Seizures and Epilepsy
Tom Nowacki, MD, FRCPC - Epilepsy/EEG Fellow
Defintions
- Epilepsy (ILAE 2014 report):
- At least two unprovoked seizures occurring >24 hours apart
- One unprovoked seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10 years
- Diagnosis of an epilepsy syndrome
- Juvenile Myoclonic Epilepsy (JME)
- Childhood Absence Epilepsy (CAE)
- Benign Epilepsy with Centrotemporal Spikes (BECTS)
- ...and many others
- What is an "unprovoked seizure"?
- "Unprovoked seizures are defined as seizures occurring in the absence of a potentially responsible clinical condition or beyond the interval estimated for the occurrence of acute symptomatic seizures." (Beghi 2010)
- What is a "symptomatic seizure"?
- "Acute symptomatic seizures are events, occurring in close temporal relationship with an acute CNS insult, which may be metabolic, toxic, structural, infectious, or due to inflammation." (Beghi 2010)
- Stroke
- Traumatic brain injury
- Acute CNS infection (encephalitis, meningitis)
- Drug intoxication or withdrawal (e.g. alcohol withdrawal)
- Other names for symptomatic seizure are provoked seizure, reactive seizure, or situation-related seizure.
- Remote symptomatic seizures are seizures that occur in the absence of an acute precipitating factor but with evidence of a past static injury
- Stroke
- Traumatic brain injury
- Past CNS infection (encephalitis, meningitis)
- Perinatal or birth injuries (cerebral palsy, etc)
Neurophysiology of Seizures
- What happens during a seizure?
- Abnormal neuronal firing
- Neuronal hyperexcitability (reduced threshold for neuronal firing)
- Neuronal hypersynchrony (neurons in a given area firing together)
- Seizures reflect abnormal function at the level of signle neurons, and the ne
- Single neurons
- Neuronal networks
- This abnormal electrical activity can be measured using an electroencephalogram (EEG) (figure)
Seizure Classification
- Partial (focal, local) seizures
- Simple partial seizures (consciousness not impaired)
- with motor symptoms
- with somatosensory or special sensory symptoms (numbness/tingling, odd smell/taste, hallucinations)
- with autonomic symptoms (sweating, abdominal sensation, tachycardia)
- with psychic symptoms (déjà vu/jamais vu sensation, fear, elation, autoscopy)
- ...2, 3, and 4 are examples of an "aura"
- Complex partial seizures (with impairment of consciousness)
- Partial seizures evolving to secondarily generalized seizures
- the most common type of seizure in adults
- Generalized seizures
- Tonic-clonic seizures
- absence seizures
- Seen in childhood absence epilepsy, these almost never occur in adults
- A seizure causing a motionless, blank stare in an adult is almost certainly a complex partial seizure, not an absence seizure
- myoclonic seizures
- tonic seizures
- clonic seizures
- atonic seizures
- (flowchart)
- this is an old classification system
- it is based on the ILAE 1981 criteria and was replaced in 2010
- but, most clinicians still use it
Seizure First Aid
Responding to a Generalized Tonic-Clonic Seizure
- Stay calm - most seizures are brief (<2 min) and resolve spontaneously
- Check the time, to record seizure duration
- During the clonic phase (limb jerking)
- Avoid moving the patient if possible - instead move hazards away from the patient
- Put something soft under the head
- Do not attempt to restrain the patient
- Do not put anything in the mouth
- After the clonic phase ends (post-ictal period)
- Roll patient on his or her side (recovery position)
- Check airway, suction secretions as needed
- Monitor vital signs
- SpO2 often drops during the seizure (as patients don't breathe during the tonic or clonic phase), but rapidly returns to normal post-ictally - supplemental O2 usually isn't necessary
- Patients are often confused or agitated for several minutes afterwards
- When to call for help
- It is the patient's first seizure
- Seizure lasts >5 min
- One seizure immediately follows another with no recovery in between
- Difficulty maintaining airway or unstable vital signs post-ictally
- Patient has sustained an injury from the seizure
- Charting after the seizure
- Record what you saw, in the order it happened, using simple descriptive words
- e.g. "the patient stopped speaking, his head turned to the left, his body went stiff, then both his arms shook for about one minute"
- avoid phrases such as "the patient started seizing", or "seizure activity was noted" - we need to know what happened!
- Useful observations to record:
- What was the patient doing before the seizure?
- Did anything seem to trigger the seizure?
- Did they have strange sensations, such as an odd taste, smell, or unusual feeling?
- Did they look blank, stare, or lose consciousness?
- Did they do anything unusual (mumble, fumble for things, wander around, or seem confused)?
- Did they colour change (pallor, cyanosis, flushing)?
- Did their breathing change (irregular, noisy, snorting)?
- Did they fall down, or go stiff or floppy?
- Did their body move? If so, how?
- Did they bite their tongue or cheek? Were they incontinent?
- How long did it last?
- How were they after? Did they need to sleep?
- How long until they were back to baseline?
Seizure Videos
All videos from 2010 AAN Continuum Epilepsy CD
Note: I have removed the videos from this version of the presentation
- Seizures
- Partial seizure evolving to a secondarily generalized tonic-clonic seizure
- The woman experiences an aura of an unusually noxious smell or odor, representing a simple partial seizure. The seizure then evolves to where the patient begins to show chewing automatisms and mouth movements, and then subsequently it generalizes. This is an example of a simple partial seizure that evolves to a complex partial seizure and then ultimately generalizes.
- Temporal lobe seizures
- This is a man with mesial temporal sclerosis. In the complex partial seizure that is displayed, the patient shows an inability to follow commands or respond.
- This segment of a man with temporal lobe epilepsy illustrates characteristic findings associated with temporal lobe epilepsy, including automatisms of chewing and fumbling with his television remote. The chewing motion along with the fumbling with his hands is quite characteristic of complex partial seizures assoicated with temporal lobe epilepsy.
- Frontal lobe seizures
- This is a man with left-handed posturing and a classic figure-4 sign. There is no loss of consciousness, and he continues pouring his own salad dressing, even though he is having a seizure. The fact that this patient has preserved consciousness during the event is suggestive of a simple partial seizure and is what distinguishes it from a complex partial seizure.
- This is a woman with frontal lobe epilepsy. The seizures consist of generalized body movements and the patient uttering expletives. It is quite easy to see how this event could be confused with a psychogenic nonepileptic seizure (PNES) event. However, the stereotypic nature of the episodes and their brief duration tend to suggest frontal lobe epilepsy. The only way to confirm this would be with an EEG recording.
- Seizure mimics
- Syncope
- This segment shows a woman with events that were mistaken for seizures. While she is having the EEG electrodes applied, she has a momentary lapse of consciousness consistent with vasovagal syncope.
- Note a classic situational trigger for vasovagal syncope - venipuncture
- Psychogenic nonepileptic seizures (PNES)
- This segment show an event consistent with PNES. PNES diagnosis is supported by retained consciousness despite bilateral motor activity, a waxing and waning course, an immediate stress trigger, and absence of postictal confusion after the event resolves.
- This woman had a prior craniotomy for cerebral arteriovenous malformation, which wold typically favour epileptic seizures. PNES is suggested by a waxing and waning course, initially falling in to the nurse's awaiting arms (actively avoiding injury), and subtle pelvic thrusting. The EEG remained normal despite bilateral motor movements and apparent loss of consciousness, all consistent with PNES.
References
- First Aid for Seizures - epilepsysociety.co.uk
- International League Against Epilepsy (ILAE) - www.ilae.org
- Beghi, E., Carpio, A., Forsgren, L., Hesdorffer, D. C., Malmgren, K., Sander, J. W., et al. (2010). Recommendation for a definition of acute symptomatic seizure. Epilepsia, 51(4), 671–675. doi:10.1111/j.1528-1167.2009.02285.x
- Fisher, R. S., Acevedo, C., Arzimanoglou, A., Bogacz, A., Cross, J. H., Elger, C. E., et al. (2014). ILAE Official Report: A practical clinical definition of epilepsy. Epilepsia, 55(4), 475–482. doi:10.1111/epi.12550
- Stafstrom, C. E., & Rho, J. M. (2012). Chapter 51 - Neurophysiology of Seizures and Epilepsy. Swaiman's Pediatric Neurology (5 ed., pp. 711–726). Elsevier Inc. doi:10.1016/B978-1-4377-0435-8.00051-2