Disturbances of Consciousness Flashcards
Define consciousness
is the state of being aware of self and the environment
Describe an “alert” patient
full wakefulness and immediate and appropriate responsiveness
Describe a “confused” patient
inability to think with the usual speed and clarity
What is obtundation?
the patient is drowsy and indifferent to the environment, but responsive to verbal stimuli
What is stupor?
the patient is unconscious but rousable when stimulated
When would a patient be described as being in a coma?
the patient is unaware of self and the environment and is not rousable
What is important for forming a Dx relating to impaired consciousness?
the duration of impaired consciousness
- can be transient or ongoing
What does the normal conscious state depend on?
the integrity of the brainstem reticular activating system and the cerebral hemispheres
What are the most common causes of transient loss of consciousness (LOC) ?
- Syncope
- Seizures
- Psychogenic/’non-epileptic’ attacks
What are uncommon causes of transient LOC?
- Hypoglycaemia
- Narcolepsy/cataplexy
- Hyperventilation
- Vertebrobasilar ischaemia
- Vertebrobasilar migraine
What is syncope?
transient LOC and posture that results from a global reduction in blood flow to the brain
What are the main symptoms of syncope?
- usually when standing
- hypotensive symptoms: light-headed, faint, blurred/dim vision, sounds seem distant, nausea, hot/cold, sweating
- pale skin colour
- shallow respiration
- floppy tone
What are the features of recovery from syncope?
- Recovery is usually rapid with no confusion
- Pallor may persist
- No focal neurological signs
What are the 5 main causes of syncope?
- Vasovagal syncope
- Situational syncope; micturition/cough
- Postural hypotension
- Primary cardiac dysfunction
- Carotid Sinus disease
What causes vasovagal syncope?
caused by a sudden drop in BP due to peripheral vasodilation (systolic drops to <60mmHg)
Describe micturition syncope
Men who get up to urinate in the middle of the night. it is a combination of vasodilation (from emptying of the bladder), postural hypotension (from standing) and bradycardia
Describe cough syncope?
sustained coughing can increase intrathroacic pressure, which impairs venous return to the heart (valsalva). Increase in CSF pressure, reduction in pCO2 and resultant vasoconstriction may be contributory
What is postural hypotension
upright posture is accompanied by an uncompensated fall in BP
Who is postural hypotension likely to occur in?
- Normal individuals
- Drugs (antihypertensives)
- Autonomic neuropathy (diabetes, Guillian-Barre)
- Hypovolemia (blood loss, sepsis, hypoadrenalism)
- Neurodegenerative disease (Parkinsons, mutlisystem atrophy)
What conditions are likely to cause primary cardiac dysfunction syncope?
- arrhythmias
- LV outflow obstruction (aortic stenosis, hypertrophic obstructive cardiomyopathy)
- RV outflow obstruction (pulmonary stenosis, pulmonary hypertension, PE)
- Ventricular failure (acute anterior MI, dilated cardiomyopathy)
How does carotid sinus disease cause syncope?
Hypertensive - less stretch needed for reflex bradycardia/decreased BP
What are the prodromal symptoms for syncope caused by hypoglycaemia?
- feeling tremulous and sweaty
- palpitations
- confusion
What are the main causes of syncope caused by hypoglycaemia?
- over treatment of diabetes
- liver failure
- hypopituitarism
- Addison’s disease
- insulinsomas
What is narcolepsy?
excessive sleepiness and sleep attacks at inappropriate times
what is catoplexy?
attacks of sudden relaxation of muscle tone; usually precipitated by emotion/laughing
What is hyperventilation?
over breathing
This results In decreased pCO2, cerebral vasoconstriction, metabolic alkalosis and decreased ionised Ca2+
What are the main features of hyperventilation?
- breathlessness and air hunger with rapid respiration
- light-headed
- perineal and digital parasethesia
- carpopedal spasm
- anxiety and fatigue
What is vertebrobasilar ischaemia and what are the main symptoms?
- brainstem = supplied by the vertebrobasilar system
- vertigo, nausea and diplopia
VERY RARE
When are non-epileptic attacks diagnosed as a reason for LOC?
diagnosis of exclusion
A specialist should be consulted before giving this diagnosis
How does syncope differ from seizures?
unrelated to posture
What are the symptoms the precede a focal seizure/aura?
- deja vu
- epigastric rising sensation
- anxiety and fear
- focal sensory symptoms
- focal twitching
What are the clinical signs of a seizure?
- Skin = blue/normal
- respiration = stertorous (noisy)
- tone = tonic-clonic
- convulsions and urinary incontinence
- tongue biting
- occasional focal neurological symptoms
What is a coma?
state of impaired consciousness in which the patient is not rousable despite external stimuli
Define a minimally conscious state
reduced cerebral metabolism on fMRI
Increased medial parietal lobe and posterior cingulate activity compared with more severe comas
Define persistent vegetative state
have lost neurological cognitive function and awareness of the environment but retain non cognitive function and preserved sleep-wake cycle
Define a permanent vegetative state
remain in a vegetative state for more than 6 months if caused by a non-TBI or more than 12 months if caused by a TBI
