11.1 The Brainstem EEG and Epilepsy Flashcards
Describe where the brainstem starts and finishes anatomically
Begins at the foramen magnum and extends to the thalamus
How is the brainstem attached to the cerebellum anteriorly?
by 3 peduncles
What is the Reticular activating system (RAS)?
What is the main neurotrasmitter released here?
Network of neurons connecting the central core of the brainstem to extensive cortical areas: controls level of consciousness and alertness!!
It receives widespread sensory input and controls ascending information. It also has decending projections which control sensitivity of motor nuclei
Cholinergic neurons near junction of pons and midbrain
What can an fMRI show us?
RAS activity alters in REM, non-REM sleep and wakefulness
Describe the sleep-wake transition of RAS, when it is used clinically and what may occur when this goes wrong
# Define sleep Define Coma
Sleep: a state of unconsciousness from which a person can be aroused
Coma: a state of unconsciousness from which a person cannot be aroused
Give 3 things important about sleep
Essential for normal human well-being
1) Memory consolidation
2) Repair of oxidative stress–restorative functions
3) Chronic sleep problems a/w neurodegeneration and mental health
What is Insomnia and give 4 causes
Failure to obtain the acquired amount or quality of sleep to function normally through the day
Causes: Mental health, drugs, pain, old age, technology
Give 4 ways to manage insomnia?
1) Sleep hygiene
2) Hypnotics
3) Z-drugs and benzodiazepines
4) Muscles relaxation, amnesic, anxiolytic, anticonvulsant
5) Enhance GABA-mediated neurotransmission
Give 4 issues with drugs given to treat insomnia
Addiction, dependence, day time sedation, tolerance
What is Hypersomnia and give 4 causes
Excessive daytime sleepiness
Causes: OSA, drugs, ETOH, depression/anxiety
What is Narcolepsy?
What symptom and what brain structure it is a/w
Irresistible sleep episodes lasting 5-30 minutes during the day
a/w cataplexy (loss of muscle tone/paralysis) and linked to abnormalities in the RAS
What is Parasomnia?
Sleep paralysis, sleep walking/talking, night terrors, confusional arousal
What is an EEG?
Electrodes on the scalp ➞ voltage recorded between 2 electrodes
Allows us to look at the brain activity of neurons and is best for sleep studies and epilepsy ➞ demonstrates several stages of sleep
What are the 4 basic waves seen on an EEG and which is seen during each stage of sleep
1) Beta – >14Hz = mental activity – frontal lobes
2) Alpha – 8-13Hz = relaxed and awake, occipital region and alters with eye opening/closing
3) Theta – 4-7Hz = drowsy, first stages of sleep
4) Delta – <4Hz = deep sleep
Compare our REM vs non-REM sleep (3)
REM:
- Increases in length throughout the night – 10mins first cycles to 50mins last
- Heart rate and respiration increase to awake levels
- Dreams
Non-REM:
- Restorative
- Decreased cerebral blood flow, reduced O2 consumption
- Reduced heart rate and breathing
What is Epilepsy?
Umbrella term for many different seizure types/syndromes
It is a brain disorder that is characterised by periodic, unpredictable seizures, caused by the rhythmic, excessive and disorganised firing of groups of neurons
List 4 ways in which epilepsy can present and describe these
1) Partial (focal) – remains within one small CNS site e.g. temporal lobe epilepsy (concious)
2) Complex – impairment of consciousness
3) Generalised – spread throughout both hemispheres and usually loss of consciousness
4) Secondary generalisation – when a partial seizure progresses into a generalized seizure
Give 2 symptoms which may occur following a seziure and describe these
1) Postictal – state of reduced consciousness following a seizure
2) Todd’s paralysis – focal weakness in part or all of the body following a seizure (mins-hrs)
Give 3 treatments of epilepsy
Treatments are aimed at suppression of the excitable focus
1) Medications- suppress neuronal membrane excitability by…
- Increase inhibitory neurons – GABA agonists
- Reduce excitatory neurons – Glutamate antagonists
- Stabilise membranes to prevent re-firing – ion channels
2) Surgical – removal of the epileptogenic focus
3) Diet – ketogenic diets
Give 4 causes of Epilepsy
Anything that damages or disrupts normal neuronal transmission such as: Trauma, haemorrhage, ischaemia, hypoxia, infection, hyperthermia, scar tissues,
NOTE: it is idiopathic 2/3rd of the time
Describe Partial (focal) epilepsy (5)
We have consciousness preserved!!
Begins with motor/ sensory/ autonomic phenomena depending on cortical area affected
Motor, sensory, visual, olfactory, auditory/vestibular, frontal
May become secondary generalized
Mimic TIA/stroke symptoms or migranous aura
Describe Complex partial epilepsy
Consciousness and memory impaired!!
Typically temporal lobe in origin e.g. temporal lobe epilepsy (due to temporal lobe scaring from insults early on in life) thus usually presents during late adolescence
Features: sensory, autonomic, motor, déjà vu, hallucinations and often a postictal phase and poor recall of events
Describe generalised epilepsy
Generalised seizures involve both cortices and usually loss of consciousness with or without convulsions
Describe Tonic/clonic or ‘Grand mal’ seizures
Initial phase of Tonic ➞ muscles go stiff and Clonic ➞ muscles jerk… followed by a period of unconsciousness
Describe Absence or ‘petit mal’ seizures
What specific EEG change may be observed
Usually diagnosed in childhood and generally grow out of it ➞ those that don’t may go onto convulsive epilepsy
Seizures typically a few seconds hence go unnoticed for some time.
Patient has no memory and no postictal state
EEG highly specific – 3Hz spike and wave pattern (NB hyperventilation)
Describe Juvenile myoclonic epilepsy
Is there a genetic link?
This is a form of generalised epilepsy (5-10%)
Onset in early adolescence and sometimes overlooked as clumsy… Eventually turn to generalized convulsion
Seizures consist of involuntary jerky movements mostly in the morning
T6 genes identified and great outcomes with specific anti epileptic drugs such as sodium valproate or lamotrigine (lifelong)
Describe Status epilepticus
Consists of continual seizure with no or little interictal period typically >5mins
This is a Medical emergency because there is a high risk of hypoxia, thermal damage, muscle damage, lactic acidosis, electrolyte imbalance, shock
