Consultant neurologist Professor Hedley Emsley discusses stroke and epilepsy, including why it may be difficult to distinguish between both conditions and the importance of a correct diagnosis.
What is the connection between seizure and stroke?
There is a complex relationship between stroke and epilepsy. With an ageing population, there is little doubt that this will become an increasingly important area.
Seizures can complicate clinical stroke – where a person is known to have had a stroke. This can happen in the form of early post-stroke seizures, or as post-stroke epilepsy (PSE).
Seizures can also happen because of blood vessel disease affecting the brain (cerebrovascular disease) even if there hasn’t been a clinical stroke. In this situation, seizures appear to increase the risk of a stroke.
Seizures in later life are often initially misdiagnosed as ‘mini-strokes’ or transient ischaemic attacks (TIAs). A typical example might be where the person is having episodes of speech disturbance and is managed as having recurrent TIAs. It is actually quite unusual to have lots of TIAs, so this is something that should cause concern.
In this situation, it is crucial to have as much detail available as possible about exactly what happens to the person during the episodes, including a witness description. For example, the person might appear vacant, pluck at their clothes (an automatism) and exhibit confused behaviour afterwards. They are unlikely to remember the episodes.
These features are not in keeping with TIA. But these episodes are very different from convulsive seizures that people associate with epilepsy, making the diagnosis of epilepsy more challenging.
Why is it important, yet difficult, to make the correct diagnosis?
Making the correct diagnosis should lead to appropriate treatment, often with a good outcome in terms of controlling epilepsy. It is also important to address any stroke risk factors, although we do need more research to guide exactly which other treatments might be appropriate.
We don’t really know how common late-onset epilepsy such as this is, because of difficulties such as making the diagnosis of epilepsy reliably in older adults. Epilepsy may not be considered when the patient is first assessed even in specialist settings – we know, for instance, that seizure is the commonest alternative diagnosis among patients initially suspected to have a stroke or TIA and accounts for 1 in 5 non-stroke/non-TIA diagnoses.
This is partly because seizures in older adults can be so varied and cause diverse problems such as falls, episodes of confusion, amnesia and ‘focal’ neurological symptoms such as temporary weakness of part of the body.
Seizures can also happen at the time of, or soon after, a clinical stroke. When these occur within seven days of stroke, these are generally regarded as early post-stroke seizures (otherwise termed ‘provoked’ or acute symptomatic). These might not need any specific additional treatment, but this depends on the individual circumstances.
Late post-stroke seizures (‘unprovoked’ or remote symptomatic seizures) are those occurring after a variable interval (days to years) following stroke; these are generally regarded as seizures occurring at least 7 days after the stroke.
Because of the risk of further seizures after even a single late post-stroke seizure, late post-stroke seizures do imply a diagnosis of post-stroke epilepsy. Again, if the correct diagnosis is made then there can be a good outcome with some studies reporting freedom from seizures with treatment in more than 80% of cases.
What do you think needs to be researched more on the topic of stroke and epilepsy?
Stroke and epilepsy is an important area of practice that is rightly receiving more attention, but there are lots still to do in terms of better understanding the relationship between the two conditions.
We need to know a lot more about how common epilepsy is after stroke, as well as in people who have not had a stroke but who may have cerebrovascular disease and/or increased risk of stroke.
We also need to understand more about why people with cerebrovascular disease develop epilepsy (particularly when they have not had a stroke) as well as how best to treat epilepsy in these settings.
Professor Emsley practises at the Greater Lancashire Hospital in Preston. You can book an appointment to see him via his Top Doctor’s profile here.