A7. Classification of unconscious conditions Flashcards
Clear consciousness definition
The brain’s ability to react (arousal or
alertness) and the adequate use of contents of memory and to
think (awareness).
Allows the adaptation of the individual to the environment and is the basis of cognition.
Awareness depends on alertness.
The anatomical basis of arousal is the
intact functioning of the
ascending reticular activating system (ARAS)
ascending reticular activating system (ARAS)
is
composed of the
- pontomesencephalic reticular formation,
- monoaminergic networks of the diencephalon and
- the intralaminar and medial nuclei of the thalamus
Disorders of consciousness:
- Disorder of arousal
- Disorder of awareness
NOTE: Locked in syndrome - Not disorder of consciousness, but often misdiagnosed as this.
Is locked in syndrome a disorder of consciousness?
Not disorder of consciousness, but often misdiagnosed as this.
what are the characteristics of Disorders of arousal
- Reduced arousal
- sleep-like state
- won’t react to awakening stimuli.
list Disorder of arousal
● Somnolence - Mildest form. Awakens with verbal stimuli, but is asleep without stimuli.
● Stupor - Patient may open eyes to painful stimuli, verbal is not enough. Slow and inappropriate reaction to stimuli.
● Coma - Cannot be awakened. Abnormal posture (decorticate or decerebrate).
i. Coma I - Preserved brainstem reflexes
ii. Coma II - Lost brainstem reflexes
● Somnolence
Mildest form of Disorder of arousal.
Awakens with verbal stimuli, but is asleep without stimuli.
Disorders of consciousness:
A. Disorder of arousal
Stupor
- Patient may open eyes to painful stimuli, verbal is not enough.
- Slow and inappropriate reaction to stimuli.
Disorders of consciousness:
A. Disorder of arousal
Coma
- Cannot be awakened.
- Abnormal posture (decorticate or decerebrate).
i. Coma I - Preserved brainstem reflexes
ii. Coma II - Lost brainstem reflexes
Disorders of consciousness:
A. Disorder of arousal
coma 1 VS coma 2
i. Coma I - Preserved brainstem reflexes
ii. Coma II - Lost brainstem reflexes
Disorders of consciousness:
A. Disorder of arousal
characteristics of Disorder of awareness
- Inadequate thinking and behavior.
- Global CNS function is impaired.
- Arousal is normal, but content of memory is disturbed, inaccessible or used inappropriately
- Signs of focal cognitive deficit (e.g. alexia, acalculia) are NOT part of this.
Signs of focal cognitive deficit (e.g. alexia, acalculia) - are they a part of disorder of awareness
- Signs of focal cognitive deficit (e.g. alexia, acalculia) are NOT part of this.
Arousal is normal, but content of memory is disturbed, inaccessible or used inappropriately
disorder of awareness
list Disorder of awareness
- Persistent vegetative state (decorticate state, apallic syndrome)
- Akinetic mutism
- Confusion
- Delirium
Persistent vegetative state (decorticate state, apallic syndrome)- how is the brainstem
Rostral brainstem remains intact
→
* Thermoregulation (hypothalamus),
* sleep-wake cycle,
* endocrine system,
* cardiorespiratory and
* other visceral functions are intact.
Persistent vegetative state is permenent if
Permanent when >30 days
in Persistent vegetative state Patients seem to be
awake with open eyes and elicitable eye movement reflexes
(e.g. vestibulo-ocular reflex)
Persistent vegetative state reaches decortication position after how many days
After days/week
Persistent vegetative state shows signs of
Signs of
* corticospinal tract lesion (e.g. Babinski reflex)
* and primitive reflexes
(suction reflex, Bulldog reflex)
can be elicited
a painful stimulus to a patient with Persistent vegetative leads to
- Increased decortication(lesion above RN)
*Flexion of upper limb,
*extension of lower limb - may see autonomic response (sweating, tachycardia, hyperventilation)
causes of Persistent vegetative state
- Extensive functional or structural impairment of cerebral cortex
(e.g.
*global cerebral ischemia, *hypoglycemia,
*renal/hepatic failure,
*post-convulsive state,
*Wernicke’s encephalopathy,
*final stages of cortical dementias) - Extensive white matter damage (diffuse axonal injury after head trauma)
- Bilateral damage to the thalamus
list Extensive functional or structural impairment of cerebral cortex which can cause Persistent vegetative state
- global cerebral ischemia
- hypoglycemia,
- renal/hepatic failure,
- post-convulsive state,
- Wernicke’s encephalopathy,
- final stages of cortical dementias)
Akinetic mutism- how do they appear
Awake, but mute and does not move
can Akinetic mutism be caused by aphasia?
Not caused by aphasia,
can see signs of comprehension
how is paralysis excluded in Akinetic mutism
Paralysis is excluded by normal withdrawal reactions to painful stimuli.
Akinetic mutism what signs are present
Usually frontal release signs are present:
sucking reflex,
bulldog reflex,
palmar grasp reflex
Akinetic mutism is caused by
-
bilateral interruption of connections between the supplementary motor area,
cingular region
and midline nuclei of the thalamus
list causes of Akinetic mutism
○ Jet bleeding (rupture of anterior communicating artery aneurysm)
○ Frontobasal contusion
○ Bilateral ischemia in the anterior cerebral artery territory (Willis-circle variants)
○ Subfalcial herniation
○ Occlusive hydrocephalus
○ Butterfly tumors growing across the corpus callosum into the prefrontal lobes
○ Tumors of third ventricle
Confusion def
Impaired thinking and attention.
Slow and vague.
Incoherent thinking.
No signs suggestive of delusions.
E.g. after epileptic seizure
(post-convulsive state or tenebrosity)
Delirium def
- Disorder of attention and awareness (old definition: also disorder of
perception. Can use this to differentiate from confusion). - Cannot focus, change or fix attention.
- Disoriented and incoherent thinking.
confusion vs delerium
delerium is a disorder of attention and awareness
(old definition: also disorder of perception.
Can use this to differentiate from confusion).
Delirium- onset?how does it evolve
Evolves quickly (hours-24h)
Delirium how are symptoms
Characteristic diurnal fluctuation of intensity, symptoms deteriorate at night or in an environment lacking stimuli.
symptoms of delerium symptoms deteriorate at
- at night or
- in an environment lacking stimuli.
in Delirium how is the sleep wake cycle
Typical inversion of sleep/wake cycle
Delirium can have autonomic instability such as
Autonomic instability (excitatory):
* sweating,
* tachycardia,
* unstable BP
Delirium may be a complication of
- right hemispheric lesions,
- metabolic disorders,
- drug or
alcohol
