Intermediate Neurology

Question 1

A 60 year old woman with resting tremor, bradykinesia, postural instability, foot drag, and masked facies is diagnosed with neuronal loss in the substantia nigra and is presenting for total knee replacement. She is on the normal assortment of medications for her above medical condition including levodopa/ carbidopa, bromocriptine, and selegiline. She reports she also has hypertension, post-operative nausea and vomiting and acid reflux. Which of the following medications would be MOST appropriate in her perioperative course:

A. Ephedrine for hypotension
B. Meperidine for post-operative pain
C. Propofol for induction
D. Metoclopramide for premedication
E. Droperidol for post-operative vom

Explain each one

Answer 1

C: Propofol for induction

The above patient has Parkinson’s disease, characterized by the above symptoms and loss of dopamine producing neurons in the substantia nigra. Patients on long-term levodopa often have problems with haemodynamic stability due to catecholamine depletion, autonomic instability, and catecholamine sensitization making direct acting vasopressors such as phenylephrine and epinephrine preferred over indirect ones such as ephedrine. Induction for patients with Parkinsosn’s disease should be done carefully as autonomic instability can lead to significant swings in blood pressure and reduced or slowly administered doses of propofol can accomplish this goal. Mepreridine is contraindicated in the setting of MAOIs such as selegiline as haemodynamic instability, hyperpyrexia, and coma can result. Dopamine antagonists such as metoclopramide and droperidol can significantly exacerbate parkinsonian symptoms.

Question 2

Can you reverse remifentanil with naloxone?

Answer 2

Yes!

Question 3

Generalized vs complex seizure. What do generalized seizures include?

Answer 3

This patient’s eye blinking can be either a partial seizure or tic disorder, but the infrequency of the symptoms as well as the association with tinnitus makes tic disorder very unlikely. The seizure progresses from an awake responsive state to one with impaired consciousness making the partial seizure “complex.” Generalized seizures characteristically have no ‘local’ onset, have impaired consciousness throughout and include absence as well as tonic/ clonic/ tonic-clonic/ atonic seizures. It is important to know what seizure symptoms patients’ have as it is not uncommon to occur post-operatively.

Question 4

A 50 year old man with traumatic brain injury (TBI) is started on levitiracetam (Keppra) immediately after the injury. The intern asks you how long it should be continued and you respond:

Answer 4

For severe head injury, it should be continued for 7 days
Antiseizure medications (most studied is perhaps phenytoin) show significant reductions in early seizures following TBI. Early seizures are defined as the first 7 days, whereas later seizures are after 7 days. The incidence of seizures increases significantly with the severity of TBI and is highest with penetrating missile injuries. It is questionable if the benefits outweigh the risks in more mild TBI. Antiseizure medications appear to be ineffective in preventing late seizures. Late seizures, especially those occurring more than a month after the TBI tend to be associated with an eliptogenic process, whereas early seizures are often isolated and do not predispose patients to late seizures.

Question 5

Status eoilepticus-why is it so dangerous? Who does it mostly happen to? Time to permanent neurological injury?

Answer 5

Persistent sustained seizures can lead to neuronal injury via supply demand mismatches (increased O2 demand without increased O2 delivery) just like any other stressed organ. Permanent neurologic injury can result within 5 minutes. Myotonic jerks is an especially poor prognostic sign, although not very specific. Although the musculoskeletal injuries associated with tonic/ clonic seizures such as bone fracture, rhabdomyolysis, and ligament injuries are worrisome, it is the neuronal injury which makes status epilepticus an emergency. Most cases of status epilepticus (~ 75%) are not in patients with previous seizure disorders, but instead significant medical/ surgical conditions such as anoxia, cerebral haemorrhage, stroke, metabolic derangements, and alcoholic withdrawal.

Question 6

In a seizure, priority number one-

Answer 6

AIRWAY!!!

Question 7

Why would you not use ketamine in a patient with a history of seizures?

Answer 7

Ketamine is not a good first line therapy for seizures as seizures can be precipitated by its use in certain individuals with underlying epilepsy.

Question 8

Which 3 anesthetic drugs can decrease the seizure threshold?

Answer 8

Etomidate, ketamine, and methohexital all can decrease the seizure threshold,

Question 9

Following multiple large doses of meperidine, a patient has a seizure. Which of the following medical conditions is most likely true regarding this patient:

A. Coronary artery disease (CAD)
B. Chronic renal insufficiency (CRI/ CKD)
C. Chronic obstructive pulmonary disease (COPD)
D. Anterior spinal cord syndrome

Answer 9

B: Chronic renal insufficiency (CRI/ CKD)

Normeperidine, a metabolite of meperidine can accumulate in the setting of kidney failure and lead to seizures.

Question 10

What is true regarding an asymptomatic carotid bruit found on physical exam:

A. The patient is at increased risk of concomitant coronary artery disease (CAD)
B. The patient most likely has aortic stenosis
C. The patient is at increased risk of perioperative stroke
D. At least 70% stenosis is needed to auscultate a cervical bruit
E. More times than not, carotid massage will result in a stroke or TIA
Explain each answer!!!!

Answer 10

A: The patient is at increased risk of concomitant coronary artery disease (CAD)

Carotid bruits are associated with underlying CAD, as the same calcification process happening in the carotid artery often occurs systemically. An asymptomatic bruit; however, does not increase the incidence of perioperative stroke. A late peaking systolic murmur with bilateral bruits is characteristic of aortic stenosis, not an isolated unilateral bruit. A bruit does not necessarily correlate with the amount of stenosis, but at 70% one often may hear a bruit. Carotid massage in the setting of carotid stenosis is a theoretical concern for embolization of plaque, but is not clinically common at all.

Question 11

How would posterior symptoms, (cerebellar function) present? Which arteries supply this area?

Answer 11

posterior” symptoms which may include cerebellar functions (coordination, balance, etc), occipital (bilateral visual) as well as more generalized symptoms such as weakness, amnesia, and confusion. The posterior portion of the circle of Willis is supplied by the basilar artery and the cerebellum is primarily supplied by arteries off the vertebral and basilar arteries

Question 12

The most common cause of intraoperative stroke from CEA is from

Answer 12

Embolism

Question 13

A 60 year old man with stroke 6 months ago has no residual symptoms although he had mild hand weakness and abnormal sensations for 2 weeks following the stroke. He presents with bowel obstruction and receives succinylcholine on induction. What is the most likely response to succinylcholine in this patient:

A. Hyperkalaemic cardiac arrest
B. Increase in serum potassium by 0.5 mEq/ L
C. Malignant hyperthermia
D. Masseter muscle rigidity (MMR)
E. Prolonged paralysis

Answer 13

B: Increase in serum potassium by 0.5 mEq/ L

Denervation injuries including stroke is a risk factor for upregulation of extrajunctional acetylcholine (Ach) receptors outside the muscle endplate. Depolarization of large quanities of these extrajunctional receptors can result in hyperkalaemia and even cardiac arrest. In the setting of ‘mild’ stroke where there is no persistent motor deficit, significant extrajunctional upregulation of receptors is very unlikely, therefore making the risk of hyperkalaemia very unlikely. In normal patients, the depolarization of multitudes of junctional Ach receptors raises potassium serum levels by 0.5 to 1.0 mEq/L transiently.

Question 14

Cerebral palsy and succinylcholine?

Answer 14

Cerebral palsy is not a risk factor for hyperkalaemia even in the setting of contractures as extrajunctional acetylcholine receptors are not upregulated. A prefasciculation dose, in all patients, may decrease myalgia following succinylcholine administration. Cereberal palsy is not a risk factor for malignant hyperthermia and these patients are put on dantrolene to treat spasticity.

Question 15

Which of the following pediatric patients would latex allergy be most likely to occur in:

A. Craniostenosis
B. Myelomeningocele
C. Cerebral palsy

Answer 15

The correct answer is: B: Myelomeningocele

Latex allergies occur most often in children with myelomeningocele, spina bifida, genitourinary disease, indwelling tubes, and multiple surgeries (as a child). Latex allergies often coexist with banana, avocado, and kiwi allergies, among others.

Question 16

Is epidural okay for people with MS?

Answer 16

Epidural anesthesia is generally considered safe,

Question 17

In MS is sux contraindicated?

Answer 17

Succinylcholine is relatively contraindicated in MS, with a stronger (maybe even absolute) contraindication in the setting of paresis and paralysis as it is a upper motor neuron demyelination causing this.

Question 18

Hyperthermia vs hypothermia-which one makes MS worse?

Answer 18

Hyperthermia, not hypothermia exacerbates MS, and this is a classic boards topic.

Question 19

Which of the following neurological and neuromuscular disorders is succinylcholine NOT contraindicated in:

A. Duchenne’s muscular dystrophy (DMD)
B. Guillain-Barre syndrome (GBS)
C. Myasthenia Gravis (MG)
D. Myotonic dystrophy (MyoD)
E. Amyotrophic Lateral Sclerosis (ALS)

Answer 19

Myasthenia Gravis (MG)

Question 20

A partner is in the process of placing a spinal anesthetic in a patient with Guillian-Barre syndrome (GBS) as you come to take the case over from her. A 22 g spinal needle is placed between L3 and L4 with CSF dripping back. What would you tell your partner at this time:

A. The patient is now at increased risk of having a GBS exacerbation
B. If the local anesthetic is not injected, the patient will not be at increased risk of having a GBS exacerbation
C. There is no contraindication to spinal anesthetic in GBS patients
D. There is no contraindication to spinal anesthetic in GBS patients so long as isobaric local anesthetic is used
E. There is no contraindication to spinal anesthetic in GBS patients so long as hyperbaric local anesthetic is used

Answer 20

B: If the local anesthetic is not injected, the patient will not be at increased risk of having a GBS exacerbation

This is a hard question, as you have to know exactly what is and what is not safe in GBS. The clue to answering this is the knowledge that spinal (and epidural) anesthetics are considered contraindicated (like MS as discussed in question 19, the evidence is sparse and weak) and lumbar punctures (LPs) are performed in GBS patients routinely by neurologists without sequelae. The anesthesiologist has placed a spinal needle in the patient which is equivalent to an LP, but until the anesthetic is injected, it would not be expected to exacerbate symptoms. There is not enough data to determine if the baricity of the anesthetic has any bearing on exacerbating the symptoms.

Question 21

What are four big perioperative concerns for patients with MyoD? And does hyper or hypo hurt them? Regarding contra tires-what 3 things to avoid?

Answer 21

There are four big perioperative concerns with patients with MyoD for anesthesiologists 1) contractures; 2) sensitivity to anesthetics; 3) aspiration risk; and 4) theoretical increased risk of malignant hyperthermia (which is probably FALSE!). Regarding contractures, three big things to avoid: 1) succinylcholine (see question 21 – sustained contractures); 2) reversal of muscle relaxation with anticholinesterases (sustained contractures); and 3) hypothermia leading to shivering and then contractures. Contractures can be so severe, ventilation and intubation is impossible.

Question 22

Myasthenia Gravis-what is it? Which neuromuscular blockers are they sensitive to? Any relation to thymus issues?

Answer 22

C: Patients with MG are exquisitely sensitive to nondepolarizing muscle relaxants

MG is characterized by Abs to Ach-Rs at the neuromuscular junctions on skeletal muscle and does not affect smooth muscle. Because there are so few receptors to block in MG, nondepolarizing muscle relaxants can cause profound paralysis at very low doses while supranormal amounts of depolarizing relaxants are needed. There is a theoretical increased risk of phase II block with these patients after using succinylcholine due to the increased dose and use of acetylcholinesterase inhibitors (for MG symptoms) which decrease succinycholine’s metabolism (board classic). Most patients with MG have laboratory evidence of Ach-R Abs and thymus hyperplasia or thymomas. MG has four different subtypes with type I being the most mild and limited at extraocular muscles. Other types (IIA, IIB, III, IV) have progressively more symptoms affecting respiratory and bulbar muscle groups putting them at increased risk for respiratory failure, airway obstruction, and aspiratio

Question 23

A 45 year old woman with myasthenia gravis (MG) presents for trigger finger release and complains of increasing weakness, especially today. Her normal dose of pyridostigmine 60 mg four times daily was increased to 80 mg two days ago by her doctor. She reports having taken her prescribed dose three hours ago this morning. What is the best way to elucidate the cause of this patient’s weakness:

A. 5 mg edrophonim IV now and observe
B. 1 mg of glycopyrrolate IV now and observe
C. 1 mg of glycopyrolate now and send to the ED
D. Acetylcholine receptor antibody (Ach-R Ab) titer
E. Urgent plasmapheresis prior to surgery

Answer 23

A: 5 mg edrophonim IV now and observe

Most likely this patient either has rapidly worsening symptoms of MG or a cholinergic crisis. Based on the history both are possible, as increasing doses of pyridostigmine is needed for worsening symptoms, while an overdose of pyridostigmine (dose was just increased two days prior) could cause cholinergic crisis. The ‘tensilon test’ is used to differentiate the two. Edrophonium is given IV, improvement in strength indicates MG causes while increased weakness indicates cholinergic crisis. Other symptoms of cholinergic overdose (salivation, bradycardia, myosis) would be present either way. Atropine would be the ‘antidote,’ in a cholinergic crisis (without MG), and glycopyrolate could also be useful for non central nervous system manifestations. Ach-R Ab titer would take to long for a result, and is also more useful for diagnosis than management. Plasmapheresis can remove circulating Ach-R Ab, but is not common prior to minor surgery.

Question 24

MG risk of post-operative mechanical ventilation:

Answer 24

disease duration > 6 years, vital capacity < 2.9 L, pyridostigmine > 750 mg / day, or concomitant respiratory disease (not kidney

Question 25

Explain each:
Which of the following is true regarding myasthenia gravis (MG):

A. MG usually improves in the last trimester of pregnancy
B. Infants of MG mothers have transient myasthenia for up to 3 weeks
C. Infants of MG mothers have life long MG
D. Infants of mothers with MG should receive early tracheostomy
E. IM neostigmine should be given to infants of MG mothers within 1 hour of birth

Answer 25

B: Infants of MG mothers have transient myasthenia for up to 3 weeks

Maternal antibodies (Abs) can cross the placenta, therefore acetylcholine receptor Abs are present at birth in these infants. The syndrome typically lasts about 1-3 weeks and resolves with clearance of the Abs. Tracheal intubation should be considered, but tracheotomy should not as the syndrome is self-limited. There is no role for IM neostigmine in these infants. In general, MG worsens in the last trimester and early post partum.

Question 26

ELS is characterized by:

Answer 26

ELS is characterized by antibodies (Abs) to voltage gated calcium channels resulting in decreased release of presynaptic acetylcholine.

Question 27

Greatest cause of morbidity and mortality in patients with DMD:

Answer 27

Respiratory complications are the greatest cause of perioperative morbidity in these patients.

Question 28

Hypokalemic periodic paralysis: What is it? What makes patients hypokalemic? What makes patients hyperkalemic? What two things affect both the hypo and hyper form?

Answer 28

manifests with weakness or paralysis of trunk and/or extremities with hypokalaemia. insulin, bicarbonate, or diuretics were given. In the hyperkalaemic form, succinylcholine can produce prolonged paralysis by mildly increasing potassium levels. Hypothermia and shivering may precipitate an attack in either form.

Question 29

Autonomic hyperreflexia-explain it, MV of it:

Answer 29

autonomic hyperreflexia characterized by stimulation below the spinal cord lesion leading to unopposed sympathetic activation due to the lack of central regulation below the lesion. This leads to hypertension below the lesion and compensatory centrally mediated vasodilation above the lesion (leading to flushing, bilateral nasal stuffiness, goose bumps, etc). For high spinal cord lesions (above ~ T6) the upper vasodilatation does not compensate for lower body vasoconstriction and uncontrolled hypertension is seen. The most common cause of autonomic hyperreflexia is distention of a hollow viscus, such as the bladder, although thermal stimulation and trauma below the lesion are commonly seen as well.

Question 30

Treatment of autonomic hyperreflexia:

Answer 30

The treatment is BP control with vasodilators, such as nitroprusside, nicardipine, or alpha blockers. Also important is stopping the stimulus.

Question 31

what are the normal effects of TCAs and how would an overdose present.

Answer 31

TCAs produce sedation, orthostatic hypotension (alpha blockade), and anicholinergic symptoms (atropine-like symptoms). Doubling the dose would worsen these effects. A frank overdose can result in seizures, coma, and dysrhythmias. Treatment is supportive.

Question 32

Does meperidine interact with TCAs?

Answer 32

Meperidine has a RARE reaction with MAOIs, probably not TCAs as described in answe

Question 33

What do TCAs do to MAC? What about ephedrine and other vasopressors?

Answer 33

Increase it
TCAs, like other drugs that increase neurotransmitter levels require an increased MAC. Use of ephedrine and other indirect vasopressors often can have an increased and unpredictable effect, and is more likely to have an increased effect than no effect at all due to increased availability of norepinephrine at post-synaptic receptors in the peripheral nervous system.

Question 34

Lithium-side effects? Does it potentate?

Answer 34

One of the more tested side effects is its ability to produce (not treat) nephrogenic diabetes insipidus. It is a teratogen and should be avoided in pregnancy. It can potentiate both depolarizing and nondepolarizing muscle relaxants, and complicates the differential for delayed arousal from anesthesia.

Question 35

A 20 year old man is scheduled for electroconvulsive therapy (ECT) and the CRNA is ready to induce the patient with glycopyrolate, methohexital, and succinylcholine and asks you if you agree with her plan. Which of the following is an appropriate response:

A. Methohexital will greatly increase the seizure threshold and should be avoided
B. Ketamine is a better choice than methohexital in this setting
C. Succinylcholine can result in hyperkalaemia with ECTs
D. Glycopyrolate can offset the bradycardia associated with the early parasympathetic response, but is generally not needed
E. Esmolol should be used prior to induction, not glycopyrolate

Answer 35

D: Glycopyrolate can offset the bradycardia associated with the early parasympathetic response, but is generally not needed

ECT has two cardiovascular responses: a short period of parasympathetic response that lasts 10 seconds and rarely needs treatment and a prolonged sympathetic response that can produce hypertension and tachycardia. Methohexital is a barbiturate that is ideal in that it does not raise the seizure threshold nor does its effects last long (good for quick discharge). Ketamine can contribute to the sympathetic response and delay discharge making it less ideal. Etomidate can produce excellent conditions for ECT but has associated nausea and vomiting as well as lasting effects. Propofol can increase the seizure threshold, but has been used effectively. Succinylcholine is perhaps the muscle relaxant of choice as it prevents the patient from hurting himself during the ECT and lasts ~ 5 minutes. Esmolol can exacerbate the early bradycardia and is probably less effective than labetalol at treating the hypertension with the sympathetic phase

Question 36

Contraindications for ECT:

Answer 36

Intracranial hypertension, aneurysm, and mass are as close as it gets to an absolute contraindication to ECT. Angina is a major risk factor, but with careful monitoring and drips available, it can be done safely. Pacemakers and epilepsy are not contraindicated.

Question 37

Go through each one!
A 18 year old woman with acute cocaine toxicity presents with chest pain and open femur fracture after being struck by a car. ECG demonstrates diffuse ST elevations and sinus tachycardia and BP is 190/110 with HR 135. Which of the following is the next BEST treatment:

A. Metoprolol and nitroglycerin
B. Calcium channel blockers
C. Internal fixation of open femur fracture
D. Hydralazine
E. Heparin gtt

Answer 37

B: Calcium channel blockers

Cocaine mediated myocardial ischaemia is a poorly defined phenomenon with evidence of thrombotic/ obstructive coronary mechanisms, coronary vasospastic, and supply/demand mismatch contributions. Beta blockers such as metoprolol are generally avoided as it may result in unopposed alpha stimulation, although they have been used safely without such effects. Calcium channel blockers can treat vasospasm, decrease myocardial oxygen demand by decreasing HR and contractility, and do not have the theoretical risk of unopposed alpha stimulation that beta blockers have. Hydralazine can precipitate worsening tachycardia, increasing oxygen demand and worsening ischaemia. Heparin should be avoided until the surgical considerations of the open fracture have been addressed. Taking the patient to the OR now is unnecessary as the leg can be stabilized for the time being, assuming there is no uncontrolled haemorrhage.

Question 38

Which of the following is NOT an immediate anesthetic concern regarding an alcoholic patient acutely intoxicated:

A. Thrombocytopaenia
B. Hypoglycaemia
C. Aspiration
D. Decreased MAC
E. Delirium tremens

Answer 38

E: Delirium tremens

Alcohol withdrawal can occur as soon as 6 hours after the last drink manifesting as tremor, hallucinations, hypertension, confusion, and agitation. Only after 2 days is delirium tremens a realistic concern. Alcoholism is a multisystem disease affecting almost every organ system. Thrombocytopaenia and hypoglycaemia can be a result of underlying liver disease. Aspiration risks for this patient may include liver/ abdominal ascites problems as well as acute alcohol intake may lead to increased risk of aspiration.

Question 39

Which of the following drugs of addiction is most likely associated with relapse among anesthesiologists:

A. Vicodin
B. Fentanyl
C. Midazolam
D. Ketamine
E. Cocaine

Which one is most associated with relapse?

Answer 39

B: Fentanyl

Fentanyl is the most commonly abused drug among anesthesiologists (actual board question) and opioid abuse is the most likely associated with relapse.

Question 40

What is the best initial strategy in dealing with a partner you suspect using addictive drugs:

A. Ignore the problem
B. Immediately contact the medical board
C. Directly confront the colleague
D. Discuss with other coworkers
E. Alert the pharmacist

Answer 40

C: Directly confront the colleague

It is recommended you confront, either by yourself or with your supervisor, the person suspected of using drugs.