11.1 The Brainstem EEG and Epilepsy

Question 1

Describe where the brainstem starts and finishes anatomically

Answer 1

Begins at the foramen magnum and extends to the thalamus

Question 2

How is the brainstem attached to the cerebellum anteriorly?

Answer 2

by 3 peduncles

Question 3

What is the Reticular activating system (RAS)?

What is the main neurotrasmitter released here?

Answer 3

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

Question 4

What can an fMRI show us?

Answer 4

RAS activity alters in REM, non-REM sleep and wakefulness

Question 5

Describe the sleep-wake transition of RAS, when it is used clinically and what may occur when this goes wrong

Answer 5

Question 6

# Define sleep
Define Coma

Answer 6

Sleep: a state of unconsciousness from which a person can be aroused

Coma: a state of unconsciousness from which a person cannot be aroused

Question 7

Give 3 things important about sleep

Answer 7

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

Question 8

What is Insomnia and give 4 causes

Answer 8

Failure to obtain the acquired amount or quality of sleep to function normally through the day

Causes: Mental health, drugs, pain, old age, technology

Question 9

Give 4 ways to manage insomnia?

Answer 9

1) Sleep hygiene
2) Hypnotics
3) Z-drugs and benzodiazepines
4) Muscles relaxation, amnesic, anxiolytic, anticonvulsant
5) Enhance GABA-mediated neurotransmission

Question 10

Give 4 issues with drugs given to treat insomnia

Answer 10

Addiction, dependence, day time sedation, tolerance

Question 11

What is Hypersomnia and give 4 causes

Answer 11

Excessive daytime sleepiness

Causes: OSA, drugs, ETOH, depression/anxiety

Question 12

What is Narcolepsy?

What symptom and what brain structure it is a/w

Answer 12

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

Question 13

What is Parasomnia?

Answer 13

Sleep paralysis, sleep walking/talking, night terrors, confusional arousal

Question 14

What is an EEG?

Answer 14

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

Question 15

What are the 4 basic waves seen on an EEG and which is seen during each stage of sleep

Answer 15

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

Question 16

Compare our REM vs non-REM sleep (3)

Answer 16

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

Question 17

What is Epilepsy?

Answer 17

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

Question 18

List 4 ways in which epilepsy can present and describe these

Answer 18

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

Question 19

Give 2 symptoms which may occur following a seziure and describe these

Answer 19

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)

Question 20

Give 3 treatments of epilepsy

Answer 20

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

Question 21

Give 4 causes of Epilepsy

Answer 21

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

Question 22

Describe Partial (focal) epilepsy (5)

Answer 22

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

Question 23

Describe Complex partial epilepsy

Answer 23

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

Question 24

Describe generalised epilepsy

Answer 24

Generalised seizures involve both cortices and usually loss of consciousness with or without convulsions

Question 25

Describe Tonic/clonic or ‘Grand mal’ seizures

Answer 25

Initial phase of Tonic ➞ muscles go stiff and Clonic ➞ muscles jerk… followed by a period of unconsciousness

Question 26

Describe Absence or ‘petit mal’ seizures

What specific EEG change may be observed

Answer 26

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)

Question 27

Describe Juvenile myoclonic epilepsy

Is there a genetic link?

Answer 27

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)

Question 28

Describe Status epilepticus

Answer 28

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