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Where are the lower motor neuron injuries located?
- Bulbar: bulbar palsies
- Anterior Horn Cell: poliomyelitis, motor system disease, polyneuritis
- Primary muscle: muscular dystrophies, myasthenia gravis, polymyositis
- Myoneural junction: myasthenia gravis
Where are the upper motor neuron injuries located?
- Motor cortex: birth injuries, neoplasms, trauma, inflammations
- Internal capsule: vascular lesions (CVA, thrombosis, hemorrhage), neoplasms, trauma, inflammations
- Brain stem: Demyelinating disease (MS), vascular lesions, neoplasms, trauma, inflammations, degenerative diseases (parkinsons)
- Spinal cord: Demyelinating diseases, neoplasms, trauma, inflammations
Describe hypo and hyper tonia
- Hypotonia: decreased muscle tone. Flaccid
- Hypertonia: increased muscle tone. Spastic
Describe hypo and hyper kinesia
- Hypokinesia: decreased movement
- Hyperkinesia: excessive movement
What is paresis vs paralysis?
- Paresis: weakness
- Paralysis: Difference in degree (paresis is weakness) and paralysis is to a greater degree.
Describe what an upper motor neuron injury is and what you would see.
- Upper=high problem between brain and spinal cord
- Example is Cerebral palsy
- Causes spastic paralysis because it’s a high level injury, brain injury
- There is a lack of inhibitory input and the result is spastic paralysis.
Describe what a lower motor neuron injury is and what you would see
- Injury between cord and muscle
- Think of it like flaccid muscle
- Cord to muscle problem because the sensation to muscle is damaged, muscle doesn’t move.
- Flaccid paralysis.
An injury below L1 is upper or lower motor neuron injury?
Anytime there is injury to cord below L1-that has to be a lower motor neuron injury.
Are bulbar palsies upper or lower motor neuron injuries?
Lower. They are the exception to the below the synapse rule. Even though it is in the brain stem it is a lower motor neuron injury
Lower motor neuron syndromes occur after the synapse at anterior horn of the spinal cord or in what other area?
in the extrapyramidal tract (at any part of that tract).
The bulb of the brain is called the ___________
If damage to this bulb it usually involves damage to......... (think bulbar palsies)
Cranial nerves and pt is said to have a bulbar palsy. And bulbar palsies are injuries to CN 9, 10, or 12
If our patient has bulbar palsy, what areas of the body is involved and what is our concern?
- If damage to this area of the brain it will effect CN 9,10, and 12.
- Develops paresis or paralysis of jaw, face, pharynx or tongue.
- If damage to this area of brain, as CRNA, our concern is weakened or paralyzed pharynx, can they manage their secretions, and area they an aspiration risk?
Myasthenia gravis and muscular dystrophy are upper or lower motor neuron injuries?
- Lower motor neuron injuries
- Expect flaccid paralysis
Say pt has positioning area, if pt’s cubical tunnel is pressed closely against their sides, and they have ulnar nerve entrapment. Is this an upper or lower motor neuron injury?
That would be a peripheral nerve and a lower motor neuron injury
There’s two types of motor dysfunction that make up extrapyramidal motor syndromes. What are they?
- Basal ganglia (part of the brain stem)
Unlike the pyramidal motor syndromes, this type of injury (extrapyramidal motor syndromes) causes ____________________.
disturbance of movement without paralysis.
Pyramidal motor syndromes will involve________________
paralysis (corticospinal tract is main motor tract so main result is paralysis)
Basal ganglia motor syndromes involve what two neurotransmitters? Is it extrapyramidal or pyramidal?
- Imbalance of Dopamine and Acetylcholine.
- Problem in basal ganglia, there is imbalance between these two NT.
If you have excessive Dopamine will you have hyper or hypo kinesia?
- Excess of Dopamine: hyperkinesia.
- If you have a relative increase of Ach, inhibitory, so it causes hypokinesia or akinesia (too little movement).
Besides the basal ganglia, what other extrapyramidal motor syndrome type is there and what are the clinical manifestations?
- Cerebellar motor syndromes.
- If pt has problems in the cerebellum they develop difficulty w/coordinating voluntary movement and disorders of gait.
But you wouldn’t expect these extrapyramidal problems to cause paralysis. What kind of problem would you expect? (Think basal ganglia and cerebellar problems)
They will cause disorders of movement w/out paralysis
For all neuro diseases, as the CRNA, what is the main concern???
- whether or not there is respiratory weakness.
- Does this pt need post-op resp support?
- Biggest problem is resp insufficiency.
- Pt is weak and this a problem.
- Resp insufficiency can take many forms.
What are the types of respiratory insufficiency?
- Progressive: ALS, weaker and weaker.
- Reversible: Guillian barre, get weak but it reverses
- Some are reversible with treatment: myasthenia gravis, they take a drug (pyridostigmine) and they get better.
- Reversible resp insufficiency Relapsing: pt w/MS. After surgery they get sicker/weaker and then they get better.
Clinical s/s of dysautonomia
labile BP, orthostatic hypotension, high resting HR.
If someone has dysautonomia and they have low BP, what would you give?
- give a direct acting drug.
- They have altered amount of NT in presynaptic vesicle. So we need to give a direct acting drug (phenylephrine) because they can have an erratic response to an indirect acting drug. (like ephedrine).
What are our concerns w/a patient who has dysautonomia?
- Can also have cardiac conduction abnormalities.
- Be very careful w/induction drugs-can have very labile induction pressures.
- Tend to have decreases myocardial contractility.
- Any pt that has dysfunction of autonomic NS, worried about BP stability and induction drugs and anesthetic drugs
What is the pathophysiology of Parkinsons?
- Not enough Dopamine.
- Disorder of basal ganglia.
- Not expecting paralysis because it’s extrapyramidal (basal ganglia) so have disordered movement.
- So relative to that decrease in Dopamine is relatively too much Ach.
What are the clinical manifestations of Parkinsons?
- Akinesia and tremor.
- There is associated ANS dysfunction.
What types of medications will a patient w/Parkinson's be on?
- This patient will be taking Levodopa.
- Anticholinergic drugs to try and take Ach down. (Artane or Cogentin are the brand names)
What is the goal of treatment in Parkinson's?
- So the therapeutic regimen is levodopa to try to increase dopamine.
- Goal of medical treatment: to enhance dopaminergic activity.
What is important to know about Levodopa?
- Levodopa is taken as a pill, can be systemic effects of it.
- These pt can have BP lability.
- If they have too much, relative excessive, too much hypertension and vice versa.
- Because therapy w/levodopa can effect systemic levels of dopamine, as well as in the basal ganglia.
As CRNA what is the most important thing to remember about the meds for a parkinson's patient?
- All of these drugs have very short ½ lives, all should be maintained throughout surgery.
- Don’t want to alter the medications.
- Don’t want them stopping meds before surgery.
- Continue the prescribed Parkinson medications through the morning of surgery.
As CRNAs, we use anti-dopaminergic drugs. However these are contraindicated in Parkinson's patients. So what would you AVOID?
Droperidol & Metaclopromide are contraindicated because it will further inhibit Dopamine.
Say we were sedating pt w/Parkinson’s. Want to sedate pt and we know Ach too high (relative deficiency of Dopamine) so what kind of medications would be good to give?
- Anticholinergic drug, would theoretically be helpful.
- (Scopolamine, anticholinergic and crosses BBB, Benadryl, central acting anticholinergic).
- Propofol (experimental) has been shown to decrease the tremors of Parkinson's.
What would we give if a Parkinson's patient gets hypotensive?
give direct acting vasopressor (phenylephrine)
Why do we volume load Parkinson's patients?
People w/ANS dysfunction can have venous pooling, so keep them volume loaded.
What disorder is the "opposite" of Parkinson's?
- Dopamine is high and Ach is low
- Huntington's disease
What would be helpful to give in a patient w/Huntington's disease?
- Drug that might helpful is Reglan (anti-dopaminergic).
- Don’t want anticholinergic, tt would lower Ach even further.
- Still reverse MR with neostigmine and glycopyrrolate but tailor dose of glyco.
What is the pathophysiology of MS?
- demyelination of the nerve axon.
- It’s an autoimmune disease effecting the CNS, it seems to occur in genetically susceptible individuals after environmental exposure
Is MS more common in men?
NO! 2x as common in women than in men
In MS there is a loss of myelin covering the axons. The myelin sheath covering of nerves is what allows impulse to travel. They are abnormal in MS and they have plaque that demyelinate nerves. So there is a progression of MS from
inflammation to demyelination to axonal damage
Symptoms of pt can be multifocal. Depends on which nerves are effected. What areas are often involved and what would the patient have?
- the brain stem is demyelinated (nystagmus)
- the optic nerve is often effected
- *My dad has MS and his FIRST SYMPTOM was double vision*-
How is MS diagnosed?
plaque is seen on MRI (see plaque covering the myelin) can also diagnose it w/SSEP.
What is the most likely cause of exacerbation of MS in the peri-op period?
- temperature elevation.
- So even 1 degree centigrade increase in temp can predispose these patients to breakdown of the NMJ.
Can you use NDMR in patients w/MS?
- Yes but there can be abnormal responses in either direction
- Start low and check TOF
What is our concern with local anesthetics and MS?
be careful w/local anesthetics because the BBB may be more permeable to local anesthetics.
Why can't we give a spinal in patients w/MS?
- Spinal anesthesia has been implicated in post-op exacerbations and this may be because of LA neurotoxicity.
- Mylein in nerves in spinal cord is protective.
- In pt w/MS don’t have normal meylin sheath may be more susceptible to toxicity from LA.
Can you give a patient w/MS an epidural?
Yes, Epidural anesthesia has not been shown to cause problems w/MS. (further away from nerve root).
What is the other demylinating disease Denise mentioned (besides MS)?
- Charot Marie Tooth disease
- Less common but same issues w/anesthetic.
- Hereditary, it’s a genetic disease.
What is the pathophysiology behind amyotrophic lateral sclerosis?
- Motor neuron disease involving both upper and lower motor neurons
- Both the pyramidal tract and the anterior horn of spinal cord are involved.
In ALS, When the disease is limited to upper motor neurons (brain) it’s called
primary lateral sclerosis.
In ALS, it can also involve the bulb of the brain stem. If it involves the bulb it’s called
What are the S/S of ALS? (Reflects both upper and lower motor neuron involvement)
- There is progressive skeletal muscle weakness and atrophy.
- The early symptom is usually bulbar involvement (dysphagia is early symptom, can’t swallow d/t weakness of pharynx and tongue) & there is no effective treatment
What are our concerns in the pre-anesthesia assessment of a patient w/ALS?
- Respiratory involvement
- Caution w/MR!!
- Muscle wasting predisposes these patients to succinylcholine induced hyperkalemia leading to cardiac arrest.
- Can also be increased sensitivity to the NDMR. They are already weak (any pt w/neuromuscualr disease) they can be sensitive to NDMR.
What could happen if we give a patient a muscle relaxant and they have ALS?
- Give small dose & have no twitches or takes a long time to recover.
- Being careful w/MR is key to this patient population!
- Whenever possible, MR should be completely avoided.
Can we give a spinal anesthetic to a patient w/ALS?
- Generally avoided for fear of exacerbating the disease.
- If a patient has weakness and then you give a spinal anesthetic, and there’s some change in neuro status, there is some concern about the effect of the spinal anesthetic on their status.
- Weakness post-op. Is it because of spinal anesthetic? Maybe.
Another disease similar to ALS is ...........
Friedrich’s ataxia and spinal muscular atrophy.
What is Friedrich’s ataxia?
- involves both upper and lower motor neurons (like ALS)
- There is degeneration of both the spinocerebellar and the pyradmial tracts (read about it-per Denise)
What is so important to remember about Friedrich's ataxia?
Cardiomyopathy is present in 10-50% of these patients!!
In Fredrich's ataxia, muscles in the back can get weak and cause what?
- kyphoscoliosis: present in 80% of these patients
- Respiratory restrictive disease--> produces a steady deterioration of resp.
What is Syringomyelia and Syringobulbia ?
- Syringomyelia: abnormality of embryologic development where there is a slowly progressing degeneration of the spinal cord.
- Syringobulbia: degeneration of the bulb which is in the brain stem.
What is a big problem in Syringomyelia and Syringobulbia?
- Obstruction of outflow of CSF from the 4th ventricle, more likely w/syringobulbia.
- **If you have obstruction of 4th ventricle, through the foramen of Magendie or the foramen of Lushka---one of those pathways is blocked**
What is the cause of Guillian Barre?
Cause of Guillian Barre is unknown but a virus proceeds the symptoms in 70% of patients
What are the characteristics of Guillian Barre?
- There is lower motor neuron involvement.
- Paralysis is flaccid.
- The disease can vary from paresis of the legs to total motor paralysis.
- There can be bulbar involvement and pharyngeal muscle weakness.
True or False. In Guillian Barre, ANS dysfunction is a prominent finding.
Is nerve damage in Guillian Barre permanent?
- Sometimes it’s just inflammation of nerve (polyneuritis) and it resolves and sometimes the nerve is actually destroyed and then it’s permanent.
Can you use Succinylcholine in Guillian Barre?
Depends on how weak they are. If just noticed a problem, but walking into hospital. No atrophy, can use succinylcholine w/out problem. But if patient has atrophy, get up regulation, more Ach receptors, more K+ release.
How should we dose MR in a patient w/Guillian Barre?
Give a small dose (1/2 dose) of NDMR because they are already weak, and monitor TOF.
What should we avoid in prophyria?
Barbs, etomidate, enflurane, and methoxyflurane
What is the pathophysiology of myasthenia gravis?
- Chronic autoimmune disease caused by destruction of functioning Ach receptors.
- Pt develops antibodies to own Ach receptors in own NMJ and destroy them.
What gland is involved in myasthenia gravis?
- The origin of abnormal antibodies is not known but the thymus gland seems to have a role.
- If pt is having thymus removed, should ask if they have myasthenia gravis.
As many as ____% of pt w/myasthenia gravis have hyperplasia of the thymus gland.
70: &There is often involvement of the bulbar muscles.
What common drug is a patient w/Myasthenia gravis taking?
- Pt is treated w/anticholinesterase drugs. Neostigmine will increase Ach, they take pyridostigmine (PO version).
- Act by increasing amount of Ach at NMJ. So if we have decreased Ach receptors, to have nerve transmitting, want to have more Ach in them, so nerve conduction is faulty, want whatever few #s of Ach receptors you have, want to keep them full of Ach.
Besides pyridostigmine, what other drug might a patient w/myasthenia gravis be on?
- They also tend to take immunosuppressants.
- Usually corticosteroids, in hopes of decreasing their antibodies.
- So this patient would likely be taking pyridostigmine and prednisone
What type of surgery would a patient with myasthenia gravis be having?
- Thymectomy can be done w/an open sternum or transcervical (small incision).
- The thymectomy decreases the production of the antibodies
If our patient taking pyridostigmine for myasthenia gravis do we need to use neostigmine to reverse the NDMR?
Yes, ven though they are taking an anticholinesterase drug, they are usually more sensitive to NDMR so we still need to give neostigmine
Can we give Succinylcholine to a patient w/Myasthenia gravis?
- Yes but they are resistant to succinylcholine, it’s all or nothing, have to give enough succs to block all the receptors.
- If very few receptors, it will take more succinylcholine to block receptors, (more of a gap between the receptors) so it takes more succinylcholine.
- And they are tx w/anticholinesterase drugs (so they have a lower plasma cholinesterase), takes more succinylcholine to paralyze them but the duration is longer.
A strong recommendation is to avoid MR (both Depolarizing and Non-Depolarizing) for pt w/myasthenia gravis. If you need to, what should you do?
use a NDMR and decrease the dose by 2/3 and use a nerve stimulator.
What is Myasthetic syndrome?
- resembles myasthenia but the anticholinesterase drugs are not effective.
- And also associated w/small cell lung cancer
Is muscular dystrophy hereditary?
- x linked recessive gene.
- Thought to be a mutation of the dystrophin gene on the x chromosome
What is muscular dystrophy?
Painless degeneration and atrophy of skeletal muscles. Nerves ok, reflexes intact, but profound muscle weakness.
What is the pathophysiology of muscular dystrophy?
- Problem is a dystrophin deficient muscle, so the muscle becomes more permeable to Ca+.
- There is an increase muscle cell breakdown, causes an increase creatinase.
Can also be cardiac involvement in muscular dystrophy. Is it related to the degree of muscle weakness?
No, Cardiac is unrelated to degree of muscle weakness
Muscle dystrophy is similar to MH and you should avoid the same triggers such as....
- Succinylcholine and volatiles
- Hyperkalemic cardiac arrest can occur after administration of succinylcholine (why FDA did Black bx warning)
- The administration of potent inhaled anesthetics in pt w/Muscular dystrophy has resulted in extreme elevations of creatinine, gross myoglobinurea, and cardiac arrest.
- Also been cases of rhabdomyolosis w/ and w/out cardiac arrest even w/they JUST received the inhaled agents (no succs)
When does the weakness of muscular dystrophy usually develop?
Usually patient w/this disease weakness begins to develop within the end of the 1st decade of life.
What are some anesthesia (GI) considerations in muscular dystrophy?
- Hypomotility of GI tract may delay gastric emptying
- Presence of weak laryngeal reflexes
Is the response to NDMR in muscular dystrophy normal?
TRUE or FALSE. You should have dantrolene available when giving anesthesia to a patient w/muscular dystrophy?
TRUE Dantrolene should be available d/ increased incidence of MH
What kind of anesthesia can be helpful post-op in a patient with muscular dystrophy?
Regional anesthesia can be helpful and post-op neuraxial analgesia can facilitate CPT
What is Steinert’s disease?
Dystrophy, degeneration of skeletal muscle.
Is Steinert's disease hereditary?
What is Steinhart's disease (Myotonia) characterized by?
- Contracture of a skeletal muscle after the muscle stimulation ceases.
- Hallmark sign of it, inability to relax a hand grip. Can’t let go
What is the underlying pathophysiology in Myotonia Dystrophy?
- That inability to relax skeletal muscle results from abnormal Ca+ metabolism.
- Intracellular ATP fails to return Ca to sarcoplasmic reticulum.
What are some important things (as CRNAs) that we should know about myotonic disorders?
- They are susceptible to MH. In addition to that, myotonia (contraction of muscle) can be precipitated by succinylcholine and anticholinesterase drugs.
- Myotonia can also be precipitated by cold temperatures and shivering. Increase OR ambient temp to reduce shivering.
- Surgical manipulation and electrocautery.
What is periodic paralysis caused by?
- Dyskalemic familial periodic paralysis: K+ levels can be high or low.
- Really rare, pt will become paralyzed, except diaphragm.
- If they have high K, no succinylcholine.
True or False. People with Central core disease are susceptible to MH
Are peripheral nerves and the NMJ affected by myotonic dystrophy?
No Peripheral nerves and the neuromuscular junction are not affected.
How can we induce relaxation in myotonia dystrophy?
GA, regional anesthesia, and NMB are not able to prevent or relieve this muscle contraction. Infiltration of contracted skeletal muscle w/LA may induce relaxation.
What is Myotonia dystrophica?
Most common & most serious form of myotonia.
Is myotonia dystrophica inherited?
Yes, Inherited as autosomal dominant trait.
What things should we consider in our patient w/myotonia dystrophy?
consider the likelihood of cardiomyopathy, resp muscle weakness, and potential for abnormal responses to anesthetic drugs.
When giving anesthetic medications, what should we remember for the patient w/myotonia dystrophy?
- Volatiles cause myocardial depression.
- No succinylcholine because prolonged skeletal muscle contraction can result.
- Response to NDMR is normal.
- Careful titration of NMB and short acting ones can obviate need for reversal (which could precipitate skeletal muscle contractions).
- These pt are sensitive to resp depressant effects of barbs, opioids, benzos, and propofol.
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