Applied Physiology: Lecture 3 - Neuro Cont'd (Disease)

Question 1

What is Myasthenia Gravis?

Answer 1

Chronic autoimmune disorder.

Occurs at a rate of 1:7500.

Question 2

What demographic is most affected by Myasthenia Gravis?

Answer 2

Women aged 20-30 years; men over 60 years.

Question 3

What causes Myasthenia Gravis?

Answer 3

Decrease in functional AcH receptors at NMJ due to circulating antibodies. (either by destruction or inactivation). Unknown origin of antibodies. However, thymus glad implicated

Question 4

What is the implication of the thymus gland in Myasthenia Gravis?

Answer 4

Thymus gland is implicated in the unknown origin of antibodies.

Question 5

What percentage of AcH receptors can be lost in Myasthenia Gravis?

Answer 5

Up to 70-80 percent.

Present as very weak, and unhealthy. Typically no muscle mass.

Question 6

Which muscles are most vulnerable in Myasthenia Gravis?

Answer 6

Muscles innervated by cranial nerves. Facial muscles you will see it

Question 7

Classic initial signs and symptoms of Myasthenia Gravis?

Answer 7

1. Ocular Symptoms (most common initial presentation):
   Ptosis (drooping of one or both eyelids)

Diplopia (double vision), due to weakness of extraocular muscles

2. Bulbar Symptoms:
   Dysarthria (slurred or nasal speech)

Dysphagia (difficulty swallowing, especially with liquids)

Fatigable chewing (jaw tires during meals)

3. Limb and Neck Weakness:
   Proximal muscle weakness, especially in the arms and legs

Neck muscle weakness, causing “head drop”

4. Respiratory Muscle Weakness (less common early, but can be life-threatening):
   May present as dyspnea or fatigue with breathing

.

Key Feature:
Fluctuating weakness that gets worse with exertion and improves with rest is a hallmark

Question 8

How is Myasthenia Gravis classified?

Answer 8

Depends on skeletal muscles involved and symptom severity.

Question 9

What characterizes Type 1 Myasthenia Gravis?

Answer 9

Involves extraocular muscles only (10%).

Question 10

What is Type 2A Myasthenia Gravis?

Answer 10

Slowly progressive, mild form, respiratory muscle sparing. Good response to ACH esterase and steroid therapy

Question 11

What distinguishes Type 2B Myasthenia Gravis?

Answer 11

More rapid than 2A, less response to pharmaceuticals, respiratory muscles may be involved.

Question 12

What is Type 3 Myasthenia Gravis?

Answer 12

Acute onset, rapid deterioration, skeletal muscle strength loss within 6 months.

Question 13

What characterizes Type 4 Myasthenia Gravis?

Answer 13

Severe, progresses from Type 1 or 2.

Question 14

Differential Diagnosis of Myasthenia Gravis

Answer 14

Look at Stoetlings 7th or 8th Edition (this chart is older)

Question 15

What is the primary treatment for Myasthenia Gravis?

Answer 15

Thymectomy (surgical treatment).

Question 16

What is the main anticholinesterase therapy used for Myasthenia Gravis?

Answer 16

Pyridostigmine.

Anticholinesterase: decreases the enzyme responsible for breaking down ACH. Yields larger concentration of ACH

Immunosuppressive therapy iesteroids, plasmapheresis (short term help)

Question 17

What is the onset and duration time for oral Pyridostigmine?

Answer 17

30 minutes.
Peaks in 2 hours
DOA 3-6 hours
Less SE profile and Lasts longer than Neostigmine

Less than 120 mg PO, q 3 hours

Higher total dose, approaching 600-700 mg may indicate post op mechanical ventilation

Larger doses can induce cholinergic crisis

Question 18

What is a Cholinergic Crisis?

Answer 18

Overabundance of AcH.

High dose of Pyridostigmine can cause it

Stimulation of nicotinig and muscarinic AcH receptors leading to muscle weakness and respiratory distress:
B – Bradycardia or Bronchorrhea (copious secretions)
L – Lacrimation
U – Urination
D – Diarrhea
S – Salivation

Question 19

What occurs during a Cholinergic Crisis?

Answer 19

Stimulation of nicotinic and muscarinic AcH receptors.

Question 20

What can cause a Cholinergic Crisis?

Answer 20

Organophosphate poisoning.

Question 21

What is a Myasthenic Crisis?

Answer 21

Severe life-threatening complication of myasthenia gravis. Worsening muscle weakness, effecting muscles of respiration. May require intubation and mechanical ventilation.

Triggered by stress, surgery, infection.

Treatment: IVIG, plasmapheresis.

Question 22

Cholinergic Crisis vs Myasthenic Crisis

Answer 22

Myasthenic Crisis
Severe life threatening complication of myasthenia gravis. Worsening muscle weakness, effecting muscles of respiration. May require intubation and mechanical ventilation.

Triggered by stress, surgery, infection.

Treatment: IVIG, plasmapheresis.

Cholinergic crisis
Overabundance of AcH.

Stimulation of nicotinic and muscarinic AcHreceptors.

Organophosphate poisoning.

Leads to muscle weakness, respiratory distress, BLUDS

Question 23

Cholinergic Crisis vs Myasthenic crisis (Differentiation)

Answer 23

Both can occur in a patient with Myasthenia Gravis.

Myasthenic crisis: Not enough AcH

Cholinergic crisis: too much AcH

How do we differentiate the 2?

Edrophonium test:
Edrophonium is an AcHesterase inhibitor

2mg Edrophonium: If symptoms get better then its Myasthenic crisis. If symptoms get worse: Cholinergic crisis.

Question 24

What is the Edrophonium test used for?

Answer 24

To distinguish between Myasthenic crisis and Cholinergic crisis.

Question 25

Anesthetic Considerations when taking Pyridostigmine and MG

Answer 25

May need post op vent support (talk about it in preop) Dose of pyridostigmine daily? Surgery type? Severity of Dz, concomitant COPD, OSA? Increases sensitivity to NDMRs, increased resistance to Succ... so would need more Sux and less Roc Sugamaddex may be the best choice. Or if you can avoid any NMJ blockade, that would be ideal.

Question 26

Myasthenia Gravis and Atracurium

Answer 26

Dose response curve to Atracurium Left shift from normal Sensitive to NDMR

Question 27

What is Myasthenic Syndrome also known as?

Answer 27

Lambert Eaton Syndrome.

Question 28

What antibodies are involved in Myasthenic Syndrome?

Answer 28

Immunoglobulin G antibodies to Ca channels. Acquired autoimmune disease

Question 29

Myasthenic Syndrome

Answer 29

Skeletal muscle cell depolarizes, but no Calcium enters the cell. No muscle contraction ACHesteraseinhibitors are not effective in Myasthenic syndrome Sensitive to NDMRS and Succ Polyneuropathy that develops in elderly patients should always arouse suspicion of undiagnosed cancer. Myasthenic (Eaton-Lambert) syndrome may be observed in patients with carcinoma of the lung.

Question 30

Myasthenic Syndrome vs MG

Answer 30

Question 31

What is Myotonic Dystrophy?

Answer 31

Hereditary condition without NMJ involvement, instead a repetitive prolonged discharges of repetitive muscle action potentials. Stems from abnormal Calcium metabolism GA, Regional, NDMB not helpful in relieving contractures.

Question 32

What is the characteristic of Myotonia Congenita?

Answer 32

A type of myotonic dystrophy.

Question 33

Anesthetic considerations with Myotonic Dystrophy?

Answer 33

Avoid Succ: Prolongs skeletal muscle contraction. NDMR okay. No increased/decreased sensitivity or resistance What about reversal - use sugammadex, avoid neostigmine because it increased AcH at NMJ and this may exacerbate mytononia and worsen muscle stiffness Watch for hypersomnolence effect of narcotics and benzos. (central respiratory depressive effects + weak respiratory muscles) Assess for cardiomyopathy, respiratory muscle weakness. How do your anesthetics make cardiomyopathy worse? (See Below) Normothermia, avoid shivering

Question 34

What is Schwartz-Jampel Syndrome?

Answer 34

A type of myotonic dystrophy.

Question 35

What anesthetic should be avoided in myotonic dystrophy?

Answer 35

Succinycholine.

Question 36

What are Non-depolarizing muscle relaxants (NDMR) in myotonic dystrophy?

Answer 36

Okay to use; no increased/decreased sensitivity or resistance.

Question 37

What should be monitored in anesthetic considerations for myotonic dystrophy?

Answer 37

Hypersomnolence effect from narcotics and benzodiazepines.

Question 38

What is Muscular Dystrophy?

Answer 38

Painless degeneration and atrophy of skeletal muscles; progressive and linear. Skeletal muscle weakness but muscles remain innervated. Reflexes and sensation remain in tact

Question 39

What is Duchenne's Muscular Dystrophy? (pseudo hypertrophic)

Answer 39

Most severe, childhood progressive type; X-linked recessive. 3:10,000 births, X linked recessive. Can be seen in 2-5 YO males Most severe, childhood progressive type

Question 40

What are the initial symptoms of Duchenne's Muscular Dystrophy?

Answer 40

Waddling gait, frequent falling, difficulty climbing stairs (pelvic muscle weakness) Affected muscles fill with fat. Appear large (pseudo hypertropic)

Question 41

What is the typical age for patients to become wheelchair-bound in Duchenne's Muscular Dystrophy?

Answer 41

By age 8-10 years. Long bone fractures, mental retardation often accompanies

Question 42

What is the serum Creatine Kinase level in Duchenne's Muscular Dystrophy?

Answer 42

Elevated 20-100x normal.

Question 43

What is the typical age of death in Duchenne's Muscular Dystrophy?

Answer 43

By age 15-25 years.

Question 44

What anesthetic considerations are there for Duchenne's Muscular Dystrophy?

Answer 44

Cardiopulmonary involvement and may require post-op intubation. Delayed gastric emptying Weak laryngeal reflexes (aspiration) No Succ (undiagnosed kids always a concern). Because muscle membranes are unstable and it depolarizes muscle membranes it can result in massive efflux of potassium resulting in hyperkalemia and possible MH like reactions (but not true MH) Roc (extreme caution) No volatile agents - can cause the MH like reactions as well

Question 45

What is Guillan Barre?

Answer 45

Acute Idiopathic Polyneuritis; an Autoimmune disorder mistakes healthy neurons for bacteria or virus.. Mostly age >50yo

Question 46

What are common causes of Guillan Barre?

Answer 46

Includes Campylobacter, Influenza, HIV, Syphilis, Zika, Epstein Barr, Hepatitis A, B, C, E.

Question 47

What is the initial pattern of weakness in Guillan Barre?

Answer 47

Acute onset weakness begins in lower limbs and spreads cephalad. Since the invention of the polio vaccine, GB has become the most common cause of acute paralysis 1-2:100,000

Question 48

What type of paralysis occurs in Guillan Barre?

Answer 48

Flaccid paralysis with loss of reflexes (lower motor neuron involvement) Autonomic nervous system involvement as the spread moves cephalad.

Question 49

What is the treatment for Guillan Barre?

Answer 49

No Cure Supportive treatment including plasmapheresis and IVIg therapy.

Question 50

GB Anesthetic Considerations

Answer 50

Do they have ANS involvement? Thorough preop eval! Yes, they do, BP can fly around based on sitting up or laying down, etc. Limited to Lower Motor neuron Dz? Yes Avoid Succ(increased risk of hyperKdue to denervated muscles) Roc okay, may need lower dose (from my experience) Post op intubation? Assess your patient preop. Will probably come with a tracheostomy (always look for a cuff)

Question 51

What is Multiple Sclerosis?

Answer 51

Demyelination disease in the axonal CNS with demyelinated plaques.

Question 52

Are genetics implicated in Multiple Sclerosis?

Answer 52

Yes, but no clear genetic correlation. No clear understanding on which nerves and why will be affected. 2X women than men

Question 53

What are the types of Multiple Sclerosis?

Answer 53

* Relapsing remitting * Chronic progressive (usually after 35 yos) Clinical manifestations depend on which CNS nerves are affected. How does remission occur? Yes, but its an ebbs and flows deal... partially Happens due to: Reduction in inflammation Compensatory neural mechanisms Some degree of remyelination Do the nerves re-myelinate? Yes, but partially (factor of remission) Treatment: Interferon B

Question 54

What anesthetic considerations are there for Multiple Sclerosis?

Answer 54

GA okay; avoid spinal (could be toxic with no myelin sheath); epidural probably okay; regional okay. Avoid factors that cause exacerbation Temperature increase Fever Infection Prolonged response to NDMRs (Roc) has been observed (decreased muscle mass) Exaggerated response to Succ leading to hyperkalemia is possible If patient on corticosteroid therapy, may need to stress dose Post op evaluation

Question 55

What is CIDP? (WONT TEST ON THIS)

Answer 55

Autoimmune disorder targeting myelin sheath on PERIPHERAL nerves. Progressive weakness, sensory and motor loss. Usually progresses from extremities and moves proximal Closely related to GBS Considered to be the long term form of GBS Treatment is similar to that of GBS

Question 56

What anesthetic considerations exist for CIDP? (WONT TEST ON THIS)

Answer 56

Avoid or limit muscle relaxants. Effects can be prolonged Avoid Sux. Demyelinating lesion! Regional is okay Reversal with Sugamadexis a good choice. If a patient is on steroids, might need a stress dose. Consult with attending and surgeon. This is a pretty rare disorder, the data isn’t out there. But we use or logic and common sense from understanding the pathogenesis and pathophysiology of the disease.

Question 57

What is Parkinson's Disease?

Answer 57

Neurodegenerative disorder with loss of dopaminergic fibers. Loss of Dopaminergic fibers in basal ganglia, results in depletion of dopamine Results in unopposed AcH stimulation in this system

Question 58

What is the single largest risk factor for Parkinson's Disease?

Answer 58

Increasing age.

Question 59

What are symptoms of Parkinson's Disease?

Answer 59

Skeletal muscle tremor, akinesia, rigidity, dementia, and depression. Dementia and depression often concomitant

Question 60

What is the treatment for Parkinson's Disease?

Answer 60

Dopamine precursor is the treatment: Carbidopa/Levodopa. Increases concentration of dopamine in CNS. Carbidopa prevents break down of levodopa before it reaches CNS. DBS is the surgical approach. Proper way to do this anesthetic? 2 ways? Carbidopa class? Levodopa SE?

Question 61

Anesthetic considerations for Parkinson's?

Answer 61

Must continue their Parkinson's medication regimen. Long case…how can you administer Carbidopa/Levodopa to the patient? Might need to administer via the NG/OG tube since it is oral Avoid Droperidol. (Recent pulled off shelves at HCA), Haloperidol. Dopamine antagonist. Your choice of anesthetic DBS anesthetic?

Question 62

What is Deep Brain Stimulation (DBS)?

Answer 62

A surgical approach for treating Parkinson's Disease.

Question 63

What anesthetic options should be avoided in Parkinson's patients?

Answer 63

Droperidol and Haloperidol.

Question 64

What is Ankylosing Spondylitis?

Answer 64

Chronic progressive inflammatory disease involving articulations of spine joints Begins at SI joint and moves toward cranium.

Question 65

What are the symptoms of Ankylosing Spondylitis?

Answer 65

Loss of lordosis and exaggerated kyphosis.

Question 66

What is the treatment for Ankylosing Spondylitis?

Answer 66

NSAIDs such as indomethacin, diclofenac, and Infliximab.

Question 67

AS anesthetic Considerations

Answer 67

Difficult intubation. Plan ahead. Thorough preop airway exam Awake fiberoptic? CMAC? Airway in…What about positioning? Can they lay flat? Restrictive lung pattern from costochondral rigidity

Question 68

What is Complex Regional Pain Syndrome (CRPS)?

Answer 68

Usually occurs after an injury or surgery, most commonly a limb. But can also occur with no obvious injury Burning, stinging, tearing type of pain. Inconsistent location of pain is also seen.

Question 69

What is the etiology of CRPS?

Answer 69

Unknown; may involve overactivation of inflammatory cascade, dysregulation of pain mediating neuropeptides, CNS sensitization, SNS dysregulation, possible genetic role.

Question 70

What are anesthetic considerations for CRPS?

Answer 70

Have to do good Pre-Op evaluation as they are typically on extremely high pain meds. 200-300 mgs of Ketamine... have to plan with pharamacy Must have a plan in place for surgery on the affected limb.

Question 71

CRPS anesthetic considerations

Answer 71

Is the surgery on the affected limb? IE is CRPS located in the ankle and are you doing an ankle surgery on the same side? Must have a plan in place. These patients may be followed by a pain clinic/doctor. Look at what they are taking. And Don’t underestimate hyperalgesia in this patient population. Thorough preop evaluation. Multimodal approach, including NSAIDS, pregabalin, NMDA, Alpha 2 agonism, opiods, regional. Set expectations and make PACU aware of this patient..

Question 72

What is Diabetic Neuropathy?

Answer 72

Condition from long-standing uncontrolled diabetes causing neuronal ischemia. Microvascular damage leading to neuronal ischemia, glycosylated neurons, denervation, reduced nerve conduction velocity.

Question 73

What are the symptoms of Diabetic Neuropathy?

Answer 73

Sensory loss in distal extremities, commonly the feet. Tingling and numbness very common. ANS dysfunction: Gastroparesis, resting tachycardia, urinary retention, impotence. More prone to positioning injury due to already compromised nerves.

Question 74

What is the Sorbitol-Aldose Reductase Pathway?

Answer 74

Pathway where aldose reductase reduces glucose to sorbitol. High glucose levels in the blood leads glucose into this pathway vs the insulin pathway. Sorbitol Dehydrogenase oxidizes sorbitol to fructose. High glucose levels over activate this pathway leading to excess sorbitol levels in the cells, leading movement of water into cell (osmosis) which leads to cell swelling. Build up in retinal tissues, renal tissues, lead to diabetic nephropathy and diabetic retinopathy.

Question 75

What are the consequences of high glucose levels?

Answer 75

Leads to diabetic nephropathy and diabetic retinopathy.

Question 76

What are aldose reductase inhibitors?

Answer 76

Medications such as Epalrestat, Sorbinil, Tolrestat, and Ponalrestat.

Question 77

Anesthetic considerations Diabetes

Answer 77

Thorough Preop Eval Assess kidney function, NPO status, degree of lability of blood glucose levels Assess current glucose level, last insulin dose. If having surgery on the diabetic extremity, assess neuro status. Most patients despite not feeling much will tell you they feel everything. Pick which anesthetic suits the patient best. Safest most effective option. Understand how your medicines work in renal disease if that is appreciated. Ensure adequate perfusion. Increase MAPS. Diabetes is a very very deep rabbit hole. We will stop here for now.

Question 78

What should be assessed during preoperative evaluation for diabetic patients?

Answer 78

Kidney function, NPO status, blood glucose levels.

Question 79

What are positioning considerations for diabetic patients?

Answer 79

More prone to positioning injury.

Question 80

What can diabetic patients expect during surgery?

Answer 80

Most report they feel everything despite not feeling much.

Question 81

What is the anesthetic choice for diabetic patients?

Answer 81

Choose the anesthetic that suits the patient best.