L7: Coma Flashcards
Def of Conscioussness
Two components of conscious behavior.
1. Awareness: content of consciousness
2. Arousal: appearance of wakefulness
Full consciousness
- An awake state in which one is aware of oneself and the environment.
Wakefulness
A function of the ascending reticular activating system (ARAS)
Awareness
A function of the cerebral cortex
Levels of Arousal
Levels of Arousal
- Alert
Appearance of wakefulness, awareness of the self and environment.
Levels of Arousal
- Lethargy
Mild reduction in alertness
Levels of Arousal
- Obtundation
◈ Moderate reduction in alertness.
◈ ↑↑ response time to stimuli
Levels of Arousal
- Stupor
◈ Deep sleep
◈ patient can be aroused only by vigorous and repetitive stimulation.
◈ Returns to deep sleep when not continually stimulated
Levels of Arousal
- Coma
- Sleep like appearance and behaviorally unresponsive to all external stimuli (Unarousable unresponsiveness, eyes closed)
Other Names of Vegetative state
(Coma vigil)
(Apallic syndrome)
Etiology of Vegetative state
◈ Traumatic brain injury
◈ Diffuse cerebral hypoxia
Parts Damaged in Vegetative state
- Both cerebral hemispheres
- AND/OR the thalamus bilaterally
Parts Spared in Vegetative state
- Brainstem
- Hypothalamus
CP of Vegetative state
- History
- Perceptual & Self-Awareness
- Sleep-Wake Cycles
- Movement
- Eye Movement
- Brainstem Reflexes
- Respiratory Functions
Etiology of Locked-in Syndrome
◈ Bilateral ventral pontine stroke
◈ Direct trauma to the ventral pons
Parts Damaged in Locked-in Syndrome
Ventral Pons
Parts Spared in Locked-in Syndrome
- Cerebral cortex & Reticular Activating System (RAS)
- Spinothalamic tract (Dorsal pons)
- Centers of Vertical gaze and blinking of eye (Midbrain)
CP of Locked-in Syndrome
- History
- Perceptual & Self-Awareness
- Sleep-Wake Cycles
- Movement
- Eye Movement
- Brainstem Reflexes
- Respiratory Functions
Def of Cerebral Edema
- Excess accumulation of water in the intra and/or extra cellular spaces of the brain
Etiology of Cerebral Edema
- Head injury
- Allergic reaction
- Stroke
- Acute liver disease
- Cardiac arrest
Types of Cerebral Edema
Pathophysiology of Vasogenic Cerebral Edema
Breakdown of tight endothelial junctions → ↑ capillary permeability → extracellular accumulation of fluids
(White matter 1ry affected)
Etiology of Vasogenic Cerebral Edema
◈ Ischemic stroke (late stages)
◈ Traumatic brain injury (early stages)
◈ Space occupying lesion (Tumor, abscess, Hge)
◈ Inflammation
BBB integrity in Vasogenic Cerebral Edema
Breakdown
Pathophysiology of Cytotoxic Cerebral Edema
- Damage to brain parenchyma cells → impaired Na+/K+ ATPase function → intracellular accumulation of Na+, fluids → expansion of neurons, glial, and endothelial cells
(Grey matter 1ry affected)
Etiology of Cytotoxic Cerebral Edema
◈ Ischemic stroke (early stages)
◈ Traumatic brain injury (late stages)
◈ Various toxins (Hyperammonemia)
◈ Reye’s syndrome
◈ Severe hypothermia
BBB Integrity in Cytotoxic Cerebral Edema
Intact
Pathophysiology of Interstitial Cerebral Edema
- Blocked CSF drainage → ↑ ventricular pressure → movement of Na+ & water across the ventricular wall
into the paraventricular (interstitial) space
Etiology of Interstitial Cerebral Edema
◈ Hydrocephalus
◈ Idiopathic intracranial hypertension
BBB Integrity in Interstitial Cerebral Edema
Intact
Pathophysiology of Osmotic Cerebral Edema
Osmolarity of plasma > intracerebral → osmotic gradient → water diffusion across BBB into interstitial fluid
Etiology of Osmotic Cerebral Edema
◈ Hypernatremia (SIADH)
◈ Iatrogenic (rapid correction of hyperglycemia in DKA or hypernatremia)
BBB Interity in Osmotic Cerebral Edema
Intact
