Neuroscience (Approach to Loss of Consciousness)

Question 1

State the 4 levels of impariment of consciousness

Answer 1

Level 1 - Lethargy
- difficultu maintaining aroused state

Level 2 - Obtunded
- responsive to non-pain stimuli

Level 3 - Stupor
- responsive only to pain

Level 4 - Comatose
- no clinical repsonse to external stimuli
- only occurs if large areas of brain are affected

Question 2

State the 3 components of the glasgow coma scale.

State the minimally passable value for patient to be diagnosed as CONSCIOUS

Answer 2

GLASGOW COMA SCALE
- eye-opening response - out of 4
- best verbal response - out of 5
- best motor response - out of 6

minimally 12/15

Question 3

State some limitations of the glasgow coma scale

Answer 3

1. Difficulty evaluating eye-opening response for patients with severe orbito-facial injury
2. Difficulty assessing best verbal response for intubated patients
3. Lack of neuro-ophthalmic evaulation - pupillary size and reactivity
4. Lack of assessment of brainstem reflex functions

Question 4

State the causes of loss of consciousness (13)

Answer 4

1. traumatic brain injury
2. cerebrovascular disease
3. seizures or status epilepticus
4. syncope
5. CNS infection
6. sepsis
7. medication
8. drug/alcohol abuse
9. toxic substances
10. metabolic crisis
11. electrolyte abnormalities
12. major organ failure
13. post-infectious/inflammation disorders

Question 5

SYNCOPE
- ____ cerebral ____
- Loss of ____ and ____ ____
- ____ reduction of energy substrates to ____ ____ due to (1) or (2)
- Presentation =
- Pre-syncope presentation =
- Risk factors =
- Types of syncope =

Answer 5

SYNCOPE
- TRANSIENT cerebral HYPOPERFUSION
- Loss of CONSCIOUSNESS and POSTURAL TONE
- ABRUPT reduction of energy substrates to CEREBRAL CORTEX due to (1) CEREBRAL PERFUSION or (2) OXYGENATION IN BLOOD
- Presentation = pallor, sweating, brief stiffening, few irregular myoclonic jerks (episode <30s)
- Pre-syncope presentation = dizziness, nausea, feeling of warmth, sweating, vision greying, hearing muffled
- Risk factors = peripheral vasodilation + increased vagal tone
- Types of syncope = neurally-mediated OR cardiogenic

Question 6

State the presentation of SYNCOPE and PRE-SYNCOPE

Answer 6

SYNCOPE
- loss of consciousness and postural tone
- pallor and sweating
- brief extesnor stiffening or spasms
- few irregular myoclonic jerks
- whole episode lasts less than 30 seconds
- rapid recovery with no post-ictal confusion
- gradual onset, less than a minute

PRE-SYNCOPE
- lightheadedness, dizziness, nausea
- feeling of warmth
- sweating
- vision greying
- hearing muffled

Question 7

State examples of neurally-mediated syncope and cardiogenic syncope

Answer 7

NEURALLY-MEDIATED SYNCOPE
- vasovagal syncope
- reflex anoxic seizures
- orthostatic syncope
- reflex-mediated situational syncope

CARDIOGENIC SYNCOPE
- cardiac arrhythmias (bradycardia, tachycardia)
- cardiac defects (aortic stenosis)
- cardiomyopathy

Question 8

State some infectious/inflammatory disorders whcih can cause syncope

Answer 8

1. multiple sclerosis
2. acute disseminated encephalomyelitis (ADEM)

Question 9

Define seizures

Answer 9

seizure = sudden and unusual electrical changes in cortical neurons, resulting in brief alteration in person’s consciosuness, sensation and metabolism

Question 10

State everything you know about acute seizures

Answer 10

ACUTE SEIZURES = seizures resulting from acute systemic metabolic disturbace or from acute disturbance of brain strucure or metabolism

Causes:
1. hypoglycaemia or electrolyte distubrance
2. head trauma
3. stroke
4. alcohol or alcohol withdrawal
5. drugs or drug withdrawal

Question 11

State the causes of acute seizures

Answer 11

ACUTE SEIZURES
- hypoglycaemia or electrolyte disturbance
- head trauma
- stroke
- alcohol or alcohol withdrawal
- drugs or drug withdrawal

Question 12

State everything you know about epilepsy

Answer 12

EPILEPSY = chronic condition characterised by predisposition to recurrent, usually spontaneous seizures
- Reflex epilepsies occur in response to specific sensory stimulus and are hence not spontaneous

(1) Pathophysiology
- Increased excitatory neuronal discharges which spread to adjacent areas → spread across corpus callosum to opposite hemisphere
- Fewer inhibitory neurotransmitters

(2) Differentials
- Breath holding spell - precipitated by noxious, painful stimuli or suprise
- Cyanosed, limp, unresponsiveness
- Crying and cessation of breathing in expiration
- Rapid recovery

Question 13

State the pathophysiology of epilepsy

Answer 13

• Increased excitatory neuronal discharges which spread to adjacent areas → spread across corpus callosum to opposite hemisphere
• Fewer inhibitory neurotransmitters

Question 14

State the features of epileptic seizures

Answer 14

EPILEPTIC SEIZURES
- sudden stiffening followed by repetitive shakes or jerks
- sudden fall or drop of head
- blank spells and reptitive eye blinks
- loss of awareness with semi-purposeful movements
- brief involuntary purposeful movements
- spasms

Question 15

State some features of epileptic seizures from different lobes of the brain

Answer 15

frontal lobe
- tingling in hands and face
- head and eyes may tilt to one side

temporal lobe
- changes in smell
- altered behaviour
- deja vu
- lip smacking or chewing movements

parietal lobe
- jerking or tingling in UL or LL or face

occipital lobe
- flashes of light or spots