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not be as abrupt as in TA, and ictal changes of tone are usually more pronounced. The EEG
features are also different: the ictal discharge is slower (<2.5 Hz) and irregular, and may
include other paroxysmal activity. Background activity is usually abnormal, and consistent
focal abnormalities may exist.

2. Myoclonic seizures
Myoclonic seizures (MS) are shock-like, brief, irregular, arrhythmic and less often rhythmic,
clonic twitching movements singular or repetitive2,3. They may affect facial, limb, and neck
or trunk muscles with varying force, amplitude and combinations. Their force may range
from mild and inconspicuous movements of the affected muscle groups to violent movements
of limbs and body that may make the patient fall on the ground, drop or throw things or kick
in the air. Commonly, the same patients experience combinations of mild and violent jerks.
MS may affect any muscle or group of muscles. They predominantly affect eyelids, facial
and neck muscles, and the upper more than the lower limbs. MS of IGE occur mainly on
awakening. Precipitating factors include sleep deprivation, fatigue, excitement or distress,
and often photic stimulation.

In pure MS consciousness is not impaired and the patient is fully aware of them. However,
myoclonic jerks are often a consistent ictal symptom of absence seizures20,21. The EEG
hallmark of MS are generalised bursts of polyspikes/polyspike-wave with variable side
emphasis and anterior predominance.

Eliciting a clinical history of MS is not always straightforward. The answer to a direct
question ‘Do you have jerks?’ is usually negative. Diagnostic yield improves by physically
demonstrating myoclonic jerks, and by inquiring about morning clumsiness and tremors (‘Do
you spill your morning tea?’ or ‘Do you drop things in the morning?’). Demonstrating that
MS often relate to fatigue, alcohol indulgence and sleep deprivation is also essential. One has
to bear in mind that MS may not be perfectly symmetrical and that occasionally they may be
clearly lateralised, although without consistent side emphasis.

3. Generalised tonic-clonic seizures
GTCS in IGE are primary in the sense that they are generalised from onset as opposed to
the secondary GTCS in focal epilepsies. The seizure itself is the same irrespective of
epilepsy syndrome. The main difference is in the preceding and sometimes in the ensuing
clinical and EEG phases. The GTCS in focal epilepsies are secondary to a cortical focus
and may be preceded by subjective symptoms (aura) or signs that indicate a focal onset.
Post-ictal lateralising electroclinical features (such as more depressed EEG activity over
one hemisphere or asymmetry in muscle hypotonia) would also argue for a focal onset.
Conversely, GTCS in IGE will occur without initial focal features, either out of the blue or
after clusters of MS or TA, or absence status epilepticus that may warn patients of an
impending convulsion. However, one has to bear in mind that rapid secondary
generalisation may effectively conceal a focal or lateralising onset from a symptomatic
focus, and conversely that GTCS in IGE may occasionally start with focal features such as
head turning.

Though dramatic, GTCS do not bear any diagnostic significance. It is the minor seizures
that provide the clues to diagnosis, investigative procedures and appropriate management.
Patients often seek medical attention for the first time because of a GTCS. This is often
erroneously considered as the ‘first seizure’ and is not treated or investigated. The truth is
that the first GTCS in IGE is usually preceded for months or years by undiagnosed MS and
TA, and it is their recognition that should prompt suitable treatment. Conversely, patients
may not have GTCS for years but this does not necessarily mean that they are ‘seizure free’.
Absences or myoclonic jerks may continue and treatment should be optimised instead of
withdrawn.