Page 183 - ILAE_Lectures_2015

Frontal lobe epilepsy
1. Can occur throughout night but most likely in transition periods and NREM light
sleep
2. May occur several times per night, often in clusters (may be unrecognised)
3. Frequency varies
4. Age at onset variable, often childhood or teens.

Three main types of nocturnal frontal lobe seizures have been described: paroxysmal
arousals, nocturnal paroxysmal dystonia and episodic nocturnal wanderings22.

Paroxysmal arousals consist of brief, sudden eye opening, head raising or sitting up in bed, a
frightened expression and, sometimes, vocalisation. Nocturnal paroxysmal dystonia involves
dystonic posturing and hypermotor (complex motor) phenomena. Episodic nocturnal
wanderings are longer in duration (13 minutes), with associated stereotyped dystonic
movements22. People with nocturnal frontal lobe epilepsy (NFLE) will commonly have more
than one of these seizure types. Daytime inter-ictal EEG shows epileptiform abnormalities in
up to one-third of cases; this increases to 50% of nocturnal EEGs. Ictal EEG is often unhelpful
with no clear changes or only myogenic artefacts. Occasionally there may be subtle features
such as electrodecrement or rhythmic frontal slow.

If seizures are very brief, it can be particularly difficult to obtain correct diagnosis. However,
distinguishing on the basis of frequency, time of night and stage of sleep can be particularly
useful, as mentioned above. Furthermore, there are semiological features that can help
distinguish between epilepsy and parasomnia. Importantly, brevity, sitting, standing/walking,
preceding arousal or fearful emotional behaviour are not good differentiators. Stereotypy and
dystonic posturing are more common features in seizures, while yawning, waxing and
waning, prolonged duration (over two minutes) and indistinct offset are more common in
parasomnias19. This last feature is quite a notable difference between seizures and NREM
parasomnias on video. Derry and co-workers have devised a scoring system (the frontal lobe
epilepsy and parasomnia or FLEP scale) and more recently also a diagnostic decision tree to
facilitate differentiation of seizures and parasomnia23,24 (Table 2).

Parasomnias
Parasomnias are abnormal events occurring in association with sleep that are classified
according to the sleep stage from which they occur. NREM parasomnias occur from deep
NREM sleep (stage III) and REM sleep behaviour disorders (RBD) occur during REM sleep.

NREM parasomnia
1. Occurs in the first third of the night
2. 13 episodes per night
3. Frequency varies
4. Onset in childhood.

NREM parasomnias are often most difficult to differentiate from nocturnal epileptic seizures.
As for nocturnal frontal lobe seizures, there are also three main types of NREM parasomnia:
confusional arousal, night terrors (pavor nocturnis) and sleep walking (somnambulism).
There are however more uncommon types, such as sleep eating and sleep sex. There is often
a family history of NREM parasomnias that can be of any type, not necessarily the same for
all affected family members. Symptoms are often exacerbated by sleep deprivation, fever and
stress. For some patients alcohol may be a trigger but this has been disputed25. Other sleep
disorders causing sleep deprivation (such as obstructive sleep apnoea and periodic limb
movements of sleep) may also exacerbate NREM parasomnias.