Spring 2024 (Exam III) Neurological Diseases Flashcards
Cerebral Blood flow is modulated by?
Cerebral metabolic rate
CPP (MAP-ICP)
Aterial blood CO2
Aterial blood O2
Various drugs and intracranial pathologies
With autoregulation CBF is approx (blank) brain tissue per minute.
Which is _____ ml/min
this is how much of COP?
50 mL/ 100g
750 mls/ min
15%
The vault is enclosed by the?
dura mater and bone
Brain tissue, intracranial CSF and Intracranial blood have a combined volume of?
what is the normal ICP at this volume?
1200 - 1500 mls
5-15 mmHg
Monro-Kellie hypothesis:
any increase in one component of intracranial volume must be offset by a decrease in another component to prevent an elevated ICP
This diagram describes what?
monroe-kellie hypothesis
the incracranial vault is considered what?
compartmentalized
this is reflection of the dura that seperates the 2 cerebral hemispheres?
falx cerebri
a reflection of dura that lies rostral to the cerebellum and marks the border btw the supratentorial and infratentorial spaces
tentorium cerebelli
______ = Herniation of hemispheric contents under _____ ; typically, compressing branches of the anterior cerebral artery , creating a _____
Subflacine Herniation
falx cerebri
midline shift
Transtentorial Herniation is herniation of the supratentorial contents past what?
tentorium cerebelli
Transtentorial herniation causes compression in what direction?
in the rostral to caudal direction
This leads to
- AMS
- defects in gaze and ocular reflexes
- hemodynamic
- respiratory compromise
- death
Uncas is located where?
medial portion of temporal lobe
a subtype of transtentorial herniation, where the uncus herniates over the tentorium cerebelli
uncal herniation
what are the S&S of uncal herniation
Ipsilateral oculomotor nerve dysfunction
pupillary dilatation
ptosis
lateral deviation of the affected eye
brainstem compression
death
can occur due to elevated infratentorial pressure, causing the cerebellar structures to herniate through the foramen magnum
herniation of the cerebellar tonsils
S&S of cerebellar tonsils herniation
medullary dysfunction, cardiorespiratory instability and subsequently death
label the numbers
- Subfalcine → midline shift
- Transtentorial -> pushing down caudally
- Cerebellar contents through foramen magnum -> towards the medulla
- Traumatic event → cause herniation out of cranial cavity
Tumors can increase ICP in 3 ways
1) directly d/t size
2) indirectly by causing edema in surrounding brain tissue
3) by obstructing CSF flow (like with tumors involving the 3rd ventricle)
Intracranial hematomas cause increased ICP similar to mass lesions
Blood in the CSF, as is seen in subarachnoid hemorrhage, may lead to?
obstruction of CSF reabsorption, and granulations can further exacerbate increased ICP
Infections s/a meningitis or encephalitis can lead to?
edema or obstruction of CSF reabsorption
how does Hyperosmotic drugs decrease ICP?
increase osmolarity, drawing fluid across BBB
how do corticosteroids decrease ICP?
decrease swelling and enhance the integrity of the BBB
how does cerebral vasoconstricting anesthetics like propofol decrease ICP?
decrease CMRO2 and CBF
this is a progressive, autoimmune demyelination of central nerve fibers?
onset?
characterized?
multiple sclerosis (MS)
- onset is 20-40
- characterized by periods of exacerbations and remissions
Risk factors for MS
Female,
1st deg relative w/ MS,
EBV (epstein barr virus),
other AI disorders,
smoking
what triggers MS?
stress,
elevated temps,
postpartum period
S&S of MS
progressive motor weakness
sensory disorders
visual impairment
autonomic instability.
Sx vary b/o site of demyelination
is there a cure for MS?
No, managed with corticosteroids, immune modulators and targeted antibodies
For MS if respiratory compromise, consider?
Pulmonary function test
LFT’s are drawn on MS only if?
what are some considerations with steroid use?
LFT if on Dantrolene or Azathioprine (bone marrow suppression, liver function impairment)
Close attn to glucose and electrolytes as steroids may impact levels
Considerations for patients with MS on long term steroids are?
Consider giving pre-op steroids in anyone with long-term steroid use
LT steroids cause adrenal suppression, so a stress-dose of steroids may be necessary for surgery
what are some anesthetic considerations for patients with MS?
what with body temp?
avoid ?
Any increase in body temp can precipitate an exacerbation of MS sx
general and regional anesthesia and PNB’s are acceptable options
Avoid Succinylcholine as it may induce hyperkalemia
(Upregulated N-ach receptors)
Autoimmune; Antibodies generated against N-Ach-R’s at skeletal motor endplate
myasthenia Gravis (MG)
MG effects what kind of muslce?
Effects skeletal muscle, not smooth or cardiac muscle
Muscle weakness is worsened by what in MG?
S&S are exacerbated by what?
Muscle weakness, exacerbated w/exercise
Sx exacerbated by: pain, insomnia, infection, surgery
Cranial symptoms associated with MG
Ocular sx common-diplopia, ptosis
Bulbar involvement → laryngeal/pharyngeal weakness→ respiratory insufficiency, aspiration rx
This is common in 10% of MG cases
Thymic hyperplasia
(90% pts improve after thymectomy)
what is the treatment for MG?
Ach-E inhibitors (Pyridostigmine),
immunosuppressive agents
steroids,
plasmapheresis,
IVIG
Preanesthetic Considerations with MG are?
Reduce paralytic dosage to avoid prolonged muscle weakness
If respiratory compromise -> do pulmonary function tests
Optimize respiratory function
Consider pre-op steroids in anyone with long-term steroid use
Counsel patients on the increased risk of needing post-op resp support/ventilation until fully recovered from anesthesia
Why are opioids used with caution in MG?
avoid resp compromise
In MG, Ach -E inhibitors may prolong what?
Succ’s and Ester LA’s
Labs for MG include?
Labs: CBC, BMP, +/-LFT (LFT if on Azathioprine)
Close attn to glucose and electrolytes as steroids may impact levels
Disorder causing the development of autoantibodies against VG Calcium Channels
Eaton Lambert Syndrome
what is the specific MOA of the Eaton Lambert Syndrome?
Reduce Ca++ influx into the presynaptic Ca++ channels→↓Ach release @ the NMJ
S&S of Eaton Lambert Syndrome
assoc w/ ?
Sx similar to MG
Sx: progressive limb-girdle weakness, dysautonomia, oculobulbar palsy
>60% cases assoc w/ small cell lung carcinoma