Types of seizure Flashcards
classification of seizures types
Focal onset
- Aware
- Impaired awareness
Generalised onset
- Always lose consciousness
- E.g. tonic-clonic, myoclonic, atonic, nonmotor
Unknown onset
Generalised seizures pathophysiology
- Originate at a specific place in the brain and rapidly engage both hemispheres
focal seizures pathophysiology
- Originate within networks limited to one hemisphere
- May be discretely localized or more widely distributed….
- Usually don’t lose consciousness due to usually affecting one side of the brain
provoked seizures
Seizure as a result of another medical condition
Examples include:
- Drug use or withdrawal
- Alcohol withdrawal
- Head trauma and intracranial bleeding
- Metabolic disturbances e.g hyponatraemia, hypoglycaemia
- CNS Infections: meningitis and encephalitis
- Febrile seizures in infants
- Uncontrolled hypertension
- Key is to treat both the seizure and the underlying condition. Unlikely to need ongoing AED treatment if cause treated
Types of Reflex Seizure
Seizure brought on by a particular stimulus (not provoked e.g. taking drugs )
- Photogenic (strobe lights)
- Musicogenic
- Thinking
- Eating
- Hot water immersion
- Reading
- Orgasm
- Movement
focal seizures types
- With impairment of consciousness (‘complex’)
- Without impairment of consciousness (‘simple’)
- Evolving to a bilateral, convulsive seizure (‘secondary generalised’)
Focal: With impairment of consciousness (‘complex’)
Patients lose consciousness either after an aura, or at seizure onset. These seizures most commonly originate at the temporal lobe
Post-ictal symptoms are common (eg. confusion in temporal lobe seizures).
Focal: Without impairment of consciousness (‘simple’)
Patients do not lose consciousness, and only experience focal symptoms.
Post-ictal symptoms do not occur.
Focal: Evolving to a bilateral, convulsive seizure (‘secondary generalised’)
Patients experience a focal seizure, which then evolves to a generalised seizure, which is typically tonic-clonic.
This occurs in 2/3 of patients with focal seizures.
features of focal seizures
Temporal lobe - Automatisms (eg. lip-smacking); déjà vu or jamais vu, emotional disturbance (eg. sudden terror); olfactory, gustatory, or auditory hallucinations.
Frontal lobe - Motor features such as Jacksonian features, dysphasia, or Todd’s palsy.
Parietal lobe - Sensory symptoms such as tingling and numbness; motor symptoms - due to spread of electrical activity to the pre-central gyrus in the frontal lobe.
Occipital lobe - Visual symptoms such as spots and lines in the visual field.
management of focal seizures
First line: Lamotrigine or Levetiracetam
Secod line: Carbamazepine, Oxcarbazepine or Zonisamide.
Third line: Lacosamide
main types of generalised seizures
Absence
Atypical absence
Myoclonic
Atonic
Tonic
Tonic-clonic.
Typical Absence Seizures features
Absence (petit mal) seizures are brief episodes, usually lasting 3–20 seconds, of staring with impairment of awareness and responsiveness.
- Seizures begin and end suddenly.
- There is no warning before the seizure, and immediately afterward the person is alert and attentive.
- If duration is >10 seconds, there are often accompanying motor phenomena (e.g., eye blinks, brief automatic mouth or hand movements, changes in muscle tone).
- These spells usually begin between ages 4 and 14 years, and usually resolve by age 18.
Provoking factures:
hyperventilation.
Investigation findings:
- The EEG signature of absence epilepsy is the generalized 3 Hz spike-wave discharge.
- Children with typical absence seizures usually have normal development and intelligence.
Atypical absence seizures features
Atypical absence seizures also occur predominantly in children, usually beginning before 6 years of age. Atypical absence seizures usually arise during childhood, but may persist into adulthood
- Atypical absences may begin and end gradually (over seconds), usually last 5–30 seconds
Provoking factors:
Not generally provoked by rapid breathing.
Appearance:
- The child stares, but the reduction in responsiveness is usually incomplete.
- Eye blinking or slight twitching movements of the lips may be seen.
- Because atypical absence seizures often occur in children with global cognitive impairment, the seizures may be difficult to distinguish from the child’s usual behaviour.
Investigations:
The EEG usually shows generalized “slow spike-wave” complexes (i.e., <2.5 Hz). .
Tonic-Clonic Seizures features
Primary generalized tonic-clonic (also called grand mal or convulsive seizures) seizures cause loss of consciousness associated with:
1) an initial tonic phase of stiffening, a fall, and often a cry evoked by air forced through contracted vocal cords. Legs are usually extended, and arms may be extended, flexed, or each in succession.
2) The subsequent clonic phase consists of jerking of the extremities which gradually increases in amplitude and decreases in frequency before stopping.
Other signs
There may be drooling or foaming resulting from lack of swallowing and excessive salivation; biting of the tongue, cheek, or lip, causing bleeding; and bladder or bowel incontinence.
Postictal lethargy and confusion often last minutes to hours, and may be followed by transient agitation.
Investigations
The EEG shows generalized polyspikes, but these are usually obscured by muscle artefact. Postictally, there is background suppression and then diffuse slowing
