Mod 14 Brain Environment and TBI Flashcards
What are the 3 layers of the brain meninges from superficial to deep?
dura mater
arachnoid mater
pia mater
What is the dura mater?
thick connective tissue
What are the two layers of the dura mater?
- outer periosteal layer
- inner meningeal layer
What spaces are associated with the dura mater?
epidural and subdural space
What are the dural sinuses?
pathway for blood to get back into the venous system from the head cavity
Which surfaces drain into the superior sagittal sinus?
upper lateral and medial surfaces
Where do a majority of the cortex venous blood drain into?
transverse > sigmoid sinus
What is the pathway for deep structure venous drainage of the brain?
cerebral veins > straight sinus > left transverse and sigmoid sinus > internal jugular vein
What are the 3 dura septa?
- falx cerebri
- tentorium cerebelli
- falx cerebelli
What does the falx cerebri separate?
the two cerebral hemispheres
What does the tentorium cerebelli separate?
separates cerebrum from cerebellum
What does the falx cerebelli separate?
separates the two hemispheres of the cerebellum
What do the supratentorial compartment and infratentorial compartment refer to?
supra = above the tentorium cerebelli
infra = below the tentorium cerebelli
What do the dural septa do?
constrain anterior-posterior and medial-lateral brain movement
What is unique considering the blood supply of the arachnoid mater?
avascular meninge
What is important to remember about the attachment of the arachnoid to the dura?
makes a potential space with the subdural space, does not exist unless blood that isn’t supposed to be there fills the space
What is the subarachnoid space filled with?
CSF and arachnoid trabeculae (attachments to Pia mater)
How is the size of the subarachnoid space determined?
space size varies on brain location
What are the spaces where the subarachnoid space is bigger in the CNS?
cisterns
What is the role of arachnoid villi?
granulations that penetrate dural sinuses to get CSF into venous system
What is the pia mater?
delicate connective tissue
What are the two layers of the pia mater?
- epipia
- intima pia
What is the intima pia and what does it do?
cerebral vessels on top that help create a perivascular wall for blood vessels to dive into brain and get to designated location
What is meningitis?
inflammation of arachnoid and pia due to infection
What are the types of meningitis?
bacterial and fungal
west nile is viral but also has severe effect
How does meningitis start or originate?
- travel in blood from other parts of the body (liver/intestines)
- can originate in the scalp or dural sinus
What is meningoencephalitis?
when meningitis infection also impacts the brain
What are the symptoms of meningitis?
fever, headache, back pain
edema and pressure can lead to seizures/vomiting
What are the examples of focal neurologic deficits with meningitis and meningoencephalitis that can pin point where insult occurred?
cranial nerve palsy: brainstem
motor loss: primary motor cortex
language loss: left lateral hemisphere pressure
What is meningioma?
tumor that typically arises from arachnoid villi (granulations)
What is important about malignant (rare) meningioma?
they don’t penetrate any neural tissue but can still displace or compress brain tissue causing seizures
What does the CSF do?
protects and nourishes the CNS
Where and how is CSF produced?
choroid plexus
- hydrostatic pressure of 15 mL H2O
- produced at rate independent of intraventricular pressures
What is the circulatory pathway of CSF?
- ventricles
- subarachnoid space
- arachnoid villi
- dural sinuses
- venous system
How does the pressure system of the CSF work?
- pumped through with assistance of arterial pulse of choroid plexus
- villi act as one way valve
What is the relationship between pressure of the venous system and CSF?
venous < CSF = valves open
venous > CSF = valves close to prevent back flow (when lifting or coughing)
What is hydrocephalus?
increased accumulation of CSF
- causes enlarged skull in kids (skull not yet fused)
- increased intracranial pressure (ICP) in adults
What are the etiologies/ causes of hydrocephalus?
- sequelae of spina bifida
- tumor
- meningitis
How does hydrocephalus impact CSF flow?
can cause direct or indirect interruption of CSF flow
What is the cascade of compromised absorption of CSF into the venous system?
enlarged ventricles > cerebral compression > arterial compromise > adverse neuro symptoms
How do shunts affect hydrocephalus?
provide alternate route for CSF to escape
pressure sensitive tube that runs from ventricle to various locations
What are the 4 different types of shunts for hydrocephalus?
- ventriculoperitoneal shunt
- ventriculoatrial shunt
- ventriculoatrial shunt to internal jugular vein
- shunt to subarachnoid space
What is normal pressure hydrocephalus?
increase in ventricle dilation without increased intracranial pressure
When do we see normal pressure hydrocephalus?
- in elderly
- following intracranial hemorrhage
- following infection
What are the symptoms of normal pressure hydrocephalus?
large ventricular area exerts force on surrounding neural tissue
- urinary incontinence
- cognitive impairments
- gait/balance difficulties
What is TBI?
injury to the brain as a result of blow to the head
- moving head striking surface (MVA, football)
- moving surface striking head (violence, abuse)
What are the results of TBI?
skull fracture or closed head injury that can lead to various brain insults
What are the two types of skull fracture?
depressed: area of skull pushed down into neural tissue
compound: skin is broken, and skull is splintered
Which lobes of the brain are at risk of coup - counter coup impacts?
frontal and temporal lobes
What is an epidural hematoma?
collection of arterial blood in space between dura and cranium
typically associated with more abrupt deterioration of function
How do epidural hematomas occur?
result of torn meningeal artery that impacts intracranial pressure
What is a subdural hematoma?
collection of venous blood in space between dura and arachnoid mater
How do subdural hematomas occur?
result of torn cerebral vein that impacts intracranial pressure
How is the development of deterioration with subdural hematomas?
slow development of pressure that leads to slow deterioration of function
severity of symptoms vary
What is the difference between a subdural and epidural hematoma?
sub: vein, slow
epi: artery, fast
What is a herniation?
shift of the brain that is result of increased fluid in the brain
What are the types of herniations?
- subfalcial: cingulate gyrus pushed under falx cerebri to oppositie hemisphere (altered consciousness
- uncal: medial temporal lobe pushed into tentorial notch (CN III and midbrain compression)
- cerebellar: cerebellum pushed down into foramen magnum (brainstem and cervical spine)
How can intracranial pressure be checked?
checked with spinal tap (lumbar cistern) and measured by manometer
What can the spinal tap procedure be used for?
analysis for:
- subarachnoid/intracerebral hemorrhage
- bacterial meningitis = cloudy CSF (WBCs)
What is diffuse axonal injury (DAI)?
stretch of nerve fibers as result of rotational forces on the brain
What happens during DAI?
white matter of cerebrum and brainstem under shear forces causing damage to axons
What impairments happen because of DAI?
impairment of higher level functioning (decision making, executive function)
What is cerebral contusion?
swelling and capillary hemorrhage (bruise on cerebrum)
What is cerebral laceration?
actual tears in neural tissue
What is a concussion?
mTBI
- head trauma with symptoms that can last seconds to weeks
What are the symptoms of a concussion?
headache, dizziness, confusion, visual impairments
What can be the potential results of multiple concussions in one’s life?
- prolonged symptoms/increased severity
- susceptibility to adverse neurometabolic changes
- susceptibility to ALS or alzheimers
What is a coma?
profound state of unconsciousness where a person cannot be aroused
What is the cause of a coma?
compromised brainstem and thalamic reticular activating system
What other pathologies often come with a coma?
contusion, herniation, hemorrhage
What is posturing?
body pattern often seen in a coma determined by lesion’s locations in association to the red nucleus
What is decorticate posturing?
- lesion above red nucleus
- loss of UE flexor inhibition
- one tract unchecked
- UEs flexed and adducted, LEs extended
What is decerebrate posturing?
- lesion below red nucleus
- loss of extensor inhibition
- two extensor tracts unchecked
- extension of all extremities, IR of UEs, plantar flexion of feet
What is involved in a TBI examination?
- level of coma (Glasgow scale)
- loss of consciousness
- memory impairments
- cognition/judgement impairments
- emotional impairments
- motor/sensory impairments
- functional mobility independence
What are other considerations when it comes to TBI?
- previous level of functioning
- psychosocial factors (how injury took place and support system)
What are the levels of the Glasgow coma score?
mild = 13-15
moderate = 9-12
severe < 8
What is the Ranchos Los Amigos Scale of Cognitive Function?
scale that assesses cognitive functioning in individuals in coma, not a fluid scale but is hierarchical
- can track individuals progress
What is the management and rehab of a coma?
- monitor vitals
- protect skin
- monitor ICP
What is management and rehab of an acute-outpatient setting?
- interdisciplinary approach
- motor/sensory/function movements similar to CVA
- challenge is creating ideal environment for motor learning when individual has multiple impairments
