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mistaken as evidence for epilepsy  are listed in Table 2. Epileptic seizures are brief, highly
stereotyped, paroxysmal alterations in neurological function that conform to a number of now
well-described syndromes. Broadly speaking, it is any variation from this clinical picture –
an atypical sequence of events – that will raise the suspicion of epilepsy. Despite 30 years of
videotelemetry there is no reliable shortcut to making the diagnosis: to recognise DS the
clinician must have experience with epilepsy. Some features worth highlighting are the long
duration of DS, their tendency to begin gradually, and to show a waxing and waning of motor
activity followed by an abrupt recovery, asynchronous movements (including side-to-side
head or body movements), eye closure, ictal crying and preserved recall after a period of
unresponsiveness20. An episode of motionless unresponsiveness77 lasting over five minutes
is unlikely to have an organic cause3. Patients with DS commonly report injuries. Friction
burns may be characteristic of DS. Bite injuries are reported in DS, especially to the tip of
the tongue and lip21, but severe scarring is extremely rare. Seizures during sleep are reported
just as frequently in DS (around 50%) as in epilepsy65.

Table 2. Comparative semiology of dissociative epileptic seizures.
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Dissociative seizures Epileptic seizures

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Duration over two minutes common rare

Recall for a period of unresponsiveness common very rare

Motor features common rare
Gradual onset common rare
Eyes closed common rare
Thrashing, violent movements common rare
Side-to-side head movement occasional rare
Pelvic thrusting occasional very rare
Opisthotonus, ‘arc de cercle’ common very rare
Fluctuating course rare common
Automatisms

Weeping occasional very rare

aIncontinence occasional common

aInjury occasional common
Biting inside of mouth very rare common
Severe tongue biting

aStereotyped attacks common very rare

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aThree features that are commonly misinterpreted as evidence for epilepsy have been included.
Otherwise the table lists clinical features that are useful in distinguishing DS from epileptic seizures.

Figures for frequency of these features are approximate: common >30%; occasional 1030%; rare
<10%; very rare <5%. (Adapted from Mellers20)