Consciousness and brain activity

Medical definition of consciousness?

State of being aware of and responsive to ones surroundings

Locked in syndrome

Awareness, sleep wake cycle and meaningful behaviour,

• BUT this is isolated due to facial and body paralysis

Minimally conscious state

Intermittent periods of awareness and wakefulness

• Displays some meaningful behaviour

Unresponsive wakefulness syndrome vs minimally conscious state

Unresponsive wakefulness syndrome = has sleep wake cycles BUT lacks awareness

• only reflexive, non-purposeful behaviour

Chronic coma vs brainstem death

BOTH = no awareness or sleep wake cycles

BUT chronic coma shows reflexive behaviour unlike brainstem death

Normal state of unconsciousness

Sleep

Abnormal cause of a loss of consciousness

• coma

• anaesthesia

• unresponsive wakefulness syndrome

Most common cause of loss of conscious worldwide?

Malaria

Common causes of lass of consciousness in UK

• Stroke

• CV

• Diabetes

• Drug induced

• epilepsy

• head injury or raised ICP

• dementia

First stage of assessment on unconscious patient

ABC - if immediate attention is needed

GCS

Glasgow coma scale - reliable and objective measure of consciousness

3 components of GCS

• Eye opening (1-4)

• verbal response (1-5)

• motor response (1-6)

Best eye movement response - GCS

1. NO RESPONSE

2. opening in response to pain

3. opening in response to speech

4. spontaneous eye opening

Best verbal response - GCS

1. NO RESPONSE

2. Incomprehensible

3. Inappropriate speech (random and exclamatory)

4. Confused convo (conversational manor, but disorientated & confused)

5. Orientated (day, time, year, location…)

Best motor response - GCS

1. NO RESPONSE

2. Extensor posturing of pain

3. Abnormal flexor response

4. Withdraws to pain

5. Localised response to pain

6. Obeys command

Critical score on GCS?

8 - suggests need for incubation

GCS 13-15

Mild head injury

GCS 9-12

Moderate head injury

GCS 3-8

Severe head injury

NHS definition of brainstem death

• Unconscious state & fail to respond to outside stimuli

• HR & BR can only be maintained by ventilator

• Clear evidence of serious brain injury/damage (that cant be cured)

Definition of death

Permanent loss of consciousness, combined with permanent loss of capacity to breath

Requirement of DRs testing for brainstem death

Must be carried out by 2 DRs with 5 years full GMC registration

• at least one must be a consultant

Pupillary response

Shine torch in eyes - CN I, II

Corneal reflex

cornea touched with gauze, observe for eyelid movement - CN V, VII

Central motor response

pinch supraorbital notch - CN V, VII

Pharyngeal reflex

Stimulate the oropharynx with tongue depressor (look for gag reflex) - CN IX, X

Cough reflex

Suction catheter into carina - CN IX, X

Oculovestibular reflex

Ice cold water into each ear, normally causing eyes to move - CN III, IV, VI, VIII

Apnoea test

Disconnect ventilator for 5 mins - see if any effort is made by the patient to breath

What system in the brainstem is essential for consciousness

RAS

Reticulate formation

Collection of nuclei throughout midbrain, that extend into the hindbrain and spinal cord

4 principal nuclei of the RAS

• Locus coeruleus

• Raphe nuclei

• Ventral tegmental area

• Cholinergic nuclei