Page 182 - ILAE_Lectures_2015

Obstructive sleep apnoea (OSA) is more common in patients with epilepsy than in the general
population and may be related to severity of epilepsy. The risk factors for OSA are however
the same as in the general population (male gender, obesity, age). OSA may fragment sleep
as well as cause sleep deprivation that may have detrimental effect on seizure control. In older
adults with late onset seizures or worsening of seizure control, OSA has been associated with
seizure exacerbation17. Several studies have also shown an improvement of seizure control
after treatment of concomitant OSA18-21.

Table 1. Effect of antiepileptic drugs on sleep.

Effect on sleep Effects on sleep disorders

Sleep Sleep Stage I Stage II Stage III REM Improves/ Worsens

efficiency latency treats

Phenobarbitone ↑ ↓ - ↑ 0 ↓ Sleep onset OSA

insomnia

Phenytoin 0 ↓↑ ↑ ↓ 0 or ↓ None known None known

Carbamazepine 0 00 0 0 0 RLS RLS

Valproate - 0↑ ↓ 0 0 None known OSA*

Ethosuximide - -↑ - ↓ - None known None known

Gabapentin 0 00 0 ↑ ↑ RLS OSA*

Lamotrigine 0 0† 0 ↑ ↓ ↑ None known None known

Topiramate 0 ↓0 0 0 0 OSA* None known

Tiagabine - -- - ↑ - Insomnia None known

Levetiracetam - -- - ↑ - None known None known

Pregabalin ↑ -- - ↑ - None known OSA*

0, no change; -, not reported; ↑, increase; ↓, reduction; OSA, obstructive sleep apnoea; REM, rapid eye

movement; RLS, restless leg syndrome

*Due to change in weight

†Lamotrigine may be associated with insomnia (clinical observation but rarely reported in the

literature)

Epilepsy and AEDs may also aggravate OSA. AEDs could reduce respiratory drive and upper
airway tone and some drugs are also associated with weight gain. Identification and treatment
of both epilepsy and OSA is hence important to optimise patient outcome.

Differential diagnosis of paroxysmal nocturnal events

Paroxysmal nocturnal events often represent a differential diagnostic challenge for the
clinician. Patient recall is often poor and the bed partner is often the person instigating contact
with medical professionals. Despite this, there may still be a limited history as events occur
during the night when it is dark, and the witness may be asleep at the onset and miss part of
the events. The witness may also not be alert enough to provide a good description of the
events. However, there may be no witness account at all for individuals who sleep alone.
‘Routine investigations’ such as EEG are often normal and hence not helpful for the
differential diagnosis.

There are, however, some clinical features that may help in differentiating nocturnal events:

1. Timing of events during sleep, i.e. soon after sleep onset or later towards morning?
2. How often during the night, i.e. how many events each night?
3. Frequency of events, i.e. do events occur every night, once per week, once per month,

less frequently and does the frequency vary over time?
4. Lifetime duration, i.e. at what age did events start and has there been any change in

frequency/severity over time?