9 - Reticular formation Flashcards
Define arousal:
Emotional state associated with some kind of goal or avoidance of something noxious
Define consciousness:
An awareness of both the external and internal world states, requiring 1) cerebral cortex and 2) reticular formation
Where is the reticular formation located?
Brainstem
Which neurotransmitters are important in the reticular formation and its connections with the cerebral cortex?
- MAINLY Ach
- Histamine
- Glutamate
The reticular formation achieves input from where?
- Cerebral cortex
- Somatosensory system
The reticular system connects with the cortex via which 3 structures in the brain?
1) Basal forebrain nuclei
2) Hypothalamus
3) Thalamus
What are the 3 factors which contribute to a GCS score?
1) Best motor response
2) Best verbal response
3) Eye opening
What is the scoring system for the best motor response in a GCS score?
6 = obeys command 5 = localise to pain 4 = withdraws from pain 3 = flexes to pain 2 = extends to pain 1 = no response
What is the scoring system for the best verbal response in a GCS score?
5 = orientated 4 = confused conversation 3 = inappropriate words 2 = incomprehensible sound 1 = no response
What is the scoring system for eye opening in a GCS score?
4 = spontaneous 3 = responds to speech 2 = responds to pain 1 = no response
How can you assess consciousness?
- GCS
- EEG
What is an EEG and what does it do?
Encephalalogram
- Measures the combined activity of thousands of neurones in a given part of the cortex
What are the 3 possible mechanisms resulting in a disorder of consciousness?
1) Diffuse cortical dysfunction (ie metabolic disturbance)
2) Pressure inhibiting the reticular activating system (ie RICP)
3) Direct lesion to the reticular activating system (ie brainstem infection)
Which disorder of consciousness results in a flat EEG?
Brain death
What is the GCS score of someone in a coma?
GCS < 8
In which disorder of consciousness is there no detectable sleep-wake cycle?
Coma
What are some common causes of a coma?
- Drug poisoning
- Hypoxia
- Stroke
What is are the main differences between coma and persistent vegetative state?
Persistent vegetative state: - spontaneous eye opening - can localise to pain via brainstem reflexes - Detectable sleep-wake cycle All of which do not occur in a coma
Which of a coma and persistent vegetate state is damage to the cortical cells only?
Persistent vegetative state
- Coma is also damage to brainstem
What is the name given to the disorder of consciousness resulting from a brainstem stroke?
Locked-in syndrome
Where is the damage in Locked-in syndrome, and how does it present?
Corticospinal tracts damaged at the Pons
- All somatic motor functions lost
- Eye movements preserved
- Consciousness and sensation fully intact
Occlusion of which arteries results in a brainstem stroke?
Basilar and Pontine arteries
What are the 3 types of delirium?
- Hypoactive
- Hyperactive
- Mixed
Describe someone with hypoactive delirium:
Sleepy, apathetic, lethargic, decreased motor activity
Describe someone with hyperactive delirium:
Agitated, aggressive, irritable, restless
- May have hallucinations/delusions
What are the most common type of hallucinations experienced by people with hyperactive delirium?
Visual hallucinations
What are the risk factors of delirium?
- Old age > 65yrs
- Multiple co-morbidities
- Dementia
- Physically fragile
- Renal impairment
- Previous delirium
Name some types of drugs which can precipitate delirium:
- Benzodiazepines
- Opioids
- Anticholinergics
- Anti-parkinsonian medications
- Steroids
- Anaesthesia
Name some COMMON causes of delirium in the elderly:
- Pneumonia
- UTI
- Sensory deprivation (no glasses/hearing aid)
- Faecal impaction
- Urinary retention
- Renal failure
This is only a few!!
In which disorder of consciousness is there a reversal of the sleep-wake cycle?
Delirium
