Sleep, wakefulness, epilepsy and EEG Flashcards Preview

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Flashcards in Sleep, wakefulness, epilepsy and EEG Deck (26)
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1
Q

Sleep is usually described in relation to consciousness

A

a) easily reversible state of inactivity with a b) lack of interaction with the environment.

2
Q

Consciousness has been described as having three states (Antonio Damasio)

A

Wakefulness – animal is alert, detects objects and pays attention to them Core consciousness –wakefulness plus emotional responses, and simple
memory.
Extended consciousness – all of the above plus self awareness, autobiographical memory, language and creativity.

3
Q

what are the theorised functions of sleep

A
  • processing and storage of memories
  • recuperation of the bodies immune system
  • to conserve energy
4
Q

There are two main forms of externally discernable sleep

A

1) when the eyes move rapidly from side to side (REM sleep) or
2) when they do not (non REM, slow wave or deep sleep) however there are other determinants

5
Q

how can the neuronal activity during the different stages of wakefulness be measured

A

Electroencephalogram (EEG)

6
Q

how does an EEG work

A
  • Post synaptic activity of individual neurons not picked up
  • Post synaptic activity of synchronised dendritic activity can be picked up.
  • Synchronisation is either by neuronal interconnections or by pacemaker
  • The more neurons that are synchronised, the bigger the peaks on the EEG.
7
Q

Influence of the thalamus on brain waves during somnolence:

A

when the brain wants to be awake it actively inhibits sleep and vice versa:

  • excitation arrives at the reticular formation and therefore this activates depolarisation which travels to the thalamus, this produces a nonrhythmic output which results in increased arousal (alpha and beta waves)
  • when inhibition arrives at the reticular formation this produces hyperpolarisation which means the thalamus produces a rhythmic output which results in slow EEG waves in the cerebral cortex
8
Q

Epilepsy definition

A

a continuing tendency to have recurrent, unprovoked seizures.

9
Q

what are the three main Classe of seizure

A
  • partial
  • generalised
  • unclassified
10
Q

simple partial seizure

A
  • consciousness is preserved with +ve or –ve symptoms. Symptoms are related to areas affected in brain
11
Q

complex partial

A

this can cause an impairment on consciousness, they start all over the brain or start at a focal point and spread all over, this is most common in the temporal lobe

12
Q

Stages of complex partial seizures.

A
  • Often begin with aura (fear, anxiety, déjà vu, olfactory sensation) linked to location
  • Unresponsiveness then
  • automatisms (lip smacking, patting, swallowing etc) & unusual sounds (grunting)
  • Occasionally autonomic responses (Tachycardia pupil dilation)
  • Post ictal headache common, often confusion.

these can evolve into generalised seizures which involve the whole of the brain and which impair consciousness

13
Q

generalised seizures

A

both hemispheres are widely involved from the onset and the manifestations of the seizure are determined by the cortical site at which the seizure arises

ALWAYS ALTERATION TO CONCIOUSNESS

14
Q

Absence seizures (Petit mal)

A

two forms, most (typical) are: • sudden onset (no aura) and
• abrupt cessation
• brief duration (20 sec),
• attack may be associated with mild clonic jerking of the eyelids

15
Q

Myoclonic seizures:

A

myoclonic jerking is seen in a wide variety of seizures but when this is the major seizure type, it is treated differently to some extent from partial leading to generalized – treating Juvenile myoclonic seizures with carbamazepine will make them worse

16
Q

• Atonic seizures:

A

sudden loss of postural tone; most often in children but may be seen in adults – generally rare.

17
Q

• Tonic-clonic seizures (grand mal):

A

major convulsions with rigidity (tonic) and jerking (clonic), this slows over 60-120 sec followed by stuporous state (post-ictal depression)

18
Q

Major convulsions, usually with two phases:

A
  • 1) Tonic phase: muscles will suddenly tense up, causing the person to fall to the ground if they are standing.
  • 2) Clonic phase: muscles will start to contract and relax rapidly, causing convulsions
19
Q

Convulsions:

A

− motor manifestations
− may or may not be present during seizures
− excessive neuronal discharge

20
Q

Status Epilepticus

A
  • More than 30 minutes of continuous seizure activity
  • Two or more sequential seizures spanning this period without full recovery between seizures
  • Medical emergency
21
Q

Relevant features of epilepsy are

A
  • +/- Aura/warning/fear/Deja vu from patient
  • Abnormal movements (lip smacking, patting, stroking) reported by patient or witness
  • After effects? – memory loss, confusion, headache for mins or hours
  • interictal examination which is usually normal
22
Q

Non- invasive tests to confirm an epilepsy diagnosis

A
  • ECG: Primarily done to check for abnormal function as there is a correlation between epilepsy and some cardiac problems such as arrhythmias and atherosclerosis.
  • EEG: Interictal EEG is used to detect interictal epileptiform activity (IEA) which is a series of characteristic waves and spike used to predict the type of epilepsy
  • CT scan: not normally done unless there is suspicion of a brain tumour or MR scans are not available. Resolution is lower, but cortical shrinkage or scars can be identified
  • MRI: Used to identify areas of scarring, reduced perfusion, dysplasia (malformation) or areas of cortex damaged during stroke.
23
Q

Pre-disposition

A

scar tissue
developmental issues
Pyramidal cell damage
sub-optimal regulation of neuronal excitability

24
Q

disease that can cause it

A

Tumours

25
Q

triggers for seizures

A

Tiredness – up all night
Alcohol
Certain drugs like anti depressants (tri-cyclic Anti depressant) Change of medication

26
Q

An anti epileptic drug (

A

• Is a drug which decreases the frequency and/or severity of seizures in people with epilepsy.