CNS: blood supply and CSF Flashcards
1
Q
What is important to be in blood flow to the brain
A
- brain cannot store glucose, oxygen
- consistent blood supply essential
- cortex uses more O2 than brainstem
- cortex more vulnerable to hypoxia
2
Q
What is the blood brain barrier
A
- specialized permeability barrier - between CNS capillaries and extracellular space
- Tight junctions between capillary cells
- exclude large molecules
- protects brain from potentially harmful organic substances
- this can be a problem with medicaiton
3
Q
Describe the blood brain barrier and its relation to parkinsons
A
- Dopamine is unable to cross the BBB
- use L dopa that can cross which is a metabolic precursor
4
Q
Venous system of the brain
A
- Cerebral veins drain into dural sinuses => internal jugular vein
- Superficial veins drain the cortex and adjacent white matter then empty into superior sagittal sinus
- deep cerebral veins drain the basal ganglia, diencephalon, and nearby white matter, then empty into the straight sinus.
5
Q
Cerebrospinal Fluid System
function
A
- Regulates extracellular environment
- supplies water, amino acids, ions to extracellular fluid
- removes metabolic waste from CNS
- protects CNS (buoyancy => shock absorption
6
Q
Ventricular system within the brain
what are they?
A
- CSF filled spaces in the brain
- Lateral Ventricles-paired-one in each cerebral hemisphere
- 3rd ventricle-narrow slit in midline of diencephalon-walls are thalamus and hypothalamus
- 4th ventricle-posterior to pons and medulla, but anterior to cerebellum. Continuous with central canal of spinal cord
7
Q
How do the ventricles form?
A
- neutral tube forms when neural folds grow toward each other
- groove zips closed rostrally and caudally leaving open ends (neuropore)
- Day 28 neural tube expands (embryonic stage of development) to form 3 enlargements - ventricles
8
Q
What is the Choroid plexus
A
- Membranous material in the ventricles that secretes CSF
- network of capillaries embedded in contnective tissue and epithelial cells
9
Q
What are the types of choroid plexus
A
- 2 large plexuses: floors of lateral ventricles
- smaller plexuses: roofs of 3rd and 4th ventricles
10
Q
Flow of CSF
A
- cerebrospinal fluid is secreted into the ventricles and flows throughout the subarchnoid space where it cushions the CNS
- the choroid plexus transports ions and nutrients form the blood into the CSF
- From the lateral ventricles, third and fourth ventricle, into subarachnoid space surrounding brain and spinal cord. CSF then reabsorbed into the venous sinuses.
11
Q
CSF absorption
A
- Midline structures near top of skull.
- Meninges=dura mater, arachnoid, pia mater-cover brain and spinal cord
- Arachnoid villi/granulations allow CSF to flow into the sinuses
- Subarachnoid space filled with CSF
12
Q
Examples of CSF disorders
A
- hydrocephalus
- chiari malformation
- meningitis
- hematome
- brain herniation
- CSF leak
- Spina Bifida
13
Q
What is Hydrocephalus
A
- CSF circulation blocked = pressure builds up in ventricles
- infants: ventricles, hemispheres and cranium expand
- adults: cranium cannot expand and therefore compression of White matter occurs
14
Q
What are some signs of hydrocephalus in adults
A
- Gait dysfunction: wide base, shuffling, difficulty starting/stopping
- balance
- headache
- incontience
- frontal lobe dysfunction
- cognitive changes
Wobbly: trouble with balance
Wet: incontience
Wacky: cognitive
15
Q
What are some signs of hydrocephalus in infants
A
- enlarged head
- enlarged anterior fontanel
- difficulty feeding
- downward looking eyes- sunsetting sign
- inactivity/regression in function
16
Q
Causes of
hydrocephalus
A
- commonly caused by
- failure of the fourth ventricle foramina to open (communicating hydrocephalus),
- blockage of the cerebral aqueduct (noncommunicating hydrocephalus),
- cysts in the fourth ventricle (Dandy-Walker cysts), and Arnold-Chiari malformation
17
Q
Treatment of hydrocephalus
A
- Surgical implantation of shunt
- children or adults
- ventricle to peritoneal cavity
- contains valve: prevents reverse flow
Can do a lumbar puncture to see if symtpoms improve with removal of soem CSF - PT may do a TUG before and after this
18
Q
VP shunt placement Procedure
A
- while patient is under general anesthesia an incision is made behind ear
- another smalle surgical cut is made in patients abdomen
- a small hole is drilled into skull
- through this opening a catheter is passed into a ventricle
- a 2nd catheter is placed under the skin behind ear and guided distall usually into abdominal cavity
- surgeon may make a small cut in neck to help position the catheter
19
Q
What are the signs of a VP shunt failure
A
- headache
- irritability
- nausea and vomiting
- changes in arousal and personality (flat affect)
- loss of motor function
- visual changes
- these symptoms can appear quickly and require immediate medical attention
20
Q
Arnold-Chiari Malformation
A
- Downard displacement of cerebellar tonsils through foramen magnum
- the resulting pressure on cerebellum can block flow of CSF causing a range of symptoms including cerebellar and brainstem signs
21
Q
Types of Arnold-Chiari Malformation
A
- Arnold-Chiari type I is not associated with defects of the lower neural tube and consists of herniation of the cerebellar tonsils through the foramen magnum into the vertebral canal
- Type II consists of malformation of the brainstem and cerebellum, leading to extension of the medulla and cerebellum through the foramen magnum.
22
Q
Arnold-Chiari Malformation Symptoms
A
- Suboccipital headache: initiated/exacerbated by coughing, straining or sneezing
- loss of pain and temperature sensation on shoulders and lateral upper limbs if upper central spinal cord is abdnormal
- uncoordinated movements, paresis
- impaired fine motor control
- unsteady gait
- temporary visual distrubances
- dizziness and vertigo due to brainstem and cranial nerve compression
- deafness, tongue, fascial muscle and laterla eye movement weakness
- difficulty swallowing
23
Q
Arnold-Chiari Malformation Treatment
A
- surgery: Posterior fossa decompression
- craniectomy (removal of bone in skull) widens the foramen magnum
- dura overlying the tonsils is opened and a dural path is sewn on to expand the space
24
Q
Meningitis
A
- Inflammation of membranes that surround the brain and spinal cord
- bacterial: Contagious via respiratory and throat secretions; can be life threatening- requires immediate medical attention and antibiotics
- Viral: Spread via respiratory and throat secretions as well as through enteroviruses; doesn’t respond to antibiotics but usually not as serious as bacterial meningitis (in healthy adults).
*can get the virus that causes this without meningitis
25
Q
A
26
Q
Symptoms of meningitis
A
- Headache
- fever
- confusion
- vomiting
- neck stiffness
- pain that may intensify with head movement sneezing or coughing
- photophobia
27
Q
Epidural Hematoma
A
- Results from arterial bleeding between the dura mater and skull,
- Usually occurs when middle meningeal artery is torn by a fracture of the temporal or parietal bone
- function may be normal at first
28
Q
Epidural Hematoma
symptoms
A
- develop rapidly due to fast arterial bleeding
- Headache, vomiting, decreased consciousness, hemiparesis, Babinski’ sign
usually after trauma
29
Q
Subdural hematoma
A
- Between dura and arachnoid
- produced by venous bleeding
- symptoms are more gradual
30
Q
Symptoms of subdural hematoma
A
- similar to epidural hematoma with congitive issues being more prominent
- Headache, vomiting, decreased consciousness, hemiparesis, Babinski’ sign
31
Q
Subarachnoid hemorrhage
A
- Occurs in CFS-filled space between arachnoid and pia which contains the major blood vessels of the brain
32
Q
Types of subarachnoid hemorrhage
A
- Non-traumatic (spontaneous): aneurysm or AVM (tangles of arteries and veins)
- Traumatic (more common)
33
Q
Symptoms of subarachnoid hemorrhage
A
- wide range
- headache
- meningeal iritation (nuchal rigidity and photophobia)
- CN and other neuro deficits
- decrease consciousness, coma, and death
34
Q
Subarachnoid hemorrhage
prognosis
A
- mild impairments to death
- mortatlitiy rate is 50%
worst headahce of my life, may result in secondary hydrocephalus
35
Q
Intracerebral/intraparnchyma hemorhage
A
- occurs within the brain parenchyma in cerebral hemispheres, brainstem, cerebellum or Spinal cord
- many causes, both traumatic and non-traumatic
- tumors, blood coagulation abnormalities, vessel abnormalities
36
Q
Symptoms of intracerebrral/intraparenchymal hemorrhage (ICH)
A
- depends on which strucutre damaged and to what extent
37
Q
Increase in intracranial pressure
causes
A
- cerebral edema
- hydrocephalus
- tumors
- space-occupying lesions
38
Q
intracranial pressure symptoms
A
- vomiting and nausea
- headahce
- drowsiness
- frontal lobe gait
- ataxia and visual and eye movement problems
39
Q
Brain Herniation types
A
- Cingulate herniation
- Uncal herniation
- Central herniation
- Tonsillar herniation
Herniation = protrusion of part of the brain
40
Q
Cingulate Hernation
A
- A mass in one hemisphere displaces the cingulate cortex
- Cingulate cotex: plays a role in limbic system
- may cause ACA compression leading to contralateral LE weakness
41
Q
Uncal herniation
A
- Space-occupying lesion in the temporal lobe displaces the uncus medially
- compresses the midbrain, intefering with the function of the oculomotor nerve and consciousness
- consciousness (effects asending eticular activiting system)
Uncal = parahippocampus gyus
42
Q
Central Herniation
A
- a space-occupying lesion in the cerebrum exerts pressure on the diencephalon, moving the diencephalon, midbrain, and pons inferiorly
- branches of the basilar artery are stretched
- results in brain ischemia/edema
- possible bilateral paraylsis, impaired consciousness and oculomotor control
43
Q
Tonsillar herniation
A
- Pressure from an uncal herniation, tumor in the brainstem or cerebellum hemorrhage of edema may force the cerebellar tonsils through the foramen magnum
- brainstem compression interfering with vital signs, consciousness and flow of CSF
44
Q
CSF leak symptoms
A
- headche esp. back of head
- headache is moe severe when patient is upright/disappears when patient is lying flat
- neck discomfort
- light sensitivity
- nausea
45
Q
CSF leak
how do they typically occur
A
- most cases are noted after spinal surgery, lumbar puncture, myelograms, or trauma to head or neck
- in some cases, there are spontaneous leaks/ruptures in dura
46
Q
Treament of CSF leak
A
- Bed rest
- increased fluid intake
- caffeine
- epidural blood patch: a syringe of patient’s own blood is injected into spine
- either at exact site of leak or at a safe location in lumbar spine
- may need to be repeated several times
47
Q
Spina bifida
A
- neural tube defect
- during the first month of pregnancy, the spinal canal does not form completely resulting in a defect in which the spinal cord and meninges protrude
- inferior neuropore does not close
48
Q
Spina bifida occulta
A
- one or more vertebrae are malformed
- occulta means hidden and indicates that a layer of skin covers the malformation or opening in the spine
- this type of spina difida rarely causes disability or symptoms
49
Q
Meningocele
A
- meninges covering the spinal cord stick out of the spinal canal
- but the spinal cord remains in place within the spinal canal
- may be asymptomatic or have impaired spinal cord function
50
Q
Myelomeningocele
what is it and symptoms
A
- most common types
- spinal cord and meninges prrotrude through the defect in the spinal canal
- causes lower limb paralysis and sensory loss, bladder and bowel dysfucntion
- intellectual disbaility if hydrocephalus also present
