7. Classification of unconcious conditions Flashcards
Define conciousness
The brain’s ability to react (arousal or altertness), adequate use of memories, and to think (awareness).
Anatomical bases of arousal
Ascending reticular activating system (ARAS). Composed of pontomesencephalic reticular formation, monoaminergic networks of diencephalon and the intralaminar and medial nuclei of thalamus.
Disorder of conciosuness: categorization
- Disorder of arousal
- Disorder of awareness
Undercategorization of arousal disorders
Disorders of arousal
- Somnolence
- Stupor
- Coma
Undercategorization of disorders of awareness
Disorder of awareness
- Peristent vegetative state
- Akinetic mutism
- Confusion
- Deilirium
Define somnolence
Wakes with verbal stimuli, but asleep without stimuli
Define stupor
May open eyes to painful stimuli. Still asleep when verbal stimuli.
Define coma
Cannot be awakened. Abnormal posture (decorticate or decerebrate)
Classification of coma
Coma I. preserved brainstem reflexes
Coma II. Lost brainstem reflexes
What is a disorder of arousal?
Reduced arousal, sleep-like state, won’t react to awakening stimuli
What is a disorder of awareness?
Inadequate thinking and behaviour. Global CNS function impaired. Arousal normal. Content of memory disturbed or used inappropriately.
Define perisistent vegetative state
Disorder of consciousness in which patients with severe brain damage are in a state of partial arousal rather than true awareness. Midbrain intact: thermoreg., sleep cycle, endocrine system, other visceral functions intact.
Location and function of the midbrain
- The rostral most portion of brainstem. Connects diencephalon and cerebrum with pons.
- Consists of cerebral peduncles, tegmentum and tectum
- Function: arousal, wakefullness, sleep, temp. regulation, vision, hearing and motor control
Characteristic/clinical of persistent vegetative state
- Persistent when > 1 month
- Eyes open, eye movement reflexes (e.g. vestiulo-ocular reflex)
- Decortiate position after days/weeks
- Sings of corticospinal tract lesion (e.g. babinski)
- Painful stimulus can increase decortication and may see autonomic respone (sweating, tachycardia, hyperventilation)
Decorticate position
Plantar flexion, wrist- and forearm flexion, legs internally rotated and arms adducted
Decerebrate position
Plantar flexion, hand flexed, wrist pronated, arm extended and edducted. No flexion at the arm (laying on the chest)
Causes of persistent vegative state
Extensive functional or structural impairment of cerebral cortex:
- global cerebral ischemia
- hypoglycemia
- renal/hepatic failure
- Wernicke’s encephalopathy
- Extensive white matter damage
- Bilateral damage to thalamus
Definition of akinetic mutism
Awake, but mute and does not move
Clinical features akinetic mutism
- Signs of comprehension (so not aphasia)
- Normal withdrawal to pain stimuli (so not paralysis)
- Frontal release signs/primitive reflexes: sucking-, bulldog-, and palmar grasp reflex
Etiology akinetic mutism
Bilateral interruption of connections bw. the supplementary motor area, cingular region and midline nuclei of thalamus.
- jet bleeding
- frontobasal contusion
- bilateral ischemia in anterior cerebral artery territory
- subfacial herniation
- occlusive hydrocephalus
- tumors of 3rd ventricle
Definition of confusion
Impaired thinking and attention. Slow and vague. Incoherent thinking. No signs suggestive of delusions.
Define delirium
Disorder of attention and awereness. Cannot focus, change or fix attention. Disoriented and incoherent thinking.
Characteristics of delirium
- Evolves quickly (<24h)
- Fluctation of intensity; sympt. worse at night or in environment lacking stimuli
- Change in sleep/wake cycle
- Autonomic instability: sweating, tachycardia, unstable BP
Brainstem reflexes
- Pupillary Light Reflex
- Corneal Reflex
- Oculo-vestibular Reflex
- Pain Stimulus
- Gag Reflex
- Cough Reflex
Causes of deilirum
Complication of right hemispheric lesions, metabolic disorders, drugs, alcohol, infection (UTI) in elderly
