Neurologic Diseases (Exam III) Flashcards
Name the pertinent vasculature of the circle of Willis.
This card is just to look at the picture on the other side.
What factors affect cerebral blood flow?
- CMR (cerebral metabolic rate)
- CPP (cerebral perfusion pressure)
- ICP
- PaCO₂
- PaO₂
What drugs and/or metabolic states will increase CMR?
- Hyperthermia
- Seizures
- Ketamine
- N₂O
Brain tumors (most common) and 8 total types
- Astrocytomas: Astrocytes are the most common CNS glial cells
- Gliomas: Primary tumors. Least aggressive astrocytomas. Often found in young adults w/new onset seizures
- Pilocyctic astrocytomas: Children & young adults
Mostly benign, good outcomes if resectable - Anaplastic astrocytomas: Poorly differentiated
Usually evolve into Glioblastoma Multiforme - Glioblastoma Multiforme: Carry a high mortality
Usually requires surgical debulking & chemo
Life expectance is usually within weeks, even w/treatment - Meningiomas: Usually benign. Arise from dura or arachnoid tissue
Good prognosis w/surgical resection - Pituitary Adenomas: Noncancerous, varying subtypes
Transsphenoidal or open craniotomy for removal is usually curative - Acoustic Neuromas: Usually benign schwannomas involving the vestibular component of CN VIII within the auditory canal
Good prognosis w/resection +/- radiation - Metastatic Carcinomas: can vary widely in origin & symptoms
Outcomes are generally less favorable
All Grand Parents Are Giggly Motivators and Pleasing Acoustic Machines
Brain tumors Preanesthesia considerations
- Review history & physical
- Inquire about previous therapies, presenting symptoms & neurological deficits
- Radiation damage may lead to lethargy and AMS
- Chemotherapy may also have neurological effects
- Pts are often on steroids to minimize cerebral edema
- Will need to continue steroids, monitoring glucose levels
- Anticonvulsants common (supratentorial lesions, closer to motor cortex)
- Autonomic dysfunction may manifest on EKG, labile HR & BP’s
- CBC, BMP (glucose), EKG
- CT/MRI
- Pre-op steroids & antiseizure meds per surgeon
Mannitol often used to reduce intracranial volume & pressure
Name the three components of the brain that form the Monroe-Kellie Doctrine.
- Brain 80%
- Blood 12%
- CSF 8%
What is the Monroe Kellie Doctrine?
Any increase in one component of the intracranial space (blood, brain tissue, CSF) must be met with an equivalent decrease in another to prevent increased ICP.
Methods to decrease ICP
- Elevation of the head: encourages jugular venous outflow
- Hyperventilation: lowers PaC02
- CSF drainage: external ventricular drain (EVD)
- Hyperosmotic drugs: increase osmolarity, drawing fluid across BBB
- Diuretics: induce systemic hypovolemia
- Corticosteroids: decrease swelling and enhance the integrity of the BBB
- Cerebral vasoconstricting anesthetics (propofol): decrease CMR02 and CBF
- Surgical decompression
Causes of Increased ICP
- Tumors (directly b/c of size, indirectly b/c of edema, or obstructing CSF flow)
- Intracranial hematomas
- Blood in CSF
- Infections
What is the normal CPP range?
80 - 100 mmHg
What are the two types of hydrocephalus? Which is more common?
- Obstructive (most common)
- Communicating
Hydrocephalus treament
The majority of cases require surgical treatment
Ventriculoperitoneal (VP) shunt or endoscopic third ventriculostomy (ETV)
VP shunt: drain placed in ventricle of the brain and empties into peritoneum
Severe hypoxia will have what effect on cerebral blood flow?
↓O₂ = ↑CBF
PaCO₂ levels are directly proportional to ______ of the cerebral vasculature.
vasodilation
Ex. ↑PaCO₂ = ↑dilation
What does increased central venous pressure do to the brain?
- ↓ venous drainage
- ↑ cerebral blood volume
What things will increase cerebral venous pressure?
- Jugular compression (cervical collar, head rotation, etc.)
- ↑ intrathoracic pressure (coughing, PEEP)
- Vena Cava thrombus
What range is normal for ICP?
5 - 15 mmHg
What symptoms are seen with abnormally high ICP?
- Headache
- N/V
- Papilledema
- ↓LOC
What is the most common site of brain herniation?
Uncal
↑ICP forces temporal uncus into the infratentorial space (see 3 on the figure below).
Subfalcine Herniation
Herniation of hemispheric contents under the falx cerebri; typically, compressing branches of the anterior cerebral artery, creating a midline shift
Transtentorial Herniation
Herniation of the supratentorial contents past the tentorium cerebelli, causing brainstem compression in a rostral to caudal direction. This leads to AMS, defects in gaze and ocular reflexes, hemodynamic and respiratory compromise, and death
Uncal Herniation
a subtype of transtentorial herniation, where the uncus (medial portion of temporal lobe) herniates over the tentorium cerebelli. This results in ipsilateral oculomotor nerve dysfunction
Sx: pupillary dilatation, ptosis, and lateral deviation of the affected eye, brainstem compression and death
Why do the pupils become fixed and dilated with uncal herniation?
CN-3 (oculomotor) crosses near tentorium and is compressed by the herniation.
How can elevated ICP be treated?
Long list
- Elevate HOB 30°
- Hyperventilate
- Drain CSF
- Mannitol
- Diuretics
- Corticosteroids
- Surgical decompression
Hypothermia ______ CBF and CMR.
decreases
What is the Glascow Coma Scale?
see picture below
When would one see bradycardia with a spinal injury?
If the injury is at T1 - T4.
Are more strokes ischemic or hemmorrhagic?
- Ischemic (80%)
- Hemmorrhagic (20%)
Which type of stroke is more likely to cause death?
Hemmorrhagic (4x more likely)
What are specific risk factors for hemmorrhagic stroke?
- HTN
- Cigarettes
- Cocaine
- Female
Hemorrhagic Stroke Treatment
- Conservative tx is centered on the reduction of ICP, blood pressure control, seizure precautions, and vigilant monitoring
- Surgical treatment involves evacuation of the hematoma
- May remain intubated depending on cardiopulmonary stability
ICU monitoring required postoperatively
What are Causes for ischemic stroke?
- large artery atherosclerosis
- small vessel occlusion
- cardioaortic embolic (emboli from aFib)
- other etiology
- underterminded etiology
Ischemic stroke treatment and Pre-anesthetic considerations
- PO Aspirin is often the recommended initial tx for acute ischemic stroke
- IV or intra-arterial recombinant tissue plasminogen activator (TPA) is used when specific criteria is met and must be initiated within a limited time window
- Thrombectomy devices have been used to stent vessels and remove clots
- Revascularization: performed in interventional radiology (IR), allowing for angiographic assessment and radiographic guidance during administration of thrombolytics or thrombectomy
- Pre-anesthetic evaluation should be concise & efficient, avoiding any delay in treatment
- Focus on baseline neuro assessment, ability to safely lay flat, and cardiovascular function
- Determine whether procedure could be done under sedation, or if a secure airway necessary
- Patients w/ischemic stroke frequently have CV risk factors, including HTN, DM, CAD, Afib, and valvular disease, that could impact vasoactive drug choices and hemodynamic goal
Clinical presentation of Anterior Cerebral artery occlusion
Contralateral leg weakness
Clinical presentation of Middle Cerebral artery occlusion
- Contralateral hemiparesis and hemisensory deficit
- aphasia
- contralateral visual field defect
Clinical presentation of Posterior Cerebral artery occlusion
- Contralateral visual field defect
- contralateral hemiparesis
Clinical presentation of Penetrating arteries artery occlusion
- Contralateral hemiparesis
- contralateral hemisensory deficits
Clinical presentation of Basilar artery occlusion
Oculomotor deficits and/or ataxia with crossed sensory and motor deficits
Clinical presentation of Vertebral artery occlusion
Lower cranial nerve deficits and/or ataxia with crossed sensory deficits
Where is bleeding located with an epidural hematoma?
Inbetween the dura and the skull
What intracranial bleed is characterized by:
lucidity → unconscious → conscious → unconscious
Epidural hematoma
Where is bleeding in subdural hematomas located?
Between the dura mater and the arachnoid mater.
What intracranial bleed is often characterized as the “worst headache of one’s life”?
Subarachnoid hemorrhage
What location is often the site of bleeding in subarachnoid hemmorhaging?
Circle of Willis (usually aneurysmal rupture)
Cerebral _______ is one of the complications often caused by subarachnoid hemorrhage.
vasospasm
Often occurs 3rd day post bleed and peaks 5-7 days in.
Cerebrovascular disease
- High rx pts for CVA that pause LA anticoags (Warfarin) will need SA anticoags (LMWH, IV unfractionated heparin) to bridge the gap
Cerebrovascular disease anesthetic considerations
- Careful review of history, deficits, imaging, treatments, and co-existing diseases
- Assess orientation, pupils, bilateral grip strength, LE strength
- Ask about headaches, tinnitus, vision/memory loss, bathroom issues
- Look at route cause of CVA: Vascular disease, embolic (a-fib, prosthetic valve, right to left shunt/PFO)
- Imaging: Carotid U/S, CT/MRI head & neck, echocardiogram
- Preop EKG
- CBC, BMP, possible T & C
- Cerebral oximetry if possible
- Aline, 2 IVs and/or CVC
Cerebral Aneurysms
Majority aneurysms not diagnosed before rupture
Only 1/3 aneurysm pts have sx before rupture
Sx: Headache, photophobia, confusion, hemiparesis, coma
Rx: HTN, smoking, female, oral contraceptives, cocaine use
Dx: CT/angio, MRI, Lumbar puncture w/CSF analysis if rupture suspected
Intervention should be performed within 72h of rupture for best outcomes
Pt may be on steroids, glucose monitoring important
Cerebral Aneurysms anesthesia considerations
CT/MRI, EKG, Echo, CBC, BMP, T&C w/blood available
BP control, mannitol? *aim is to avoid rupture
seizure prophylaxis
Post subarachnoid hemorrhage vasospasms
- Risk for vasospasm 3-15 days post SAH
- Free hgb triggers inflammatory mediators, which reduce nitric oxide availability and increase endothelin 1, leading to vasoconstriction
Triple H therapy (Hypertension, Hypervolemia, Hemodilution) - Interventional treatments s/a balloon dilation and direct injection of vasodilators relieve the spasm
Arteriovenous Malformations (AVM)
- Arterial to venous connection w/o intervening capillaries
- Creates an area of high flow, low resistance shunting
- Believed to be congenital
Treatment and anesthesia considerations for AVM
- Tx: radiation, angio-guided embolization, surgical resection (higher mortality)
- Pre-anesthesia: H&P, review meds, imaging, CBC, BMP, T&C, EKG, Echo
BP control, mannitol?, seizure prophylaxis, CVC or 2 Lg bore IV’s, Aline
AVM grading
Based on size, eloquence, and patterns of venous drainage then compared to the pt’s neuro deficit
Chiari Malformation (4 types)
Congenital displacement of the cerebellum
Type 1: downward displacement of cerebellum
Type 2 (Arnold Chiari): downward displacement of cerebellar vermis, often assoc w/myelomeningocele
Type 3: Rare; occipital encephalocele w/downward cerebellar displacement
Type 4: cerebellar hypoplasia w/o displacement of posterior fossa contents
*Not compatible with life
Sx: headache, extending to shoulders/arms, visual disturbances, ataxia
Chiari Malformation treatment and anesthesia considerations
Tx: Surgical decompression
Pre-anesthesia: Review H&P, deficits, imaging, CBC, BMP, T&C
May hyperventilate to ↓ICP, Lg bore IV x 2 or CVC, Aline
Tuberous Sclerosis AKA_____
AKA “Bourneville Disease”
Autosomal dominant disease causing benign hemartomas, angiofibromas, and other malformations that can occur anywhere in the body
Anesthesia considerations airway compromise, heart and kidney involvement
Von Hippel-Lindau Disease
Autosomal dominant
Benign tumors of the CNS, eyes, adrenals, pancreas and kidneys
May present w/ pheochromocytoma
Anesthesia considerations: HTN with pheo
Neurofibromatosis
Autosomal dominant
3 types:
Type 1 (most common)
Type 2
Schwannomatosis (rare)
Anesthesia considerations account for increased ICP, airway issues, scoliosis, possibility of pheochromocytoma
How is cerebral vasospasm treated?
Triple “H” Therapy
- HTN
- Hypervolemia
- Hemodilution
What type of hemorrhage occurs within the brain tissue itself?
Intracerebral (intra-parenchymal) hemorrhage.
What s/s are associated with Parkinson’s disease?
- Muscle rigidity
- Pill-rolling tremor
- Bradykinesia
- Postural instability
What drugs will counteract levodopa and are contraindicated in Parkinson’s patients?
- Metoclopramide
- Haloperidol
- Droperidol
- Promethazine
What treatments are used for Multiple Sclerosis?
- Corticosteroids
- Interferon
- Azathioprine
- Methotrexate
MS signs and symptomes
- motor weakness
- sensory disorders
- visual impairment
- autonomic instability. Sx vary based on site of demyelination
MS: preanesthetic considerations
- Assess existing deficits
- If respiratory compromise, consider pulmonary function tests
- Labs: CBC, BMP, +/-LFT
- LFT if on Dantrolene & Azathioprine (bone marrow suppression, liver function impairment)
- Close attn to glucose and electrolytes as steroids may impact levels
- Consider giving pre-op steroids in anyone with long-term steroid use (adrenal suppression)
- Temperature management is critical
Any increase in body temp can precipitate an exacerbation of MS sx - GA, RA & PNB’s are acceptable options
- Avoid Succinylcholine as it may induce hyperkalemia
- Upregulated N-ach receptors
Myasthenia Gravis
- Autoimmune; Antibodies generated against N-Ach-R’s at skeletal motor endplate
- Effects skeletal muscle, not smooth or cardiac muscle
- Muscle weakness, exacerbated w/exercise
MG Treatment
- Ach-E inhibitors (Pyridostigmine),
- immunosuppressive agents,
- steroids,
- plasmapheresis,
- IVIG
MG Preanesthetic Considerations
*similar to MS
* Assess existing deficits
* If respiratory compromise, consider pulmonary function tests
* Optimize respiratory function
* Reduce paralytic dosage to avoid prolonged muscle weakness
* Caution with opioids to avoid respiratory compromise
* Ach-E inhibitors may prolong Succs and Ester LA’s
* Labs: CBC, BMP, +/-LFT (LFT if on Azathioprine)
* Close attn to glucose and electrolytes as steroids may impact levels
* 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
Eaton-Lambert Syndrome
- Disorder causing the development of autoantibodies against VG Calcium chnls
- Reduce Ca++ influx into the presynaptic Ca++ channels→↓Ach release @ the NMJ
- Sx similar to MG
- > 60% cases are assoc w/ small cell lung carcinoma
Eaton-Lambert Signs and symptomes
- rogressive limb-girdle weakness
- dysautonomia
- oculobulbar palsy
Eaton-Lambert Treatment
- Selective K+ chnl blocker “3-4 diaminopyridine”
- Ach-E inhibitors
- immunologics (Azathioprine)
- steroids
- plasmapheresis
- IVIG
Eaton-Lambert preanesthetic considerations
- Assess existing deficits
- If respiratory compromise, consider pulmonary function tests
- VERY sensitive to ND-NMB & D-NMB
- Optimize respiratory function
- Extreme caution on paralytic and opioid dosing
- Counsel on risks for needing post-op resp support until fully recovered from anesthesia
Muscular Dystrophy (and most common one)
- Hereditary disorder of muscle fiber degeneration c/b breakdown of the dystrophin-glycoprotein complex, leads to myonecrosis, fibrosis, and skeletal muscle mbrn permeability. 6 types of MD.
- most common is Duchenne’s MD
Muscular Dystrophy signs and symptomes
- progressive muscle wasting without motor/sensory abnormalities
- kyphoscoliosis
- long bone fragility
- respiratory weakness
- frequent pneumonia
- EKG changes
- Also can have elevated serum creatining kinase because of muscle wasting
MD Preanesthetic Considerations
- CBC, BMP, PFTs, consider CK
- Pre-op EKG, echocardiogram. Evaluate for cardiomyopathy
- Caution with ND-NMB’s, careful monitoring throughout
- “Hypermetabolic Syndrome” similar to MH seen with Succs & volatile anesthetics
- can lead to: rhabdomyolysis, hyperkalemia, Vfib, cardiac arrest
- Avoid Succs & VA as they exacerbate instability of muscle membrane
- Consider low dose rocuronium and TIVA for GA
- Have MH cart with Dantrolene available
- RA preferred over GA to avoid triggers and cardiopulmonary complications
Myotonic Dystrophies (4)
- Myotonia: prolonged contraction after muscle stimulation
- Myotonic Dystrophy: most common myotonia. Onset 20-30’s
Sx: muscle wasting in face, masseter, hand, pre-tibial muscles
may also affect pharyngeal, laryngeal, diaphragmatic muscles
cardiac conduction may be affected; 20% have MVP - Myotonia Congenita: Milder form, involving the skeletal muscles
smooth & cardiac muscles are spared - Central Core disease: Rare. Core muscle cells lack mitochondrial enzymes
Sx: Proximal muscle weakness & scoliosis - Myotonias are triggered by stress & cold temps
Tx: No cure. Sx managed w/Quinine, Procainamide, Steroids
Myotonic Preanesthetic considerations
- Assess the extent of cardiac and pulmonary abnormalities
- Assess breath and heart sounds for abnormalities
- GI hypomotility-↑aspiration risk
- High rx of endocrine abnormalities. Look at thyroid & glucose levels
- Keep patients warm to avoid flare-ups
- Avoid Succinylcholine b/c fasciculations trigger myotonia
- Optimize preop respiratory status
- Caution with opioids to avoid post-op respiratory depression
- Pts are increased risk for post-op resp weakness
Dementia (3 major syndromes)
Alzheimer’s (70%), Vascular dementia (25%), Parkinsons (5%)
* Assess baseline cognition
* RA preferred
* Increased risk for post-op delirium (consider TIVA)
Parkinsons Disease and triad of disease
- Degeneration of dopaminergic fibers of basal ganglia
- Unknown cause; Advanced age is biggest risk factor
- Dopamine regulates (inhibits excess stimulation) the extrapyramidal motor system, which is stimulated by Ach
* Triad: skeletal muscle tramor, rigidity, akinesia
Parkinsons preanesthetic considerations
- Assess severity, with special attn to degree of pulmonary compromise
- Review home meds, as many may interact with our drugs (ex. MAOIs)
- Review basic labs along w/PFT if respiratory sx
- May need EKG, Echo if indicated
- ↑aspiration risk (dysphagia, possible dementia)
- PO Levodopa must be continued to avoid unstable extreme extrapyramidal effects s/a chest wall rigidity
- Avoid Reglan, Phenothiazines, Butyrophenones
- Avoid Demerol if on MAOI
- Deep brain stimulators may need to be disabled to avoid interaction w/cautery
- If cautery used, bipolar recommended as it reduces scattering of electro-currant
What induction agent is a good first-line agent for treatment of acute seizures?
Propofol
What anesthetic drugs may be used to locate seizure foci due to their EEG potentiating effects?
Etomidate
Methohexital
What are the s/s of seizures whilst under anesthesia?
- ↑HR
- HTN
- ↑ ETCO₂
Seizure disorders
- Seizure: transient, paroxysmal, synchronous discharge of neurons in the brain
- Can be c/b transient abnormalities: hypoglycemia, hyponatremia, hyperthermia, intoxication
- or can be epilepsy
- anriepileptic drugs decrease neuronal excitability
Seizure disorders anesthesia considerations
- Determine source of seizures (if known) and how well they are controlled. Want anti-seizure drugs on board before incision
- Review drugs and pharmacokinetic/pharmacodynamic actions
-
Phenytoin, Tegretol, Barbiturates are enzyme-inducers
Likely require higher doses of hepatically-cleared medications
Traumatic Brain injury
Categorized: “penetrating” or “non-penetrating,” d/o breech of dura
Severity categorized by Glasco-Coma Scale
Primary or secondary injuries
TBI anesthesia considerations
- review co-morbidities
- degree of injury
- imaging
- labs
- gross neurologic exam. *Do not delay emergent surgery
- C-spine stabilization
- adequate IV access, CVC, Aline, possible uncrossmatched blood if no time for T & C
Refrain from NGT/OGT –potential for basal skull fx
Intra-op ISTAT labs, Pressors, Bicarb, Calcium, & Blood products
