PBL 3 Flashcards
What is a convulsive seizure
another name for tonic clonic: involve the whole body (gran mal seizures).
what is an unprovoked seizure
seizure that first occurs 6 months following a traumatic brain injury or stroke.
What is secondary epilepsy
resulting from a condition/procedure that are high risk for developing epilepsy (craniotomy, traumatic brain injury, stroke, brain tumour, CNS infection etc.
What conditions can cause secondary epilepsy
craniotomy, traumatic brain injury, stroke, brain tumour, CNS infection
what is an epileptic seizure
the clinical event that occurs when there is an excessive, sustained and synchronized electrical discharge in a network of neurons.
name two types of epilepsy
focal
General
What is the difference between focal and generalised epilepsy
focal - usually confined to one hemisphere and thus one cortical region
general - goes over both hemispheres
name two focal seizures
- simple parietal seizure
- complex parietal seizure
describe what a simple partial seizure is
Simple Partial Seizures
Seizure limited to focal area.
o Symptoms therefore depend on area affected.
No loss of consciousness.
Associated with focal structural disease including developmental abnormalities, strokes, trauma and tumours.
describe what a complex partial seizure is
Altered awareness (often debatable) = dyscognitive symptoms.
Associated with automatisms (purposeless and repetitive movements).
Most commonly involved structure is the temporal lobes.
where does generalised epilepsy originated from
- suggested it is in the somatosensory cortex
When does generalised epilepsy come about
- starts at a young age
describe absent seizures
Unresponsiveness and behaviour arrest.
Usually occurs in childhood.
May occur many times each day, lasting about 5 seconds.
describe tonic clonic seizures
Prior patients my experience aura
o A simple partials seizure with vague symptoms
This type of seizure usually has two phases:
Tonic Phase: lasts about 10-40 seconds.
Patient becomes very rigid: all muscles undergo tonic, sustained contraction.
o Patient falls to the floor
Respiratory muscles and laryngeal muscles also contract: patient may let out a cry/grunt as air is forced out of chest through vocal cords.
o Patient can become cyanotic.
Clonic Phase: muscles go into strong, rhythmic contractions of about 2-3 minutes. Jerky breathing and tachycardia. May be accompanied o Urinary and faecal incontinence. o Tongue biting
Coma Period: patient’s breathing gradually becomes normal and color returns to normal.
Length related to previous tonic-clonic seizures.
When patients awake: may be confused and have a headache.
or
• Premonition (a vague sense that a seizure is imminent) this is sometimes called aura
• Pre-tonic-clonic phase (a few myoclonic jerks or brief clonic seizures)
• Tonic phase (tonic contraction of the axial musculature; upward eye deviation and pupillary dilatation; tonic contraction of the limbs; cyanosis; respiratory muscle contraction - “epileptic cry”; tonic contraction of jaw muscles)
• Clonic phase - jerks of increasing amplitude followed by relaxation (sphincter opening may occur)
• Postictal period (generalized lethargy; decreased muscle tone, headaches, muscle soreness)
What is status epileptics
Occurs if seizures continue with patient regaining consciousness (+5 minutes) or recurrent seizures over the same time with incomplete recovery between them.
If generalized this condition is a medical emergency.
describe paroxysmal depolarising shift
Occurs in neurons in which uncontrolled/sustained discharges occur.
In the PDS the membrane is depolarized by 30-40mV, and remains so for a few seconds.
o May be accompanied by a burst of action potentials.
May be caused by activation of the glutamate receptors of the NMDA type.
how glutamate and GABA can lead to epilepsy
One of the most important theories in epilepsy is that seizures occur due to an imbalance between the excitatory (glutamate) and inhibitory (GABA) neurotransmitter systems.
describe how glutamate and GABA lead to epilepsy
o GABA antagonists and glutamate agonists are triggers for seizures.
o Drugs that encourage GABA transmission are antiepileptics.
o In prolonged seizures glutamate levels rise and GABA levels fall.
o Rise in CSG GABA are seen to correlate with action of antiepileptic Vigabatrin.
name the structural changes that occur in epilepsy
- reorganisation of the tissue in temporal lobe epilepsy
- sprouting of mossy fibres of granule cells
- neurogenesis
- chandelier cells
describe the structural changes that occur in epilepsy
Reorganisation of the tissue in temporal lobe epilepsy:
• Loss of CA2 and CA3 hippocampal areas.
• Possible sclerotic hippocampus.
Sprouting of Mossy Fibres of Granule Cells
• Leads to reverbant excitatory circuits.
Neurogenesis
• Formation of new neurons (also in response to epilepsy episodes) change circuits.
Chandelier Cells
Widespread, inhibitory interneurons that inhibit pyramidal cells.
o Express high levels of GABA Transporter GAT-1.
In some forms of epilepsy there is a loss of chandelier cells, impacting excitability of pyramidal cells.
o Often sufficient in patients with lower average numbers of inhibitory neurons.
Another cause may be an intrinsic increased neuronal excitability, specifically abnormalities in the membrane.
What is the non pharmalogical treatment for epilepsy
a. Non-pharmalogical treatment.
Surgical
Resection of seizure onset zone in brain.
If patient has failed 2 AEDs often drug treatment will not work.
o Patients with focal epilepsy will be referred.
Corpus Callosotomy
o Can be used in patients with drop attacks/atonic seizures.
Vagus Nerve Stimulation
Can reduce seizures by more than 50% in most patients that have the treatment.
Ketogenic Diet.
all AEDS……
ALL AEDs HAVE THE POTENTIAL TO BE TERATOGENIC
Patients should know that abnormality is low and not different from the general population
what are the safer anti epileptic drugs in pregnancy
Carbamazepine and Iamotrigine are generally the safest anti-epileptic drugs in pregnancy.
What are the risks of major congenial malformations with anti epileptic drugs
Carbamazepine: 2.2%
Iamotrigine: 3.2%
(!) Valproate: 6.2% vs 3.5% in untreated women with epilepsy
