Week 11- Neurological Disorders Flashcards
Initial response to bruising
- Vasodilation and increased blood flow to the area of injury
- Pressure surrounding the injury site
- Increased intracerebral pressure - decreased blood flow
- Edema develops over a period of hours
Normal Functioning Brain
- Adjusts blood flow to your metabolic needs
- Based on O2 & CO2 levels in the blood and Cerebrospinal fluid (chemoreceptors
- Decreased CO2 levels will cause- Hypervenilation- cerebral vasoconstriction and cerebral ischemia (hypoxia)
- Increased CO2 levels will cause- Hyperventilation, vasodilation and edema (hypoxia)
Intracranial Pressure
- The pressure inside of the cranium as a result of: brain tissues, blood, CSF
- Normal pressure 5-15mm hg
- 15 mm hg upper limit of normal
- Volume changes of any one are at the expenses of the others
- Blood supply can’t be compromised (need oxygen and glucose to survive)
- No room for the tissues to expand
What are the different brain pressure?
- ICP- Intracranial pressure (<15 m hg)
- CPP- Cerebral Perfusion Pressure- pressure needed to maintain blood flow to the brain (70-80mm hg), No less than 60 mm hg (doubles the patients chances of death)
- MAP-Mean Arterial Pressure (70-100mm hg).<60 can be deadly to main organs
Cerebral Perfusion Pressure
- CPP= MAP - ICP
- ICP <15 mm hg normally
- With brain swelling or bleeding inside the skull- Increased ICP- Decreased CPP- Cerebral vasodilation, increased ICP-
- When ICP= MAP, BLOOD FLOW STOPS
ICP- Early Signs
- Shifts CSF to the spinal cavity to compensate
- Decreasing cerebral blood flow
- Effective for a short time until you become hypoxic
- Hypoxia triggers arterial vasodilation in the brain in an attempt to improve blood supply- adds fluid volume
- Bc of these responses, ICP is significantly elevated before apparent
Other Early Signs and Symptoms of ICP
- Severe headache- stretching of the dural layer and walls of the large blood vessels
- Vomiting- projectile without food intake association- pressure stimulating the emetic centre of the medulla
- Papilledema- swelling of the optic discs and ICP
- Seizures
- Signs increase in severity until ICP is controlled
Vital Signs of ICP
- If ICP continues to build up, there is a sequence of events that occurs in an attempt to supply oxygen to the brain
- Cerebral ischemia- cushing’s reflex in the vasomotor centre of the brain (decreasing pulse, increasing systolic pressure w widening pulse pressure, irregular respirations)
- Attempt to increase the blood supply to the brain
Systemic Vasoconstriction
- Increases the BP and forces more blood into the brain to relive the ischemia
- Baroreceptors in the carotid arteries to the increase in BP by slowing the HR
- Chemoreceptors respond to low CO2 levels from accelerated systemic circulation by slow the RR
Then…
- Improved cerebral circulation relieves the ischemia and the vasoconstriction relaxes…
- Rising ICP causes ischemia to recur and the cycle is repeated
Results of Increased ICP
- The brain responds to ischemia by one mechanism… but the feedback control for increased BP uses other mechanisms to protect the rest of the body
- The 2 mechanisms are in conflict of interest
- Eventually severe ischemia and neuronal death prevent any circulatory control and BP drops
- Respiratory Centre control is destroyed resulting in abnormal resp patterns
- Death is inevitable of the pressure is not released
Cushing’s Response
- HTN, Bradycardia, Irregular Respirations
- As the pressure arises- the body’s reflex mechanism cant keep up- Uncompensated
- Pressure increase to a critical point where there is no perfusion- deterioration and death occurs
What is Cerebral Herniation Syndrome?
- Brain swelling eventually forces tissues downward through the foramen magnum
- Obstruction of blood flow
- Pressure on the brain stem- vital centres that causes death
What are the S&S of Cerebral Herniation Syndrome?
- Decreased LOC
- Coma
- Dilation of pupil on same side
- Paralysis on the opposite side of the body
- Decerebrate posturing (extension)
- Increased BP
- Bradycardia
What is the treatment for Cerebral Herniation Syndrome?
- Hyperventilation to reduce swelling 1:3 secs
- Hyperventilation causes vasoconstriction, which causes blood to go to the brain, reducing blood flow
Scalp Wounds
- Vascular and bleed well
- Vasospasm is inhibited- prolonged and significant bleeding
- Without skull injuries- direct pressure is indicated
What are the different Skull Injuries?
- Linear nondisplaced
- Depressed
- Compound
- Suspected skull injuries with large contusions
- Leave protruding objects in place
- Transport immediately
What are the different brain injuries?
- Concussion
- Cerebral contusion
- Diffuse axonal injury
- Anoxic brain injuries
- Closed head injuries- countercoup injuries
Concussion
- History of trauma- Mild blows to the head causing sudden excessive movement of the brain- LOC
- No structural damage to the brain- reversible interference of brain function
Brief disruption of neural function:
- Period of unconscious or confusion
- Return to normal
- Short term memory loss (amnesia)
Concussion Sign and Symptoms
- Headache, dizziness, tinnitus (ringing sound), nausea
What is a cerebral contusion?
- Bruised brain tissue with ruptured small blood vessels (usually from a blow to the head)
- Brain swelling may be rapid and severe
What are the sign and symptoms of cerebral contusion?
(depends on force):
- prolonged unconscious
- Altered LOC
- Personality changes
- Profound confusion
- Persistent amnesia
- Abnormal behaviour
- Focal neurological signs
What are Basilar Fractures?
- Occur at the base of the skull
- Often accompanied by leaking CSF through the nose and ears
- Often occur when the forehead hits a car windshield with considerable force
- Diagnosed with dark discolouration around the eyes and behind the ears