useful label  dissociative convulsions. In recognition of the fact that many patients with this
disorder do not actually suffer a ‘convulsion’, the term dissociative seizures is probably
better.

Psychiatric disorders that may be mistaken for epilepsy

A list of the medical and psychiatric disorders that may be mistaken for epilepsy is given in
Table 1. The clinical features distinguishing epilepsy from paroxysmal cardiological,
neurological and other medical disorders are reviewed elsewhere in this section9,10. Syncope
is probably the most frequent missed diagnosis in non-specialist settings but by the time
patients are referred to specialist epilepsy clinics DS is by far the most important differential
diagnosis1. Indeed, the possibility of DS should be one of the first considerations in a patient
with medically intractable seizures.

Apart from DS a number of psychiatric disorders may occasionally be mistaken for epilepsy
and vice versa. The most important example is panic disorder which may be confused with