Epilepsy Flashcards
What is a Seizure?
‐temporary reaction to sudden excessive electrical activity of cortical
‐loss of awareness or consciousness, movement or sensory neurons disturbances, changed mood or mental function
‐may be from known cause or of “IDIOPATHIC” (= unknown) cause
‐usually SELF‐TERMINATE within seconds to minutes
What type of an event is a seizure?
ACUTE
What is Epilepsy?
- individual must have had 2 or more idiopathic seizures for epilepsy diagnosis
What type of event is epilepsy?
- is the CHRONIC neurological disorder –> RECURRENT seizures
What are the diff diagnosis paths for provoked/non-provoked epilepsy?
NOT provoked:
- primary seizure
- examine patient history
- diagnostic tests
- EPILEPSY DIAGNOSIS –> determine epilepsy syndrome
- examine treatment options
Provoked:
- investigate underlying cause
What are the clinical testing options?
- Assess Brain Electrical Activity (Electroencephalography - EEG)
- Brain Imaging
- Functional Brain Imaging
- Blood Tests
- Neurological Evaluation
Describe Assess Brain Electrical Activity (Electroencephalography - EEG)
- non-invasive recording of brain’s electrical activity by network of electrodes placed over the scalp
- can detect synchronous epileptic electrical activity
- most common diagnostic test used for epilepsy
What is the disadv of EEG?
b/c seizures are sporadic, A PERSON WITH EPILEPSY MAY HAVE A NORMAL EEG
Describe Brain Imaging
‐ Computerized Tomography (CT) Scan
‐ Magnetic resonance imaging (MRI) causing the seizures (e.g.’s tumor, cyst, bleeding
‐both CT and MRI used to reveal abnormalities that might be
What are the Functional Brain Imaging types?
- Functional MRI (fMRI)
- Positron emission tomography (PET) Scan
- Single-photon emission computerized tomography (SPECT)
What is Functional Brain Imaging used for?
is done to identify the exact location of where:
- epileptic activity is originating from
- areas processing language, movement etc.
These are important things to know if a surgical therapeutic approach is being planned!
Describe Blood Tests
- check for infections, toxins, genetic conditions, electrolyte imbalance,
genetic markers etc. - can be diagnostic, & determine if seizure was triggered by toxin etc.
Describe Neurological Evaluation?
- assessment of broad neurological function (ex: sensory, motor, cognitive) to
- detect deficits (if present)
- determine type of seizures experienced
What is Epilepsy’s Prevalence?
- 75% diagnosed before age 30
- For 64% of ppl with epilepsy, it is their only neurological condition
- when there is another one, migraine is most common, then brain injury, stroke
- No difference in prevalence of diabetes or heart disease for those with epilepsy, but they can have increased need of health services due to other chronic issues (e.g. higher incidence of incontinence)
- Medication is primary treatment, and able to eliminate seizures in ~70% of cases.
What is Epilepsy’s Impact?
- Persons with epilepsy have a mortality rate 2‐3 times the general population.
- 39% of household residents living with epilepsy and not having another neurological persistent/repetitive seizures condition reported epilepsy did not affect their life at all.
What is the pathophysiology underlying Epilepsy?
Alteration of Channel Function can –> hyper-excitability of neurons
Neurons may become hyper‐excitable because of:
- Increasing their own resting excitability
- Increasing their activation by other neurons
Explain how Alteration of Channel Function can –> hyper-excitability of neurons
e.g. “channelopathy” (class of disorder caused by alterations in ion channels)
-if this change is excitatory, then spontaneous neural activity can occur and
may manifest as Epilepsy
-hereditary alteration of some type of ion channel
-may be a single mutation of a particular channel subtype
-channels might have several possible loci where mutation –> changes in ion flow
-mutation of different types of channels may be involved
______ of voltage-gated Na+ channels can cause generalized epilepsy
discreet mutation
- is a type of “channelopathy”
What are the altered Postsynaptic Ionotropic Actions?
Increasing Excitation: ↑ excitation –> more excitable cell
Decreasing inhibition: Either ↑ excitation OR ↓ inhibition –> more excitable neuron
therefore, pathophys. is increase excitability, but there are diff ways to achieve it
Neurons may become hyper‐excitable because of:
Increasing their own resting excitability:
E.g.’s
- Increased sodium channel activation/conductance
- Decreased potassium channel activation/conductance
Increasing their activation by other neurons:
‐ Increased excitatory synaptic actions (e.g. glutamatergic)
‐ Decreased inhibitory synaptic actions (e.g. GABA or glycine)
channel activation/conduction at presynaptic
2+
‐ Increased Vdep Ca synapses.
These changes would make THE NEURONS MORE EXCITABLE (i.e., facilitates their production of AP’s)
The neurons that are firing more may have __________ on their neighbours! (the activity _______)
excitatory actions
spreads
What are the 2 types of Seizures?
- Generalized Seizures (involve BOTH cerebral cortices)
- Partial (Focal) Seizures
(restricted to 1 part of brain)
What are the 6 types of Generalized Seizures?
- Tonic-clonic (grand mal) seizures
- Clonic Seizures
- Tonic Seizures
- Atonic Seizures
- Myoclonic Seizures
- Absense (petit mal) Seizures
Tonic‐clonic (grand mal) seizures:
- Most noticeable
- Body stiffens, jerks, shakes, LOSS OF CONSCIOUSNESS
- May lose bladder &/or bowel control
- Usually last 1-3 mins
Clonic Seizures:
- Muscles have spasms, may make face, neck arms jerk rhythmically
- May last several mins
Tonic Seizures:
- Muscles tense up. Often happens while asleep
- Usually last <20 secs
Atonic Seizures:
- Muscles suddenly lose all tone. Head may drop, may fall (“falling sickness”)
- Usually <15 secs, but can be repetitive
- May need to wear a helmet
Myoclonic Seizures:
- Usually NO warning, & NO loss of consciousness
- Muscles suddenly jerk (as if had been shocked)
- Sometimes ppl have both atonic & myoclonic seizures
Absence (petit mal) Seizures:
- NO AURA (no sensory disturbance preceding the seizure - like a smell or something)
- SEEM DISCONNECTED from surroundings & UNRESPONSIVE
- Eyes may ROLL BACK, or just STARE BLANKLY
- Usually last only a FEW SECS & are often NOT REMEMBERED as having occurred, & continue with activity
- Most COMMON IN CHILDREN
- May occur MANY TIMES DAILY, so might be mistaken for inattentiveness in school
What are the 3 types of Partial (Focal) Seizures?
- Simple Focal Seizures
- Complex Focal Seizures
- Secondary Generalized Seizures
Simple Focal Seizures:
- Change how senses read the world
- May be preceded by strange sensory feelings (smells, visual flashes etc.)
– i.e. an “AURA” - Unlikely to lose consciousness
- Can RECALL MEMORY OF SEIZURE
Complex Focal Seizures:
- May lose consciousness, yet appear to be awake.
- May exhibit behaviours like gagging, laughing, crying, lip smacking etc.
- Probably due to activation of limbic system.
- May last several mins
- DO NOT REMEMBER seizure
Secondary Generalized Seizures:
- Focal seizure that evolves into a generalized seizure (i.e. spreads)
- Can –> convulsions or atonia (just like generalized seizures)
How long do seizures usually last?
only a few secs to mins
What is Status Epilepticus?
denotes seizures that persists for a long time (> 5 minutes).
‐ may be convulsive or non‐convulsive.
‐ may repeat without recovery.
‐ may lead to neurological disability
- VERY SERIOUS MEDICAL CONDITION! (~20% risk of death within 30 days)
Which is a VERY SERIOUS MEDICAL CONDITION! (~20% risk of death within 30 days)?
Status Epilepticus
Secondary Seizures =
Seizures triggered by:
- Heavy Trauma
- Head Injury
- Stress
- Sleep deprivation
- Drug use
- Poor nutrition
- Disease or infection
- Alcohol withdrawal
- Alcohol is a CNS depressant
- Heavy use decreases seizure threshold (b/c inhibition is decreased)
(anyone is susceptible to seizure with high alcohol levels) - PATIENTS WITH EPILEPSY ADVISED TO AVOID ALCOHOL
- can also (-)ly impact anti-epileptic drugs (AEDs)
–> less effective (more vulnerable to seizure) - increase side effects of AEDs
Secondary Seizures:
Fibrile Seizures: (or “Pediatric Fibrile Seizures”)
- Seizure caused by a FEVER.
- Common in infants and children.
- Involve convulsions (tonic or clonic)
- Usually last for a few minutes.
- Not associated with any residual neurological dysfunction.
- Not indicative of epilepsy
What is the immediate care for epilepsy?
First Aid
What is the treatment for Complex Focal?
- Guide person away from danger
- Do NOT restrain
What is the treatment for Atonic?
- Call 911 if injuries from the fall
What is the treatment for Tonic-Clonic (grand mal)?
- Protect from head injury
- Turn person on side to keep airway clear
- Do NOT restrain
- DO NOT PUT ANYTHING IN MOUTH
- Cover in case of incontinence
- Reassure when recovered
When do you call 911?
if seizure lasts LONGER than 5 mins (status epilepticus), consciousness does not return, occurred in water, difficulty breathing or chest pain, injured, or if individual is not known to have epilepsy
What is the treatment of Epilepsy?
- There is NO CURE
- Goal is to decrease the frequency & severity of seizures
What are the 2 strategies for treatment of epilepsy?
- Pharmacological Treatment
- Non-pharmacological Treatment
Pharmacological Treatment:
- “Anti-Epileptic Drugs” (AEDs), (also called “anticonvulsants”)
= the primary therapeutic strategy (become quite effective) - AEDs can eliminate seizures in ~70% of epileptic patients
- AEDs usually are effective because they aim to reduce overall excitability by:
a) DECREASING EXICTATION of neurons.
‐e.g.carbamazepine blocks voltage gated Na channels
b) INCREASING INHIBITION of neurons.
‐e.g. benzodiazapines increase Cl flow through GABA channels
What are the Non-pharmacological treatments?
- Ketogenic Diet
- Vagal Nerve Stimulation
- Surgery
Ketogenic Diet:
- High fat, low carbohydrate diet decreases seizure incidence.
- Usually only considered for children when AEDs have been ineffective.
- Thought that a metabolite (decanoic acid) produced in response to the diet has anti-epileptic properties (mech unknown)
Vagal Nerve Stimulation:
- Therapeutic electrical stimulation of the vagus nerve (CN X) via an implanted stimulator
- May prevent and/or disrupt epileptic type discharges in the brain.
- Mech unknown
Surgery:
- Option when AEDs not effective
- Aim to REMOVE FOCI OF EPILEPTIC ACTIVITY, & NOT DAMAGE IMP. BRAIN FUNCTION THAT MAY BE CLOSE BY! (need for functional imaging)
- Pioneered by Dr. Wilder Penfield (MNI in Montreal)
