ASDS Primer Flashcards
What muscle opens the eye? What CN innervates it?
- Levator palpebrae superioris
- Innervated by CN III
What CN innervates each of the following extraocular muscles?
- Medial rectus
- Lateral rectus
- Superior rectus
- Inferior rectus
- Superior oblique
- Inferior oblique
Mnemonic: LR6SO4R3
Lateral rectus = CN VI
Superior oblique = CN IV
Rest of the muscles: CN III
What is the function of each of the following extraocular muscles?
- Medial rectus
- Lateral rectus
- Superior rectus
- Inferior rectus
- Superior oblique
- Inferior oblique
- Medial rectus = adducts
- Lateral rectus = abducts
- Superior rectus = upward gaze
- Inferior rectus = downward gaze
- Superior oblique = incyclotorsion
- Inferior oblique = excyclotorsion
What pharyngeal arch do the muscles of facial expression originate?
Second pharyngeal arch
Lower, middle and upper facial muscles originate from what embryonic structure?
- Lower face muscles: embyronic platysma; do NOT have bony insertions
- Upper and middle facial muscles: embryonic sphincter colli profundus muscle; have bony insertions
True or false:
The supraorbital foramen (of CN V1) can be palpated along the orbital rim and the midpupillary line.
True
Inject perpendicular to skin at orbital rim at midpupillary line to numb forehead and frontal scalp
Where is the infraorbital nerve (of CN V2) foramen located?
Describe the cutaneous and intraoral approach for anesthesia.
What would be numbed?
- Cutaneous approach: inject 1 cm inferior to orbital rim at midpupillary line
- Intraoral approach: inject between first and second upper premolars angling needle toward midpupillary line
- Numbs medial cheek, upper lip and nasal ala
How would you perform a mental nerve (of CN V3) block?
Describe the cutaneous and intraoral approaches.
What would be numbed?
- Cutaneous approach: Inject perpendicular to skin at midpupillary line (2.5 cm lateral to the midline) and 1 cm inferior to the lower second premolar
- Intraoral approach: inject between the first and second lower premolars
- Numbs lower lip and portions of chin
How would you perform a supratrochlear nerve (of CN V1) block?
What areas of the face would be numbed?
- Inject perpendicular to skin at junction of glabella and medial eyebrow
- Numbs mid forehead, glabella and frontal scalp
Describe the approach to a median nerve block.
What tendon is your landmark? Where do you inject?
- Find palmaris longus tendon by touching thumb to last two digits of hand with wrist slightly flexed
- Median nerve is between palmaris longus and flexor carpi radialis tendons
- Inject to radial side of palmaris longus tendon at proximal wrist crease
Describe the approach to an ulnar nerve block.
What tendons are landmarks? Where do you inject?
- Touch thumb to last two digits of hand with wrist turned in a slightly ulnar direction to identify palmaris longus and flexor carpi ulnaris tendons
- Inject radial to flexor carpi ulnaris tendon at proximal crease of wrist at ulnar styloid process
Describe how to perform a posterior tibial nerve block.
What areas are made numb by this?
- Palpate posterior tibial artery near medial malleolus - nerve is lateral to artery
- Inject into groove between medial malleolus and Achilles tendon
- Numbs heel and middle of the sole of foot
Describe how to perform a sural nerve block.
What areas are made numb by this?
- Inject into groove between lateral malleolus and Achilles tendon
- Numbs fifth toe and lateral side of sole of foot
Describe how to perform a deep peroneal nerve block.
What areas are made numb by this?
- Ask patient to dorsiflex against resistance to visualize extensor hallucis longus tendon → inject lateral to this tendon down to bone
- Another approach is to inject subcutaneously between first and second toes
- Numbs skin between first and second toes
Describe how to perform a saphenous and superficial peroneal nerve block.
What areas are made numb by this?
- Inject anesthestic subcutaneously from malleolus to malleolus on dorsal surface of foot
- Numbs instep and medial ankle (saphenous nerve), and skin of toes other than outside of fifth toe (sural nerve) and in between first and second toes (deep peroneal nerve)
Describe how to find Erb’s point.
What nerves arise from here? What would nerve injury lead to?
- Draw an imaginary line from the angle of the jaw to the mastoid process.
- From the midpoint of this line, drop a perpendicular line down 6 cm, which will intersect with the posterior border of the sternocleidomastoid muscle.
- The cervical plexus emerges (lesser occipital, great auricular, transverse cervical and supraclavicular nerves)
- CN XI (spinal accessory nerve): innervates trapezius muscle → damage can result in winged scapula, shoulder and neck pain, shoulder drop, trapezius atrophy, arm paresthesias, or inability to abduct arm
Describe how to find the temporal branch of CN VII.
What could nerve damage lead to?
Where is it most susceptible to injury?
- Draw a line from the earlobe to the lateral brow and from the tragus to highest forehead crease
- Damage results in brow ptosis and paralysis of frontalis → inability to elevate forehead
- Note its susceptibility to injury as it crosses temple
At the jawline, what nerve is most susceptible to injury?
What can nerve damage result in?
- Marginal mandibular nerve → only has one ramus and covered only by skin and platysma, which is a thin muscle
- The marginal mandibular nerve is the facial nerve MOST susceptible to injury for this reason.
- Damage results in drooling and crooked smile
Name the branches of the ophthlamic nerve.
- Nasociliary
- Frontal
What is the sensory innervation to the nasal tip?
Anterior ethmoidal nerve (V1)
What is innervated by the lesser occipital nerve?
Posterior notch of ear
Regarding the properties of local anesthetics, what determines the following:
- Potency
- Duration of action
- Ester versus amide
What structural component binds to the sodium channel?
- Potency: lipid solubility → aromatic end
- Duration of action: protein binding
- Ester versus amide: intermediate chain
- Amine end binds to sodium channel
All anesthetics except what are vasodilating?
Cocaine
This is why vasoconstrictors such as epinephrine are often added.
What microsomal liver enzyme metabolizes amide local anesthetics?
Cytochrome P450 3A4
Therefore, use with caution in liver disease patients
In general regarding local anesthetics, which has a shorter duration of action - esters or amides?
Esters have a shorter duration of action.
True or false: Local anesthetics can be excreted in breast milk.
True
What serious adverse effect can prilocaine cause? How does this manifest?
In whom should prilocaine be avoided?
What is the treatment for this adverse effect?
Methemoglobinemia
Avoid in children under 1 year old and those with G6PD deficiency
Manifests as cyanosis
Treat with methylene blue
What life threatening adverse effect can bupivicaine cause?
Cardiac toxicity not preceded by convulsions and not responsive to resuscitation efforts
Local anesthetics affect which nerve fibers first?
C-type fibers and A-delta fibers
“You may feel pressure but not pain.”
They affect A-beta fibers last, which are responsible for pressure.
Longest duration WITHOUT epinephrine?
Longest duration WITH epinephrine?
- Longest duration WITHOUT epinephrine: ropivicaine (2-6 hours)
- Longest duration WITH epinephrine: bupivicaine (4-8 hours)
In what conditions is epinephrine absolutely contraindicated?
- Pheochromocytoma
- Uncontrolled hyperthyroidism
If a true allergy to an anesthetic agent occurs, what should be given?
Antihistamines and consider epinephrine 0.3 mL 1:1000 subcutaneously
What should be given in moderate to severe lidocaine toxicity?
- Diazepam
- Maintain airway
- Respiratory support (in severe toxicity)
What does EMLA stand for and what is it made of?
In whom should it be avoided?
How is it usually applied? How long should you wait?
Eutectic Mixture of Local Anesthesia
- Contains lidocaine and prilocaine in oil-in-water emulsion cream
- Caution in infants (methemoglobinemia due to prilocaine), around eye (corneal injury), broken skin, and large surface areas
- Applied under occlusion for up to 1 hour
What is another name for LMX?
Is occlusion needed?
In whom should it be avoided?
Liposomal Encapsulated Lidocaine
- Occlusion not needed
- Avoid in children < 20 kg with surface areas larger than 100 cm2; mucosal sites (use benzocaine or tetracaine instead)
What are methods to decrease anesthetic injection pain?
- Use small bore needles
- Mix anesthetic fresh (makes it less acidic)
- Alkalinize with sodium bicarbonate
- Use topical anesthetic or cooling
- Counter irritate skin around needle entry point
- Warm lidocaine
- Inject slowly
- Re-enter at previously anesthetized sites
Which local anesthetic has the shortest duration of action?
Procaine
What are the three types of scalpel handles?
- Bard-Parker
- Bard-Parker round knurled handle
- Beaver
What type of scissors are these?
O’Brien
Used for cutting suture in delicate areas and tight spaces
What type of scissors are these?
Spencer
Curved blade with notch on one blade at end for suture cutting
What is notable about povidone iodine / iodoform?
- Mechanism of action
- Coverage
- Cons
- Directly halogenates microbial proteins to form salts
- Broad antimicrobial activity, including to spores
- Must completely dry to be bactericidal
- Neutralized by blood, sputum
- Must be washed off to avoid contact dermatitis
- Can cause neonatal hypothyroidism when there is chronic maternal use
What is notable about chlorhexidine?
- Mechanism
- Coverage
- Duration of activity
- Cons
- Disrupts microbial cell membranes, precipitating out cell contents
- Broad spectrum coverage, including to viruses and TB
- Residual activity up to 6 hours
- Can cause keratitis, conjunctivitis, and otitis
What is notable about hexachlorophene?
- Mechanism
- Coverage
- Cons
- Disrupts microbial cell membranes; bacteriostatic
- Covers gram + cocci but nothing else
- Teratogen
- Neurotoxicity in infants as it can be absorbed through skin
What is notable about isopropyl alcohol?
- What is the optimal strength/concentration?
- Mechanism
- Cons
- 70% is optimal strength for antiseptic action
- Denatures proteins
- Fastest onset of action
- Flammable, irritant, no residual activity
What is the temperature of a steam autoclave?
- 2 Pascals of pressure and 121 degrees Celsius for 15-30 minutes
- Corrosive → can dull sharp instruments
Which sterilization method should be used for heat- and moisture-sensitive instruments?
Gas sterilization
What is suture memory a function of? (3)
- Elasticity
- Plasticity
- Diameter
Name the best and worst suture types in terms of tissue reactivity and initial tensile strength for absorbable and nonabsorbable sutures.
Why is silk used on mucosal surfaces?
Knot security, pliability and ease of handling, despite increased tissue reactivity
What is the difference between elasticity and plasticity?
- Elasticity: snaps back into place after swelling (“poliglecaprone 25 has high elasticity”)
- Plasticity: stretches and stays without breaking
What are treatment modalities for BCCs?
- ED&C
- Excision
- MMS
- Radiation
- Cryotherapy
- Topical imiquimod and 5-FU
- Intralesional interferon alpha
- PDT
- Vismodegib (inhibits sonic hedgehog signaling pathway by binding to smoothened receptor; belongs to 2-arylpyridine class)
What is the pathogenesis of BCCs?
- Inactivation of patched (PTCH) tumor suppressor gene
- Activation of smoothened (SMO) or hedgehog (SHH) genes
- Mutations in CDKN2A or point mutations in p53
What are genetic syndromes associated with BCCs? (7)
- Gorlin syndrome (nevoid basal cell carcinoma syndrome)
- Bazex-Dupre-Christol syndrome
- Rombo syndrome
- Brooke-Spiegler syndrome
- Schopf-Schultz-Passarge syndrome
- Linear unilateral BCC syndrome
- Xeroderma pigmentosum
A 2.4 cm BCC on the thigh should be treated with what modality?
MMS as it is > 2 cm
What is the risk of developing a second BCC within five years of the first?
40% within five years
What is the most common tumor to arise in a nevus sebaceous?
SPAP
What is the rate of metastasis of a SCC of the lip and ear?
- Lip: ~13%
- Ear: ~11%
What type of UVR promotes photocarcinogenesis, such as in a SCC?
What tumor suppressor genes can become inactivated?
UVB
- Can inactivate p53, p16, and p14
What genes can be mutated in PUVA-associated SCC? (2)
- p53 (tumor suppressor gene)
- Ras proto-oncogene
- Risk increases after 250 treatments
What particular biologic has been linked to increased risk of SCC?
What melanoma chemotherapy has been associated with eruptive keratoacanthomas as a side effect?
- Etanercept
- Vemurafenib
What type of NMSC is discoid lupus associated with?
SCC
Is an oral retinoid effective in preventing SCCs?
Yes, acitretin
Which of the following is more important for the development of BCCs, SCCs, and melanomas, respectively?
- Chronic sun exposure
- Intermittent high intensity sun exposure
- Chronic sun exposure → SCCs
- Intermittent high intensity sun exposure → BCCs
What is the mechanism of action of imiquimod?
TLR-7 inhibitor
What is the mechanism of action of 5-FU?
Thymidylate synthase inhibitor, blocking the synthesis of the pyrimidine called thymidine
Can PDT be used to treat:
- AK?
- SCCis?
- iSCC?
- AK: Yes
- SCCis: Yes
- iSCC: No
What gene is associated with familial melanoma?
CDKN2A
- Encodes p16 (required for cell cycle arrest) → negative regulator of Rb pathway
- Encodes p14 → negative regulator for p53 pathway (loss of p14 function decreases p53 function, leading to enhances survival of altered cells)
Half of all melanomas harbor a mutation in what oncogene?
BRAF V600
A protein kinase within RAS-RAF signaling pathway that plays role in cell growth and proliferation
What is the risk of developing a second melanoma after the first?
3.5-4.5%
What are examples of adjuvant therapies for metastatic melanoma?
- Interferon alpha
- Ipilimumab (CTLA-4 receptor antibody)
- Vemurafenib (BRAF inhibitor; used in BRAF V600E positive melanoma patients)
- PD-1 and PDL-1 inhibitors (e.g., nivolumab and pembrolizumab)
- MEK (mitogen-activated protein kinase kinase) inhibitors
- Dacarbazine
- Temozolomide
- High-dose IL-2
What is the most common type of melanoma?
Where are the most common locations for this subtype among men and women?
Superficial spreading melanoma (70% of all melanomas)
- Location: trunk (men) and legs (women)
Patients with nevus of Ota may be at higher risk of what type of melanoma?
Uveal melanoma
What type of melanoma does not have a radial growth phase?
Nodular melanoma
When should sentinel lymph node biopsy be considered?
Breslow depth > 0.8 cm or < 0.8 cm with ulceration
How often should a patient with newly-diagnosed melanoma be screened with a TBSE?
- q3 months for 2 years,
- q6 months for 3 years,
- Then annually
What type of electrosurgery causes collateral tissue damage?
Electrocoagulation
What temperature is needed for keratinocyte destruction?
-20 to -30 degrees Celsius
“Fusiform is a more accurate way to describe an elliptical shape.”
What is an M-plasty used for?
Decrease scar length so as to not interfere with a free margin
What are the stages of healing after graft placement?
- Imbibition: day 1
- Inosculation: day 2-3
- Epidermal proliferation: day 4-8
- Neovascularization: day 7
- Sensory nerve restoration: day 14 and beyond
When is the earliest that dermabrasion of a skin graft can occur?
4-6 weeks after skin grafting
What is a composite graft?
- What are the four stages of composite graft “take”?
A modified full thickness skin gtaft of skin plus cartilage, fat or perichondrium
- Usually used for repair of full thickness alar rim defects using ear helical rim or crus
- Four stages of graft take:
- Initially graft blanches
- Turns pale pink by 6 hours
- Turns dusky blue by 24 hours (venous congestion)
- Turns pink by day 7, indicating graft survival
What is the treatment for chondritis or perichondritis of a donor site for a free cartilage graft?
- Cool compresses
- NSAIDs
What is wound strength at the following points after surgery?
- 2 weeks
- 1 month
- 1 year
- 2 weeks: 3-5% normal wound strength
- 1 month: 35%
- 1 year: 80%
What is an axial pattern flap?
- How many stages are needed?
- When does pedicle division typically occur?
- What are two examples of axial pattern flaps?
- Axial pattern flap → flap based upon a named vessel for blood supply
- Require 2 stages for completion
- Pedicle division typically at 3 weeks
- Paramedian forehead flap → supratrochlear artery
- Abbé flap → superior or inferior labial artery
What are advancement and rotation flaps also known as?
What are transposition flaps also known as?
- Advancement and rotation flaps are also known as “sliding” flaps
- Transposition flaps are also known as “lifting” flaps
When a lip wedge repair is performed, what are the four layers involved in the closure?
- Mucosa
- Muscle
- Dermis
- Epidermis
When are mucosal advancement flaps classically used?
What undermining plane is desired?
- Restoring vermillion border
- Undermining takes place deep to minor salivary glands and superficial to orbicularis oris muscle
What is a Rintala flap?
- Superiorly based rectangular advancement flap for closure of midline defects of the proximal to mid-nose
What is a Peng flap?
- Used to repair central nasal tip defects (modification of Rintala flap)
What type of flap is a rotation flap?
Random pattern flap
In a rotation flap, what can be used to improve flap mobility and reduce wound tension?
A “back cut”
How do you recognize a rotation flap?
Where is the key stitch placed?
A curved line and a linear line
Key stitch at point of maximal tension as in picture
Rieger flap
- What are alternative names for it?
- What is it used for?
- The flap is elevated to what level to avoid a deformity?
- Where is the area of pivotal restraint?
- Also known as dorsal nasal rotation flap, Hatchet flap, and glabellar turn-down flap
- Used for medium-sized defects of distal third of the nose
- Flap elevated to level of perichondrium to include underlying nasal musculature to avoid “pig nose” deformity
- Area of pivotal restraint: ipsilateral medial canthus and attachment of nasal musculature to nasofacial sulcus
What is a Mustarde flap used for? What kind of flap is it?
Rotation flap of cheek and temple skin to close lower eyelid or infraorbital defect
Avoids wound closure tension along eyelid margin
- What is a modified Tenzel flap?
- What is it used for?
- To what level is the flap elevated?
- Combines features of both a rotation and advancement flap
- Used for partial thickness defects of mid to lateral lower eyelid
- Elevated just above orbicularis oris musculature
- Recruits tissue near lateral canthus to avoid ectropion
What kind of flap is a transposition flap? How do you recognize it?
A random pattern flap
Look for linear lines that zigzag (“little dipper”)
Donor tissue not adjacent to flap, but lifts over intact skin to fit into primary defect
What is the difference between a nasolabial transposition flap and a nasolabial interpolation flap?
Both are transposition flaps
Nasolabial/melolabial transposition flap is a one-stage flap
Nasolabial/cheek-to-nose interpolation flap is a two-stage flap
What type of flap is a rhombic flap? How can you recognize it?
How many potential closures are there?
Where is the key stitch placed?
A transposition flap (originally described by Limberg)
Looks like a “question mark” or “big dipper”
Has eight potential closures
The secondary defect is closed first with the key stitch.
What is a DuFourmental flap?
- Modification of rhombic flap
- Narrows angle of tip of secondary defect (i.e., less than 60 degrees) and creates a shorter arc of rotation for flap
- Widened pedicle base, decrease in tip volume, decrease in pivotal restraint at flap base, creating lateral tip tension instead of vertical tip tension
In a bilobed flap, what is the order of defect closures?
- Secondary lobe site (sometimes referred to as tertiary site) closed first
- Flap sutured into primary defect
- Trimming and suturing into place of secondary lobe into secondary defect
Make sure to undermine to the nasofacial sulcus
Incise down to periosteum and undermine in submuscular plane (subnasalis)
Where is the key stitch of a bilobed transposition flap?
How is the bilobed transposition flap designed?
For a paramedian forehead flap, what side is the pedicle positioned relative to the wound?
Pedicle positioning is contralateral to the predominant side of the wound to avoid flap torsion causing impaired blood supply
I.e., left-sided nasal defect should utilize a PMFF based on the right supratrochlear artery
What is a lip-switch flap?
What is the alternative name for this?
When is this used?
What named artery is it based on?
- An (axial) interpolation flap
- Also known as Abbé flap
- Includes both muscle and mucosa from donor flap
- Best flap for restoring full-thickness tissue and bulk
- Lip defects amenable to Abbé flap are lateral to midline and one-third to one-half of the lip and do not involve oral commissure
- Based on the superior or inferior labial artery (depending on which side the flap is coming from - upper or lower lip)
- Flap divided at 3 weeks per usual
If flap dehiscence occurs within 24 hours, what can you do? What if it occurs AFTER 24 hours?
- <24 hours → okay to resuture
- >24 hours → often left to heal by secondary intention
Ear helix pain one week after surgery may be due to what?
Chondritis (versus infection)
Treatment is NSAIDs