Epilepsy

What is epilepsy?

Epilepsy is a condition involving seizures that originate in the brain. These seizures are also known as epileptic insults (fits). They are caused by a sudden, temporary disturbance of the electrical signalling in the brain. They vary from person to person because epilepsy has many different causes, and these are not always clear.

Possible causes are: genetic predisposition, a congenital brain disorder (such as tuberous sclerosis complex (TSC), Down syndrome, the fragile-X syndrome, Rett syndrome and Angelman syndrome), brain damage caused during birth (resulting in an epileptic syndrome such as West syndrome and Lennox Gastaut syndrome), inflammation (such as meningitis or encephalitis), brain damage due to an accident (cerebral haemorrhage or cerebral infarction), a brain tumour or pharmaceutical intoxication. ⁴⁸⁰

What are the complaints associated with epilepsy?

The following may be seen during an epileptic seizure:

• Motor complaints: contraction of a single muscle, muscle group or several muscles (convulsions)
• Sensory complaints: changes in hearing, sight, touch, taste, smell, disturbed perception of space and time
• Autonomous complaints: sweating, blushing, nausea, goosebumps, palpitations
• Psychomotor complaints: temporarily disturbed memory, temporarily impaired speech
• Psychological complaints: spontaneous anxiety, anger, euphoria, hallucinations

The pattern of an epileptic fit depends on the type of fit. A distinction can be made between 'generalised' and 'partial' epileptic fits. A generalised seizure (a tonic clonic seizure or an absence seizure) involves abnormal electrical discharges throughout the brain resulting in a loss of consciousness or change in consciousness. In a partial or focal seizure, only a certain part of the brain (the focus) is affected by abnormal electrical discharges. There is no effect on consciousness. A partial seizure can lead to a secondary generalised seizure. The local discharge then extends to the entire brain.

Epilepsy and the use of anti-epileptics often cause sleep disorders. ¹¹⁹

Children with epilepsy have a very high risk (up to 40%) of ADHD, and particularly of the ADD variant without hyperactivity.  ¹²⁰

The behavioural problems mainly concern internalising problems such as anxiety, fear of failure, insecurity and depression.

The frequency of seizures may fluctuate depending on hormonal fluctuations during the menstrual cycle. It has been found that there are twice as many seizures on the first day of the cycle than on day 8 of the cycle, the day with the fewest seizures.  ¹⁰⁰⁰

The regulation of the cycle is an issue that has to be addressed in the combination of epilepsy and menstruation. Anti-epileptics reduce blood levels of oral contraceptives (in other words, the pill), and so the dose should actually be increased to avoid a higher risk of pregnancy, with anti-epileptics having a possibly harmful effect on the unborn child. (Epilepsy guideline, Dutch Association for Neurology, 2014).

A recent systematic review of neuropsychiatric comorbidity in epilepsy showed that people with epilepsy did not generally have neuropsychiatric conditions more often, with the exception of a tendency towards negative mood. More severe forms of epilepsy were associated with neuropsychiatric conditions, and people with both epilepsy and intellectual disabilities are more likely to have neuropsychiatric conditions than people with epilepsy but with no intellectual disabilities. ⁵³⁴

A systematic review of somatic conditions and challenging behaviour in people with intellectual disabilities shows that behaviour problems are seen in people with frequent and severe seizures, with generalised epileptic activity identified by EEG and with comorbid conditions (such as visual impairment or spasticity). ¹²¹

In addition, there are syndromes that are associated with both intellectual disabilities and epilepsy and with a specific behavioural phenotype (including self-injurious behaviour). Examples are the Rett syndrome and the fragile-X syndrome. ⁴⁸⁰

How common is epilepsy in the general population?

The prevalence of active epilepsy in people ≥ 55 years is approximately 0.9%. The prevalence of active epilepsy and epilepsy in histories is 1.5%. ¹²²

How common is epilepsy in people with intellectual disabilities?

Epilepsy is much more common in people with intellectual disabilities. The epilepsy is also more serious and harder to treat.

A review article looking at the misdiagnosis of epilepsy in people with intellectual disabilities showed that 25% of the diagnoses were mistaken. Either epilepsy was failed to be diagnosed and the symptoms were diagnosed as a psychiatric condition or a motor condition, or epilepsy was diagnosed when the correct diagnosis was syncope or conversion. ¹²³

Several studies of epilepsy in people with intellectual disabilities have found an average prevalence of 22%.
A Dutch review of international articles on health problems in children with intellectual disabilities showed that 22% had epilepsy. ¹²⁵

The European POMONA questionnaire survey of a random sample of 1269 adults with intellectual disabilities found a prevalence rate for epilepsy of 28%. That study showed that 20% of the total group had had an epileptic seizure in the last 5 years; 57% of them had seizures less than once a month, 19% once a week but not every week, 15% at least once a week, and 9% had an epileptic seizure every day. ¹²⁶

A Rotterdam study of 137 young people aged between 11 and 26 with severe multiple disabilities found that 68% had epilepsy. ¹²⁷

The use of anti-epileptics is known to be effective in people with intellectual disabilities. They may suffer the same side-effects of the medication as the general population. ⁴⁸¹

In a large English study, the general-practice files of 14,751 people with intellectual disabilities were compared with those of 86,221 people without. The prevalence of epilepsy in the group with intellectual disabilities was 18.5%, which was significantly higher than prevalence in people without. ⁴⁸²

A systematic review studied the prevalence of epilepsy in people with intellectual disabilities. When all studies were taken into consideration, it was found that the prevalence rate was 22%. Epilepsy was seen more frequently when intellectual disabilities were more severe. The prevalence of epilepsy in people with Down syndrome was 12.4%, falling to 10.3% when studies of older people with Down syndrome were excluded. ⁴⁸³