Epilepsy
This article was originally circulated as a neurosciences newsletter in 2010. It has been updated in 2016. It should be useful to anyone wanting to understand the causes, diagnosis and advances in treatment of epilepsy.
What is epilepsy?
Epilepsy means the tendency to have repeated epileptic seizures. Epileptic seizures are the uncontrolled discharge of cerebral neurons. These cerebral neurones are in the cerebral cortex, which is the outer layer of the brain.
What forms can epilepsy take?
Fifty per cent of patients with epilepsy have a full-blown convulsion. This is when the patient falls to the ground. He is usually stiff and has shaking muscle movements for about 1-2 minutes. There is then, usually, the postictal phase, when the patient is drowsy and confused. This can last for half an hour.
Fifty per cent of seizures do not cause convulsions. These seizures can be simple partial seizures, when the patient is fully awake, or complex partial seizures, when the patient loses awareness. The most common complex partial seizures arise from the temporal lobe and are preceded by strange feelings in the stomach, but this progresses to loss of awareness and the patient may have automatic behaviour. For example, it is quite possible to walk down the High Street, purchase a pint of milk, and return home in a full blown seizure and the patient will not remember having done this.
What is the cause of epilepsy?
In 80% of patients the cause is not identified. It is recognised, with modern advances, that many of these patients have a genetic abnormality. This may affect one of the neurotransmitter systems in the brain that relays neurone information, and leads to a process of hyper-excitability. Conversely, the genetic process may affect the GABAergic inhibitory neuronal system. There is a lot of interest in abnormalities of the sodium channel, significantly because many patients respond to medications that act on the sodium channel, like Lamotrigine or Phenytoin.
What are the new advances in epilepsy and its diagnosis?
We are on the cusp of major genetic advances, yet this is rarely helpful in modern day to day practices. The most significant advances are with neuroimaging, such as PET scanning, SPECT scanning or functional MRIs which look at the source of the seizure. Three Tesla MRI offers extremely high resolution images, an advantage in particular MRI sequences such as MP RAGE which enable better neuro-anatomical definition of the brain and to allow for a more accurate diagnosis.
The use of video-telemetry has allowed patients to have their seizures recorded. This allows the site of the seizures to be accurately determined, and this, potentially, offers further advances.
Medical advances
There are new drugs being developed for the treatment of epilepsy. In the last few years we have seen the introduction of drugs like Pregabalin, Lacosamide, and Zonisamide which have the potential for treatment of patients with epilepsy, although they are usually reserved for intractable epilepsy, when first line drugs are not effective.
Many years ago the only drugs available were Valproate, Carbamazepine and Phenytoin, but more modern therapies, like Lamotrigine and Levetiracetam give better seizure protection with fewer side effects, both in the short and long term.
Surgical advances
With an accurate definition of the site of the epilepsy, modern neurosurgery along with conventional neurosurgery or gamma knife neurosurgery offers significant chances of improvement in epilepsy, in selected patients. Where patients are selected correctly, 80 per cent of patients can be completely cured with epilepsy surgery, compared to a less than 1 per cent chance in those patients with intractable epilepsy on drug treatment alone.
Dr OC Cockerell, Consultant Neurologist
Epilepsy means the tendency to have repeated epileptic seizures. Epileptic seizures are the uncontrolled discharge of cerebral neurons. These cerebral neurones are in the cerebral cortex, which is the outer layer of the brain.
What forms can epilepsy take?
Fifty per cent of patients with epilepsy have a full-blown convulsion. This is when the patient falls to the ground. He is usually stiff and has shaking muscle movements for about 1-2 minutes. There is then, usually, the postictal phase, when the patient is drowsy and confused. This can last for half an hour.
Fifty per cent of seizures do not cause convulsions. These seizures can be simple partial seizures, when the patient is fully awake, or complex partial seizures, when the patient loses awareness. The most common complex partial seizures arise from the temporal lobe and are preceded by strange feelings in the stomach, but this progresses to loss of awareness and the patient may have automatic behaviour. For example, it is quite possible to walk down the High Street, purchase a pint of milk, and return home in a full blown seizure and the patient will not remember having done this.
What is the cause of epilepsy?
In 80% of patients the cause is not identified. It is recognised, with modern advances, that many of these patients have a genetic abnormality. This may affect one of the neurotransmitter systems in the brain that relays neurone information, and leads to a process of hyper-excitability. Conversely, the genetic process may affect the GABAergic inhibitory neuronal system. There is a lot of interest in abnormalities of the sodium channel, significantly because many patients respond to medications that act on the sodium channel, like Lamotrigine or Phenytoin.
What are the new advances in epilepsy and its diagnosis?
We are on the cusp of major genetic advances, yet this is rarely helpful in modern day to day practices. The most significant advances are with neuroimaging, such as PET scanning, SPECT scanning or functional MRIs which look at the source of the seizure. Three Tesla MRI offers extremely high resolution images, an advantage in particular MRI sequences such as MP RAGE which enable better neuro-anatomical definition of the brain and to allow for a more accurate diagnosis.
The use of video-telemetry has allowed patients to have their seizures recorded. This allows the site of the seizures to be accurately determined, and this, potentially, offers further advances.
Medical advances
There are new drugs being developed for the treatment of epilepsy. In the last few years we have seen the introduction of drugs like Pregabalin, Lacosamide, and Zonisamide which have the potential for treatment of patients with epilepsy, although they are usually reserved for intractable epilepsy, when first line drugs are not effective.
Many years ago the only drugs available were Valproate, Carbamazepine and Phenytoin, but more modern therapies, like Lamotrigine and Levetiracetam give better seizure protection with fewer side effects, both in the short and long term.
Surgical advances
With an accurate definition of the site of the epilepsy, modern neurosurgery along with conventional neurosurgery or gamma knife neurosurgery offers significant chances of improvement in epilepsy, in selected patients. Where patients are selected correctly, 80 per cent of patients can be completely cured with epilepsy surgery, compared to a less than 1 per cent chance in those patients with intractable epilepsy on drug treatment alone.
Dr OC Cockerell, Consultant Neurologist