Understanding Epilepsy

22nd November 2017

 

What is it?

Epilepsy is a group of neurological diseases which is commonly recognised as violent seizures or convulsions (having an ‘epileptic fit’) but it should be considered as a spectrum disorder (1)­­, affecting different people in different ways from the overt and sometimes violent convulsions to brief, subtle changes in consciousness that are barely detectable.

Epilepsy can be acquired at any time by other injuries or illnesses, such as stroke, traumatic brain injury, tumors or infection but for the majority of genetic cases, the causes are largely unknown (2). 

It is suggested that an episode may be caused by either

  • the resistance of excitatory neurons decreased (3) 
  • the up-regulation of excitatory circuits (3,4)
  • the down-regulation of inhibitory circuits (3,4)
  • failure of the blood–brain barrier may also be a causal mechanism as it would allow substances in the blood to enter the brain (5)

 

What are the Triggers?

An seizure may be brought on by an number of triggers, both physical and psychological including:

  • Emotional stress
  • Sleep deprivation / exhaustion
  • Hormonal changes
  • Low blood sugar
  • Flashing lights
  • Alcohol / drugs
  • Use of certain medications

Emotional stress (21%), sleep deprivation (12%), and tiredness (10%) are the most cited triggers. (6)

 

What are the Symptoms?

To understand how the symptoms of chaotic, random brain activity manifest, one has to understand how different episodes affect the brain.

 

Classification

A lot of attention is given in training to the different classifications of seizures.   This can be confusing for the lay responder for several reasons:

  • Changes in terminology over time (e.g. from ‘grand-mal’ to ‘tonic-clonic’  or ‘partial’ versus ‘focal’)
  • Many subdivisions within categories
  • Similarities between sub-divisions (e.g. compare Focal Impaired with Generalised Typical or Conic versus Myoclonic)

The most current and widely recognised classification system is the  International league Against Epilepsy’s 1980 International Classification of Seizure Types.  In 2017 some changes were made to the 1980 classifications (7)

  • Change of “partial” to “focal
  • Certain seizure types can be either of focal, generalized, or unknown onset
  • Seizures of unknown onset may have features that can still be classified
  • Awareness is used as a classifier of focal seizures
  • The terms dyscognitive, simple partial, complex partial, psychic, and secondarily generalized were eliminated
  • New focal seizure types include automatisms, autonomic, behavior arrest, cognitive, emotional, hyperkinetic, sensory, and focal to bilateral tonic–clonic seizures. Atonic, clonic, epileptic spasms, myoclonic, and tonic seizures can be either focal or generalized
  • New generalized seizure types include absence with eyelid myoclonia, myoclonic absence, myoclonic–tonic–clonic, myoclonic–atonic, and epileptic spasms
after Fisher et al (2017)

after Fisher et al (2017)

 

Onset

The origin - or ‘onset’ - of the seizure relates to the part of the brain which is affected – this may be Focal (previously referred to as Partial), Generalized or of Unknown origin.  If the onset is known this forms the prefix of the seizure type.

Focal seizures are limited to one hemisphere or part of one hemisphere of the brain. 

A casualty experiencing a Focal seizure may retain complete awareness or suffer from impaired awareness; this level of awareness may optionally be included in the seizure type.

During a Focal Onset Aware seizure (formerly Simple Partial) you may not be able to tell because the person is fully alert and able to interact.  The person may need to tell you what is happening.  Most Focal Aware Seizures last less than 2 minutes and there is no need for First Aid treatment if the casualty remains fully alert. (8)

During a Focal Onset Impaired Awareness Seizure (formerly Complex Partial) the casualty will not be able to respond meaningfully or may not be aware of their environments around them.  It is common for the casualty to be confused for a short period after the episode.

Focal Onset Impaired Awareness seizures are also short in duration, about 30 seconds to 2 minutes and typically involve a reduction in consciousness (manifested in ‘staring blankly’).  No First Aid is required unless they have injured themselves during the episode.  (9)

 

Generalized Seizures affect the whole of the brain and typically manifest in physical behaviour and without awareness. 

Focal seizure may develop into a Generalized seizure, called a Focal to bilateral tonic–clonic (previously 'secondary generalisation'.)

If the origin of the seizure is unknown, the seizure type is not prefixed with an onset.

 

Response

Depending on which part of the brain has been affected the seizure may manifest in particular ways which can simply be subdivided as motor onset or non-motor onset (10).

Motor responses include:

Automatisms
Coordinated, purposeless, repetitive motor activity such as picking clothing or lip-smacking

Atonic
Loss of tone, typically lasting 1-2 seconds.  Colloquially known as ‘drop attacks’ if the casualty is standing they may suddenly drop to the floor.  Children may exhibit a ‘nodding’ of the head only.  (11).  No First Aid is necessary for the seizure but may be required for the resulting injuries from the fall.

Clonic  
Repetitive spasms of the muscles presenting as jerking or convulsions.  Discrete Clonic seizures are rare and typically last from a few seconds to a minute (12)

Epilpetic Spasm (previously infantile spams)
Presents as a sudden flexion and/or extension of the limbs and trunk usually more sustained than a myoclonic movement but not so sustained as a tonic   They commonly occur in clusters and most often during infancy but can occur at any age.

Hyperkinetic
A repetitive automatism of the trunk or proximal limbs (pelvis, shoulders) producing irregular sequential ballistic movements, such as pedaling, pelvic thrusting, thrashing, rocking movements or inappropriately rapid performance of a movement.

Myoclonic
Irregular, brief (<100 msec) involuntary contraction(s) of muscles(s).  Myoclonic is less regularly repetitive and sustained than clonic.  No First Aid treatment is necessary for this seizure.

Tonic
A sustained increase in muscle contraction lasting a few seconds to minutes.  In a Generalized Tonics Seizure, affecting the whole brain, the whole body can become affected including the chest and diaphragm, inhibiting breathing.   The casualty may become cyanosed (‘turning blue’) as breathing becomes restricted.  Most tonic seizures last less than 20 seconds (13) as such, usually, no first aid is needed unless a person’s awareness is affected. Preventing injury is one of the most important first aid steps.

Tonic-Clonic
Tonic-Clonic seizure is one of the more common epileptic seizures, widely referred to as an ‘epileptic fit’ and historically known as a ‘Grand Mal’ seizure.

The first phase is the Tonic Seizure which becomes a Clonic seizure, the second phase.  The whole event may last for 1 to 3 minutes.

A Tonic Clonic seizure which lasts more than 5 minutes is a medical emergency (14) and a seizure that lasts for 10 minutes or more OR occurs three times without an normal recovery in between could be a serious condition known as Status Epilepticus.

 

Focal Non-motor responses:

Autonomic
Gastrointestinal sensations, a sense of heat or cold, flushing, piloerection (goosebumps), palpitations, sexual arousal, respiratory changes, or other autonomic effects.

Behaviour arrest (previously complex partial seizures or absence seizures )
A cessation of movement and unresponsiveness as the predominant aspect of the entire seizure

Cognitive
The patient reports or exhibits deficits in language, thinking or associated higher cortical functions during seizures and when these symptoms outweigh other manifestations of the seizure. Déjà vu, jamais vu, hallucinations, illusions, and forced thinking are examples of induced abnormal cognitive phenomena

Emotional
Including fear, anxiety, agitation, anger, paranoia, pleasure, joy, ecstasy, laughing (gelastic), or crying (dacrystic).

Sensory
Somatosensory (perception of touch, pressure, pain, temperature, position, movement, and vibration), olfactory (smell), visual, auditory, gustatory (taste), or vestibular (balance and spatial orientation) sensations

 

Generalized Non-motor (previously Absence) responses

Typical
A sudden onset, interruption of ongoing activities, a blank stare, possibly a brief upward deviation of the eyes. Usually the patient will be unresponsive when spoken to. Duration is a few seconds to half a minute with very rapid recovery.  

Following an Absence Seizure the casualty is almost always fully aware and able to continue what they are doing.   No First Aid is required (15)

Atypical
Changes in tone that are more pronounced than in typical absence or the onset or cessation is not abrupt.

Myoclonic
An absence seizure with rhythmic three-per-second myoclonic movements, causing ratcheting abduction of the upper limbs leading to progressive arm elevation. Duration is typically 10–60 seconds.   Impairment of consciousness may not be obvious.

Eyelid Myolconia
Jerking of the eyelids at frequencies of at least 3 per second, commonly with upward eye deviation, usually lasting less than 10 secons, often precipitated by eye closure. There may or may not be associated brief loss of awareness

 

Motor and Non-Motor repsonses

Motor and Non-Motor repsonses


What is the treatment?

In most cases there is no treatment required for epileptic seizures unless the casualty has injured themselves during the seizure.

 

At the start of the seizure

  • If possible remove objects near the casualty or move the casualty to a wider area if safe to do so.  Whilst the seizure itself is not normally immediately life threatening, the casualty may injure themselves during the seizure.
  • Record the time the seizure started.
  • Remove bystanders to preserve dignity.
  • DO NOT force their airway open or restrain them in any way, allow the seizure to end.

If the seizure has passed

  • Obtain an accurate history from casualty to rule out causes.

Arrange immediate transfer to hospital if:

  • This is the casualty’s first seizure
  • The seizure lasts longer than 5 minutes 
  • The casualty has more than three seizures in a row without recovery in-between
  • The casualty shows signs of difficulty breathing or breathing stops

 

 

References
 

  1. Jensen FE  (2011)  Epilepsy as a Spectrum Disorder: Implications from novel clinical and basic neuroscience.  Epilepsia. 2011 Jan 1; 52(s1): 1–6.
     
  2. Noebels, JL.; Massimo A (2012). Jasper's Basic Mechanisms of the Epilepsies. Oxford University Press. pp. 466, 470
     
  3. Hammer, edited by Stephen J. McPhee, Gary D. (2010). "7". Pathophysiology of disease : an introduction to clinical medicine (6th ed.). New York: McGraw-Hill Medical. ISBN 978-0-07-162167-0.
     
  4. Goldberg, EM; Coulter, DA (May 2013). "Mechanisms of epileptogenesis: a convergence on neural circuit dysfunction.". Nature reviews. Neuroscience. 14 (5): 337–49
     
  5. Oby, E; Janigro, D (November 2006). "The blood-brain barrier and epilepsy.". Epilepsia. 47 (11): 1761–74.
     
  6. Nakken KO, Solaas MH, Kjeldsen MJ, Friis ML, et al. (2005)  “Which seizure-precipitating factors do patients with epilepsy most frequently report?” Epilepsy and Behaviour.  6:85–89
     
  7. Fisher RS, Cross JH, French JA, Higurashi N, Hirsch E, Jansen FE, Lagae L, Moshé SL, Peltola J, Roulet Perez E, Scheffer IE, Zuberi SM  (2017)  “Operational classification of seizure types by the International League Against Epilepsy: Position Paper of the ILAE Commission for Classification and Terminology”.  Epilepsia.  Apr;58(4):522-530.
     
  8. https://www.epilepsy.com/learn/types-seizures/focal-onset-aware-seizures-aka-simple-partial-seizures - accessed 22nd November 2017
     
  9. https://www.epilepsy.com/learn/types-seizures/focal-onset-impaired-awareness-seizures-aka-complex-partial-seizures - accessed 22nd November 2017
     
  10. Fisher RS, Cross JH, D'Souza C, French JA, Haut SR, Higurashi N, Hirsch E, Jansen FE, Lagae L, Moshé SL, Peltola J, Roulet Perez E, Scheffer IE, Schulze-Bonhage A, Somerville E, Sperling M, Yacubian EM and Zuberi SM.  (2017)  “Instruction manual for the ILAE 2017 operational classification of seizure types”.  Epilepsia.  58: 531–542
     
  11. https://www.epilepsy.com/learn/types-seizures/atonic-seizures - accessed 22nd November 2017
     
  12. http://www.epilepsy.com/learn/types-seizures/clonic-seizures accessed 22nd November 2017
     
  13. http://www.epilepsy.com/learn/types-seizures/tonic-seizures - accessed 22nd November 2017
     
  14. http://www.epilepsy.com/learn/types-seizures/tonic-clonic-seizures  accessed 22nd November 2017
     
  15. https://www.epilepsy.com/learn/types-seizures/absence-seizures - accessed 22nd November 2017